OS Therapies Inc

Overview and Mission

OS Therapies Incorporated (“OS Therapies,” the “Company,” “we,” “our” or “us”) is a clinical stage biopharmaceutical company focused on the identification, development and commercialization of treatments for Osteosarcoma (OS) and other solid tumors. Our mission is to address the significant need for new treatments in cancers of the bone in children and young adults. Osteosarcoma is an extremely challenging and often aggressive cancer that has particular treatment challenges due to its location, changing genotypes and high metastases rates. We are currently seeking to answer the call for new treatments that will prevent metastasis and the recurrence of metastases with our lead core product candidate OST-HER2 (also known as OST31-164), a cancer immunotherapy product candidate that produces a cellular immune response against the cancer antigen HER2.

In 2021, we opened a clinical study to produce data for the U.S. Food and Drug Administration (FDA) to evaluate the safety and efficacy of OST-HER2 in patients after resection of recurrent Osteosarcoma, which achieved full enrollment of 41 patients in October 2023. In the first quarter of 2025, we announced that our Phase IIb clinical trial achieved its primary endpoint with statistical significance. In October 2025, we announced final two-year overall survival data from the Phase IIb trial, in which 75% (27 of 36 evaluable patients) of OST-HER2-treated patients achieved two-year overall survival from the most recent pulmonary resection, compared with 40% in historical control patients (p < 0.0001). OST-HER2 was observed to be well-tolerated in the study. In January 2026, we announced positive immune biomarker data from the Phase IIb trial indicating that activation of immune blood biomarkers in the interferon gamma pathway correlated with, and was predictive of, overall survival, distinguishing long-term survivors (≥ two years) from short-term survivors (< one year). These biomarker findings are based on exploratory analyses and have not been validated as surrogate endpoints for clinical benefit. Based on the totality of the data generated to date, including the observed survival outcomes, safety profile and the significant unmet medical need in this patient population, we intend to engage with the FDA regarding potential regulatory pathways for OST-HER2.

We have engaged in ongoing regulatory interactions with the FDA, the United Kingdom Medicines and Healthcare products Regulatory Agency (MHRA), and the European Medicines Agency (EMA) regarding the clinical and biomarker data for OST-HER2 in recurrent, fully resected pulmonary metastatic Osteosarcoma. Following submission of the Non-Clinical and Chemistry, Manufacturing & Controls (CMC) modules of our Biologics License Application (BLA) to the FDA at the end of January 2026, we anticipate submitting the clinical BLA module following an expected Type B meeting with the FDA in the second quarter of 2026 and completing conditional Marketing Authorization Application (MAA) submissions to both the MHRA and the EMA in the second quarter of 2026. We also anticipate releasing additional biomarker data in the second quarter of 2026 to further characterize immune pathway activation and its relationship to clinical outcomes. We expect to initiate confirmatory clinical studies in the third quarter of 2026 in support of conditional approval pathways. If OST-HER2 receives approval under the FDