Erasca Inc

Overview

At Erasca, our name is our mission: toeraseca ncer.

We are a clinical-stage precision oncology company singularly focused on discovering, developing, and commercializing therapies for patients with RAS/MAPK pathway-driven cancers. Molecular alterations in RAS, the most frequently mutated oncogene, and the MAPK pathway, one of the most frequently altered signaling pathways in cancer, account for approximately 5.4 million new patients diagnosed with cancer globally each year. Our company was co-founded by leading pioneers in precision oncology and RAS targeting to create novel therapies and combination regimens designed to comprehensively shut down the RAS/MAPK pathway for the treatment of cancer. We have assembled one of the deepest, wholly-owned or controlled RAS/MAPK pathway-focused pipelines in the industry, which is focused on modality-agnostic programs aligned with our three therapeutic strategies of: (1) targeting key upstream and downstream signaling nodes in the RAS/MAPK pathway; (2) targeting RAS directly; and (3) targeting escape routes that emerge in response to treatment. The target breadth and molecular diversity represented in our pipeline enable us to pursue a systematic, data-driven, portfolio-wide clinical development effort to identify single agent and combination approaches with the goal of prolonging survival in numerous patient populations with high unmet medical needs.

Our modality-agnostic approach aims to allow us to selectively and potently target critical signaling nodes with the most appropriate modality, including small molecule therapeutics and large molecule therapeutics. Our purpose-built pipeline includes three clinical-stage programs (a pan-RAF inhibitor, an ERK inhibitor, and a central nervous system (CNS)-penetrant EGFR inhibitor), and additional discovery-stage programs targeting other key oncogenic drivers. We believe our world-class team’s capabilities and experience, further guided by our scientific advisory board (SAB), which includes the world’s leading experts in the RAS/MAPK pathway, uniquely position us to achieve our bold mission of erasing cancer.

Of the approximately 5.4 million new patients diagnosed globally per year with cancers driven by RAS/MAPK pathway molecular alterations, over 70% have limited or no targeted therapy treatment options. While the RAS/MAPK pathway has been well characterized and validated based on multiple compounds approved or in development targeting discrete signaling nodes in the cascade, most of these compounds face resistance and tolerability challenges, highlighting the need for new approaches to target this pathway. We believe that to effectively shut down a pathway that signals as promiscuously as RAS/MAPK, a holistic approach must be taken to target not just individual nodes, but multiple nodes and cooperative mechanisms in parallel. As depicted in the following figure and described below, we are pursuing three therapeutic strategies that may be used in combination with the goal of comprehensively, and perhaps synergistically, shutting down the RAS/MAPK pathway.

Target upstream and downstream MAPK pathway nodes with single agents and combinations intended to clamp these oncogenic drivers. For example, our lead product candidate, naporafenib, targets RAF, a key node of the RAS/MAPK pathway. We are developing naporafenib in combination with trametinib (MEKINIST) (MEK inhibitor) and other targeted therapies to delay emergence of resistance in response to RAS/MAPK pathway inhibition. We are also evaluating drug combinations targeting upstream and downstream nodes to shut down, or “clamp,” the signaling of various oncogenic drivers, such as receptor tyrosine kinases (RTKs), NF1, RAS, RAF, and MEK alterations, trapped between the inhibited nodes. We refer to this approach as a "MAPKlamp." With this MAPKlamp approach, we hope to induce tumor regression in RAS/MAPK pathway-driven cancers, while also blocking the in-pathway escape routes that lead to tumor resistance.

Target RAS, the midstream MAPK pathway node, directly with single agents and combinations. We are discovering and developing molecules that have the potential to inhibit RAS in its inactive GDP state (RAS-GDP) as well as its more prevalent active GTP state (RAS-GTP). Utilizing our in-house discovery efforts employing structure-based drug design (SBDD), we are developing proprietary compounds against KRAS mutations beyond G12C, such as pan-KRAS (ERAS-4).

Target escape routes enabled by other proteins or pathways to further disrupt RAS/MAPK pathway signaling. RAS-driven cancers utilize escape routes, namely cooperative mechanisms, to develop resistance to targeted therapies. By shutting down these potential escape routes, we aim to provide more robust inhibition of oncogenic signaling.

To pursue these therapeutic strategies, we have assembled and are developing one of the deepest pipelines targeting multiple signaling nodes to shut down the RAS/MAPK pathway. We intend to study these agents either alone or in rational combinations across multiple relevant tumor types. The following table summarizes our current, wholly-owned or controlled, modality-agnostic pipeline to eradicate RAS/MAPK pathway-driven cancers, and programs that arise from an investment made by Erasca Ventures, LLC (Erasca Ventures) in a third party.

Our lead product candidate is naporafenib, for which we plan to initiate a pivotal Phase 3 trial in the first half of 2024 for patients with NRAS-mutated (NRASm) melanoma. We dosed the first patient in a Phase 1b trial in August 2023 for patients with RAS Q61X solid tumors to inform additional clinical development pathways for naporafenib. Naporafenib is a pan-RAF inhibitor with first-in-class and best-in-class potential for patients with NRASm melanoma, RAS Q61X solid tumors, and other RAS/MAPK pathway-driven tumors. RAF proteins are ubiquitously expressed serine-threonine kinases that constitute a key node of the RAS/MAPK pathway downstream of RAS and upstream of MEK. The RAF protein family consists of ARAF, BRAF, and CRAF (RAF1) that are activated through dimerization. Mutations in RAF proteins have been observed in many cancers, such as melanoma, colorectal cancer (CRC), non-small cell lung cancer (NSCLC), and thyroid cancer. We in-licensed naporafenib from Novartis Pharma AG (Novartis) in December 2022. Naporafenib has been dosed in over 500 patients to date, whereby safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) have been established in both monotherapy and select combinations, with clinical proof-of-concept (PoC) data in combination with trametinib for patients with NRASm melanoma, which includes NRAS Q61X melanoma, and preliminary clinical PoC data in combination with trametinib for patients with RAS Q61X NSCLC. In December 2023, we announced that the US Food and Drug Administration (FDA) granted Fast Track Designation (FTD) to naporafenib in combination with trametinib for the treatment of adult patients with unresectable or metastatic melanoma who have progressed on, or are intolerant to, an anti‑programmed death-1 (ligand 1) (PD‑(L)1)-based regimen, and whose tumors contain an NRAS mutation (NRASm). Programs that receive FTD may benefit from early and frequent interactions with the FDA during the clinical development process and, if relevant criteria are met, the FDA may consider reviewing portions of a marketing application before the sponsor submits the complete application.

We are pursuing a broad development strategy for naporafenib, which includes our SEACRAFT trials designed to evaluate naporafenib’s development opportunities in combination with other targeted therapies. We are prioritizing rapid development for naporafenib plus trametinib in the Phase 1b SEACRAFT-1 trial for patients with RAS Q61X solid tumors, which dosed its first patient in August 2023, and in the planned Phase 3 SEACRAFT-2 trial for patients with NRASm melanoma. SEACRAFT-1 is supported by clinical PoC data in patients with NRAS Q61X melanoma and preliminary clinical PoC data in patients with KRAS Q61X NSCLC. SEACRAFT-2 is supported by clinical PoC data in patients with NRASm melanoma, as presented by Novartis at the European Society for Medical Oncology Congress 2022 (ESMO Congress 2022) medical conference and as published in March 2023 by de Braud et al. in the Journal of Clinical Oncology. In connection with our SEACRAFT-1 and -2 trials, we have announced clinical trial collaboration and supply agreements (CTCSAs) with Novartis for its MEK inhibitor, trametinib (MEKINIST). We are sponsoring and funding the clinical trials and Novartis is providing its drug to us free of charge.

Our next most-advanced product candidate is ERAS-007 (our oral ERK1/2 inhibitor), which targets the most distal node of the RAS/MAPK pathway. The extracellular signal-regulated kinases (ERK), ERK1 and ERK2, belong to a family of serine-threonine kinases that regulate cellular signaling. ERK proteins propagate signaling for multiple cellular functions involved in cell growth and differentiation, which are often overactivated in RAS/MAPK pathway-driven cancers. We in-licensed ERAS-007 from Asana BioSciences (Asana) based in part on preclinical studies that demonstrated the highest potency and longest target residence time of any ERK inhibitors of which we are aware. ERAS-007 was evaluated as a single agent in a Phase 1 clinical trial in patients with advanced solid tumors completed by Asana. Forty-nine patients were enrolled and administered ERAS-007 once a day (QD) or once weekly (QW). Objective responses were observed at doses from 120 mg to 250 mg QW in patients with multiple tumor types (melanoma, salivary gland tumor, NSCLC, and thyroid cancer) that all harbor alterations (BRAF, HRAS, and NRAS) in the RAS/MAPK pathway, supporting the development of ERAS-007 QW as a combination therapy in patients with diverse, biomarker-selected tumor types. In this trial, ERAS-007 demonstrated a reversible and manageable adverse event profile.

We have developed a clinical development plan that has included multiple tumor types for ERAS-007, which we refer to as our HERKULES series of clinical trials. In September 2021, we dosed the first patient in HERKULES-3, a Phase 1b/2 master protocol clinical trial for ERAS-007 in combination with various agents in patients with gastrointestinal (GI) cancers. In connection with our HERKULES-3 trial, we have announced CTCSAs with Pfizer Inc. for its BRAF inhibitor, encorafenib (BRAFTOVI), Eli Lilly and Company (Lilly) for its EGFR antibody, cetuximab (ERBITUX), and Pierre Fabre for its BRAF inhibitor, encorafenib (BRAFTOVI), in key international territories. In all these cases, we are sponsoring and funding the clinical trial and the partner is providing its drug to us free of charge.

The master protocol for the HERKULES-3 Phase 1b/2 clinical trial provides the flexibility to explore additional combinations and expand into other GI cancer indications. In May 2023, we announced encouraging preliminary data for the ERAS-007 combination with encorafenib and cetuximab (EC) in patients with EC-naïve BRAFm CRC in a poster presentation that we presented at the American Society of Clinical Oncology Annual Meeting in June 2023.

In June 2023, we provided updates with respect to our HERKULES-1 trial (for patients with solid tumors caused by RAS/MAPK pathway alterations), HERKULES-2 trial (for patients with EGFR-mutated or KRAS-mutated NSCLC), and one of the sub-studies of our HERKULES-3 trial (for patients with KRAS- or NRAS-mutant CRC and KRAS-mutant PDAC). These updates consisted of the following:

•

HERKULES-1: ERAS-007 plus ERAS-601 in patients with advanced solid tumors: We have deprioritized evaluation of this combination as dose escalation safety data do not support continued evaluation of the regimen tested

•

HERKULES-2: ERAS-007 plus osimertinib in patients with post-osimertinib EGFR-mutant NSCLC: We have deprioritized evaluation of this combination in this indication as clinical efficacy data do not support continued evaluation

•

HERKULES-3 sub-study that consisted of ERAS-007 plus palbociclib in patients with KRAS- or NRAS-mutant CRC and KRAS-mutant PDAC: We have deprioritized evaluation of this combination in this indication as clinical efficacy data do not support continued evaluation

As a result of these deprioritizations, we are no longer enrolling patients in the HERKULES-1 trial, the HERKULES-2 trial, or the HERKULES-3 sub-study that consisted of ERAS-007 plus palbociclib described above.

With respect to the HERKULES-3 Phase 1b trial for ERAS-007 plus EC in EC-naïve BRAFm CRC patients, we anticipate a Phase 1b dose expansion data readout in the first half of 2024.

Our third clinical program is ERAS-801, an investigational CNS-penetrant EGFR inhibitor. In February 2022, we dosed the first patient in our THUNDERBBOLT-1 Phase 1 clinical trial for ERAS-801 in patients with recurrent glioblastoma (GBM). In May 2023, we announced that the FDA granted FTD to ERAS-801 for the treatment of adult patients with GBM with EGFR gene alterations. In June 2023, we announced that the FDA granted Orphan Drug Designation (ODD) to ERAS-801 for the treatment of patients with malignant glioma, which includes GBM. Provided that the product candidate is approved by the FDA for the orphan-designated disease or condition, ODD entitles a party to the potential for seven years of post-approval marketing exclusivity, subject to certain exemptions, and financial incentives such as tax advantages and user fee waivers. In November 2023, we announced that a maximum tolerated dose (MTD) was identified for ERAS-801. We anticipate presenting Phase 1 monotherapy data from THUNDERBBOLT-1 in 2024.

In June 2023, we announced that we deprioritized ERAS-3490, our CNS-penetrant KRAS G12C inhibitor, due to the increasingly competitive landscape for small- and mid-cap biopharma companies in the KRAS G12C inhibitor market, despite the program's potential for differentiation in this market.

In November 2023, we announced that we deprioritized the FLAGSHP-1 Phase 1b combination trial of ERAS-601 SHP2 inhibitor with cetuximab (ERBITUX). Though ERAS-601 achieved confirmed responses as a monotherapy and in combination with cetuximab, preliminary data did not justify further development of this combination in the FLAGSHP-1 indications.

We are also advancing additional programs targeting key oncogenic drivers in the RAS/MAPK pathway, which we will need to successfully progress through discovery and IND-enabling activities prior to advancing these programs into clinical development, if at all.

Our core values, team, and social mission

We are a team of experienced drug discoverers, developers, and company builders who are united by our mission to erase cancer and passionate about creating potentially life-saving precision oncology medicines singularly focused on targeting the RAS/MAPK pathway. Our leadership team has broad and deep experience in oncology, including advancing therapeutic candidates from discovery research to clinical development, regulatory approval, and commercialization. Our core values are embodied by our quest for the CURE:

Dr. Jonathan Lim, our Chairman, CEO, and Co-Founder, has helped pioneer transformative advancements in precision oncology and drug delivery, including leading Ignyta’s trailblazing pursuit of a global tissue agnostic label for ROZLYTREK, which became the first drug in biopharmaceutical history to achieve the unprecedented triple crown of breakthrough designations with BTD (FDA), PRIME (EMA) and Sakigake (PMDA). He has served as Chairman and/or CEO and founding investor of six biotechnology companies that have collectively achieved global regulatory approval and launch of seven therapeutic products in oncology, immunology, and drug delivery, benefitting thousands of patients worldwide.

Dr. Michael Varney, our Chair of R&D, SAB member, and a member of our board of directors, is a pioneer drug discoverer and biotech leader. His leadership at Agouron resulted in the discovery of multiple currently marketed anti-cancer agents, including XALKORI and INLYTA. As Executive Vice President and Head of Genentech’s Research and Early Development (gRED) and a member of the Roche Corporate Executive Committee, he was responsible for all aspects of gRED innovation, drug discovery and development, and built a team-based organization that today contributes to more than 40% of Genentech’s development portfolio, including the marketed anti-cancer agents ERIVEDGE and COTELLIC. Under his leadership, gRED teams discovered and developed successful medicines that include VENCLEXTA with AbbVie, the first BCL-2 inhibitor, and POLIVY, an antibody drug conjugate for the treatment of diffuse large B-cell lymphoma.

Dr. Shannon Morris, our Chief Medical Officer, initially joined us as Senior Vice President of Clinical Development and was promoted to Chief Medical Officer in April 2023. She has more than 20 years of experience in the life sciences industry with a focus in oncology drug development, including contributions in both early and late phase development, as well as in both targeted and immune-based therapies. Prior to joining Erasca, she was responsible for the clinical development of lerapolturev, a novel poliovirus-based therapeutic targeting GBM, at Istari Oncology. Prior to Istari, she was the clinical lead for the approval of COSELA. During her time at GSK and MedImmune, she held positions of increasing responsibility and was involved in the development of a number of molecules, including the early development of MEKINIST, and supported the successful biologics license application for IMFINZI in bladder cancer.

Dr. David Chacko, our Chief Financial Officer and Chief Business Officer, joined us from Versant Ventures, where he was a Principal with both investing and operating responsibilities. He helped lead investment opportunities across multiple therapeutic areas and advanced several Versant portfolio companies operationally through company formation, fundraising, corporate and business development, and clinical and regulatory activities. His prior roles at Alcon/Novartis, McKinsey, SR One, and Morgan Stanley bring to Erasca deep experience in strategy, finance, fundraising, business development, and operations.

Many members of our leadership team have worked together previously at Ignyta or Roche/Genentech, or have joined us from other leading companies in the biopharmaceutical and life science tools sectors such as Illumina, Lilly, Medivation, Merck, Myovant, Neurocrine, Pfizer, and Turning Point, and have worked on numerous oncology drugs that have been approved and launched for the benefit of patients.

Dr. Lim founded Erasca with Dr. Kevan Shokat (Professor and Chair of the Department of Cellular and Molecular Pharmacology at UCSF; Professor of Chemistry at the University of California, Berkeley; and an investigator at the Howard Hughes Medical Institute). In addition to Dr. Shokat, our SAB includes the following RAS/MAPK pathway experts:

•

Dr. Stephen Blacklow is a world expert in SHP2 who helped pioneer development of the first SHP2 inhibitor with Novartis, and is the Gustavus Adolphus Pfeiffer Professor of Biological Chemistry and Molecular Pharmacology, Biological Chemistry and Molecular Pharmacology at Harvard Medical School; a Professor of Pathology at the Brigham And Women’s Hospital; a Professor of Cancer Biology at the Dana-Farber Cancer Institute; and the Chair of the Department of Biological Chemistry and Molecular Pharmacology at Harvard Medical School.

•

Dr. Karen Cichowski is a world expert in RAS/MAPK pathway signaling, including elucidating how deregulated cell signaling drives tumorigenesis in nervous system, lung, prostate, and breast cancers, combining translational mouse modeling techniques with basic biochemical and cell biological studies, and in identifying novel combination therapies to shut down aberrant RAS/MAPK pathway signaling. She is Professor of Medicine at Harvard Medical School and Professor of Medicine/Genetics at Brigham and Women’s Hospital.

•

Dr. Ryan Corcoran is a gastrointestinal oncologist with a primary interest in translational oncology research who focuses on targeted therapies directed against mutations commonly found in human cancers, such as BRAF and KRAS mutations. He also is a world expert in ERK, having studied nearly every ERK inhibitor that has been or is being developed in the field. He is also the Director of the Gastrointestinal Cancer Center Program; the Scientific Director of the Termeer Center for Targeted Therapy at Massachusetts General Hospital Cancer Center; and an Associate Professor of Medicine at Harvard Medical School.

•

Dr. George Demetri is a world expert in targeted oncology therapies who pioneered the development of GLEEVEC that helped launch the revolution in precision oncology. He is the Director of the Center for Sarcoma and Bone Oncology at the Dana-Farber Cancer Institute; the Director of the Ludwig Center at the Dana-Farber/Harvard Cancer Center; and Executive Director for Clinical and Translational Research at the Ludwig Institute for Cancer Research.

•

Dr. Pablo Rodriguez-Viciana is a world expert in the RAS/MAPK pathway whose major focus is the function of the SHOC2 phosphatase complex as a unique regulatory node required for efficient RAS/MAPK pathway activation in the context of diseases such as cancer and RASopathies. He has served as the group leader at the UCL Cancer Institute since 2008 and is a former postdoctoral researcher in Dr. Frank McCormick’s lab at the University of California, San Francisco.

•

Dr. Michael Varney is a pioneer drug discoverer and biotech leader and the former Executive Vice President and Head of Genentech’s gRED and a former member of the Roche Corporate Executive Committee.

At Erasca, while our mission to erase cancer inspires us, we know we can do more to make an even broader contribution to society. To that end, we are pursuing environmental, social, and governance (ESG) initiatives that are aligned with our core mission.

•

Erasca Foundation: In May 2021, we established the Erasca Foundation, a nonprofit California public benefit corporation, which was funded by the donation of 1,093,557 shares of our common stock (which at the time represented 1% of our capital stock), in conjunction with our initial public offering (IPO). In 2023, the Erasca Foundation provided funding for initiatives to positively impact society, including providing funding to Life Science Cares, Curebound Cancer Research, and Lazarex Cancer Foundation.

•

Environmental initiatives: Both of our physical buildings limit their carbon footprint. Our San Diego office is Gold Level Leadership in Energy and Environmental Design (LEED) certified, and our San Francisco office is Platinum Level LEED certified. Each building is easily accessible by public transportation and has electric vehicle charging stations and indoor bike racks. We also encourage our employees to recycle, including recycling programs for a subset of our lab supplies. While we rely on third-party vendors to conduct our drug manufacturing, our chemists that are engaged in the manufacturing process are committed to increasing efficiencies, reducing materials, and minimizing waste.

•

Code of Conduct and Ethics: Our Code of Business Conduct and Ethics applies to all of our employees, officers and directors, and requires the highest standards of business ethics. The Code of Business Conduct and Ethics and other corporate governance documents are located in the “Corporate Governance” section of the “Investors” page of our website located at www.erasca.com.

•

Inclusive clinical trial participation: We intend to make clinical trials of our product candidates more accessible to diverse patient populations and plan to partner with others who are like-minded in this regard.

•

Drug access program: If our products become commercially available, we intend to pursue initiatives to provide patients with access to such drugs, including through patient assistance programs and compassionate use programs.

Our corporate strategies to erase cancer

Our mission is to erase cancer by eradicating RAS/MAPK pathway-driven cancers. Our corporate strategies to achieve our mission include:

•

Relentlessly focus on patients and society in our mission to erase cancer. There are approximately 5.4 million new patients diagnosed globally per year with cancers driven by RAS/MAPK pathway alterations, over 70% of whom have limited or no targeted therapy treatment options. We are a team of experienced drug discoverers, developers, and company builders who are united by our mission to erase cancer and passionate about creating potentially life-saving precision oncology medicines.

•

Develop novel single agent and combination regimens to comprehensively shut down the RAS/MAPK pathway for the treatment of cancer. We are pursuing three therapeutic strategies that may be used in combination to comprehensively, and perhaps synergistically, shut down the RAS/MAPK pathway: (1) target upstream and downstream MAPK pathway nodes with single agents and combinations intended to clamp these oncogenic drivers; (2) target RAS directly with single agents and combinations; and (3) target escape routes enabled by other proteins or pathways to further disrupt RAS/MAPK pathway signaling. Our strategic focus on the RAS/MAPK pathway allows us to comprehensively target critical nodes in the pathway that could drive cancer signaling.

•

Advance our deep, modality-agnostic RAS/MAPK pathway-focused pipeline. Our internally and externally sourced RAS/MAPK pathway-focused pipeline, comprising several targeted therapy programs, is one of the deepest in the industry. Our modality-agnostic approach aims to selectively and potently target critical

RAS/MAPK signaling nodes with the appropriate modality, including small molecule therapeutics and large molecule therapeutics. Naporafenib (our pan-RAF inhibitor), ERAS-007 (our ERK inhibitor), and ERAS-801 (our CNS-penetrant EGFR inhibitor) are currently being studied in clinical trials. Given the high unmet medical need of the patients we seek to treat, we will continually evaluate the potential for expedited development and review pathways.

•

Internally and externally source, on a global basis, potentially disruptive programs targeting RAS/MAPK pathway alterations. We have built a productive and efficient internal discovery engine. Our world-class structural biology team generates on average more than 100 protein structures annually and we use computational biology and computational chemistry to accelerate our discovery activities. While we have strong internal capabilities, we also believe that innovation is a collective, global endeavor and a single platform is unlikely to discover all the best ideas and approaches. We therefore plan to continue to opportunistically evaluate synergistic, in-pathway opportunities, regardless of origin, that meet our high scientific bar. Our extensive network and relationships provide us preferential—and at times exclusive—access to certain assets of interest.

•

Lead the next revolution in precision oncology. The first wave of precision oncology included tyrosine kinase inhibitors such as ROZLYTREK, approved for select tumors that harbor ROS1 or NTRK fusions. While these initial development efforts focused on specific disease-causing alterations in areas of high unmet medical need, these patient populations were modest in size. We believe that to effectively shut down a pathway that signals as promiscuously as RAS/MAPK and encompasses a range of alterations, a holistic approach must be taken to target not just specific individual mutations, but multiple alterations and cooperative mechanisms in parallel. We are pursuing tissue agnostic and tissue specific indications using flexible trial designs intended to efficiently transition molecules through each phase of development with the goal of identifying early efficacy signals warranting additional resource allocation for both monotherapy and combination approaches.

•

Evaluate opportunities to accelerate development timelines and enhance the commercial potential of our programs in collaboration with third parties. We own or control worldwide development and commercialization rights to our entire pipeline of targeted therapy programs. This provides us with the flexibility to explore combinations of our agents with each other, other investigational agents, and/or standard of care therapies. We intend to continue evaluating opportunities to work with partners that meaningfully enhance our capabilities with respect to the development and commercialization of our product candidates. In addition, we intend to commercialize our product candidates in the United States. We intend to explore partnerships in selected geographies to maximize the worldwide commercial potential of our programs.

Our singular focus on the RAS/MAPK pathway

Background

The RAS/MAPK pathway is one of the most frequently altered signaling pathways in cancer. Molecular alterations in key signaling nodes within the RAS/MAPK pathway have been shown to drive cell proliferation across a wide range of tumor types. As described further below, our wholly-owned or controlled pipeline targets all of the key signaling nodes colored in purple, either directly or indirectly as single agents and in combination in order to prolong survival in a wide range of patient populations.

EGFR

RTKs like EGFR are proteins that are embedded in the cell membrane and relay growth signals from the outside environment to the cell’s internal machinery. At rest, these proteins reside on the cell membrane as inactive monomers. Growth factors secreted by nearby cells bind to specific RTKs, such as epidermal growth factor (EGF) binding to EGFR, and cause these RTKs to dimerize. Dimerized RTKs activate one another through transphosphorylation of their intracellular regions. Intracellular proteins, such as adapter proteins, bind to these phosphorylated regions and propagate the pro-growth signals within the cell via one or more signaling pathways. Cells express a variety of RTKs so that environmental cues can be relayed to specific cell populations in specific contexts. EGFR mediates pro-growth signaling in skin and in the ducts and outer surfaces of many organs.

Overactive RTK signaling can result in uncontrolled cell growth and survival that transforms normal cells into cancer cells.

SHP2

SHP2 is a protein tyrosine phosphatase and a key positive regulator of the growth signals from the RTK growth factor receptors to the intracellular signaling pathways (including RAS/MAPK and PI3K) that promote growth and survival of normal cells and cancer cells. As such, SHP2 is a convergent node for upstream RTK signaling, such that activated SHP2 upregulates (“turns up”) the positive signals and downregulates (“turns down”) the negative signals in the signaling cascades. SHP2 also serves as a central node in relaying the growth and survival signals from RTKs such as EGFR to RAS/MAPK and other intracellular pathways. SHP2 is an attractive target because SHP2 inhibition ubiquitously blocks the growth signals from multiple RTKs, thereby preventing cancer cells from bypassing the blockade on a specific RTK (e.g., EGFR inhibitor) through activation of other RTK growth factor receptors (e.g., MET).

NF1

NF1, or neurofibromin, is a protein that accelerates the transition of RAS proteins from the active RAS-GTP state to the inactive RAS-GDP state. NF1 is classified as a GTPase activating protein (GAP) because it boosts the ability of RAS to hydrolyze bound GTP to GDP. Although RAS can autonomously hydrolyze GTP, it is dependent on GAPs such as NF1 to rapidly cycle it from the active state to the inactive state and thereby prevent overactive signaling. If NF1 is inactivated due to a mutation (NF1 loss-of-function mutation), RAS proteins may spend more time in the active RAS-GTP state. This can result in hyperactive RAS/MAPK pathway activation that drives aberrant cell growth and ultimately tumorigenesis. This is observed in patients affected by a genetic disorder caused by somatic mutations in the NF1 gene called neurofibromatosis type 1. NF1 loss-of-function mutations are observed in a variety of cancers, including melanoma and CRC, where they activate RAS/MAPK signaling alone or in conjunction with other RAS/MAPK pathway activating mutations.

RAS

RAS proteins are ubiquitously expressed GTPase proteins. The RAS protein family consists of KRAS, NRAS, and HRAS proteins and acts as the entry node in the RAS/MAPK signaling pathway. KRAS is the most abundantly expressed RAS protein followed by NRAS and then HRAS. RAS proteins act as signaling transducers since they are recruited to activated RTK complexes where they are converted into an active conformation (RAS-GTP) that enables them to activate downstream effector proteins, such as RAF proteins. The activation state of a RAS protein is dictated by the phosphorylation state of the bound guanosine; RAS adopts an inactive RAS-GDP conformation when bound to GDP and an active RAS-GTP conformation when bound to GTP. Conversion of RAS into an active conformation is mediated by binding to co-factor proteins, e.g., SOS1, and these co-factor proteins enable the exchange of the RAS-bound nucleotide from GDP to GTP. In the active state, RAS-GTP proteins interact with multiple effector proteins to propagate cell signaling through multiple pathways. For example, activated RAS-GTP proteins interact with RAF proteins to activate MAPK signaling, and PI3K proteins to activate PI3K pathway signaling. RAS can transition from the active state into the inactive state by hydrolyzing its bound nucleotide from GTP to GDP either intrinsically or catalyzed through interactions with co-factor proteins, such as NF1. RAS proteins are the most frequently mutated oncoproteins in cancer. These mutations occur at hotspots, such as amino acid residues 12, 13, and 61, and these hotspot mutations impair RAS’s ability to hydrolyze GTP to GDP. As a result, mutant RAS-GTP remains in the active state for prolonged periods of time resulting in hyperactive stimulation of the RAS/MAPK and other pathways.

RAF

RAF proteins are ubiquitously expressed serine-threonine kinases that are a part of the RAS/MAPK pathway and whose activity is regulated by RAS proteins. The RAF protein family consists of ARAF, BRAF, and CRAF (RAF1). In the absence of activated RAS-GTP, RAF proteins assume an autoinhibited conformation in complex with downstream effector proteins, MEK1 and MEK2. RAF proteins can homodimerize (e.g., BRAF-BRAF dimers) or heterodimerize (e.g., CRAF-BRAF dimers). When RAF proteins bind to activated RAS-GTP, they adopt an active conformation that results in activation of their kinase domains. The activated kinase domains then phosphorylate complexed MEK proteins, activating those proteins and releasing them from the RAF-MEK complex. Activated MEK then signals further down the RAS/MAPK pathway. Mutations in RAF proteins, especially in BRAF, have been observed in many cancers, such as melanoma, CRC, NSCLC, and thyroid cancer. For example, the BRAF V600E mutation (a class I BRAF mutation) is frequently observed in melanoma and this mutation enables BRAF to constitutively activate MEK as a monomer. Approved BRAF inhibitors for class I mutations include vemurafenib, dabrafenib, and encorafenib. Class II BRAF mutations enable BRAF to constitutively dimerize and activate MEK. Class III BRAF mutations impair the ability of the mutant BRAF protein to phosphorylate MEK, but class III mutant BRAF proteins can aberrantly dimerize with wildtype RAF proteins and enable their dimerized wildtype RAF partners to activate MEK. To our knowledge, there are no approved inhibitors of BRAF Class II or Class III mutations. A number of inhibitors targeting BRAF Class II and Class III mutations, as well as pan-RAF inhibitors designed to disrupt wildtype RAF signaling, are in development; however, to our knowledge, none have received regulatory approval.

MEK

MEK1 and MEK2 proteins are ubiquitously expressed serine-threonine kinases that are activated by RAF-mediated phosphorylation and signal downstream by activating ERK proteins. MEK1 and MEK2 proteins form complexes with RAF proteins in the inactive state and are recruited as a unit to activated RAS-GTP. RAS-GTP then activates the RAF-MEK complex by binding to RAF, which then activates MEK via phosphorylation and releases from the RAF-MEK complex.

Activated MEK then selectively phosphorylates ERK1 and ERK2 proteins, which are the terminal nodes of the RAS/MAPK pathway. Currently approved MEK inhibitors, such as trametinib, binimetinib, cobimetinib, and selumetinib, allosterically bind MEK proteins and inhibit MEK activation, either as free proteins alone or in complex with RAF. The inhibition of RAS/MAPK signaling by MEK inhibitors can result in an upregulation of signaling upstream of MEK due to negative feedback loops within the RAS/MAPK pathway. This increased signaling pressure can overwhelm MEK inhibitors and result in reactivation of MAPK signaling. Most MEK inhibitors are approved in combination with a BRAF inhibitor partially due to their vulnerability of being overwhelmed by the reactivation of MAPK signaling. In this combination, BRAF inhibitors attenuate upstream signaling pressure on MEK inhibitors, and MEK inhibitors further limit downstream MAPK signaling not inhibited by the BRAF inhibitor.

ERK

The extracellular signal-regulated kinases (ERK), ERK1 and ERK2, are ubiquitous serine-threonine kinases that regulate cellular signaling in both physiological and pathological states and comprise the terminal node of the RAS/MAPK pathway. Once activated by MEK, ERK proteins phosphorylate thousands of downstream proteins, propagating RAS/MAPK signaling across multiple cellular functions. In contrast to currently approved allosteric MEK inhibitors, ERK inhibitors in development are ATP-competitive and as a result, their potency is robust against the activated state of ERK. Based on this property, ERK inhibitors potentially can overcome drug resistance mechanisms that involve reactivation of RAS/MAPK pathway signaling, such as a rebound of RAS/MAPK signaling resulting from the alleviation of negative feedback or an upstream RAS/MAPK pathway protein adopting an acquired resistance mutation.

Patient lives at stake annually with RAS/MAPK pathway alterations

At Erasca, we are on a bold mission to erase cancer. The journey will be long, and it won’t be easy. But patients with cancer are waiting, and we are eager to make new therapies available as soon as possible. Our mission will involve delivering new therapies to patients in markets where there are limited or no approved targeted therapies, which are referred to as “blue oceans” (adapted from Blue Ocean Strategy by Chan Kim & Renée Mauborgne), as well as markets where there are already approved or soon to be approved product offerings, or “red oceans.” Of the approximately 5.4 million new patients diagnosed globally per year with cancers driven by RAS/MAPK pathway alterations, over 70% (approximately 4 million patients) are in blue oceans with limited or no targeted therapy treatment options. We intend to commercialize our product candidates in the United States. In other parts of the world, we intend to explore partnerships in selected geographies to maximize the worldwide commercial potential of our programs.

Our therapeutic strategies for shutting down the RAS/MAPK pathway

We believe that to effectively shut down a pathway that signals as promiscuously as RAS/MAPK, a holistic approach must be taken to target not just single nodes, but multiple nodes and cooperative mechanisms in parallel. Our internally and externally sourced RAS/MAPK pathway-focused pipeline, comprising several targeted therapy programs, is one of the deepest in the industry. The target breadth and molecular diversity represented in our pipeline enable us to pursue a systematic, data-driven, portfolio-wide clinical development effort to identify single agent and combination approaches that aim to prolong survival in numerous patient populations with high unmet medical needs. We are pursuing three therapeutic strategies that may be used in combination with the goal of comprehensively, and perhaps synergistically, shutting down the RAS/MAPK pathway:

Target upstream and downstream MAPK pathway nodes with single agents and combinations intended to clamp these oncogenic drivers. For example, our lead product candidate, naporafenib, targets RAF, a key node of the RAS/MAPK pathway. We are developing naporafenib in combination with the MEK inhibitor trametinib and other targeted therapies to delay emergence of resistance in response to RAS/MAPK pathway inhibition. We are also evaluating drug combinations targeting upstream and downstream nodes to shut down, or "clamp," the signaling of various oncogenic drivers such as RTKs, NF1, RAS, RAF, and MEK alterations, trapped between the inhibited nodes. With our MAPKlamp approach, we hope to induce tumor regression in RAS/MAPK pathway-driven cancers, while also blocking the in-pathway escape routes that lead to tumor resistance.

Target RAS, the midstream MAPK pathway node, directly with single agents and combinations. We are discovering and developing molecules that have the potential to inhibit RAS in its inactive GDP state (RAS-GDP) as well as its more prevalent active GTP state (RAS-GTP). Utilizing our in-house discovery efforts employing SBDD, we are developing proprietary compounds against KRAS mutations beyond G12C, such as pan-KRAS (ERAS-4).

Target escape routes enabled by other proteins or pathways to further disrupt RAS/MAPK pathway signaling. RAS-driven cancers utilize escape routes, namely cooperative mechanisms, to develop resistance to targeted therapies. By shutting down these potential escape routes, we aim to provide more robust inhibition of oncogenic signaling.

Our strategic focus on the RAS/MAPK pathway allows us to comprehensively target critical nodes in the pathway that could drive signaling. As shown in the figure below, our wholly-owned or controlled pipeline targets, either directly or indirectly, each of the signaling nodes colored in purple.

Our innovation model

Due to the magnitude of the challenge of erasing cancer, we are combining our robust internal discovery and development capabilities with a global in-licensing and acquisition strategy to assemble one of the industry’s deepest, modality-agnostic RAS/MAPK pathway-focused pipeline. We believe these complementary approaches to innovation provide us with important optionality, both therapeutically and strategically, as we endeavor to bring forth the next generation of potentially differentiated targeted therapies for RAS/MAPK pathway-driven cancers.

Internal discovery and development

We have built a productive and efficient internal discovery engine at the heart of which lies SBDD, a key tool for the discovery of novel small molecule therapeutics and protein degraders. By elucidating the three-dimensional structure of the potential drug molecule or degrader bound to the target protein of interest, scientists can better understand and iterate on the structure-activity relationship of their hit and lead compounds or degraders.

We also use computational biology and computational chemistry to accelerate our discovery activities. We have standardized how we characterize our compounds across in vitro/vivo activity, drug distribution, metabolism, and PK, structural, and secondary pharmacology assays, and centralized the storage of these data for automated analyses. These data are continuously reviewed by our scientific teams, and promising trends, including unpredicted ones that arise serendipitously, are prioritized for future exploration.

We supplement our medicinal chemistry efforts with fragment screens and machine learning approaches. We are using DNA encoded library (DEL) screens to identify novel chemical matter with promising activity against targets of interest. These “hits” give us starting points for our early-stage drug discovery programs, and also provide opportunities to diversify molecular designs for later-stage discovery programs. DEL screens interrogate the binding of billions of compounds against our targets and increase the likelihood that we will discover a fragment that we can eventually transform into a potent therapy. We also sift through our integrated drug discovery data sets using machine learning algorithms to identify meaningful patterns that help inform next steps for our discovery projects. These analyses are conducted internally and through external collaborations, including ones that specialize in artificial intelligence.

Based on our previous collective experiences at Ignyta, Roche/Genentech, Pfizer, and elsewhere, our team has extensive precision oncology expertise with dynamic clinical trial designs such as adaptive trials, biomarker-based basket and umbrella studies, and master protocols. We will continue to leverage this experience, in collaboration with industry and academic partners, in order to quickly demonstrate clinical proof-of-concept in a variety of tumor types for both single agent and combination approaches.

External sources of innovation

We believe innovation in cancer therapy is a collective, global endeavor unlikely to emerge from a single company or a single platform. There are exciting product candidates, technologies, and approaches in development worldwide, and our innovation model gives us the flexibility to supplement our internal efforts with externally sourced assets through collaboration, in-license, or acquisition. We also established Erasca Ventures, our wholly-owned subsidiary, in March 2021 to make equity investments in early-stage biotechnology companies that are aligned with our mission and strategy. In March 2022, Erasca Ventures made an equity investment in Affini-T Therapeutics, Inc. (Affini-T), which is developing potential best-in-class T-cell receptor (TCR) cell therapies targeting multiple oncogenic driver mutations, including KRAS G12V and KRAS G12D. To date, we have in-licensed or acquired novel therapies from multiple geographic regions, including our lead program, naporafenib, which we in-licensed from Novartis, and our oral ERK1/2 inhibitor, ERAS-007, which we in-licensed from Asana.

We leverage our extensive network of preferred relationships with our Scientific Advisory Board and our Research, Development, and Commercial Advisory Board, as well as leading institutional investors, investment banks, academic institutions, and biopharmaceutical companies that keep us apprised of assets of strategic interest. We pursue the best science in the world, regardless of its origin, and will continue to opportunistically evaluate additional opportunities to strengthen and diversify our pipeline through academic and biopharmaceutical collaborations, in-licenses, acquisitions, and strategic investments that meet our high scientific bar and can help us advance our mission to erase cancer.

Modality-agnostic pipeline

Cancer is a complex, heterogeneous disease that is unlikely to succumb to a one-size-fits-all approach. We believe shutting down the RAS/MAPK pathway in cancer requires a systematic, data-driven approach to development, part of which involves choosing the most appropriate technology for the target of interest, or what we call a modality-agnostic approach. We therefore seek to understand the biology of the target of interest first, and then choose the therapeutic modality best suited to optimally inhibit that target. We are currently utilizing several modalities to target the RAS/MAPK pathway, including small molecule therapeutics and large molecule therapeutics.

For example, we are developing proprietary bispecific antibodies that are designed to bind EGFR in both the active and inactive conformations, potentially leading to deeper inhibition of EGFR-mediated RAS/MAPK pathway signaling. In addition to inhibiting EGFR signaling, our bispecific antibodies are designed to induce higher orders of EGFR receptor clustering on the cell surface, which may induce anti-tumor activity mediated by the immune system, such as antibody-dependent cellular cytotoxicity, antibody-dependent cellular phagocytosis, and/or complement-dependent cytotoxicity. We believe these design attributes can potentially enable our proprietary bispecific anti-EGFR antibodies to achieve meaningfully improved activity relative to currently approved anti-EGFR antibodies, such as cetuximab, panitumumab, and amivantamab, since those antibodies preferentially bind EGFR only in the inactive state and may not as strongly elicit anti-tumor immunological responses.

Our pipeline

We have assembled one of the deepest, wholly-owned or controlled RAS/MAPK pathway-focused pipelines in the industry, consisting of modality-agnostic programs aligned with our three therapeutic strategies of: (1) targeting key upstream and downstream signaling nodes in the RAS/MAPK pathway; (2) targeting RAS directly; and (3) targeting escape routes that emerge in response to treatment. The table below summarizes our current pipeline. We have exclusive worldwide development and commercial rights for all of our programs (excluding programs in our pipeline that arise from an investment made by Erasca Ventures in a third party).

Naporafenib: our pan-RAF inhibitor

Our lead product candidate is naporafenib, for which we plan to initiate a pivotal Phase 3 trial in the first half of 2024 for patients with NRASm melanoma. We dosed the first patient in a Phase 1b trial in August 2023 for patients with RAS Q16X solid tumors to inform additional clinical development pathways for naporafenib. Naporafenib is a pan-RAF inhibitor with first-in-class and best-in-class potential for patients with NRASm melanoma, RAS Q61X solid tumors, and other RAS/MAPK pathway-driven tumors. In-licensed from Novartis, naporafenib has been dosed in over 500 patients to date, whereby safety, tolerability, PK, and PD have been established in both monotherapy and select combinations, with clinical PoC data in combination with trametinib for patients with NRASm melanoma, which includes NRAS Q61X melanoma, and preliminary clinical PoC data in combination with trametinib for patients with RAS Q61X NSCLC.

We are pursuing a broad development strategy for naporafenib, which includes our SEACRAFT trials designed to evaluate naporafenib’s development opportunities in combination with other targeted therapies. We are prioritizing rapid development for naporafenib plus trametinib in the Phase 1b SEACRAFT-1 trial for patients with RAS Q61X solid tumors, which dosed its first patient in August 2023, and in the planned Phase 3 SEACRAFT-2 trial for patients with NRASm melanoma. SEACRAFT-1 is supported by clinical PoC data in patients with NRAS Q61X melanoma and preliminary clinical PoC data in patients with KRAS Q61X NSCLC. SEACRAFT-2 is supported by clinical PoC data in patients with NRASm melanoma, as presented by Novartis at the ESMO Congress 2022 medical conference and as published in March 2023 by de Braud et al. in the Journal of Clinical Oncology.

Preclinical profile of naporafenib

Naporafenib is designed to be a reversible, potent and selective ATP-competitive type 2 pan-RAF kinase inhibitor. It has been shown to be most potent against BRAF and CRAF with biochemical IC50 values of 0.1 and 0.2 nM, respectively, but also showed biochemical activity against ARAF with an IC50 of 6.4 nM. Naporafenib is designed to be selective for RAF family kinases, biochemically inhibiting only three non-RAF kinases at >80% at 1 µM (i.e., PDGFRB, DDR1, and DDR2).

As a pan-RAF inhibitor, naporafenib is differentiated from BRAF V600E inhibitors since naporafenib inhibits both RAF monomers and dimers. BRAF V600E inhibitors inhibit monomeric BRAF V600E proteins while simultaneously enabling dimerization of these inhibited monomers with uninhibited RAF proteins, thereby resulting in paradoxical activation of downstream RAS/MAPK pathway signaling. Naporafenib’s ability to inhibit both RAF monomers and dimers enables it to effectively inhibit RAS mutants from signaling downstream without the paradoxical activation observed with BRAF V600E inhibitors.

In the KRAS Q61K-mutated NSCLC cell line Calu-6, naporafenib inhibited downstream MEK phosphorylation with an IC50 value of 14 nM after a two-hour treatment. In a 265-cell line panel, naporafenib tended to show the strongest activity against RAS Q61X-mutated cell lines relative to RAS G12X/G13X mutant and RAS WT cell lines. Naporafenib showed monotherapy activity in vivo in the KRAS Q61K-mutated NSCLC cell line-derived xenograft (CDX) model, Calu-6, achieving tumor regressions at orally administered doses of 100 mg/kg QD and 300 mg/kg QD. Naporafenib plus trametinib showed combination benefit in the Calu-6 CDX model, achieving tumor regression as a combination while the respective monotherapy treatments only achieved moderate tumor growth inhibition (i.e., a tumor growth inhibition ratio (T/C) ≥26%). Naporafenib and trametinib are ideal combination partners since they target two vertically adjacent nodes in the RAS/MAPK pathway, RAF and MEK, and both stabilize their targeted proteins in the inactive state; naporafenib in an ATP-competitive manner and trametinib in an allosteric manner.

Naporafenib tended to show strongest in vitro activity against cell lines that harbor RAS Q61X mutations relative to RAS G12X/G13X mutations or are RAS wildtype. Stronger activity denoted by lower IC50 values. IC50 values were measured by CellTiter-Glo Luminescent Cell Viability Assay after 72-120 hour incubation with naporafenib. IC50 values were normalized to DMSO control.

In vivo activity of naporafenib (LXH254) monotherapy (left) and naporafenib plus trametinib (right) in the KRAS Q61K-mutated NSCLC CDX model Calu-6. Naporafenib was orally administered daily in both studies and trametinib was orally administered either daily or every other day. T/C percentages indicate the average size of the treatment group relative to vehicle on last treatment day. Smaller T/C values indicate better activity. Regression is measured by the change in average tumor size in the treatment group relative to the change in average tumor size in the vehicle group.

The naporafenib and trametinib combination achieved tumor regression in 60% of patient-derived NRAS Q61X-mutated melanoma models (n=10 total). Demonstrating in vivo synergy, regressions were only observed in the combination and not in either monotherapy treatment group.

The activity of LXH254 monotherapy, trametinib monotherapy, and the naporafenib and trametinib combination were characterized across 10 NRASm melanoma models. Each bar represents a patient-derived xenograft (PDX) model. The best response change in tumor volume was selected as the minimum observed change in tumor volume observed after treatment day 10. Each treatment group consisted of 3-5 mice. Tumor volume change measured the average tumor size at end of treatment relative to average tumor size at initiation of treatment. Arrowheads indicate models that were treated with a reduced dose of trametinib at 0.0375 mg/kg QD. Tumor regression classification required a best response tumor volume change of ≤ ‑30%.

Novartis' clinical development of naporafenib

Over 500 patients to date have been dosed with naporafenib either as monotherapy or in combination with other anti-cancer agents (investigational or approved). These agents include trametinib (MEK inhibitor), LTT462 (rineterkib; ERK inhibitor), dabrafenib (BRAF V600E inhibitor), ribociclib (CDK4/6 inhibitor), EGF816 (EGFR inhibitor), and spartalizumab (anti-PD-1). The safety, tolerability, PK, and PD have been established in both monotherapy and select combinations. Specifically, the doublet combinations of naporafenib with trametinib, rineterkib (LTT462), and ribociclib have been evaluated in both Phase 1b dose finding and Phase 2 clinical trials, and PoC has been achieved for the combination of naporafenib and trametinib in patients with NRASm melanoma, which includes NRAS Q61X melanoma, and preliminary clinical PoC has been achieved for that same combination in patients with RAS Q61X NSCLC.

Our initial development strategy will focus on the naporafenib combination with trametinib in these patient populations (e.g., NRASm melanoma) as well as expanded versions of these patient populations (e.g., RAS Q61X-mutated solid tumors), which represent high unmet medical needs without approved targeted therapy options. We will also continue to evaluate clinical activity with other combinations in biomarker-defined populations. Our ultimate goal is to maximize the clinical benefit of naporafenib in the greatest number of patients with cancer.

Eight clinical trials conducted by Novartis investigating naporafenib either as monotherapy or combination therapy are completed or ongoing:

•

CLXH254X2101 is a first-in-human trial of naporafenib as single agent and in combination with spartalizumab.

•

CLXH254X2102 is a Phase 1b trial of naporafenib in combination with rineterkib (LTT462), or with trametinib, or with ribociclib.

•

CEGF816X2102 is a Phase 1b trial of EGF816 in combination with selected targeted agents, including naporafenib.

•

CLXH254C12201 is a Phase 2 trial of naporafenib in combination with rineterkib (LTT462), or with trametinib, or with ribociclib.

•

CADPT01C12101 is a Phase 1b trial of select drug combinations, including rineterkib (LTT462) and the selective BRAF kinase inhibitor dabrafenib in combination with naporafenib.

•

CPDR001X2X01B is an open-label, multi-center rollover protocol for continued characterization of safety and tolerability for patients who have participated in a Novartis-sponsored spartalizumab trial as single agent or in combination with other treatments.

•

CLXH254A02101 is a Phase 1, randomized, open-label, three period, crossover trial to evaluate the relative bioavailability of three naporafenib formulations in healthy volunteers.

•

CLXH254C12106 is a Phase 1, randomized, open-label, three period, crossover trial to investigate the effect of food and the effect of the proton-pump inhibitor, rabeprazole on the pharmacokinetics of a single oral dose of naporafenib in healthy volunteers.

Clinical safety and tolerability

Monotherapy. A total of 87 patients were enrolled in the monotherapy dose escalation portion of the first-in-human trial (CLXH244X2101) of naporafenib in patients whose tumors had MAPK pathway alterations and progression following standard-of-care (SOC) treatment. 43 patients in total were enrolled in six QD dosing cohorts (range 100 mg to 1200 mg QD) and 44 patients in total were enrolled in four BID dosing cohorts (200 mg to 800 mg BID). An MTD was not identified for the QD schedule while the MTD/recommended dose for expansion (RDE) for the BID schedule was determined to be 600 mg twice a day (BID). The monotherapy dose expansion portion of the trial was not opened in order to focus on combination development. During naporafenib monotherapy dose escalation, five patients experienced 7 dose-limiting toxicities: decreased platelet count (1200 mg QD); neuralgia, maculopapular rash, pruritus (600 mg BID); increased blood bilirubin, hyponatremia, peripheral sensory neuropathy (800 mg BID). For the single-agent cohort, treatment-related adverse events (TRAEs) of any grade were reported in 79 (90.8%) patients. The most frequent (occurring in ≥20% of patients) were dermatitis acneiform (maculopapular pustular eruptions) (24.1%, no Grade 3/4 events), rash (24.1%, Grade 3/4: 1.1%), and fatigue (20.7%, Grade 3/4: 2.3%).

Naporafenib plus trametinib. Two trials have evaluated the combination of naporafenib plus trametinib: the dose finding Phase 1b trial CLXH254X2102 and the Phase 2 trial CLXH254C12201.

The CLXH254X2102 trial enrolled patients who had advanced or metastatic KRAS or BRAF mutant NSCLC or NRASm melanoma with progression following SOC treatment. A total of 115 patients were treated with naporafenib plus trametinib in combination in 5 dose cohorts. Four cohorts received naporafenib and trametinib (doses are listed as naporafenib mg BID/trametinib mg QD): 200/0.5 (6 patients), 200/1 (54 patients), 400/0.5 (44 patients), 400/1 (5 patients), and a fifth cohort was administered 400 mg naporafenib BID continuously and trametinib 1 mg QD following a 2 weeks on/2 weeks off schedule (6 patients). Thirty-six patients in total were enrolled in dose escalation while 30 were enrolled in the NRASm melanoma expansion cohorts. During dose escalation, six patients reported 6 DLTs: dermatitis acneiform (one patient each in the 200/1 and 400/0.5 cohorts), maculopapular rash (one patient each in the 200/1 and 400/1 cohorts), increased lipase (one patient in the 200/1 cohort), and Stevens-Johnson syndrome (one patient in the 400/1 cohort). Two RDEs were identified: naporafenib 200 mg BID plus trametinib 1 mg QD and naporafenib 400 mg BID plus trametinib 0.5 mg QD. For the dose expansion portion of the trial, TRAEs of any grade were reported in 100% of patients. The most frequent (occurring in ≥20% of patients enrolled in dose expansion) TRAEs were rash (80.0%, Grade 3/4: 33.3%), nausea (30.0%, no Grade 3/4 events), diarrhea (30.0%, no Grade 3/4 events), blood creatinine phosphokinase increased (30.0%, Grade 3/4: 13.3%), constipation (23.0%, no Grade 3/4 events), stomatitis (20.0%, Grade 3/4: 3.3%) and vomiting (20.0%, no Grade 3/4 events).

The CLXH254C12201 trial enrolled patients with NRASm or BRAFm melanoma who have received prior systemic therapy for unresectable or metastatic melanoma with an anti-PD-1/L1-based regimen and were restricted to a maximum of two prior lines of systemic immune checkpoint inhibitor (ICI)-containing immunotherapy for unresectable or metastatic melanoma. The combination of naporafenib plus trametinib was evaluated at the RDEs of 200/1 (30 patients) and 400/0.5 (22 patients) where both naporafenib plus trametinib were administered continuously BID and QD, respectively. The most frequent (occurring in ≥20% of patients) TRAEs were rash (39.6%, Grade 3/4: 9.4%), dermatitis acneiform (34.0%, Grade 3/4: 7.5%), pruritis (26.4%, Grade 3/4: 1.9%), blood creatinine phosphokinase increased (20.8%, Grade 3/4:1.9%), and fatigue (20.8%, Grade 3/4: 1.9%).

Other combination data from ongoing Novartis trials. The trials referenced above were initiated by Novartis prior to the effective date of our license agreement with Novartis, and we will coordinate with Novartis in connection with the public release of data from these trials.

Summary. Naporafenib administered as monotherapy has been generally well tolerated when administered using either a QD or BID schedule. When combined with trametinib, the frequency and severity of AEs increased, as would be expected for a combination versus monotherapy. The most common toxicities observed for the naporafenib plus trametinib combination were related to skin findings, all of which were consistent with those observed with trametinib monotherapy or other trametinib combinations. While skin toxicity (manifesting as rash and dermatitis acneiform) was a common TRAE, we believe mandatory primary prophylaxis for rash could reduce both the frequency and severity of these events, thereby increasing the potential for improvement in long-term tolerability and increased efficacy. This approach has been implemented for SEACRAFT-1 and will be implemented in SEACRAFT-2. In addition, the fact that naporafenib monotherapy has been generally well tolerated, coupled with the observation that it has been administered with multiple other therapies with a variety of mechanisms of action (e.g., trametinib, LTT462, spartalizumab) without clinically relevant drug-drug interactions suggest that naporafenib may be an optimal partner for combination approaches.

Clinical Pharmacology

Monotherapy naporafenib showed a relatively rapid absorption with a median time to reach peak plasma concentration (Tmax) ranging from approximately 2 to 4 hours. Similar median Tmax ranges were observed when naporafenib was administered in combination with trametinib, LTT462, and ribociclib. The effective half-life is approximately 20-25 hours. The clinical exposure was approximately dose proportional across the dose range tested between 100 mg and 1200 mg QD as well as 200 mg and 600 mg BID. No significant drug-drug interactions have been observed between naporafenib and trametinib, LTT462, or ribociclib in the dose ranges tested. Other clinical pharmacology studies are ongoing.

Clinical Efficacy

Monotherapy. In the first-in-human dose escalation trial CLXH254X2101, two patients achieved confirmed partial responses (PRs): a patient with KRAS G12V-mutated ovarian cancer was treated with naporafenib 300 mg QD, and a patient with HRAS G13R-mutated head and neck cancer was treated with naporafenib 400 mg QD.

Naporafenib plus trametinib. A total of 71 patients with NRASm melanoma were dosed with the combination of naporafenib and trametinib at two different doses across two different trials (Phase 1b CLXH254X2102 and Phase 2 CLXH254C12201) in the post immuno-oncology (IO) setting. A pooled analysis across these trials showed a 31% confirmed overall response rate (ORR) for the 39 patients who received naporafenib 200 mg BID and trametinib 1 mg QD (200/1; one of the two RDEs) and a 22% confirmed ORR for the 32 patients who received naporafenib 400 mg BID and trametinib 0.5 mg QD (400/0.5; the other RDE). The duration of response (DOR) for the 200/1 pooled dataset was 7.4 months, the median progression-free survival (mPFS) was 5.1 months, and the median overall survival (mOS) was 13.0 months. The DOR for the 400/0.5 pooled dataset was 10.2 months, the mPFS was 4.9 months, and the mOS was 14.1 months. Both the mPFS and mOS for the pooled dataset at each dose were longer than their comparable benchmarks.

For both ORR and PFS, we believe the most robust benchmark is the randomized Phase 3 NEMO trial, which was a randomized Phase 3 trial evaluating binimetinib versus dacarbazine in NRAS melanoma. Since both ORR and PFS directly measure the activity of trial treatments, we believe the data in this trial are generalizable to the patient population enrolled in both Novartis’ Phase 1b and Phase 2 trials referenced above, despite the NEMO trial primarily enrolling treatment-naïve patients (~80%). In contrast to ORR and PFS, the OS results observed for the Phase 3 NEMO trial reflect not only the trial treatments (dacarbazine or binimetinib) but also the therapies received by patients after discontinuing the trial treatment. More specifically, since (i) ~45% of patients in either arm of the NEMO trial were reported to have received IO-based therapy after dacarbazine or binimetinib and (ii) IO-based therapy prolongs overall survival compared to other therapies available at that time, the mOS as measured by a Kaplan-Meier analysis would be predicted to overestimate the OS benefit provided by either dacarbazine or binimetinib without the IO-based therapy. In contrast, in the two naporafenib plus trametinib studies, all patients received IO-based therapy prior to enrollment, and since OS in clinical trials is measured from when a patient enters the trial, we believe that the results in NEMO likely overestimate the mOS values compared to the two naporafenib plus trametinib studies. In addition, while we believe that the mOS results from NEMO likely overestimate the potential OS benefit from dacarbazine or binimetinib, the mOS from the naporafenib plus trametinib combination is still quantitatively longer than that observed in either arm in the NEMO trial.

Since no randomized trials have been completed for patients with NRASm melanoma in the post-IO setting, other potential OS benchmarks available for comparison to the results from the pooled naporafenib plus trametinib analysis are either from published literature describing retrospective chart reviews of comparable patient populations or from data generated in similar patient populations enrolled in either the Phase 1b or Phase 2 trials themselves. In four publications describing retrospective chart reviews in patients with melanoma receiving either cytotoxic chemotherapy or MEK inhibitor monotherapy in the post-IO setting, the mOS was approximately 7 months. Similarly, for patients with BRAF/MEK-inhibitor resistant BRAFm melanoma enrolled in the Phase 2 trial and treated with naporafenib plus trametinib, which did not induce responses in this particular patient population, the mOS was approximately 7 months. We believe that the consistency of the mOS values for both the retrospective chart reviews and BRAF/MEK-inhibitor resistant BRAFm melanoma patients in the Phase 2 trial suggest that for patients with melanoma being treated in the post-IO setting, the natural history of their disease is represented by a mOS of approximately 7 months. In contrast, the mOS observed for patients with NRASm melanoma treated with naporafenib plus trametinib was approximately 13 to 14 months. This near doubling of OS demonstrated by naporafenib plus trametinib compares favorably relative to the historical benchmarks described above.

In summary, naporafenib plus trametinib demonstrated anti-tumor activity in patients with NRASm melanoma in a pooled analysis from two trials (Phase 1b: CLXH254X2102 and Phase 2: CLXH254C12201), and across two different dose levels of naporafenib and trametinib.

Summary. We believe clinical PoC in patients with NRASm melanoma, which includes Q61X melanoma, and preliminary PoC for patients with RAS Q61X NSCLC have been established for the combination of naporafenib and trametinib, which is designed to inhibit MEK, a downstream node of the RAS/MAPK pathway. Although clinical trial data across separate trials may not be directly comparable due to differences in trial protocols, conditions and patient populations, these data compare favorably with the clinical activity observed with the standard of care agents used to treat patients with NRASm melanoma who have progressed on immunotherapy.

Development strategy for naporafenib

Naporafenib’s clinical development plan is centered on the quick and efficient capitalization on the clinical PoC established in patients with NRASm melanoma (which includes NRAS Q61X melanoma) and the preliminary clinical PoC established in patients with RAS Q61X NSCLC. In December 2023, we announced that the FDA granted FTD to naporafenib in combination with trametinib for the treatment of adult patients with unresectable or metastatic melanoma who have progressed on, or are intolerant to, an anti‑programmed death-1 (ligand 1) (PD‑(L)1)-based regimen, and whose tumors contain an NRAS mutation (NRASm).

NRAS-mutated melanoma. NRASm melanoma accounts for approximately 69,000 newly diagnosed patients worldwide. The frontline standard of care for patients with NRASm melanoma is an anti-PD-1/L-1-based regimen (immunotherapy) where the PD-1/L-1 inhibitor is administered as monotherapy or in combination. The highest unmet need in this population is in the post-IO setting, where there is no single global regulatory or accepted SOC. Rather, an analysis of regulatory approvals of drugs for patients with melanoma, published treatment guidelines, and the feedback from an advisory board attended by treating physicians in North America, Europe, and Australia indicate that the treatment choices for this post-IO patient population include cytotoxic chemotherapy (e.g., dacarbazine, temozolomide, etc.), single agent MEK inhibitors (e.g., trametinib, binimetinib, cobimetinib), and clinical trials. In addition, there is no clear preference for what type of chemotherapy or MEK inhibitor should be administered. The best reference data for chemotherapy in patients with NRASm melanoma are from the NEMO trial. The patient composition is 82% treatment-naïve, 16% 2 nd line, 2% 3 rdline or more. The major strength of these reference data is this is the largest and most recent phase 3 dataset in which all patients had NRASm melanoma and are relatively homogeneous, with the vast majority being treatment-naïve. The major weakness is that only 21% of patients had received prior IO therapy. In the NEMO trial, the ORR for chemotherapy was 7%, the mPFS was only 1.5 months, and mOS was 10.1 months. Furthermore, the NEMO trial showed that the MEK inhibitor binimetinib had an ORR of 15%, a mPFS of 2.8 months, and a mOS of 11.0 months. A cross-trial comparison suggests that the combination of pan-RAF inhibitor plus MEK inhibitor may be superior to MEK inhibition alone or standard of care chemotherapy. We plan to test this hypothesis in a randomized controlled trial in the post-IO setting for potential registration (SEACRAFT-2).

RAS Q61X solid tumors. Patients with NRASm tumors represent approximately 399,000 newly diagnosed patients worldwide. Work in nonclinical models suggests that RAS Q61X and RAS G13R mutations are particularly sensitive to pan-RAF inhibition due to a dependency on CRAF for downstream RAS/MAPK pathway signaling. Early confirmation of this hypothesis has been seen in patients with NRASm melanoma, where 80-90% of patients have NRAS Q61X mutations. In CLXH254X2102 (Phase 1b trial), a confirmed ORR of 44% was observed in 16 patients with NRAS melanoma, with 15 of these patients with documented Q61X mutations. (See left figure below.) To test this hypothesis in other tumor types, naporafenib plus trametinib was evaluated in 49 patients with KRAS-mutated NSCLC, including 4 patients with tumors harboring KRAS Q61X or G13R mutations. Objective responses were observed in 3 out of the 4 patients. (See right figure below.) Remarkably, 2 out of the 3 patients with KRAS Q61-mutated tumors had confirmed PRs, and the 3 rd responder had a KRAS G13R-mutated tumor with an unconfirmed PR. In contrast, only 1 out of 45 patients without KRAS Q61X or G13R mutation responded. Based on these early signals, another development path for naporafenib plus trametinib is to pursue a tissue agnostic indication in patients with solid tumors with RAS Q61X mutations. We are testing this hypothesis in an ongoing Phase 1b trial (SEACRAFT-1).

Clinical development plan for naporafenib

Naporafenib is our most advanced clinical-stage program. We believe it has the potential to change the standard of care in a number of indications with high unmet medical need, including in patients with NRASm melanoma, as well as patients with RAS Q61X solid tumors.

SEACRAFT-1. The SEACRAFT-1 trial is a Phase 1b trial to establish the PoC for the tissue-agnostic hypothesis in patients with RAS Q61X solid tumors. In addition to NRAS Q61X melanoma and KRAS Q61X NSCLC, the trial is enrolling patients with other solid tumors that harbor any RAS Q61X mutation, who have either progressed on, or are intolerant, to standard of care treatment, or for whom no standard of care exists. If PoC is established by demonstrating anti-tumor activity across a broad range of tumor types, we plan to discuss with regulatory authorities a potential fast-to-market strategy in an indication where no approved standard of care exists, to address high unmet medical need. We dosed the first patient in the SEACRAFT-1 trial in August 2023. We anticipate a Phase 1b combination data readout from SEACRAFT-1 between the second and fourth quarters of 2024.

SEACRAFT-2. The SEACRAFT-2 trial will formally test the hypothesis supported by the clinical PoC data in patients with NRASm melanoma. We plan to enroll NRASm melanoma patients who have progressed on, or are intolerant to, SOC ICI therapy into a potentially registration-enabling randomized Phase 3 trial in which patients will receive either naporafenib plus trametinib or physician’s choice of therapy (dacarbazine, temozolomide, or trametinib monotherapy). We have designed the trial to demonstrate superiority in PFS and/or OS based on benchmarks from published literature. Important details of the trial design, such as the primary endpoints and choice of therapy in the physician’s choice comparator arm, have been discussed with regulatory authorities. In addition, we have added a dose optimization stage to the trial design that will enable selection of the optimal naporafenib plus trametinib dosing regimen that will then be incorporated into the potentially registration-enabling portion of the trial. We expect to initiate the SEACRAFT-2 trial in the first half of 2024 and have Phase 3 Stage 1 randomized dose optimization data in 2025.

In addition, we plan to introduce proactive safety management, including mandatory primary rash prophylaxis, and other elements that are designed to improve the safety and tolerability of this regimen for patients participating in our trials.

Other development opportunities. A strong motivation to add naporafenib to our precision oncology pipeline is the potential synergy of naporafenib with our other agents that target the RAS/MAPK pathway, including but not limited to ERAS-007. These combinations will allow us to evaluate a number of biomarker-defined patient populations for whom there are no approved targeted therapies. These may include other RAS/MAPK pathway mutations beyond those being studied by SEACRAFT-1 and SEACRAFT-2. These development opportunities may expand the potential impact of naporafenib to larger patient populations. We plan to explore these combinations and patient populations in a Phase 1b trial. We are conducting preclinical studies to assess the optimal indications to inform the clinical design and will then commence the trial once the design has been finalized.

ERAS-007: our ERK inhibitor

ERAS-007 is designed to be a potent and selective oral inhibitor of ERK1/2. We in-licensed ERAS-007 from Asana based in part on preclinical studies that demonstrated the highest potency and longest target residence time of any ERK inhibitors of which we are aware. In a Phase 1 clinical trial completed by Asana, ERAS-007 demonstrated single-agent activity including objective responses in patients with tumors harboring RAS/MAPK pathway alterations and was well tolerated. We are currently evaluating ERAS-007 in the HERKULES-3 clinical trial, for which we dosed the first patient in September 2021.

Preclinical profile of ERAS-007

ERAS-007 is a potent, reversible, and ATP-competitive inhibitor of ERK1 and ERK2 with a biochemical IC50 (a measure of 50% inhibition) against both ERK1 and ERK2 of 2 nM and cell-based mechanistic IC50 against pRSK of 7 nM. In the BRAF V600E CRC cell line RKO, ERAS-007 showed superior potency to a comparator ERKi, ulixertinib, and comparable potency to binimetinib, a MEK inhibitor. In addition, ERAS-007 exhibited long biochemical residence time while bound to ERK, which has been measured as 550 minutes against ERK2. This longer target residence time compared to other clinical-stage ERK inhibitors may allow for longer intervals between doses in patients.

ERAS-007 IC50s against ERK1 and ERK2 were characterized in a biochemical kinase activity. Cell-based IC50 was characterized by the ability of ERAS-007 to inhibit ERK from phosphorylating one of its downstream targets, RSK1. pRSK represents RSK1 phosphorylation.

ERK2 residence time for ERKi(s), ERAS-007 and ulixertinib, and MEKi(s), trametinib and binimetinib, were determined by BLI and SPR, respectively.

This biochemical potency has translated into strong anti-proliferative activity in cell lines with mutations in the RAS/MAPK pathway compared to other clinical-stage ERK inhibitor compounds. In 14 out of 14 cell lines that harbored activating RAS/MAPK pathway alterations, ERAS-007 exhibited potent activity with a less than 1 µM IC50. In two KRAS G12C cell lines, ERAS-007 showed greater potency compared to ulixertinib, an ERK inhibitor, comparable potency to binimetinib, a MEK inhibitor, and sotorasib, a KRAS G12C inhibitor. Cellular signaling studies demonstrated that ERAS-007 inhibited phosphorylation of downstream targets of ERK such as ribosomal S6 kinases (RSK), Fos-related antigen (FRA), and ETS domain-containing protein (ELK) in the BRAF V600E CRC HT-29 cell line. Demonstrating its selectivity, in seven out of eight cell lines that did not harbor any activating RAS/MAPK pathway alterations, ERAS-007 showed weak inhibition with a greater than 10 µM IC50. Together, these results suggest that ERAS-007 is a potent and selective ERK inhibitor with the ability to inhibit cell growth in multiple models of RAS/MAPK pathway-driven cancers relative to other agents used in these settings.

ERAS-007, ulixertinib and ravoxertinib were profiled in 3 BRAF mutant, 1 HRAS mutant, 8 KRAS mutant, 2 NRAS mutant, and 8 wildtype RAS and wildtype RAF cell lines. Nanomolar IC50 values are represented on the y-axis. Lower IC50s denote stronger activity.

Inhibition of signaling by kinases is typically achieved by either: (1) ATP-competitive inhibition whereby an inhibitor blocks ATP binding or (2) allosteric inhibition whereby an inhibitor does not block ATP binding but rather binds to a different region to prevent the kinase from signaling downstream. Currently approved MEK inhibitors, trametinib, binimetinib, selumetinib, and cobimetinib, are allosteric MEK inhibitors. A potential limitation of these allosteric MEK inhibitors is that they preferentially bind MEK in the inactive state and have weaker inhibitory activity against activated MEK proteins. Another limitation is that some MEK inhibitors preferentially disrupt activation via one RAF family member (e.g., BRAF) but not another (e.g., CRAF). Due to negative feedback regulation in the RAS/MAPK pathway, inhibition of downstream signaling nodes can result in RAS/MAPK pathway feedback reactivation that is mediated through multiple members of the RAF family. This increased upstream signaling pressure can serve as a resistance mechanism to MEK inhibitors and has been observed in the clinic. As an ATP-competitive ERK inhibitor, ERAS-007 has been shown to more robustly block RAS/MAPK pathway reactivation than allosteric MEK inhibitors. As shown in the figure below, ERAS-007 continuously inhibited downstream ERK activity in a KRAS G12C-mutated CRC cell line; whereas the RAS/MAPK pathway was reactivated beginning as early as 24 hours after treatment with each of the three MEK inhibitors, which is illustrated with the emergence of the dark P-RSK bands (darker intensity equates to higher signaling or reactivation) in the following Western blots.

Western blot characterization of three MEK inhibitors (selumetinib, binimetinib, and trametinib) and two ERK inhibitors (ulixertinib and ERAS-007) in the KRAS G12C-mutated CRC cell line SW1463. The phosphorylation states of RSK (P-RSK), ERK (P-ERK), CRAF (P-CRAF) and MEK (P-MEK) are shown. Band intensity indicates level of phosphorylation. Total GAPDH (GAPDH), a housekeeping gene, is used as a protein loading control. Times, in hours, represent the duration of compound incubation. NT means “no treatment,” and this sample serves as a negative control. The level of P-RSK, highlighted in dotted red rectangles, indicates ERK signaling activity. The absence of a P-RSK band indicates inhibition of ERK signaling activity and thereby inhibition of RAS/MAPK pathway signaling.

When combined with encorafenib in BRAF V600E-mutated cell lines, ERAS-007 blocked the RAS/MAPK pathway feedback reactivation that was observed with MEK or other ERK inhibitors at one-tenth the concentration. These results provide further support that inhibition of ERK by ERAS-007 may lead to more complete and durable blockade of the RAS/MAPK pathway relative to other inhibitors of ERK or MEK, either alone or in combination.

Treatment of two BRAF V600E-mutated CRC cell lines, RKO and HT-29, with encorafenib in combination with the MEK inhibitor binimetinib, the ERK inhibitor ERAS-007, the ERK inhibitor LY3214996, and the ERK inhibitor ravoxertinib. The Western blot gels depict phosphorylation of RSK (P-RSK) and ERK (P-ERK). Higher levels of phosphorylation are depicted by higher (i.e., darker) band intensity. Total GAPDH protein (GAPDH) serves as a loading control. ERK signaling activity is represented by the phosphorylation state of RSK (P-RSK), which is a downstream target of ERK. The column values indicate the duration of compound incubation of up to 72 hours.

Preclinical anti-tumor activity of ERAS-007

We further showed the breadth of ERAS-007 in vivo activity in CRC, pancreatic cancer, melanoma, and neuroblastoma models harboring alterations in the BRAF, NRAS, or KRAS nodes of the RAS/MAPK pathway. In the BRAF V600E-mutated melanoma CDX A375 model, ERAS-007 showed dose-dependent tumor inhibition with a maximal 104% tumor growth inhibition (TGI) at 30 mg/kg BID (p-value < 0.001 across all ERAS-007 doses relative to vehicle control). In the NRAS Q61K-mutated neuroblastoma CDX SK-N-AS model, ERAS-007 showed dose-dependent tumor inhibition with a maximal 82% TGI at 25 mg/kg BID (p-value < 0.001 across all ERAS-007 doses relative to vehicle control). In the KRAS G12D pancreatic CDX Panc-1 model, ERAS-007 showed dose-dependent TGI with a maximal 94% TGI at 40 mg/kg BID (p-value < 0.001 across all ERAS-007 doses relative to vehicle control). In the KRAS G13D CRC CDX HCT116 model, ERAS-007 showed 101% TGI at 25 mg/kg BID (p-value < 0.001 relative to vehicle control). ERAS-007 showed superior TGI to ulixertinib at 75 mg/kg QD in Panc-1 at doses ranging from 20 mg/kg BID to 40 mg/kg BID. TGI values >100% indicated tumor regression.

ERAS-007 showed significant TGI in pancreatic cancer, CRC, melanoma, and neuroblastoma CDX models at doses ranging from as low as 10 mg/kg BID (p-value < 0.001). At doses ranging from 20 mg/kg BID to 40 mg/kg BID, ERAS-007 showed superior TGI to a clinical-stage ERK inhibitor, ulixertinib, at 75 mg/kg QD, in pancreatic cancer Panc-1 and MIA PaCa-2 CDX models. ERAS-007 at 25 mg/kg BID also showed superior TGI to ravoxertinib at 50 mg/kg BID in the CRC HCT-116 CDX model. Relative to trametinib at 1.5 mg/kg QD, ERAS-007 showed superior TGI in the MIA PaCA-2 CDX model at doses ranging from 20 mg/kg BID to 40 mg/kg BID and in the pancreatic cancer CDX Panc-1 at 40 mg/kg BID. In the neuroblastoma S-K-NAS model, ERAS-007 showed superior TGI at doses as low as 12.5 mg/kg BID to trametinib at 0.15 mg/kg QD. Error bars represent standard error of the mean (SEM).

ERAS-007 showed statistically significant TGI in BRAF V600E CRC and mutant KRAS NSCLC CDX models as a monotherapy and in combination with standard of care targeted therapies and with ERAS-601 (our first MAPKlamp). In the BRAF V600E CRC CDX model RKO, ERAS-007 exhibited 82% TGI as a monotherapy (p-value < 0.001), 88% TGI in combination with encorafenib (p-value < 0.001) and 93% TGI in combination with encorafenib and cetuximab (p-value < 0.001). In the BRAF V600E CRC CDX model WiDr, ERAS-007 exhibited 102% TGI as a monotherapy (p-value < 0.001), 109% TGI in combination with encorafenib (p-value < 0.001), and 111% TGI in combination with encorafenib and cetuximab (p-value < 0.001). Indicated with an asterisk in the graphic, both ERAS-007 combinations achieved statistically significant TGI relative to either the encorafenib and cetuximab combination or ERAS-007 monotherapy (p-values < 0.01).

In the KRAS G12V NSCLC CDX model NCI-H441, the MAPKlamp combination of ERAS-007 at 30 mg/kg QD and ERAS-601 at 15 mg/kg QD achieved a statistically significant TGI of 113% (p-value < 0.001), demonstrating statistically significant benefit relative to the respective monotherapy doses of both ERAS-007 at 30 mg/kg QD and ERAS-601 at 15 mg/kg QD (p-value < 0.01). ERAS-007 as a monotherapy at 30 mg/kg BID and 30 mg/kg QD doses achieved statistically significant TGI of 115% (p-value < 0.001) and 94% (p-value < 0.001), respectively. ERAS-601 as a monotherapy at 30 mg/kg QD and 15 mg/kg QD doses achieved statistically significant TGI of 101% (p-value < 0.001) and 87% (p-value < 0.001), respectively. In the KRAS G12A NSCLC CDX model NCI-H2009, the MAPKlamp combination of ERAS-007 at 30 mg/kg QD and ERAS-601 at 15 mg/kg QD achieved statistically significant TGI of 107% (p-value < 0.001). MAPKlamp achieved a statistically significant combination benefit relative to the respective monotherapy doses of both ERAS-007 at 30 mg/kg QD and ERAS-601 at 15 mg/kg QD (p-value < 0.01). The MAPKlamp combination also showed statistically significant superior TGI relative to ERAS-007 monotherapy at 30 mg/kg BID (p-value < 0.05) and ERAS-601 monotherapy at 30 mg/kg QD (p-value < 0.01). These doses represent the maximum monotherapy nonclinical active doses for ERAS-007 and ERAS-601. ERAS-007 as a monotherapy at 30 mg/kg BID achieved statistically significant TGI of 93%). ERAS-601 as a monotherapy at 30 mg/kg QD and 15 mg/kg QD doses achieved statistically significant TGI of 90% (p-value < 0.001) and 73% (p-value < 0.001), respectively. TGI values >100% indicated tumor regression.

ERAS-007 was profiled in two BRAF V600E CRC CDX models, RKO, which was insensitive to encorafenib and cetuximab treatment, and WiDr, which was sensitive to encorafenib and cetuximab treatment. In both models, ERAS-007 combinations showed superior TGI to encorafenib (Encor.) and cetuximab (Cetux.) monotherapies and to the encorafenib and cetuximab combination (p-value < 0.01). The asterisk in the WiDr graphic indicates that the TGI of the ERAS-007 combinations relative to either the encorafenib and cetuximab combination or ERAS-007 monotherapy was statistically significant (p-value < 0.01). In two mutant KRAS NSCLC CDX models, NCI-H441 and NCI-H2009, the MAPKlamp combination of ERAS-007 and ERAS-601 achieved statistically significant TGI relative to vehicle (p-values < 0.01) and showed statistically significant combination benefit relative to the respective monotherapy doses used in the MAPKlamp combination (p-values < 0.01). At their active monotherapy doses, ERAS-007 and ERAS-601 also achieved significant TGI in both models as monotherapies (p-values < 0.01).

Clinical development of ERAS-007

Four completed or ongoing clinical trials have evaluated ERAS-007 as monotherapy or in combination in patients with cancer:

•

ASN007-101 is a completed open-label, first-in-human, dose-finding trial of ASN007 (ERAS-007) in patients with advanced solid tumors.

•

HERKULES-1 is an ongoing open-label, Phase 1b/2, open-label, trial of ERAS-007 (ERK inhibitor) administered as monotherapy or in combination with ERAS-601 (SHP2 inhibitor) to patients with advanced or metastatic solid tumors. HERKULES-1 is no longer enrolling patients.

•

HERKULES-2 is a completed open-label Phase 1b/2 master protocol of agents targeting the mitogen-activated protein kinase pathway in patients with advanced non-small cell lung cancer.

•

HERKULES-3 is an ongoing open-label Phase 1b/2 master protocol of agents targeting the mitogen-activated protein kinase pathway in patients with advanced gastrointestinal malignancies.

Monotherapy. ASN007-101 was a Phase 1, open-label, dose finding trial, to evaluate the safety, tolerability, PK, PD, and preliminary anti-tumor activity of ERAS-007 in patients with advanced solid tumors. The trial was completed on June 30, 2020, when the sponsor (Asana) terminated the trial after the primary objective was achieved; the primary objective was to evaluate the safety and tolerability of ERAS-007, characterize the DLTs, determine an MTD, and recommend a Phase 2 dose. Forty-nine patients were treated with ERAS-007 monotherapy at doses ranging from 10 to 80 mg QD (n=17) and 80-350 mg once weekly (QW) (n=32). Based on all safety and tolerability data collected, 40 mg QD and 250 mg QW were considered the MTDs for the QD and QW dosing regimens, respectively. ERAS-007 exhibited relatively rapid absorption, with Tmax generally attained within 4 hours post dose. Terminal half-life (t1/2) was approximately 30 hours. Systemic exposure for ERAS-007 generally increased in a dose related manner. The observed accumulation was consistent with the half-life and dosing frequency of ERAS-007. ERAS-007 showed an expected, reversible, and manageable safety results. Gastrointestinal, skin and ocular toxicities were the most common adverse events (AEs) reported. Objective tumor responses and durable disease control with ERAS 007 were observed in diverse tumor types at doses ranging from 120 to 250 mg once weekly (QW) in patients with BRAF-, HRAS-, and NRAS-driven cancers.

HERKULES-1 is a Phase 1b/2, open-label, dose escalation and dose expansion trial to assess the safety, tolerability, PK, exploratory PD, and preliminary evidence of clinical activity of ERAS 007 monotherapy in patients with advanced or metastatic solid tumors, as well as the dose escalation of ERAS-007 in combination with ERAS-601. The purpose of the monotherapy portion of HERKULES-1 was to assess an alternative schedule of administration of ERAS-007 as well as the effect of food on the administration of ERAS-007. As noted in the ASN007-101 trial, while the QW schedule of ERAS-007 demonstrated clinical activity with acceptable safety results, the PK profile coupled with the safety results suggested that ERAS-007 dosed in a twice a day, once a week (BID-QW) regimen may improve exposure, prolong ERK1/2 inhibition, and increase antitumor activity while maintaining acceptable safety margins. Hence, a primary objective of this protocol is to determine the MTD and recommended dose (RD) of ERAS-007 as a monotherapy administered BID-QW in patients with advanced solid tumors. As of November 30, 2023, 28 patients were treated with ERAS-007 monotherapy at doses ranging from 50 to 125 mg administered BID-QW. Dose escalation for the BID-QW cohort was capped at 125 mg which has an equivalent weekly dose intensity to the MTD identified for the QW schedule (i.e., 250 mg). No DLTs were observed in the BID-QW dose finding cohorts. TRAEs of any grade were reported in 26 (92.9%) of the patients in the BID-QW cohorts, and no Grade 4 or 5 TRAEs were reported in the BID-QW cohorts. The most frequent (occurring in ≥ 20% of patients in the BID-QW cohorts) were nausea (42.9%, Grade 3: 3.6%), dermatitis acneiform (39.3%, Grade 3: 0%), fatigue (32.1%, Grade 3: 7.1%), vomiting (28.6%, Grade 3: 0%), retinopathy (28.6%, Grade 3: 3.6%), diarrhea (25.0%, Grade 3: 0%), and vision blurred (21.4%, Grade 3: 3.6%). Of the 18 patients treated in the BID-QW cohort who were efficacy evaluable, one patient with KRAS G12V pancreatic cancer had an unconfirmed response. As of November 30, 2023, 7 patients were dosed with the combination therapy of ERAS-601 and ERAS-007. The only dosing cohort to open administered ERAS-007 50 mg BID-QW in combination with ERAS-601 40 mg BID (3/1). ERAS-007 TRAEs reported in more than 1 patient included dysgeusia, diarrhea, abdominal pain, rash maculo papular, and fatigue. Of the 7 patients enrolled in the first dosing cohort (ERAS-007 50 mg BID-QW + ERAS-601 40 mg BID [3/1]), 6 were DLT-evaluable, and 2

DLTs were observed: Grade 3 neutropenia which did not recover to an absolute neutrophil count of ≥1000 cells/mm3 within 10 days, and Grade 3 elevated AST. Since the DLT frequency exceeded the per protocol-defined criteria, dose escalation to the next level was not pursued. Based on the inability to increase the dose beyond this first cohort, the decision was made not to pursue this combination further and the cohort was closed to enrollment.

Summary. As a monotherapy, ERAS-007 has shown reversible and manageable adverse events, which we believe were consistent with other RAS/MAPK-pathway inhibitors (e.g., MEK inhibitors). In the first in human trial, the ERAS-007 QW dosing schedule was better tolerated than QD dosing based on the TRAEs reported. In HERKULES-1, the TRAEs observed for the BID-QW schedule suggest that this schedule may provide an alternative intermittent option for combination development. Transient nausea and vomiting observed with either the QW or BID-QW dosing schedules were manageable. Skin toxicities have been noted as a class effect of inhibitors of RAF, MEK, or ERK. Less skin toxicity was observed with intermittent dosing of ERAS-007 compared to continuous daily dosing. Ophthalmic toxicities have been observed during treatment with MEK targeted agents and occur with ERK inhibitors, and reversible retinopathy is a well-known MEK/ERK inhibitor class effect.

Rationale for combining with other targeted agents

Since ERK is the terminal node of the RAS/MAPK pathway and activates hundreds to thousands of downstream proteins, we believe an ERK inhibitor is an attractive combination partner to achieve maximal inhibition of the RAS/MAPK pathway. In combination with RTK, SHP2, RAS, and/or RAF inhibitors, an ERK inhibitor has the potential to further inhibit RAS/MAPK pathway signaling and delay development of resistance. The RAS/MAPK pathway is regulated by negative feedback mechanisms that desensitize the pathway when active. In the presence of a RAS/MAPK pathway inhibitor, pathway signaling activity is reduced, alleviating negative feedback mechanisms and sensitizing the RAS/MAPK pathway to upstream signaling. This sensitization can prevent RAS/MAPK pathway inhibitors from achieving therapeutic levels of pathway inhibition. Another challenge for RAS/MAPK pathway inhibitors is the activation of RTKs that can generate sufficient upstream RAS/MAPK pathway signaling pressure that overwhelms RAS/MAPK pathway inhibitors. Combining upstream RAS/MAPK pathway inhibitors with an ERK inhibitor can potentially enable pathway inhibition in the absence of negative feedback and in the presence of additional upstream signaling pressure. The activity of RAS/MAPK pathway inhibitors can also be bypassed by the emergence of activating mutations in RAS/MAPK pathway proteins that lie downstream. For example, activating mutations in RAS can emerge as a resistance mechanism against EGFR inhibitors in mutant EGFR NSCLC, and MEK mutations can develop as a resistance mechanism against BRAF plus MEK inhibitors in melanoma. As the terminal node of the RAS/MAPK pathway, ERK inhibition can help address activating RAS, RAF, or MEK mutations that can act as resistance mechanisms to RAS/MAPK pathway inhibitors.

BRAF V600E CRC as an example that ERK inhibition can reduce the emergence of resistance

While the combination of a BRAF inhibitor and an EGFR inhibitor (encorafenib plus cetuximab) has been approved for the second- and third-line treatment of BRAF V600E CRC, only 20% of patients experience an objective response, and only half of these responses last more than 6 months. Therefore, emergence of resistance is a major therapeutic barrier to long-term clinical benefit. Analysis of post-progression biopsies and cell-free DNA samples revealed a heterogeneous collection of resistance mutations in the RAS/MAPK pathway, including KRAS, NRAS, MEK1, and MEK2. A set of published experiments conducted by researchers at Massachusetts General Hospital modeled this clinical resistance in a pooled clone model system and xenograft models. Seven different resistant BRAF V600E CRC cells, each engineered with one of these resistance mutations, were introduced at 1% allele frequency into a pool of sensitive BRAF V600E CRC cells. Of all combination therapies evaluated, a triple blockade of BRAF, EGFR, and ERK (identified with a red box around the image below) proved to be the most effective in reducing tumor volume and preventing the emergence of resistant clones.

These data suggest that: (1) in tumors that are highly addicted to the RAS/MAPK pathway, such as BRAF V600E CRC, resistance mechanisms are dominated by reactivation of this critical pathway via mutations within the pathway, and (2) an ERK inhibitor can potentially overcome these resistance mechanisms by blocking the terminal node of the pathway. Therefore, we believe combining ERAS-007 with other RAS/MAPK pathway inhibitors (e.g., KRAS G12C inhibitor and BRAF inhibitor) as either initial therapy or in the post-progression setting in patients who have been treated with RAS/MAPK pathway inhibitors may lead to improved clinical activity.

Development strategy for ERAS-007

We are pursuing clinical development for ERAS-007 in combination with approved and investigational agents.

As shown in the schema below, HERKULES-3 is a Phase 1b/2 master protocol evaluating novel combination therapies for patients with GI malignancies. Sub-Study A of the HERKULES-3 trial is focused on patients with BRAF V600E-mutated CRC, representing approximately 180,000 new patients worldwide each year. The master protocol for this clinical trial may be expanded in the future to include other novel combinations and indications in GI cancers. We dosed the first patient in HERKULES-3 in September 2021.

The standard of care for patients with BRAF V600E CRC in the second-/third-line metastatic setting is EC, an anti-BRAF and anti-EGFR doublet therapy. Only 20% of patients respond, nearly all patients experience disease progression, and the mOS is less than 9 months. The prognosis for patients in the post-EC setting is worse. In preclinical models of BRAF V600E CRC, the addition of an ERK inhibitor to BRAF inhibitor plus EGFR inhibitor substantially enhanced anti-tumor activity and reduced the development of resistance to BRAF inhibitor plus EGFR inhibitor. When the dosing regimen of ERAS-007 was changed from QW to BID-QW in an effort to decrease Cmax-driven toxicity, Part A2 was opened for escalation. The highest dose evaluated and cleared by the safety review committee was 100 mg ERAS-007 BID-QW in combination with the approved doses of EC. While dose escalation initially enrolled two patient populations (BRAF V600E

CRC patients who are naïve to EC treatment and who have been treated with EC), expansion is focused on those patients who are EC-naïve.

HERKULES-3 Sub-Study A: BRAF V600E CRC

As of March 23, 2023, 20 patients with BRAFm CRC had been treated with escalating doses of ERAS-007 in combination with the approved doses of EC. The combination showed acceptable preliminary safety and tolerability results with 17 (85%) patients experiencing ERAS-007-related AEs, most of which were grade 1 and 2 with no grade 4 or 5 events. The most common (occurring in ≥ 20% of patients) ERAS-007-related AEs were fatigue (35%, Grade 3: 5%), diarrhea (30%, Grade 3: 0%), headache (25%, Grade 3: 5%), anemia (25%, Grade 3: 10%), nausea (25%, Grade 3: 0%), subretinal fluid (20%, Grade 3: 0%), and vomiting (20%, Grade 3: 0%). As of May 21, 2023, in EC-naïve efficacy-evaluable patients, across all dose levels, the response rate was 38% (3/8) and the disease control rate (complete response [CR] + partial response [PR] + stable disease [SD]) was 63% (5/8). At the highest dose evaluated (ERAS-007 100 mg BID-QW), the response rate was 50% (3/6; 2 confirmed PRs and 1 unconfirmed PR) and the disease control rate was 67% (4/6). Both confirmed responders were still on treatment with duration of exposure > 40 weeks as of the data cut-off.

Summary. ERAS-007 in combination with EC has shown acceptable safety and tolerability results with the most common ERAS-007-related events generally consistent with the mechanism of action with no new safety signals identified. Encouraging clinical activity has been observed in EC-naïve patients and additional enrollment is ongoing. Updated interim data are expected in H1 2024.

ERAS-801: our CNS-penetrant EGFR inhibitor

EGFR is a transmembrane protein and member of the ErbB family of receptor tyrosine kinases (RTKs) that under normal conditions bind various growth factors to activate cellular signaling to regulate homeostasis. However, when the receptor is overexpressed, amplified, and/or mutated, it becomes oncogenic, thereby contributing to cell survival, proliferation, and metastasis.

EGFR-mediated signaling plays a key role in the growth of many tumor types. Targeting of wildtype EGFR (wtEGFR) and mutant variants of EGFR (EGFRm) by small molecules and antibodies has resulted in improved patient outcomes in NSCLC, CRC, and HNSCC. However, the ability of these agents to effectively target wtEGFR and EGFRm in the CNS remains an unmet medical need. For example, in primary CNS tumors like GBM that have amplification of wtEGFR as well as expression of a mutation in the extracellular domain, the most common of which is epidermal growth factor receptor variant III (EGFRvIII), approved small molecule EGFR inhibitors have not demonstrated clinical activity.

The lack of clinical activity is likely multifactorial, but we believe there are two primary reasons why approved EGFR inhibitors are not effective: (1) the molecules do not penetrate the CNS well, and (2) the molecules are weak inhibitors of GBM-relevant mutant EGFR proteins, such as EGFRvIII, as homodimers or heterodimers that include wildtype EGFR.

ERAS-801 is designed to be a potent, selective, reversible, and orally available small molecule with both: (1) highly enhanced CNS penetration (8.2:1 brain:plasma ratio in mice, based on updated PK data generated by Erasca) and (2) the ability to target both EGFR mutants such as EGFRvIII, the most common mutant form of EGFR found in GBM, and wtEGFR, which heterodimerizes with EGFRvIII.

High CNS penetration of ERAS-801

Whereas approved EGFR inhibitors have suboptimal CNS penetration for primary brain tumors, as shown below, ERAS-801 showed substantially higher values of Kpand Kp,uu(partition coefficients that measure bound and unbound drug concentration, respectively) compared to osimertinib, afatinib, erlotinib, gefitinib, and dacomitinib. The figure below is for illustrative purposes only and is not a head-to-head comparison. These data were generated from different studies, and caution should be exercised when comparing data across studies.

Dual targeting of EGFR alterations and wtEGFR in GBM to address heterodimerization

The most common mutant form of EGFR found in GBM is EGFRvIII. Given the promiscuous nature of EGFR signaling, ERAS-801 has been specifically designed to have activity against both EGFR alterations such as EGFRvIII and wildtype EGFR, as we believe that wtEGFR inhibition is critical to impairing the growth of EGFR altered GBM because of the propensity of wtEGFR to heterodimerize with EGFRvIII to drive oncogenic signaling, as seen below with substantial co-expression of EGFRvIII and wtEGFR.

Panel A shows that the EGFR splice variant mutant EGFRvIII may be expressed in a subset of GBM tumor cells and that it can be co-expressed with wildtype EGFR. Panel B shows a zoomed in diagram of a GBM tumor cell membrane that harbors both wildtype EGFR and EGFRvIII. Wildtype EGFR can homodimerize with another wildtype EGFR protein or heterodimerize with EGFRvIII, in each case potentially leading to oncogenic signaling. In panels C and D, an immunohistochemistry-stained section of GBM tumor tissue shows wildtype EGFR-expressing tumor cells in brown and EGFRvIII-expressing tumor cells in blue. Regions that are stained both brown and blue express both wildtype EGFR and EGFRvIII proteins while regions that are stained brown but not blue express wildtype EGFR only.

Preclinical profile of ERAS-801

In preclinical studies, ERAS-801 has demonstrated strong biochemical and cell-based potency, as well as strong biochemical selectivity. ERAS-801 has shown high potency against EGFR with a biochemical IC50 of 0.3 nM and high CNS penetration. It also showed high selectivity for EGFR based on a biochemical screen of 484 kinases in which ERAS-801 at 10 µM inhibited only two non-EGFR family kinases at greater than 90%.

In cell-based assays, ERAS-801 was potent against wildtype EGFR with an IC50 of 1.3 nM and EGFRvIII with an IC50 of 1.5 nM. In an 18 in vitro patient-derived GBM cell panel, ERAS-801 showed statistically significantly greater in vitro activity in EGFR amplified GBM models than in non-amplified models, as measured by IC50 values (t-test p-value = 0.01). ERAS-801 exhibited submicromolar IC50s in 83% of EGFR amplified models (n=6) and in only 17% of non-EGFR amplified models (n=12).This GBM cell panel included the most frequent types of EGFR alterations observed in GBM: amplification, EGFRvIII, extracellular domain mutations (e.g., A289V and A289D), and chromosome 7 polysomy.

The CNS penetration of ERAS-801 was studied in mice following single oral dose administration. ERAS-801 exhibited extensive CNS penetration in mice. The brain-to-plasma partition coefficient (Kp) based on AUC ratio of the total concentrations of ERAS-801 was 8.2; whereas the corresponding unbound partition coefficient (Kpuu) of ERAS-801 was 1.3. ERAS-801 also exhibited extensive CNS penetration in rats, measured both after a single oral dose and after 14 days of continuous once daily oral administration. After a single dose, Kp of ERAS-801 was 9.3, whereas Kpuu of ERAS-801 was 1.7. After 14 days of once daily oral administration, Day 14 mean Kp was 3.3-4.8.

ERAS-801 was evaluated at 25 mg/kg QD in 19 patient-derived glioma models. This patient-derived glioma model set was intended to capture the heterogeneity of GBM by encompassing a variety of disease stages (e.g., primary or recurrent), patient sex, and MGMT methylation status. Survival benefit indicated the duration that mice treated with ERAS-801 survived relative to mice treated with vehicle. An asterisk indicates models in which survival benefit was statistically significant (Logrank test p-value < 0.05). In this model set, ERAS-801 treatment resulted in significant survival benefit in 83% of patient-derived glioma models that harbored an EGFR amplification. In contrast, ERAS-801 treatment resulted in significant survival benefit in 23% of models that did not harbor an EGFR amplification, EGFRvIII, or EGFR extracellular domain mutation. Survival benefit associated with a p-value < 0.05 was considered significant.

Development strategy for ERAS-801

GBM is a difficult-to-treat, aggressive cancer that can occur in the brain or spinal cord. Current therapy consists primarily of surgical resection of the tumor, followed by radiation and chemotherapy. Once GBM recurs, therapeutic options for patients are limited. EGFR amplifications and mutations are detected in up to 60% of GBM cases and are generally indicative of poor prognosis. In May 2023, we announced that the FDA granted FTD to ERAS-801 for the treatment of adult patients with GBM with EGFR gene alterations. In June 2023, we announced that the FDA granted ODD to ERAS-801 for the treatment of patients with malignant glioma, which includes GBM. In February 2022, we dosed the first patient in our THUNDERBBOLT-1 Phase 1 clinical trial in recurrent GBM that will evaluate the safety, PK, and PD effects of ERAS-801 as a single agent. Preliminary evaluation of anti-tumor activity will also be performed in patients who have tumors harboring alterations in EGFR. In November 2023, we announced that the MTD was established, and the program transitioned to the next phase of development focusing on identification of the recommended Phase 2 dose and efficacy signal seeking. Preliminary clinical data from the THUNDERBBOLT-1 trial are expected in 2024.

ERAS-601: our SHP2 inhibitor

ERAS-601 is designed to be a potent and selective oral inhibitor of SHP2. In preclinical studies, ERAS-601 has demonstrated strong in vitro potency relative to other SHP2 inhibitors (RMC-4550 and TNO155) and favorable absorption, distribution, metabolism, and excretion (ADME) and PK properties, which we believe support its use in a broad range of combination therapies.

In our first-in-human trial, FLAGSHP-1, we evaluated the safety, tolerability, PK, PD, and preliminary anti-tumor activity of ERAS-601 in patients with advanced or metastatic solid tumors; however, this trial was deprioritized in November 2023, even though ERAS-601 administered as a monotherapy was safe and tolerable while achieving confirmed responses as a monotherapy and in combination with cetuximab. We consider ERAS-601 a potential combination agent with other RAS/MAPK pathway targeting compounds in our pipeline, as well as with standard of care agents.

Preclinical profile of ERAS-601

In a biochemical assay, ERAS-601 potently and selectivity inhibited full length SHP2 with an IC50 value of 4.6 nM as shown in the table on the left below. By binding to an allosteric pocket that is present only in the inactive conformation of SHP2, ERAS-601 inhibited SHP2 activity by stabilizing the protein in the inactive state. No ERAS-601 activity was observed against 10 other phosphatases (including SHP1), and ERAS-601 showed no strong inhibition of any kinase in a 300-kinase panel (i.e., less than 30% inhibition at 1 µM), demonstrating high selectivity as shown in the table on the right below.

Biochemical on-target activity of ERAS-601 against SHP2 (left) and biochemical activity of ERAS-601 in a panel of 12 phosphatases (right). PTPN11 (SHP2) catalytic domain protein is a truncated form of SHP2 (246 aa – 593 aa). This truncated form contains a phosphatase domain and is missing two regulatory domains. The PTPN11 (SHP2) catalytic domain does not harbor the binding site of ERAS-601 due to these missing domains, while the PTPN11 (SHP2) full length protein does harbor ERAS-601’s binding site.

The ADME/PK properties of ERAS-601 have been extensively evaluated in non-clinical studies. As shown in the table below, ERAS-601 demonstrated favorable physicochemical and PK properties, including low risk of drug-drug interaction (DDI), negligible CYP enzyme inhibition, and moderate plasma protein binding. It also showed high oral bioavailability and low clearance across multiple animal species. We believe these properties support ERAS-601’s development in a broad range of combination therapies.

Preclinical anti-tumor activity of ERAS-601

As shown in the table below, ERAS-601 significantly inhibited tumor growth as a monotherapy in 18 in vivo models, including HPV-negative, triple wildtype, KRAS G12D, KRAS G12V, EGFR amplified, BRAF Class I and III, and NF1 loss-of-function mutations. In 13 models, ERAS-601 was administered at QD and BID dose schedules. Both dose schedules were well tolerated and showed significant TGI. In a PK/PD study, ERAS-601 also achieved time and dose-dependent increases in plasma concentrations and concomitant reductions in RAS/MAPK pathway signaling, as measured by pERK, in the KRAS G12C-mutated NSCLC xenograft model NCI-H358. Tumor pERK1/2 levels were reduced by more than 50% when ERAS-601 total plasma concentrations exceeded or approximated the IC50/fu, which is the in vitro cellular pERK IC50 unbound fraction in plasma.

ERAS-601 exhibited significant TGI relative to vehicle control (p-value < 0.05) in two HPV-negative, three triple wildtype (KRAS/NRAS/BRAF wildtype), five KRAS mutant, one EGFR amplified, three BRAF mutant, and four NF1 LOF mutant CDX and PDX models. Significant TGI was observed at both 30 mg/kg QD and 10 mg/kg BID doses. *p-value < 0.05 **p-value < 0.01 ***p-value < 0.001 (p-values assessed relative to vehicle control)

Preclinical activity of ERAS-601 combination therapies

As shown in the figures below, when combined with an EGFR inhibitor, ERAS-601 showed significantly greater TGI than dosing of these inhibitors as monotherapies. This benefit was observed in models that harbored mutations both upstream and downstream of SHP2. These ERAS-601 combinations were generally well tolerated across the tested models as demonstrated by the minimal percentage body weight changes observed.

ERAS-601 combined with cetuximab showed significant TGI in four CDX and PDX models. The ERAS-601 and cetuximab (EGFR inhibitor) combination showed TGI in two HPV-negative HNSCC CDX and PDX models and two triple wildtype (KRAS/NRAS/BRAF wildtype)CRC PDX models relative to vehicle control (p-value < 0.01) and superior TGI to cetuximab monotherapy treatment.

Development strategy for ERAS-601

Our development plan aims to advance ERAS-601 in combination with other targeted agents to prevent and overcome adaptive resistance mechanisms in order to achieve more durable clinical benefit. Given the wide range of cancers that are dependent on SHP2, we believe ERAS-601 could serve as a backbone for compelling combination therapies to prolong survival for patients.

MAPKlamp: our therapeutic strategy targeting proximal and distal nodes of the RAS/MAPK pathway

MAPKlamp is our novel approach targeting upstream and downstream nodes in the RAS/MAPK pathway designed to shut down, or "clamp," the signaling of various oncogenic drivers, such as RTKs, NF1, RAS, RAF, and MEK alterations trapped between inhibited nodes. With our MAPKlamp approach, we aim to induce tumor regression in RAS/MAPK pathway-driven cancers, while also blocking the main escape routes that lead to tumor resistance.

ERAS-4: our program targeting KRAS mutations beyond G12C

Nearly 2 million patients annually worldwide are affected by KRAS mutations other than KRAS G12C. For example, nearly 700,000 of these patients are affected by tumors that harbor KRAS G12D, which is the most prevalent KRAS mutation. Activating KRAS mutations beyond G12C result in hyperactive RAS/MAPK pathway signaling and are frequently observed in NSCLC, CRC, endometrial cancer, and pancreatic cancer. Our ERAS-4 program endeavors to develop small molecules that potently and selectively inhibit KRAS mutations beyond G12C, such as KRAS G12D and KRAS G12V. These inhibitors will prevent RAS-mediated signaling by locking mutant KRAS in the inactive GDP-bound state and/or obstructing mutant KRAS's ability to bind downstream effector proteins, such as BRAF and CRAF. We are accelerating advancement of this program by leveraging our in-house chemistry, biology, and structural biology expertise gained from working on our RAS-GDP and other RAS-GTP programs. We have generated multiple series of orally bioavailable pan-KRAS inhibitors with low nanomolar IC50 potencies in biochemical and cellular assays against KRAS G12D and KRAS G12V, with high selectivity against NRAS and HRAS. ERAS-11930, an ERAS-4 molecule, showed comparable in vivo activity, when administered orally at 150 mg/kg BID, to MRTX1133, when administered intraperitoneally (IP) at its MTD of 20 mg/kg BID. Though MRTX1133 was not orally bioavailable, it served as a relevant benchmark since we believed that it was considered one of the most potent S-IIP binding selective inhibitors of KRAS G12D currently in clinical development.

In vitro potency and rodent PK of four ERAS-4 compounds (teal) and three coopetitor compounds (blue). ERAS-4 showed sub-nanomolar binding affinities to KRAS G12D and KRAS WT, as measured by SPR. ERAS-4 molecules showed comparable inhibition of RAS/MAPK signaling and inhibition of cellular viability in the KRAS G12D PDAC cell line, HPAC, and the KRAS G12V CRC cell line, SW620. The ERAS-4 compounds showed promising oral bioavailability, exemplified by % F values > 10. ERAS-4 data were generated internally and coopetitor data were set forth in public disclosures. An asterisk indicates ranges that were generated in a G12X cell line panel.

ERAS-11930, orally administered at 150 mg/kg BID, achieved tumor regression in the KRAS G12D CDX PDAC model HPAC that was comparable to the maximum tolerated dose of MRTX1133 in mouse, non-orally administered (i.e., interperitoneal administration) at 20 mg/kg BID. ERAS-11930 showed dosed dependent activity, achieving 90% TGI at 50 mg/kg BID and 109% TGI (63% regression) at 150 mg/kg BID. MRTX1133 at 20 mg/kg BID, IP achieved

100% TGI (3% regression). Both ERAS-11930 doses were well tolerated throughout the treatment period of 28 days, as demonstrated by no body weight loss or health observations.

ERAS-12: our EGFR D2/D3 bispecific antibody program

Inhibition of wildtype EGFR signaling mediated by overexpression of EGFR has shown promise in treating various tumors, including HNSCC and CRC. In tumors where overexpression of EGFR is thought to be the primary driver of EGFR signaling, an antibody-based approach is the most effective way to target the receptor, and approved antibodies have demonstrated good tolerability as well as activity by inhibiting EGFR activation and mediating antibody-dependent cellular cytotoxicity, a process by which the antibody alerts the immune system to attack the bound tumor cell. However, all approved anti-EGFR antibodies target domain III (D3) only, which is the inactive conformation of wildtype EGFR, and no approved antibodies target domain II (D2), which is the active, ligand binding, conformation of wildtype EGFR. Antibodies targeting D2 are expected to be more effective when epidermal growth factor (EGF) or other members of the EGF family are overexpressed.

We are developing a bispecific antibody that is active against both the inactive and active conformations of wildtype EGFR.

Diagram (A) visualizes the EGFR antibody ER-2a binding to the extracellular domain II of EGFR wildtype (purple), which is accessible when EGFR is in the active state. EGFR assumes an active state conformation when its ligand is bound (the bound ligand is shown in blue). Diagram (B) visualizes the EGFR antibody ER-3a binding to the extracellular domain III of EGFR wildtype (purple), which is accessible when EGFR is in the inactive state. In the rectangle, the portion of ER-2b that recognizes domain II of EGFR and the portion of ER-3b that recognizes domain III of EGFR are combined into a bispecific antibody that binds EGFR in both states.

By binding to EGFR in the active D2 state, our D2/D3 bispecific antibody can likely better prevent EGFR dimerization and can potentially achieve higher levels of EGFR inhibition than currently approved EGFR antibodies. Achieving a higher level of EGFR inhibition may better control tumor growth and delay the emergence of resistance mechanisms involving EGFR that spends more time in the active conformation.

Targeting D2 via the ER-3a/2a and ER-2a antibodies show a concentration-dependent inhibition of cancer cell proliferation.

The bispecific antibody ER-3a/ER-2a and EGFR active state-binding antibody ER-2a inhibited cell growth in FaDu, an HNSCC cell line, and HCT-8, a CRC cell line, and the NSCLC cell line H1975. FaDu and HCT-8 expressed wildtype EGFR and H1975 expressed EGFR with two kinase domain mutations, L858R and T790M. EGFR’s ligand, EGF, was added to these cells to further stimulate EGFR activity and model environments where EGF is expressed. As expected, only the two antibodies that recognized the active state of EGFR, ER-3a/ER-2a, inhibited the proliferation of all three cell lines, as indicated by a reduced confluency percentage.

Our acquisition and license agreements

Novartis

In December 2022, we entered into an exclusive license agreement (as amended, the Novartis Agreement) with Novartis under which we were granted an exclusive, worldwide, royalty-bearing license to certain patent and other intellectual property rights owned or controlled by Novartis to develop, manufacture, use, and commercialize naporafenib in all fields of use. We have the right to sublicense (through multiple tiers) our rights under the Novartis Agreement, subject to certain limitations and conditions, and are required to use commercially reasonable efforts to commercialize licensed products in certain geographical markets.

The license granted under the Novartis Agreement is subject to Novartis’ reserved right to: (i) develop, manufacture, use, and commercialize compounds unrelated to naporafenib under the licensed patent rights and know-how, (ii) use the licensed patent rights and know-how for non-clinical research purposes, and (iii) use the licensed patent rights and know-how to the extent necessary to perform ongoing clinical trials and its obligations under existing contracts and under the Novartis Agreement.

Under the Novartis Agreement, we made an upfront cash payment to Novartis of $20 million and issued 12,307,692 shares of our common stock to Novartis. We are obligated to make future regulatory milestone payments of up to $80 million and sales milestone payments of up to $200 million. We are also obligated to pay royalties on net sales of all licensed products, in the low-single digit percentages, subject to certain reductions.

The Novartis Agreement will expire upon the last to expire royalty term, which is determined on a licensed product-by-licensed product and country-by-country basis, and is the later of: (i) ten years from the date of first commercial sale for the licensed product in such country, (ii) the last to expire valid claim within the licensed patent rights covering such licensed product, or (iii) the expiration of all regulatory exclusivity for the licensed product in such country. Upon expiration of the Novartis Agreement, on a licensed product-by-licensed product and country-by-country basis, we will have a fully paid-up, perpetual, and irrevocable license to develop, manufacture, use, and commercialize the licensed products.

The Novartis Agreement may be terminated in its entirety by either party in the event of an uncured material breach by the other party. Novartis may terminate the Novartis Agreement upon written notice in the event we become subject to specified bankruptcy, insolvency, or similar circumstances. We may terminate the Novartis Agreement in its entirety at any time upon the provision of prior written notice to Novartis.

Upon termination of the Novartis Agreement for any reason, all rights and licenses granted to us will terminate. In addition, upon termination of the Novartis Agreement for any reason other than its natural expiration, Novartis has an option to negotiate a license under any patent rights, know-how, or other intellectual property rights relating to the licensed products that are owned or controlled by us for the purpose of developing, manufacturing and commercializing the licensed products on terms to be negotiated between the parties.

Asana BioSciences

In November 2020, we entered into an agreement and plan of merger with Asana and ASN Product Development, Inc. (ASN) (the Asana Merger Agreement), pursuant to which ASN became our wholly-owned subsidiary. Asana and ASN had previously entered into a license agreement, which was amended and restated prior to the closing of the merger transaction (the Asana License Agreement, and collectively with the Asana Merger Agreement, the Asana Agreements), pursuant to which ASN acquired an exclusive, worldwide license to certain intellectual property rights relating to inhibitors of ERK1 and ERK2 owned or controlled by Asana to develop and commercialize ERAS-007 and certain other related compounds for all applications. We have the right to sublicense (through multiple tiers) the licensed rights under the Asana Agreements, subject to certain conditions. The foregoing license is subject to Asana’s non-exclusive right to practice the licensed rights to research and conduct preclinical pharmacology activities with a specified combination of compounds, subject to certain specified conditions. Pursuant to the Asana License Agreement, neither Asana nor ASN can directly or indirectly exploit certain classes of competing products, subject to specified exceptions. In addition, we are required to use commercially reasonable efforts to develop and obtain regulatory approval for ERAS-007 in the United States, at least one major market country in Europe, and either China or Japan.

Under the Asana Merger Agreement, we made an upfront payment of $20 million and issued 4,000,000 shares of our Series B-2 convertible preferred stock to Asana. In connection with our IPO, these shares of Series B-2 convertible preferred stock were converted into 3,333,333 shares of our common stock. We are obligated to make future development and regulatory milestone cash payments for a licensed product in an amount of up to $90 million. Additionally, upon achieving a development milestone related to demonstration of successful proof-of-concept in a specified clinical trial, we will be required to issue 3,888,889 shares of our common stock to Asana. We are not obligated to pay royalties on the net sales of licensed products.

Upon our payment to Asana of all merger consideration, including upfront cash and equity payments, the milestone payments, the equity payment related to the proof-of-concept development milestone, and all other development milestone payments, with the exception of a specific milestone that does not need to be achieved at such time and will remain subject to payment in the event that such milestone occurs at a later time, all licensed rights will become fully paid-up, perpetual, and irrevocable. The License Agreement may be terminated by either Asana or us in the event of an uncured material breach by the other party. Asana also has the right to terminate the Asana License Agreement if we fail to engage in material activities in support of clinical development and commercialization of ERAS-007 for a period of 12 consecutive months, excluding reasons outside of our reasonable control and subject to certain limitations. However, Asana’s right to terminate the Asana License Agreement for any reason ends once we have paid to Asana all merger consideration, or if Asana’s equity interest in us is publicly traded and exceeds a certain threshold value. We may terminate the Asana License Agreement at any time upon the provision of prior written notice to Asana.

Katmai Pharmaceuticals

In March 2020, we entered into a license agreement (the Katmai Agreement) with Katmai Pharmaceuticals, Inc. (Katmai) under which we were granted an exclusive, worldwide, royalty-bearing license to certain patent rights and know-how controlled by Katmai related to the development of small molecule therapeutic and diagnostic products that modulate EGFR and enable the identification, diagnosis, selection, treatment, and/or monitoring of patients for neuro-oncological applications to develop, manufacture, use, and commercialize ERAS-801 and certain other related compounds in all fields of use. We have the right to sublicense (through multiple tiers) our rights under the Katmai Agreement, subject to certain limitations and conditions, and are required to use commercially reasonable efforts to develop, manufacture, and commercialize licensed products and to meet certain specified development and launch milestones by certain dates. We are obligated to use commercially reasonable efforts to develop the licensed products first for use within the neuro-oncology field before expanding our development efforts to include other indications in the oncology field. Following the first achievement of a clinical proof-of-concept for any indication, we have the right to submit a non-binding offer to Katmai for: (i) the purchase of all licensed patent rights, know-how, and other assets owned by Katmai that are necessary or useful for the exploitation of the licensed products, or (ii) for the purchase of Katmai. Pursuant to the Katmai Agreement, neither Katmai nor we can directly or indirectly exploit certain specified classes of competing products.

The license granted under the Katmai Agreement is subject to The Regents of the University of California’s reserved right to: (i) use the licensed patent rights and know-how for educational and non-commercial research purposes, and to publish results arising therefrom, and (ii) grant licenses to the licensed know-how to third parties without notice because the licensed know-how is non-exclusively licensed to Katmai by The Regents of the University of California. Further, the license granted under the Katmai Agreement is subject to the rights of the United States government under the Bayh-Dole Act, including: (i) a non-exclusive, non-transferable, irrevocable, paid-up license to practice or have practiced the invention claimed by the licensed patent rights throughout the world, and (ii) the obligation that any licensed products used or sold in the United States be manufactured substantially in the United States.

Under the Katmai Agreement, we made an upfront payment of $5.7 million and Katmai agreed to purchase shares of our Series B-1 convertible preferred stock and Series B-2 convertible preferred stock having an aggregate value of $2.7 million. In connection with our IPO, these shares of Series B-1 convertible preferred stock and Series B-2 convertible preferred stock were converted into 395,555 shares of our common stock, in the aggregate. We are obligated to make future development and regulatory milestone payments of up to $26 million, of which $2 million was paid in March 2022, and commercial milestone payments of up to $101 million. We are also obligated to pay tiered royalties on net sales of each licensed product, at rates ranging from the mid- to high-single digit percentages, subject to a minimum annual royalty payment in the low six figures and certain permitted deductions.

Our royalty obligations and the Katmai Agreement will expire, on a licensed product-by-licensed product and country-by-country basis, on the earlier of: (i) the ten-year anniversary of the expiration of all valid claims included in the licensed patents covering the composition of matter or method of use of such licensed product in such country, or (ii) the twentieth anniversary of the first commercial sale of such licensed product in such country. Upon the expiration of the Katmai Agreement, we will have a fully paid-up and irrevocable license.

The Katmai Agreement may be terminated in its entirety by either party: (i) in the event of an uncured material breach by the other party, or (ii) in the event the other party becomes subject to specified bankruptcy, insolvency, or similar circumstances. Provided that we are in full compliance with the Katmai Agreement, we may terminate the Katmai Agreement upon written notice to Katmai. Upon termination of the Katmai Agreement for any reason, all rights and licenses granted to us thereunder will terminate. Upon termination of the Katmai Agreement, we are obligated, among other things, to: (i) grant an exclusive license to Katmai under all of our right, title and interest in all inventions and know-how developed under the Katmai Agreement existing at the time of termination that are specific to the licensed compounds or products, including without limitation all data and results related to their exploitation, and (ii) transfer to Katmai ownership and possession of all regulatory filings related to the licensed compounds and products. Unless the Katmai Agreement is terminated for our material breach, the parties will negotiate in good faith the financial terms pursuant to which the foregoing actions will be conducted, provided that our performance of such actions may not be conditioned upon the conduct or completion of such negotiations. If the parties are unable to agree upon such terms within the specified time period, then the parties will submit all unresolved matters for resolution by arbitration.

NiKang Therapeutics

In February 2020, we entered into a license agreement (the NiKang Agreement) with NiKang Therapeutics, Inc. (NiKang) under which we were granted an exclusive, worldwide license to certain intellectual property rights owned or controlled by NiKang related to certain SHP2 inhibitors to develop and commercialize ERAS-601 and certain other related compounds for all applications. We have the right to sublicense (through multiple tiers) our rights under the NiKang Agreement, subject to certain conditions, and are required to use commercially reasonable efforts to develop and commercialize licensed products. The parties are obligated to negotiate in good faith for a certain period of time to grant NiKang the exclusive commercial distribution rights in greater China once a licensed product reaches a certain development stage.

Under the NiKang Agreement, we made an upfront payment of $5 million to NiKang and reimbursed NiKang $0.4 million for certain initial manufacturing costs. In addition, we paid an additional $7 million after publication of a US patent application that covered the composition of matter of ERAS-601. We are also obligated to pay (i) development and regulatory milestone payments in an aggregate amount of up to $16 million for the first licensed product, of which $4.0 million was paid in January 2021, and $12 million for a second licensed product, and (ii) commercial milestone payments in an aggregate amount of up to $157 million for the first licensed product and $151 million for a second licensed product. We are also obligated to: (i) pay tiered royalties on net sales of all licensed products in the mid-single digit percentages, subject to certain reductions; and (ii) equally split net sublicensing revenues earned under sublicense agreements that we enter into with any third party before commencement of the first Phase I clinical trial for a licensed product.

The NiKang Agreement will expire upon the last to expire royalty term, which is determined on a licensed product-by-licensed product and country-by-country basis, and is the later of: (i) ten years from the date of first commercial sale, (ii) the last to expire valid claim within the licensed patent rights covering such licensed product, or (iii) the expiration of all regulatory exclusivity for the licensed product in such country. Upon expiration of the NiKang Agreement, on a licensed product-by-licensed product and country-by-country basis, we will have a fully paid-up, non-exclusive license to conduct research and to develop and commercialize the licensed products.

The NiKang Agreement may be terminated in its entirety by NiKang in the event of our uncured material breach, which includes our failure to use commercially reasonable efforts to satisfy certain specified clinical development diligence milestones. In addition, NiKang may terminate if we, directly or indirectly, commence a legal action challenging the validity or enforceability of any licensed patents. Further, if we acquire more than 50% of the equity or assets of a company that owns a competing small molecule that is designed to prevent the same target as set forth in the NiKang Agreement from switching to an enzymatically active state, then we must either divest such competing product or terminate the NiKang Agreement. We may terminate the NiKang Agreement at any time upon the provision of prior written notice to NiKang. Upon termination of the NiKang Agreement for any reason, all rights and licenses granted to us, as well as any sublicenses that we granted thereunder, will terminate. In addition, upon any termination (but not expiration) of the NiKang Agreement and upon NiKang’s request, the parties are obligated to meet and negotiate in good faith the terms of a license from us to NiKang to allow NiKang’s continued development, manufacture, and commercialization of the licensed products.

Emerge Life Sciences

In March 2021, we entered into an asset purchase agreement (the ELS Purchase Agreement) with Emerge Life Sciences, Pte. Ltd. (ELS) wherein we purchased all rights, title, and interest (including all patent and other intellectual property rights) to ELS’s EGFR antibodies directed against the EGFR domain II (EGFR-D2) and domain III (EGFR-D3) as well as a bispecific antibody where one arm is directed against EGFR-D2 and the other is directed against EGFR-D3 (the Antibodies). Under the ELS Purchase Agreement, we issued 500,000 shares of our common stock to ELS and made an upfront payment of $2 million. We are not obligated to pay royalties on the net sales of products covered by the acquired intellectual property. Under the ELS Purchase Agreement, ELS is committed to performing certain studies on the Antibodies to assist in development activities, the costs of which shall be mutually agreed upon and for which we will be responsible.

Pursuant to the ELS Purchase Agreement, at any time between 12 months and 36 months after the effective date of the ELS Purchase Agreement, if we reasonably determine that none of the Antibodies should be taken into human clinical trials due to safety, efficacy or CMC issues, then we have the option to select another antibody developed and solely owned by ELS that is not the subject of a license, collaboration, or option to a third party (the Option). If we elect to exercise the Option, then ELS will provide us with a list of all available antibodies that meet the aforementioned requirements, and we have the right to select one antibody from the list. Upon our selection of an antibody, ELS will assign us all rights, title and interest to such antibody (including patent and other intellectual property rights) subject to any pre-existing obligations or restrictions. In the event that we wish to have ELS conduct any studies on such optioned antibody, then after mutual agreement as to the scope of the studies, we will be responsible for the cost for such studies.

Commercialization

We intend to maintain exclusive worldwide development and commercialization rights to our product candidates (excluding programs in our pipeline that arise from an investment made by Erasca Ventures in a third party) and, if marketing approval is obtained, to commence commercialization activities by building a focused sales and marketing organization to sell our products on our own in the United States and potentially other regions such as Europe. We will likely seek commercialization partnerships for our product candidates in other regions beyond the United States and Europe. We currently have no sales, marketing, or commercial product distribution capabilities. We intend to build the necessary infrastructure and capabilities over time for commercialization in the United States and potentially other regions, following further advancement of our product candidates. Clinical data, the size of the addressable patient population, the size of the commercial infrastructure and manufacturing needs, and the status of our pipeline, may all influence or alter our commercialization plans.

Competition + Cooperation (“Coopetition”)

Although the biotechnology and pharmaceutical industries, and the oncology sector, are characterized by rapid evolution of technologies, fierce competition, and strong defense of intellectual property rights, we believe the most fearsome competitor of all is cancer itself. As such, we view other companies in this sector more as potential allies and collaborators than as competitors, as we all have a common cause: to defeat cancer. Many of the companies that are developing or marketing treatments for cancer, including major pharmaceutical and biotechnology companies that are working on therapies targeting the RAS/MAPK pathway, are companies with whom we endeavor to collaborate in our mission to erase cancer.

Collaborating with these companies alleviates some of the traditional challenges that emerging companies face with respect to financial resources, established presence in the market, expertise in research and development, manufacturing, preclinical and clinical testing, obtaining regulatory approvals and reimbursement, and marketing approved products. Similarly, recruiting and retaining qualified scientific and management personnel, establishing clinical trial sites and patient registration for clinical trials, as well as in acquiring technologies complementary to, or necessary for, programs are challenges for all companies developing or marketing treatments for cancer.

That said, our commercial potential could be reduced or eliminated if other companies develop and commercialize products that are safer, more effective, have fewer or less severe side effects, are more convenient or are less expensive than products that we may develop. Other companies also may obtain FDA or other regulatory approval for their products more rapidly than we may obtain approval for ours, which could result in these companies establishing a strong market position before we are able to enter the market or make our development more complicated.

There are numerous companies developing or marketing treatments for cancer, including many major pharmaceutical and biotechnology companies. These treatments consist of small molecule drug products, biologics, cell-based therapies, and traditional chemotherapy. There are also a number of pharmaceutical companies with product candidates in development that target the nodes involving the RAS/MAPK pathway. These include, among others, Amgen, AstraZeneca, Black Diamond Therapeutics, BioMed Valley Discoveries, Boehringer Ingelheim, BridgeBio, Bristol Myers Squibb, Deciphera Pharmaceuticals, Eli Lilly, Jacobio Pharmaceuticals, Janssen, Merck, Novartis, Pfizer, Revolution Medicines, Roche/Genentech, and Sanofi.

Intellectual property

We strive to protect the proprietary technology, inventions, and improvements that are commercially or strategically important to our business, including seeking, maintaining, and defending patent rights, whether developed internally or in-licensed/acquired from third parties. We also rely on trade secrets and know-how relating to our proprietary technology and product candidates and continuing innovation to develop, strengthen and maintain our proprietary position. We also plan to rely on data exclusivity, market exclusivity and patent term adjustments or extensions when available. Our commercial success will depend in part on our ability to obtain and maintain patent and other intellectual property protection for our proprietary technology, inventions and improvements; to preserve the confidentiality of our trade secrets; to defend and enforce our proprietary rights, including any patents or trademarks that we may own in the future; and to operate without infringing on the valid and enforceable patents and other proprietary rights of third parties. Intellectual property rights may not address all potential threats to our competitive advantage.

We continually assess and refine our intellectual property strategy as we develop new product candidates. To that end, we are prepared to file additional patent applications in any appropriate fields if our intellectual property strategy includes such filings, or where we seek to adapt to competition or seize business opportunities. Further, we are prepared to file patent applications, as we consider appropriate under the circumstances, relating to the new technologies that we develop.

We cannot be sure that patents will be granted with respect to any of our pending patent applications or with respect to any patent applications we may own or license in the future, nor can we be sure that any of our existing patents or any patents we may own or license in the future will be useful in protecting our technology.

As of December 31, 2023, our patent estate for the programs listed below, which consists of owned and in-licensed patent families, includes seventeen issued US patents, twenty-five pending US non-provisional patent applications, eight pending US provisional patent applications, one hundred seventy-seven issued foreign patents, ten pending international patent applications filed under the Patent Cooperation Treaty (PCT application), and two hundred nine pending foreign patent applications in various markets outside of the United States. In particular, we have patents and/or patent applications pending for each of our product candidates.

Naporafenib

As of December 31, 2023, we have in-licensed ten patent families from Novartis. The ten patent families relate to RAF inhibitors, their preparation, and methods of use. One of the families covers the naporafenib product candidate compound and additional RAF inhibitor compounds, their preparation and methods of use, and includes four issued US patents, eighty-six issued foreign patents, and five pending foreign patent applications. The nine additional in-licensed families cover further methods of using naporafenib, diagnostic methods, and additional RAF inhibitor compounds, their preparation and methods of use, and include four issued US patents, six pending US non-provisional applications, two pending PCT patent applications, forty issued foreign patents, and sixty-three pending foreign patent applications. The granted patents and any further patents that issue from applications from the ten in-licensed families are expected to expire between 2034 and 2043, absent any patent term adjustments or extensions.

As of December 31, 2023, we own two patent families relating to naporafenib and their methods of use and include two pending US provisional patent applications, two pending PCT patent applications and two pending foreign patent applications. Any patents issued from these patent applications are expected to expire in 2044, absent any patent term adjustments or extensions.

ERAS-007

As of December 31, 2023, we have in-licensed three patent families from Asana. The three patent families relate to ERK 1/2 inhibitors, their preparation, and methods of use. One of the families covers the ERAS-007 product candidate compound and additional ERK1/2 inhibitor compounds, their preparation and methods of use, and includes four issued US patents, one pending US non-provisional patent application, forty-six issued foreign patents, and eight pending foreign patent applications. The additional in-licensed families cover methods of using ERAS-007 and include two pending US non-provisional patent applications and twelve pending foreign patent applications. The granted patents and any further patents that issue from applications from the three in-licensed families are expected to expire between 2036 and 2042, absent any patent term adjustments or extensions.

As of December 31, 2023, we also own six patent families relating to ERAS-007. The patent families include five pending US non-provisional patent applications, one pending PCT patent application and thirty-two foreign pending patent applications. Any patents issued from these patent applications are expected to expire between 2042 and 2043, absent any patent term adjustments or extensions.

ERAS-801

As of December 31, 2023, we have sub-licensed four patent families from Katmai, which Katmai in-licensed from the University of California, Los Angeles (UCLA). One of the families covers the ERAS-801 product candidate compound and additional EGFR inhibitor compounds, their preparation and methods of use, and includes one issued US patent, one pending US non-provisional patent application, one issued foreign patent, and twenty-six pending foreign patent applications. The three additional in-licensed families relate to additional EGFR inhibitor compounds, their preparation and methods of use, and include three pending US non-provisional patent applications and ten pending foreign patent applications. The granted patent and any further patents that issue from applications from the four in-licensed patent families are expected to expire between 2038 and 2041, absent any patent term adjustments or extensions.

As of December 31, 2023, we co-own with UCLA one patent family, relating to additional EGFR inhibitor compositions, their preparation and methods of use. This patent family includes one pending US non-provisional patent application. Any patents issued from this application are expected to expire in 2041, absent any patent term adjustments or extensions.

As of December 31, 2023, we own two patent families relating to EGFR inhibitor polymorph forms and methods of using EGFR inhibitor compositions. These patent families include one pending US provisional patent application and one pending PCT patent application. Any patents issued from these applications are expected to expire between 2042 and 2044, absent any patent term adjustments or extensions.

ERAS-601

As of December 31, 2023, we have in-licensed two patent families from NiKang. These two patent families relate to SHP2 inhibitor compositions, their preparation, and methods of use. One of the families covers the ERAS-601 product candidate compound, its preparation and methods of use, and includes three issued US patents, one pending US non-provisional patent application, three issued foreign patents and twenty-three pending foreign patent applications. The second family covers additional SHP2 inhibitor compositions, their preparation and methods of use, and includes one issued US patent application, one issued foreign patent and six pending foreign patent applications. The granted patents and any further patents that issue from applications from the two in-licensed families are expected to expire in 2039, absent any patent term adjustments or extensions.

As of December 31, 2023, we also own six patent families relating to ERAS-601 and their methods of use, and include four pending US non-provisional patent applications, two pending PCT applications and nineteen pending foreign patent applications. Any patents issued from these applications are expected to expire between 2041 and 2042, absent any patent term adjustments or extensions.

ERAS-4

As of December 31, 2023, we own three patent families relating to KRAS inhibitors, their preparation, and methods of use. These patent families include five pending US provisional patent applications, one pending PCT application, and one pending foreign patent application. Any patents issued from these applications are expected to expire between 2042 and 2044, absent any patent term adjustments or extensions.

ERAS-12

As of December 31, 2023, we own two patent families relating to EGFR antibodies, their preparation, and methods of use. The patent families include one pending US non-provisional patent application, one pending PCT patent application and two pending foreign patent applications. Any patents issued from these applications are expected to expire between 2042 and 2043, absent any patent term adjustments or extensions.

Other IP programs or patents

With respect to our product candidates and processes we intend to develop and commercialize in the normal course of business, we intend to pursue patent protection covering, when possible, compositions, methods of use, dosing and formulations. We may also pursue patent protection with respect to manufacturing and drug development processes and technologies. Obtaining and maintaining patent protection depends on compliance with various procedural, document submission, fee payment, and other requirements imposed by governmental patent agencies. We may not be able to obtain patent protections for our compositions, methods of use, dosing and formulations, manufacturing and drug development processes and technologies throughout the world. Issued patents can provide protection for varying periods of time, depending upon the date of filing of the patent application, the date of patent issuance and the legal term of patents in the countries in which they are obtained. In general, patents issued for applications filed in the United States can provide exclusionary rights for 20 years from the earliest effective filing date. In addition, in certain instances, the term of an issued US patent that covers or claims an FDA-approved product can be extended to recapture a portion of the term effectively lost as a result of the FDA regulatory review period, which is called patent term extension. The restoration period cannot be longer than five years and the total patent term, including the restoration period, must not exceed 14 years following FDA approval. The US Patent and Trademark Office (USPTO) may also adjust the term of a US patent to accommodate for delays caused by the USPTO during the prosecution of a US patent application. Congress has defined the conditions upon which an applicant can receive an adjustment to the term and such requirements are established in 35 USC 154(b). Similar provisions are available in Europe and other jurisdictions to extend the term of a patent that covers an approved drug. The term of patents outside of the United States varies in accordance with the laws of the foreign jurisdiction, but typically is also 20 years from the earliest effective filing date. However, the actual protection afforded by a patent varies on a product-by-product basis, from country-to-country, and depends upon many factors, including the type of patent, the scope of its coverage, the availability of regulatory-related extensions, the availability of legal remedies in a particular country, and the validity and enforceability of the patent. Patent terms may be inadequate to protect our competitive position on our products for an adequate amount of time. In the future, if and when our therapeutic candidates receive FDA approval, we expect to apply for patent term extensions on patents covering those therapeutic candidates. We intend to seek patent term extensions in any jurisdiction where these are available and where we also have a patent that may be eligible; however, there is no guarantee that the applicable authorities, including the USPTO and FDA, will agree with our assessment of whether such extensions should be granted, and even if granted, the length of such extensions.

The patent positions of companies like ours are generally uncertain and involve complex legal and factual questions. No consistent policy regarding the scope of claims allowable in patents in the field of biopharmaceuticals has emerged in the United States. The relevant patent laws and their interpretation outside of the United States is also uncertain. Changes in either the patent laws or their interpretation in the United States and other countries may diminish our ability to protect our technology or product candidates and could affect the value of such intellectual property. In particular, our ability to stop third parties from making, using, selling, offering to sell or importing products that infringe our intellectual property will depend in part on our success in obtaining and enforcing patent claims that cover our technology, inventions and improvements. We cannot guarantee that patents will be granted with respect to any of our pending patent applications or with respect to any patent applications we may file in the future, nor can we be sure that any patents that may be granted to us in the future will be commercially useful in protecting our products, the methods of use or manufacture of those products. Moreover, even our issued patents do not guarantee us the right to practice our technology in relation to the commercialization of our products. Patent and other intellectual property rights in the pharmaceutical and biotechnology space are evolving and involve many risks and uncertainties. For example, third parties may have blocking patents that could be used to prevent us from commercializing our product candidates and practicing our proprietary technology, and our issued patents may be challenged, invalidated or circumvented, which could limit our ability to stop competitors from marketing related products or could limit the term of patent protection that otherwise may exist for our product candidates. In addition, the scope of the rights granted under any issued patents may not provide us with protection or competitive advantages against competitors with similar technology. Furthermore, our competitors may independently develop similar technologies that are outside the scope of the rights granted under any issued patents. For these reasons, we may face competition with respect to our product candidates. Moreover, because of the extensive time required for development, testing and regulatory review of a potential product, it is possible that, before any particular product candidate can be commercialized, any patent protection for such product may expire or remain in force for only a short period following commercialization, thereby reducing the commercial advantage the patent provides.

We also rely on trade secrets to protect aspects of our technology and business not amenable to, or that we do not consider appropriate for, patent protection. We seek to protect this intellectual property, in part, by requiring our employees, consultants, outside scientific collaborators, sponsored researchers and other service providers and advisors to execute confidentiality agreements upon the commencement of employment or other relationship with us. In general, these agreements provide that confidential information concerning our business or financial affairs developed or made known to the individual during the course of the individual’s relationship with us is to be kept confidential and not disclosed to third parties except in specific circumstances. In the case of employees, the agreements further provide that inventions and discoveries conceived or reduced to practice by the individual that are related to our business, or actual, or demonstrably anticipated, research or development, or made during normal working hours, on our premises or using our equipment, supplies, or proprietary information, are our exclusive property. In many cases our agreements with consultants, outside scientific collaborators, sponsored researchers and other service providers and advisors require them to assign, or grant us licenses to, inventions resulting from the work or services they render under such agreements or grant us an option to negotiate a license to use such inventions.

We seek trademark protection in the United States and in certain other jurisdictions where available and when we deem appropriate. We currently have an issued United States trademark for our “ERASCA” mark and have registrations for such mark pending in foreign jurisdictions, including the European Union. We have also filed a trademark application in the United States as well as foreign jurisdictions, including the European Union, for registration of our “MAPKLAMP” mark.

Manufacturing

We do not own or operate, and currently have no plans to establish, any manufacturing facilities. We rely, and expect to continue to rely, on third parties for the manufacture of our product candidates for preclinical and clinical testing, as well as for commercial manufacture if any of our product candidates obtain marketing approval. We are working with our current manufacturers to ensure that we will be able to scale up our manufacturing capabilities to support our clinical plans. We are also in the process of locating and qualifying additional manufacturers to build redundancies into our supply chain. In addition, we rely on third parties to package, label, store, and distribute our product candidates, and we intend to continue to rely on third parties with respect to our commercial products if marketing approval is obtained. We believe that this strategy allows us to maintain a more efficient infrastructure by eliminating the need for us to invest in our own manufacturing facilities, equipment, and personnel while also enabling us to focus our expertise and resources on the design and development of our product candidates.

Government Regulation

The FDA and comparable regulatory authorities in state and local jurisdictions and in other countries impose substantial and burdensome requirements upon companies involved in the clinical development, manufacture, marketing and distribution of drugs and biologics such as those we are developing. These entities regulate, among other things, the research and development, testing, manufacture, quality control, safety, effectiveness, labeling, storage, record keeping, approval, advertising and promotion, distribution, post-approval monitoring and reporting, sampling and export and import of our product candidates.

US regulation of drugs and biologics

In the United States, the FDA regulates drugs under the Federal Food, Drug, and Cosmetic Act (FDCA), and its implementing regulations, and biologics under the FDCA and the Public Health Service Act and their implementing regulations. FDA approval of a NDA or biologics license application (BLA) or supplement is required before any new unapproved drug, biologic or dosage form, including a new use of a previously approved drug or biologic, can be marketed in the United States.

The process required by the FDA before such product candidates may be marketed in the United States generally involves the following:

•

completion of extensive preclinical laboratory tests and preclinical animal studies, certain of which must be performed in accordance with applicable Good Laboratory Practice (GLP) regulations;

•

submission to the FDA of an investigational new drug application (IND) which must become effective before human clinical trials may be initiated and must be updated annually;

•

approval by an independent institutional review board (IRB) or ethics committee representing each clinical site before each clinical trial can be initiated;

•

performance of adequate and well-controlled human clinical trials in accordance with Good Clinical Practice (GCP) requirements to establish the safety and efficacy, or with respect to biologics, the safety, purity and potency of the product candidate for each proposed indication;

•

preparation of and submission to the FDA of an NDA or BLA, after completion of all pivotal clinical trials;

•

potential review of the product application by an FDA advisory committee, where appropriate and if applicable;

•

a determination by the FDA within 60 days of its receipt of an NDA or BLA to file the application for review;

•

satisfactory completion of an FDA pre-approval inspection of the manufacturing facilities where the proposed product drug substance is produced to assess compliance with current Good Manufacturing Practice requirements (cGMPs) and audits of selected clinical trial sites to ensure compliance with GCP; and

•

FDA review and approval of an NDA or BLA prior to any commercial marketing or sale of the drug in the United States.

Preclinical studies include laboratory evaluation of product chemistry, toxicity and formulation, as well asin vitro and animal studies to assess potential safety and efficacy. The conduct of preclinical studies is subject to federal regulations and requirements, including GLP regulations applicable to certain safety/toxicology studies.

An IND is a request for allowance from the FDA to administer an investigational drug product to humans. The central focus of an IND submission is on the general investigational plan and the protocol or protocols for preclinical studies and clinical trials. The IND also includes results of animal and in vitro studies assessing the toxicology, pharmacokinetics, pharmacology and pharmacodynamic characteristics of the product, chemistry, manufacturing and controls (CMC) information, and any available human data or literature to support the use of the investigational product. An IND must become effective before human clinical trials may be initiated. The IND automatically becomes effective 30 days after receipt by the FDA, unless the FDA, within the 30-day period, raises safety concerns or questions about the proposed clinical trial. In such a case, the IND may be placed on clinical hold and the IND sponsor and the FDA must resolve any outstanding concerns or questions before the clinical trial can be initiated. Submission of an IND therefore may or may not result in FDA allowance to initiate a clinical trial.

Clinical trials involve the administration of the investigational product to human subjects under the supervision of qualified investigators in accordance with GCP, which, among other things, includes the requirement that all research subjects, or their legal representative, provide their informed consent for their participation in any clinical trial. Clinical trials are conducted under protocols detailing, among other things, the inclusion and exclusion criteria, the objectives of the trial, the parameters to be used in monitoring safety and the effectiveness criteria to be evaluated. A separate submission to the existing IND must be made for each successive clinical trial conducted during product development and for any subsequent protocol amendments. While the IND is active, progress reports summarizing the results of the clinical trials and nonclinical studies performed since the last progress report, among other things, must be submitted at least annually to the FDA, and written IND safety reports must be submitted to the FDA and investigators for serious and unexpected suspected adverse events, findings from other studies suggesting a significant risk to humans exposed to the same or similar drugs or biologics, findings from animal orin vitro testing suggesting a significant risk to humans, and any clinically important increased incidence of a serious suspected adverse reaction compared to that listed in the protocol or investigator brochure.

Furthermore, an independent IRB for each site proposing to conduct the clinical trial must review and approve the plan for any clinical trial and its informed consent form before the clinical trial initiates at that site, and must monitor the trial until completed. An IRB is charged with protecting the welfare and rights of trial participants and considers such items as whether the risks to individuals participating in the clinical trials are minimized and are reasonable in relation to anticipated benefits. Regulatory authorities, the IRB or the sponsor may suspend a clinical trial at any time on various grounds, including a finding that the subjects are being exposed to an unacceptable health risk or that the trial is unlikely to meet its stated objectives. Some trials also include oversight by an independent group of qualified experts organized by the clinical trial sponsor, known as a data safety monitoring board or committee, which provides authorization for whether or not a trial may move forward at designated check points based on access to certain data from the trial and may recommend that the clinical trial be halted if it determines that there is an unacceptable safety risk for subjects or other grounds, such as no demonstration of efficacy. There are also requirements governing the reporting of clinical trials and clinical trial results to public registries.

The clinical investigation of a drug is generally divided into three phases. Although the phases are usually conducted sequentially, they may overlap or be combined.

•

Phase 1: The investigational product is initially introduced into healthy human subjects or patients with the target disease or condition. These trials are designed to test the safety, dosage tolerance, absorption, metabolism and distribution of the investigational product in humans, the side effects associated with increasing doses, and, if possible, to gain early evidence on effectiveness.

•

Phase 2: The investigational product is administered to a limited patient population with a specified disease or condition to evaluate the preliminary efficacy, optimal dosages and dosing schedule and to identify possible adverse side effects and safety risks. Multiple Phase 2 clinical trials may be conducted to obtain information prior to beginning larger and more expensive Phase 3 clinical trials.

•

Phase 3: The investigational product is administered to an expanded patient population to further evaluate dosage, to provide statistically significant evidence of clinical efficacy and to further test for safety, generally at multiple geographically dispersed clinical trial sites. These clinical trials are intended to establish the overall risk/benefit ratio of the investigational product and to provide an adequate basis for labeling.

Post-marketing trials, sometimes referred to as Phase 4 clinical trials, may be conducted after initial marketing approval. These clinical trials are used to gain additional experience from the treatment of patients in the intended therapeutic indication. In certain instances, such as with accelerated approval drugs, the FDA may mandate the performance of Phase 4 clinical trials as a condition of approval.

Concurrent with clinical trials, companies may complete additional animal studies and develop additional information about the biological characteristics of the product candidate, and must finalize a process for manufacturing the product in commercial quantities in accordance with cGMP requirements. The manufacturing process must be capable of consistently producing quality batches of the product candidate and, among other things, must develop methods for testing the identity, strength, quality and purity of the final product, or for biologics, the safety, purity and potency.

In addition, during the development of a new drug or biologic, sponsors are given opportunities to meet with the FDA at certain points. These points may be prior to submission of an IND, at the end of Phase 2, and before an NDA or BLA is submitted. Meetings at other times may be requested. These meetings can provide an opportunity for the sponsor to share information about the data gathered to date, for the FDA to provide advice, and for the sponsor and the FDA to reach agreement on the next phase of development.

NDA and BLA review process

Assuming successful completion of all required testing in accordance with all applicable regulatory requirements, the results of product development, including results from nonclinical studies and clinical trials are submitted to the FDA as part of an NDA or BLA requesting approval to market the product for one or more indications. The submission of an NDA or BLA requires payment of a substantial application user fee to the FDA, unless a waiver or exemption applies.

The NDA or BLA must include all relevant data available from pertinent preclinical studies and clinical trials, including negative or ambiguous results as well as positive findings, together with detailed information relating to the product’s CMC and proposed labeling, among other things. Data can come from company-sponsored clinical trials intended to test the safety and effectiveness of the product, or from a number of alternative sources, including trials initiated and sponsored by investigators.

In addition, under the Pediatric Research Equity Act (PREA), an NDA or BLA or supplement to an NDA or BLA must contain data to assess the safety and effectiveness of the biological product candidate for the claimed indications in all relevant pediatric subpopulations and to support dosing and administration for each pediatric subpopulation for which the product is safe and effective. The Food and Drug Administration Safety and Innovation Act requires that a sponsor who is planning to submit a marketing application for a drug or biological product that includes a new active ingredient, new indication, new dosage form, new dosing regimen or new route of administration submit an initial pediatric trial plan within sixty days after an end-of-Phase 2 meeting or as may be agreed between the sponsor and FDA. Unless otherwise required by regulation, PREA does not apply to any drug or biological product for an indication for which orphan designation has been granted.

Within 60 days following submission of the application, the FDA reviews the submitted BLA or NDA to determine if the application is substantially complete before the agency accepts it for filing. The FDA may refuse to file any NDA or BLA that it deems incomplete or not properly reviewable at the time of submission and may request additional information. In this event, the NDA or BLA must be resubmitted with the additional information. Once an NDA or BLA has been accepted for filing, the FDA’s goal is to review standard applications within ten months after the filing date, or, if the application qualifies for priority review, six months after the FDA accepts the application for filing. In both standard and priority reviews, the review process may also be extended for a three-month period by the FDA to review additional information deemed a major amendment to the application. Once accepted for filing, the FDA reviews an NDA to determine, among other things, whether a product is safe and effective for its intended use and whether its manufacturing is sufficient to assure and preserve the product’s identity, strength, quality and purity. The FDA reviews a BLA to determine, among other things, whether a product is safe, pure and potent and the facility in which it is manufactured, processed, packed or held meets standards designed to assure the product’s continued safety, purity and potency. When reviewing an NDA or BLA, the FDA may convene an advisory committee to provide clinical insight on application review questions. The FDA is not bound by the recommendations of an advisory committee, but it considers such recommendations carefully when making decisions.

Before approving an NDA or BLA, the FDA will typically inspect the facility or facilities where the product is manufactured. The FDA will not approve an application unless it determines that the manufacturing processes and facilities are in compliance with cGMP requirements and adequate to assure consistent production of the product within required specifications. Additionally, before approving an NDA or BLA, the FDA may inspect one or more clinical sites to assure compliance with GCP.

After the FDA evaluates the NDA or BLA and conducts inspections of manufacturing facilities where the investigational product and/or its drug substance will be produced, the FDA may issue an approval letter or a Complete Response Letter (CRL). An approval letter authorizes commercial marketing of the product with specific prescribing information for specific indications. A CRL signals that the review cycle is complete and the application cannot be approved in its present form. The CRL will generally describe all of the deficiencies that the FDA has identified in the NDA or BLA, except that where the FDA determines that the data supporting the application are inadequate to support approval, the FDA may issue the CRL without first conducting any required inspections, testing submitted product lots and/or reviewing proposed labeling. In issuing the CRL, the FDA may recommend actions that the applicant might take to place a resubmitted NDA or BLA in condition for approval, including requests for additional data, information or clarification. The FDA may delay or refuse approval of an NDA or BLA if applicable regulatory criteria are not satisfied, require additional testing or information and/or require post-marketing testing and surveillance to monitor safety or efficacy of a product.

If regulatory approval of a product is granted, such approval will be granted for particular indications and may entail limitations on the indicated uses for which such product may be marketed. For example, the FDA may approve the NDA or BLA with a Risk Evaluation and Mitigation Strategy (REMS) to ensure the benefits of the product outweigh its risks. A REMS is a safety strategy to manage a known or potential serious risk associated with a product and to enable patients to have continued access to such medicines by managing their safe use, and could include medication guides, physician communication plans, or elements to assure safe use, such as restricted distribution methods, patient registries and other risk minimization tools. The FDA also may condition approval on, among other things, changes to proposed labeling or the development of adequate controls and specifications. The FDA may also require one or more Phase 4 post-market trials and additional surveillance to further assess and monitor the product’s safety and effectiveness after commercialization, and may limit further marketing of the product based on the results of these post-marketing trials.

Expedited development and review programs

The FDA offers a number of expedited development and review programs for qualifying product candidates. For example, the fast track program is intended to expedite or facilitate the process for reviewing product candidates that meet certain criteria. Specifically, product candidates are eligible for FTD if they are intended to treat a serious or life-threatening disease or condition and demonstrate the potential to address unmet medical needs for the disease or condition. FTD applies to the combination of the product candidate and the specific indication for which it is being studied. The sponsor of a fast track product candidate has opportunities for more frequent interactions with the review team during product development and, once an NDA or BLA is submitted, the application may be eligible for priority review, if the relevant criteria are met. An NDA or BLA for a fast track product candidate may also be eligible for rolling review, where the FDA may consider for review sections of the NDA or BLA on a rolling basis before the complete application is submitted, if the sponsor provides a schedule for the submission of the sections of the NDA or BLA, the FDA agrees to accept sections of the NDA or BLA and determines that the schedule is acceptable, and the sponsor pays any required user fees upon submission of the first section of the NDA or BLA.

A product candidate intended to treat a serious or life-threatening disease or condition may also be eligible for breakthrough therapy designation to expedite its development and review. A product candidate can receive breakthrough therapy designation if preliminary clinical evidence indicates that the product candidate, alone or in combination with one or more other drugs or biologics, may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. The designation includes all of the fast track program features, as well as more intensive FDA interaction and guidance beginning as early as Phase 1 and an organizational commitment to expedite the development and review of the product candidate, including involvement of senior managers.

Any marketing application for a drug or biologic submitted to the FDA for approval, including a product candidate with a fast track designation and/or breakthrough therapy designation, may be eligible for other types of FDA programs intended to expedite the FDA review and approval process, such as priority review. An NDA or BLA is eligible for priority review if the product candidate has the potential to provide a significant improvement in the treatment, diagnosis or prevention of a serious disease or condition. For new molecular entity NDAs and original BLAs, priority review designation means the FDA’s goal is to take action on the marketing application within six months of the 60-day filing date (as compared to 10 months under standard review).

Additionally, depending on the design of the applicable clinical trials, product candidates studied for their safety and effectiveness in treating serious or life-threatening diseases or conditions may receive accelerated approval upon a determination that the product candidate has an effect on a surrogate endpoint that is reasonably likely to predict clinical benefit, or on a clinical endpoint that can be measured earlier than irreversible morbidity or mortality, that is reasonably likely to predict an effect on irreversible morbidity or mortality or other clinical benefit, taking into account the severity, rarity, or prevalence of the condition and the availability or lack of alternative treatments. As a condition of accelerated approval, the FDA will generally require the sponsor to perform adequate and well-controlled confirmatory clinical trials to verify and describe the anticipated effect on irreversible morbidity or mortality or other clinical benefit, and may require that such confirmatory trials are underway prior to granting any accelerated approval. Products receiving accelerated approval may be subject to expedited withdrawal procedures if the sponsor fails to conduct the required confirmatory trials in a timely manner or if such trials fail to verify the predicted clinical benefit. In addition, the FDA currently requires as a condition for accelerated approval pre-approval of promotional materials, which could adversely impact the timing of the commercial launch of the product.

Fast track designation, breakthrough therapy designation, priority review, and accelerated approval do not change the standards for approval but may expedite the development or approval process. Even if a product qualifies for one or more of these programs, the FDA may later decide that the product no longer meets the conditions for qualification or decide that the time period for FDA review or approval will not be shortened.

Orphan drug designation

Under the Orphan Drug Act, the FDA may grant ODD to a drug or biologic intended to treat a rare disease or condition, which is a disease or condition that affects fewer than 200,000 individuals in the United States, or more than 200,000 individuals in the United States for which there is no reasonable expectation that the cost of developing and making available in the United States a drug or biologic for this type of disease or condition will be recovered from sales in the United States for that drug or biologic. ODD must be requested before submitting an NDA or BLA. After the FDA grants ODD, the generic identity of the therapeutic agent and its potential orphan use are disclosed publicly by the FDA. The ODD does not convey any advantage in, or shorten the duration of, the regulatory review or approval process.

If a product candidate that has ODD subsequently receives the first FDA approval for the disease or condition for which it has such designation, the product is entitled to orphan drug exclusive approval (or exclusivity), which means that the FDA may not approve any other applications, including a full NDA or BLA, to market the same drug or biologic for the same disease or condition for seven years, except in limited circumstances, such as a showing of clinical superiority to the product with orphan drug exclusivity or if the FDA finds that the holder of the orphan drug exclusivity has not shown that it can assure the availability of sufficient quantities of the orphan drug to meet the needs of patients with the disease or condition for which the drug or biologic was designated. Orphan drug exclusivity does not prevent the FDA from approving a different drug or biologic for the same disease or condition, or the same drug or biologic for a different disease or condition. Among the other benefits of orphan drug designation are tax credits for certain research and a waiver of the NDA or BLA application user fee.

A designated orphan drug may not receive orphan drug exclusivity if it is approved for a use that is broader than the disease or condition for which it received ODD. In addition, exclusive marketing rights in the United States may be lost if the FDA later determines that the request for designation was materially defective or if the manufacturer is unable to assure sufficient quantities of the product to meet the needs of patients with the rare disease or condition.

Post-approval requirements

Any products manufactured or distributed pursuant to FDA approvals are subject to pervasive and continuing regulation by the FDA, including, among other things, requirements relating to record-keeping, reporting of adverse experiences, periodic reporting, product sampling and distribution, and advertising and promotion of the product. After approval, most changes to the approved product, such as adding new indications or other labeling claims, are subject to prior FDA review and approval. There also are continuing user fee requirements, under which the FDA assesses an annual program fee for each product identified in an approved NDA or BLA. Drug and biologic manufacturers and their subcontractors are required to register their establishments with the FDA and certain state agencies, and are subject to periodic unannounced inspections by the FDA and certain state agencies for compliance with cGMPs, which impose certain procedural and documentation requirements upon us and our third-party manufacturers. Changes to the manufacturing process are strictly regulated, and, depending on the significance of the change, may require prior FDA approval before being implemented. FDA regulations also require investigation and correction of any deviations from cGMPs and impose reporting requirements upon us and any third-party manufacturers that we may decide to use. Accordingly, manufacturers must continue to expend time, money and effort in the area of production and quality control to maintain compliance with cGMPs and other aspects of regulatory compliance.

The FDA may withdraw approval if compliance with regulatory requirements and standards is not maintained or if problems occur after the product reaches the market. Later discovery of previously unknown problems with a product, including adverse events of unanticipated severity or frequency, or with manufacturing processes, or failure to comply with regulatory requirements, may result in revisions to the approved labeling to add new safety information; imposition of post-market trials or clinical trials to assess new safety risks; or imposition of distribution restrictions or other restrictions under a REMS program. Other potential consequences include, among other things:

•

restrictions on the marketing or manufacturing of a product, complete withdrawal of the product from the market or product recalls;

•

fines, warning letters or holds on post-approval clinical trials;

•

refusal of the FDA to approve pending applications or supplements to approved applications, or suspension or revocation of existing product approvals;

•

product seizure or detention, or refusal of the FDA to permit the import or export of products;

•

consent decrees, corporate integrity agreements, debarment or exclusion from federal healthcare programs;

•

mandated modification of promotional materials and labeling and the issuance of corrective information;

•

injunctions or the imposition of civil or criminal penalties.

The FDA closely regulates the marketing, labeling, advertising and promotion of drug products. A company can make only those claims relating to safety and efficacy, purity and potency that are approved by the FDA and in accordance with the provisions of the approved label. The FDA and other agencies actively enforce the laws and regulations prohibiting the promotion of off-label uses. Failure to comply with these requirements can result in, among other things, adverse publicity, warning letters, corrective advertising and potential civil and criminal penalties. Physicians may prescribe, in their independent professional medical judgment, legally available products for uses that are not described in the product’s labeling and that differ from those approved by the FDA. Physicians may believe that such off-label uses are the best treatment for many patients in varied circumstances. The FDA does not regulate the behavior of physicians in their choice of treatments. The FDA does, however, restrict manufacturer’s communications on the subject of off-label use of their products. The federal government has levied large civil and criminal fines against companies for alleged improper promotion of off-label use and has enjoined companies from engaging in off-label promotion. The FDA and other regulatory agencies have also required that companies enter into consent decrees or permanent injunctions under which specified promotional conduct is changed or curtailed. However, companies may share truthful and not misleading information that is otherwise consistent with a product’s FDA-approved labeling.

In addition, the distribution of prescription biopharmaceutical products is subject to the Prescription Drug Marketing Act (PDMA) which regulates the distribution of drugs and drug samples at the federal level, and sets minimum standards for the registration and regulation of drug distributors by the states. Both the PDMA and state laws limit the distribution of prescription pharmaceutical product samples and impose requirements to ensure accountability in distribution.

Drug product marketing exclusivity

Market exclusivity provisions under the FDCA can delay the submission or the approval of certain marketing applications. For example, the FDCA provides a five-year period of non-patent data exclusivity within the United States to the first applicant to obtain approval of an NDA for a new chemical entity. A drug is a new chemical entity if the FDA has not previously approved any other new drug containing the same active moiety, which is the molecule or ion responsible for the action of the drug substance. During the exclusivity period, the FDA may not approve or even accept for review an abbreviated new drug application (ANDA), or an NDA submitted under Section 505(b)(2), or 505(b) (2) NDA, submitted by another company for another drug based on the same active moiety, regardless of whether the drug is intended for the same indication as the original innovative drug or for another indication, where the applicant does not own or have a legal right of reference to all the data required for approval. However, an application may be submitted after four years if it contains a certification of patent invalidity or non-infringement to one of the patents listed with the FDA by the innovator NDA holder.

The FDCA alternatively provides three years of non-patent exclusivity for an NDA, or supplement to an existing NDA if new clinical investigations, other than bioavailability trials, that were conducted or sponsored by the applicant are deemed by the FDA to be essential to the approval of the application, for example new indications, dosages or strengths of an existing drug. This three-year exclusivity covers only the modification for which the drug received approval on the basis of the new clinical investigations and does not prohibit the FDA from approving ANDAs or 505(b)(2) NDAs for drugs containing the active agent for the original indication or condition of use. Five-year and three-year exclusivity will not delay the submission or approval of a full NDA. However, an applicant submitting a full NDA would be required to conduct or obtain a right of reference to any preclinical studies and adequate and well-controlled clinical trials necessary to demonstrate safety and effectiveness.

Pediatric exclusivity is another type of marketing exclusivity available in the United States. Pediatric exclusivity provides for an additional six months of marketing exclusivity attached to another existing period of regulatory exclusivity or patent term if a sponsor conducts clinical trials in children in response to a Written Request from the FDA. The issuance of a written request does not require the sponsor to undertake the described clinical trials. In addition, orphan drug exclusivity, as described above, may offer a seven-year period of marketing exclusivity, except in certain circumstances.

Biosimilars and reference product exclusivity

The Biologics Price Competition and Innovation Act of 2009 (BPCIA) created an abbreviated approval pathway for biological products that are highly similar, or “biosimilar,” to or interchangeable with an FDA-approved reference biological product. Biosimilarity, which requires that there be no clinically meaningful differences between the biological product and the reference product in terms of safety, purity, and potency, is generally shown through analytical studies, animal studies, and a clinical trial or trials. Interchangeability requires that a product is biosimilar to the reference product and the product must demonstrate that it can be expected to produce the same clinical results as the reference product in any given patient and, for products that are administered multiple times to an individual, the biologic and the reference biologic may be alternated or switched after one has been previously administered without increasing safety risks or risks of diminished efficacy relative to exclusive use of the reference biologic. A product shown to be biosimilar or interchangeable with an FDA-approved reference biological product may rely in part on the FDA’s previous determination of safety and effectiveness for the reference product for approval, which can potentially reduce the cost and time required to obtain approval to market the product.

Under the BPCIA, an application for a biosimilar product may not be submitted to the FDA until four years following the date that the reference product was first licensed by the FDA. In addition, the approval of a biosimilar product may not be made effective by the FDA until 12 years from the date on which the reference product was first licensed. During this 12-year period of exclusivity, another company may still market a competing version of the reference product if the FDA approves a full BLA for the competing product containing that applicant’s own preclinical data and data from adequate and well-controlled clinical trials to demonstrate the safety, purity and potency of its product. The BPCIA also created certain exclusivity periods for biosimilars approved as interchangeable products. At this juncture, it is unclear whether products deemed “interchangeable” by the FDA will, in fact, be readily substituted by pharmacies, which are governed by state pharmacy law.

A biological product can also obtain pediatric market exclusivity in the United States, as described above, if the BLA sponsor voluntarily completes a pediatric study that fairly responds to a "written request" from the FDA to conduct such study.

FDA regulation of companion diagnostics

If safe and effective use of a drug or biologic depends on anin vitro diagnostic, then the FDA may require approval or clearance of that diagnostic, known as a companion diagnostic, at the same time that the FDA approves the therapeutic product. In August 2014, the FDA issued final guidance clarifying the requirements that will apply to approval of therapeutic products and in vitro companion diagnostics. According to the guidance, if FDA determines that a companion diagnostic device is essential to the safe and effective use of a novel therapeutic product or indication, FDA may will not approve the drug or new indication if the companion diagnostic device is not also approved or cleared for that indication. Approval or clearance of the companion diagnostic device will ensure that the device has been adequately evaluated and has adequate performance characteristics in the intended population. The review ofin vitro companion diagnostics in conjunction with the review of our product candidates will, therefore, likely involve coordination of review by the FDA’s Center for Drug Evaluation and Research or the FDA’s Center for Biologics Evaluation and Research and the FDA’s Center for Devices and Radiological Health Office of In Vitro Diagnostics and Radiological Health.

Under the FDCA, in vitro diagnostics, including companion diagnostics, are regulated as medical devices. In the United States, the FDCA and its implementing regulations, and other federal and state statutes and regulations govern, among other things, medical device design and development, preclinical and clinical testing, premarket clearance or approval, registration and listing, manufacturing, labeling, storage, advertising and promotion, sales and distribution, export and import, and post-market surveillance. Unless an exemption applies, diagnostic tests require marketing clearance or approval from the FDA prior to commercial distribution. The two primary types of FDA marketing authorization applicable to a medical device are clearance of a premarket notification pursuant to Section 510(k) of the FDCA, also called 510(k) clearance, and approval of a premarket approval application (PMA).

The PMA process, including the gathering of clinical and preclinical data and the submission to and review by the FDA, can take several years or longer. It involves a rigorous premarket review during which the applicant must prepare and provide the FDA with reasonable assurance of the device’s safety and effectiveness and information about the device and its components regarding, among other things, device design, manufacturing and labeling. PMA applications are subject to an application fee. In addition, PMAs for certain devices must generally include the results from extensive preclinical and adequate and well-controlled clinical trials to establish the safety and effectiveness of the device for each indication for which FDA approval is sought. As part of the PMA review, the FDA will typically inspect the manufacturer’s facilities for compliance with the Quality System Regulation (QSR) which imposes elaborate testing, control, documentation and other quality assurance requirements.

If the FDA’s evaluation of the PMA application is favorable, the FDA typically issues an approvable letter requiring the applicant’s agreement to specific conditions, such as changes in labeling, or specific additional information, such as submission of final labeling, in order to secure final approval of the PMA. If the FDA’s evaluation of the PMA or manufacturing facilities is not favorable, the FDA will deny approval of the PMA or issue a not approvable letter. A not approvable letter will outline the deficiencies in the application and, where practical, will identify what is necessary to make the PMA approvable. The FDA may also determine that additional clinical trials are necessary, in which case the PMA approval may be delayed for several months or years while the trials are conducted and then the data submitted in an amendment to the PMA. If the FDA concludes that the applicable criteria have been met, the FDA will issue a PMA for the approved indications, which can be more limited than those originally sought by the applicant. The PMA can include post-approval conditions that the FDA believes necessary to ensure the safety and effectiveness of the device, including, among other things, restrictions on labeling, promotion, sale and distribution. Once granted, PMA approval may be withdrawn by the FDA if compliance with post-approval requirements, conditions of approval or other regulatory standards are not maintained or problems are identified following initial marketing.

After a device is placed on the market, it remains subject to significant regulatory requirements. Medical devices may be marketed only for the uses and indications for which they are cleared or approved. Device manufacturers must also establish registration and device listings with the FDA. A medical device manufacturer’s manufacturing processes and those of its suppliers are required to comply with the applicable portions of the QSR, which cover the methods and documentation of the design, testing, production, processes, controls, quality assurance, labeling, packaging and shipping of medical devices. Domestic facility records and manufacturing processes are subject to periodic unscheduled inspections by the FDA. The FDA also may inspect foreign facilities that export products to the United States.

Other US regulatory requirements

In addition to FDA regulation of pharmaceutical products, pharmaceutical companies are also subject to additional healthcare regulation and enforcement by the federal government and by authorities in the states and foreign jurisdictions in which they conduct their business and may constrain the financial arrangements and relationships through which we research, as well as sell, market and distribute any products for which we obtain marketing authorization. Such laws include, without limitation, state and federal anti-kickback, fraud and abuse, false claims, and transparency laws and regulations related to drug pricing and payments and other transfers of value made to physicians and other healthcare providers. If their operations are found to be in violation of any of such laws or any other governmental regulations that apply, they may be subject to penalties, including, without limitation, administrative, civil and criminal penalties, damages, fines, disgorgement, the curtailment or restructuring of operations, integrity oversight and reporting obligations, exclusion from participation in federal and state healthcare programs and imprisonment.

US coverage and reimbursement

Significant uncertainty exists as to the coverage and reimbursement status of any product candidate for which we may seek regulatory approval. Sales in the United States will depend, in part, on the availability of sufficient coverage and adequate reimbursement from third-party payors, which include government health programs such as Medicare, Medicaid, TRICARE and the Veterans Administration, as well as managed care organizations and private health insurers. Prices at which we or our customers seek reimbursement for our product candidates can be subject to challenge, reduction or denial by third-party payors.

The process for determining whether a third-party payor will provide coverage for a product is typically separate from the process for setting the reimbursement rate that the payor will pay for the product. In the United States, there is no uniform policy among payors for coverage or reimbursement. Decisions regarding whether to cover any of a product, the extent of coverage and amount of reimbursement to be provided are made on a plan-by-plan basis. Third-party payors often rely upon Medicare coverage policy and payment limitations in setting their own coverage and reimbursement policies, but also have their own methods and approval processes. Therefore, coverage and reimbursement for products can differ significantly from payor to payor. As a result, the coverage determination process is often a time-consuming and costly process that can require manufacturers to provide scientific and clinical support for the use of a product to each payor separately, with no assurance that coverage and adequate reimbursement will be applied consistently or obtained in the first instance. In addition, companion diagnostic tests require coverage and reimbursement separate and apart from the coverage and reimbursement for their companion pharmaceutical or biological products. Similar challenges to obtaining coverage and reimbursement, applicable to pharmaceutical or biological products, will apply to companion diagnostics.

Third-party payors are increasingly challenging the price and examining the medical necessity and cost-effectiveness of medical products and services, in addition to their safety and efficacy. Third-party payors may not consider our product candidates to be medically necessary or cost-effective compared to other available therapies. Adoption of price controls and cost-containment measures, and adoption of more restrictive policies in jurisdictions with existing controls and measures, could further limit sales of any product that receives approval.

US healthcare reform

In the United States, there have been, and continue to be, legislative and regulatory changes and proposed changes regarding the healthcare system that could prevent or delay marketing approval of product candidates, restrict or regulate post-approval activities, and affect the profitable sale of product candidates. Among policy makers and payors in the United States, there is significant interest in promoting changes in healthcare systems with the stated goals of containing healthcare costs, improving quality and/or expanding access. In the United States, the pharmaceutical industry has been a particular focus of these efforts and has been significantly affected by major legislative initiatives.

By way of example, in March 2010, the Patient Protection and Affordable Care Act (the ACA) was passed, which substantially changed the way healthcare is financed by both governmental and private insurers, and significantly affected the pharmaceutical industry. The ACA, among other things, increased the minimum level of Medicaid rebates payable by manufacturers of brand name drugs from 15.1% to 23.1% of the average manufacturer price; required collection of rebates for drugs paid by Medicaid managed care organizations; required manufacturers to participate in a coverage gap discount program, in which manufacturers must agree to offer point-of-sale discounts off negotiated prices of applicable brand drugs to eligible beneficiaries during their coverage gap period, as a condition for the manufacturer’s outpatient drugs to be covered under Medicare Part D; imposed a non-deductible annual fee on pharmaceutical manufacturers or importers who sell certain “branded prescription drugs” to specified federal government programs; implemented a new methodology by which rebates owed by manufacturers under the Medicaid Drug Rebate Program are calculated for drugs that are inhaled, infused, instilled, implanted, or injected; expanded eligibility criteria for Medicaid programs; creates a new Patient-Centered Outcomes Research Institute to oversee, identify priorities in, and conduct comparative clinical effectiveness research, along with funding for such research; and established a Center for Medicare and Medicaid Innovation at the Centers for Medicare & Medicaid Services (CMS) to test innovative payment and service delivery models to lower Medicare and Medicaid spending, potentially including prescription drug spending.

Since its enactment, there have been judicial, executive and political challenges to certain aspects of the ACA. On June 17, 2021, the US Supreme Court dismissed a challenge on procedural grounds that argued the ACA is unconstitutional in its entirety because the “individual mandate” was repealed by Congress. Thus, the ACA will remain in effect in its current form. Prior to the US Supreme Court ruling, President Biden issued an executive order that initiated initiate a special enrollment period from February 15, 2021 through August 15, 2021 for purposes of obtaining health insurance coverage through the ACA marketplace. The executive order also instructed certain governmental agencies to review and reconsider their existing policies and rules that limit access to healthcare, including among others, reexamining Medicaid demonstration projects and waiver programs that include work requirements, and policies that create unnecessary barriers to obtaining access to health insurance coverage through Medicaid or the ACA.

In addition, other legislative changes have been proposed and adopted since the ACA was enacted. These changes included aggregate reductions to Medicare payments to providers, which went into effect on April 1, 2013 and, due to subsequent legislative amendments to the statute, will remain in effect through 2032, with the exception of a temporary suspension from May 1, 2020 through March 31, 2022, unless additional Congressional action is taken. On January 2, 2013, the American Taxpayer Relief Act of 2012 was signed into law, which, among other things, reduced Medicare payments to several providers, including hospitals, and increased the statute of limitations period for the government to recover overpayments to providers from three to five years. In addition, on March 11, 2021, the American Rescue Plan Act of 2021 was signed into law, which eliminated the statutory Medicaid drug rebate cap, beginning January 1, 2024. The rebate was previously capped at 100% of a drug's average manufacturer price.

Moreover, there has recently been heightened governmental scrutiny over the manner in which manufacturers set prices for their marketed products, which has resulted in several Congressional inquiries and proposed and enacted federal and state legislation designed to, among other things, bring more transparency to product pricing, review the relationship between pricing and manufacturer patient programs, and reform government program reimbursement methodologies for pharmaceutical products. On August 16, 2022, the Inflation Reduction Act of 2022, or IRA, was enacted into law. Among other things, the IRA requires manufacturers of certain drugs to engage in price negotiations with Medicare (beginning in 2026), imposes rebates under Medicare Part B and Medicare Part D to penalize price increases that outpace inflation (first due in 2023), and replaces the Part D coverage gap discount program with a new discounting program (beginning in 2025). The IRA permits the Secretary of the Department of Health and Human Services to implement many of these provisions through guidance, as opposed to regulation, for the initial years. On August 29, 2023, the US Department of Health and Human Services (HHS) announced the list of the first ten drugs that will be subject to price negotiations. HHS has issued and will continue to issue guidance implementing the IRA, although the Medicare drug price negotiation program is currently subject to legal challenges. While the impact of the IRA on the pharmaceutical industry cannot yet be fully determined, it is likely to be significant.

Individual states in the United States have also become increasingly active in implementing regulations designed to control pharmaceutical product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, designed to encourage importation from other countries and bulk purchasing. In addition, regional healthcare authorities and individual hospitals are increasingly using bidding procedures to determine which drugs and suppliers will be included in their healthcare programs Furthermore, there has been increased interest by third party payors and governmental authorities in reference pricing systems and publication of discounts and list prices.

We expect that additional state and federal healthcare reform measures will be adopted in the future, any of which could limit the amounts that federal and state governments will pay for healthcare product candidates and services, which could result in reduced demand for our product candidates once approved or additional pricing pressures.

EU drug regulation

In order to market any product outside of the United States, we would need to comply with numerous and varying regulatory requirements of other countries and jurisdictions regarding quality, safety and efficacy and governing, among other things, clinical trials, marketing authorization, commercial sales and distribution of our products. Whether or not we obtain FDA approval for a product, we would need to obtain the necessary approvals by the comparable foreign regulatory authorities before we can commence clinical trials or marketing of the product in foreign countries and jurisdictions such as in China and Japan. Although many of the issues discussed above with respect to the United States apply similarly in the context of the European Union (EU), the approval process varies between countries and jurisdictions and can involve additional product testing and additional administrative review periods. The time required to obtain approval in other countries and jurisdictions might differ from and be longer than that required to obtain FDA approval. Regulatory approval in one country or jurisdiction does not ensure regulatory approval in another, but a failure or delay in obtaining regulatory approval in one country or jurisdiction may negatively impact the regulatory process in others. Failure to comply with applicable foreign regulatory requirements, may be subject to, among other things, fines, suspension or withdrawal of regulatory approvals, product recalls, seizure of products, operating restrictions and criminal prosecution.

Non-clinical studies and clinical trials

Similarly to the United States, the various phases of non-clinical and clinical research in the EU are subject to significant regulatory controls.

Non-clinical studies are performed to demonstrate the health or environmental safety of new chemical or biological substances. Non-clinical studies must be conducted in compliance with the principles of good laboratory practice (GLP) as set forth in EU Directive 2004/10/EC. In particular, non-clinical studies, both in vitro and in vivo, must be planned, performed, monitored, recorded, reported and archived in accordance with the GLP principles, which define a set of rules and criteria for a quality system for the organizational process and the conditions for non-clinical studies. These GLP standards reflect the Organization for Economic Co-operation and Development requirements.

Clinical trials of medicinal products in the EU must be conducted in accordance with EU and national regulations and the International Conference on Harmonization (ICH) guidelines on GCP as well as the applicable regulatory requirements and the ethical principles that have their origin in the Declaration of Helsinki. Additional GCP guidelines from the European Commission, focusing in particular on traceability, apply to clinical trials of advanced therapy medicinal products. If the sponsor of the clinical trial is not established within the EU, it must appoint an entity within the EU to act as its legal representative. The sponsor must take out a clinical trial insurance policy, and in most EU member states, the sponsor is liable to provide ‘no fault’ compensation to any trial subject injured in the clinical trial.

Certain countries outside of the United States, including the EU, have a similar process that requires the submission of a clinical trial application (CTA) much like the IND prior to the commencement of human clinical trials. A CTA must be submitted to each country’s national health authority and an independent ethics committee, much like the FDA and the IRB, respectively. Once the CTA is approved by the national health authority and the ethics committee has granted a positive opinion in relation to the conduct of the trial in the relevant member state(s), in accordance with a country’s requirements, clinical trial development may proceed.

The CTA must include, among other things, a copy of the trial protocol and an investigational medicinal product dossier containing information about the manufacture and quality of the medicinal product under investigation. Currently, CTAs must be submitted to the competent authority in each EU member state in which the trial will be conducted. Under the new Regulation on Clinical Trials, which is currently expected to become applicable by early 2022, there will be a centralized application procedure where one national authority takes the lead in reviewing the application and the other national authorities have only a limited involvement. Any substantial changes to the trial protocol or other information submitted with the CTA must be notified to or approved by the relevant competent authorities and ethics committees. Medicines used in clinical trials must be manufactured in accordance with good manufacturing practice (GMP). Other national and EU-wide regulatory requirements also apply.

Marketing Authorizations

To market a medicinal product in the EU and in many other foreign jurisdictions, we must obtain separate regulatory approvals. More concretely, in the EU, medicinal product candidates can only be commercialized after obtaining a Marketing Authorization (MA). To obtain regulatory approval of an investigational medicinal product under EU regulatory systems, we must submit a marketing authorization application (MAA.) The process for doing this depends, among other things, on the nature of the medicinal product. There are two types of MAs:

•

the “Union MA”, which is issued by the European Commission through the Centralized Procedure, based on the opinion of the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) and which is valid throughout the entire territory of the EU. The Centralized Procedure is mandatory for certain types of products, such as: (i) medicinal products derived from biotechnology medicinal products, (ii) designated orphan medicinal products, (iii) advanced therapy products (such as gene therapy, somatic cell therapy or tissue-engineered medicines), and (iv) medicinal products containing a new active substance indicated for the treatment certain diseases, such as HIV/AIDS, cancer, neurodegenerative diseases, diabetes, other auto-immune and viral diseases. The Centralized Procedure is optional for products containing a new active substance not yet authorized in the EU, or for products that constitute a significant therapeutic, scientific or technical innovation or that the granting of authorization would be in the interest of public health in the EU; and

•

“National MAs”, which are issued by the competent authorities of the EU member states and only cover their respective territory, are available for products not falling within the mandatory scope of the Centralized Procedure. Where a product has already been authorized for marketing in an EU member state, this National MA can be recognized in another member state through the Mutual Recognition Procedure. If the product has not received a National MA in any member state at the time of application, it can be approved simultaneously in various member states through the Decentralized Procedure. Under the Decentralized Procedure an identical dossier is submitted to the competent authorities of each of the member states in which the MA is sought, one of which is selected by the applicant as the Reference member state.

Under the above-described procedures, in order to grant the MA, the EMA or the competent authorities of the EU member states make an assessment of the risk-benefit balance of the product on the basis of scientific criteria concerning its quality, safety and efficacy.

Under the Centralized Procedure, the maximum timeframe for the evaluation of a MAA by the EMA is 210 days. Where there is a major public health interest and an unmet medical need for a product, the CHMP may perform an accelerated review of a MA in no more than 150 days (not including clock stops). Innovative products that target an unmet medical need and are expected to be of major public health interest may be eligible for a number of expedited development and review programs, such as the PRIME scheme, which provides incentives similar to the breakthrough therapy designation in the US PRIME is a voluntary scheme aimed at enhancing the EMA’s support for the development of medicines that target unmet medical needs. It is based on increased interaction and early dialogue with companies developing promising medicines, to optimize their product development plans and speed up their evaluation to help them reach patients earlier. Product developers that benefit from PRIME designation can expect to be eligible for accelerated assessment but this is not guaranteed. The benefits of a PRIME designation include the appointment of a CHMP rapporteur before submission of a MAA, early dialogue and scientific advice at key development milestones, and the potential to qualify products for accelerated review earlier in the application process.

MAs have an initial duration of five years. After these five years, the authorization may be renewed for an unlimited period on the basis of a reevaluation of the risk-benefit balance, unless the EMA decides, on justified grounds relating to pharmacovigilance, to mandate one additional five-year renewal period.

Data and marketing exclusivity

The EU also provides opportunities for market exclusivity. Upon receiving MA, new chemical entity, or reference product candidates, generally receive eight years of data exclusivity and an additional two years of market exclusivity. If granted, the data exclusivity period prevents generic or biosimilar applicants from relying on the pre-clinical and clinical trial data contained in the dossier of the reference product when applying for a generic or biosimilar MA in the EU during a period of eight years from the date on which the reference product was first authorized in the EU. The market exclusivity period prevents a successful generic or biosimilar applicant from commercializing its product in the EU until 10 years have elapsed from the initial authorization of the reference product in the EU. The overall 10-year market exclusivity period can be extended to a maximum of eleven years if, during the first eight years of those 10 years, the MA holder obtains an authorization for one or more new therapeutic indications which, during the scientific evaluation prior to their authorization, are held to bring a significant clinical benefit in comparison with existing therapies. However, there is no guarantee that a product will be considered by the EU’s regulatory authorities to be a new chemical entity, and products may not qualify for data exclusivity.

Pediatric Development

In the EU, MAAs for new medicinal products candidates have to include the results of trials conducted in the pediatric population, in compliance with a pediatric investigation plan (PIP) agreed with the EMA’s Pediatric Committee (PDCO). The PIP sets out the timing and measures proposed to generate data to support a pediatric indication of the drug for which MA is being sought. The PDCO can grant a deferral of the obligation to implement some or all of the measures of the PIP until there is sufficient data to demonstrate the efficacy and safety of the product in adults. Further, the obligation to provide pediatric clinical trial data can be waived by the PDCO when these data is not needed or appropriate because the product is likely to be ineffective or unsafe in children, the disease or condition for which the product is intended occurs only in adult populations, or when the product does not represent a significant therapeutic benefit over existing treatments for pediatric patients. Once the MA is obtained in all EU Member States and trial results are included in the product information, even when negative, the product is eligible for six months’ supplementary protection certificate extension (if any is in effect at the time of authorization).

Post-Approval Requirements

Similar to the United States, both MA holders and manufacturers of medicinal products are subject to comprehensive regulatory oversight by the EMA, the European Commission and/or the competent regulatory authorities of the member states. The holder of a MA must establish and maintain a pharmacovigilance system and appoint an individual qualified person for pharmacovigilance who is responsible for oversight of that system. Key obligations include expedited reporting of suspected serious adverse reactions and submission of periodic safety update reports (PSURs).

All new MAA must include a risk management plan (RMP) describing the risk management system that the company will put in place and documenting measures to prevent or minimize the risks associated with the product. The regulatory authorities may also impose specific obligations as a condition of the MA. Such risk-minimization measures or post-authorization obligations may include additional safety monitoring, more frequent submission of PSURs, or the conduct of additional clinical trials or post-authorization safety trials.

The advertising and promotion of medicinal products is also subject to laws concerning promotion of medicinal products, interactions with physicians, misleading and comparative advertising and unfair commercial practices. All advertising and promotional activities for the product must be consistent with the approved summary of product characteristics, and therefore all off-label promotion is prohibited. Direct-to-consumer advertising of prescription medicines is also prohibited in the EU. Although general requirements for advertising and promotion of medicinal products are established under EU directives, the details are governed by regulations in each member state and can differ from one country to another.

The aforementioned EU rules are generally applicable in the European Economic Area (EEA) which consists of the 27 EU member states plus Norway, Liechtenstein and Iceland.

For other countries outside of the EU, such as countries in Latin America or Asia (e.g., China and Japan), the requirements governing the conduct of clinical trials, product licensing, pricing and reimbursement vary from country to country. In all cases, again, the clinical trials are conducted in accordance with GCP and the applicable regulatory requirements and the ethical principles that have their origin in the Declaration of Helsinki. If we fail to comply with applicable foreign regulatory requirements, we may be subject to, among other things, fines, suspension or withdrawal of regulatory approvals, product recalls, seizure of products, operating restrictions and criminal prosecution.

Data Privacy and Security Laws

Numerous state, federal and foreign laws, regulations and standards govern the collection, use, access to, confidentiality and security of health-related and other personal information, and could apply now or in the future to our operations or the operations of our partners. In the United States, numerous federal and state laws and regulations, including data breach notification laws, health information privacy and security laws and consumer protection laws and regulations govern the collection, use, disclosure, and protection of health-related and other personal information. In addition, certain foreign laws govern the privacy and security of personal data, including health-related data. Privacy and security laws, regulations, and other obligations are constantly evolving, may conflict with each other to complicate compliance efforts, and can result in investigations, proceedings, or actions that lead to significant civil and/or criminal penalties and restrictions on data processing.

Japanese drug regulation

Non-clinical studies and clinical trials

Being a member of the International Conference on Harmonization (ICH), Japan has pharmaceutical regulations fundamentally similar to those of the United States or EU.

Non-clinical studies are performed to demonstrate the health safety of new chemical or biological substances. Non-clinical studies must be conducted in compliance with the principles of Japanese good laboratory practice (GLP) which reflect the Organization for Economic Co-operation and Development requirements. Currently, Japan and EU have a mutual recognition agreement for GLP, and data generated compliant with EU requirements will be accepted by the Japanese authorities. There is no similar agreement with the United States.

Clinical trials of medicinal products in Japan must be conducted in accordance with Japanese regulations based on ICH guidelines governing good clinical practices (GCP). They focus on ethics of the clinical trial and protection of the privacy of the trial subjects. If the sponsor of the clinical trial is not established within Japan, it must appoint an entity within the country to act as its caretaker who should be authorized to act on the sponsor’s behalf. The sponsor must take out a clinical trial insurance policy, and, according to the industry agreement, should put in place a common compensation policy for the injuries from the trial.

Prior to the commencement of human clinical trials, the sponsor must complete evaluation of the safety of the investigative product, and submit a clinical trial notification and the protocol to the authorities in advance, upon agreement of the IRB of the participating institutions. When the authorities do not comment on the notification, the sponsor may proceed with the clinical trial.

Any substantial changes to the trial protocol or other information submitted must be cleared by the IRB and notified to the authorities. Medicines used in clinical trials must be manufactured in accordance with good manufacturing practice (GMP).

Product approval

To market a medicinal product in Japan, we must obtain regulatory approval. To obtain regulatory approval of an investigational medicinal product, we must submit a new drug application. The process for doing this depends, among other things, on the nature of the medicinal product and there are currently a few different pathways for approval. If the product is designed for treating certain “difficult diseases” or those whose patient size is limited, we may be able to obtain designation as an orphan drug product if it demonstrates unique therapeutic value. Approval application for such designated orphan products will be processed on an expedited basis and the authorities’ requirement for clinical data will be much limited. Separately, the latest amendment to the law introduced separate pathways for: (i) truly innovative products with a unique mode of action, and (ii) those which will satisfy unmet medical needs. These products will also be processed on an expedited basis.

The evaluation of applications will be based on an assessment of the risk-benefit balance of the product on the basis of scientific criteria concerning its quality, safety and efficacy. Once the review organization completes its review task, the matter will be considered by the advisory committee of experts, and the government will grant approval upon positive recommendation from the committee.

The volume and quality of the clinical data will be the key determinant of the approval decision. Clinical trial data generated overseas will be accepted as part of the data package consistent with the ICH recommendation. Typically, a limited dose response clinical trial for Japanese subjects is required to ensure that data are extrapolatable for the Japanese population. In a more recent development, the authorities encourage manufacturers to organize an international joint clinical trial with some Japanese participation under a joint protocol, to expedite the clinical trial process. Regulatory approval does not expire.

Licensing requirement

Separate from the approval requirement, it is also mandatory to possess a distribution license of an appropriate class for the manufacturer to commercially distribute the product in Japan. Non-Japanese companies who possess only the product approval may designate an appropriate license holder in Japan to commercially distribute the product, rather than distributing it on its own. The license is valid for 5 years.

Facilities

Our corporate headquarters is located in San Diego, California, where we lease 77,828 square feet of office and laboratory space pursuant to a lease that expires in April 2032 and may be terminated early under certain circumstances. In January 2024, we entered into an agreement to sublease 10,000 square feet of such office space with a sublease term of three years, which includes an option for the subtenant to renew for an additional year and an early termination clause.

We also lease 29,542 square feet of office and laboratory space in South San Francisco, California, pursuant to a lease that expires in October 2032, with an option to extend the term by 5 years, subject to certain conditions.

We believe our existing facilities are adequate to meet our current business requirements for the near term, and that additional space will be available on commercially reasonable terms, if required.

Employees

As of February 29, 2024, we had 126 full-time employees (FTEs), 45 of whom have doctorate degrees. Of our FTEs, 90 are engaged in research and development activities, and 36 are engaged in general and administrative activities. The majority of our employees are located in San Diego County, California. None of our employees are represented by labor unions or covered by collective bargaining units. We consider our relationship with our employees to be good.

Our human resources objectives include, as applicable, identifying, recruiting, retaining, incentivizing, and integrating our existing and additional employees. The principal purposes of our equity incentive plans are to attract, retain, and motivate selected employees, consultants, and directors through the granting of stock-based compensation awards.

Corporate Information

We were incorporated under the laws of the State of Delaware on July 2, 2018 as Erasca, Inc. Our principal executive offices are located at 3115 Merryfield Row, Suite 300, San Diego, California 92121, and our telephone number is 858-465-6511. Our website address is www.erasca.com. Our website and the information contained on, or that can be accessed through, the website will not be deemed to be incorporated by reference in, and are not considered part of, this Annual Report on Form 10-K.

We are an "emerging growth company" as defined in the Jumpstart Our Business Startups Act of 2012. We will remain an emerging growth company until the earlier of: (i) the last day of the fiscal year: (a) following the fifth anniversary of the completion of the IPO, (b) in which we have total annual gross revenue of at least $1.235 billion, or (c) in which we are deemed to be a large accelerated filer, which means the market value of our common stock that is held by non-affiliates exceeds $700.0 million as of the prior June 30th, and (ii) the date on which we have issued more than $1.0 billion in nonconvertible debt during the prior three-year period.

Available Information

Our website address is www.erasca.com. Our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K, including exhibits, proxy and information statements and amendments to those reports filed or furnished pursuant to Sections 13(a), 14, and 15(d) of the Exchange Act are available through the “Investors” portion of our website free of charge as soon as reasonably practicable after we electronically file such material with, or furnish it to, the SEC. In addition, our filings with the SEC may be accessed through the SEC’s Interactive Data Electronic Applications system at www.sec.gov. All statements made in any of our securities filings, including all forward-looking statements or information, are made as of the date of the document in which the statement is included, and we do not assume or undertake any obligation to update any of those statements or documents unless we are required to do so by law.

We use the “Investors” portion of our website as a means of disclosing material non-public information and for complying with our disclosure obligations under Regulation FD. Investors should monitor such website, in addition to following our press releases, SEC filings and public conference calls and webcasts. Information relating to our corporate governance is also included on our website. The information in or accessible through the SEC and our website are not incorporated into, and are not considered part of, this Annual Report on Form 10-K.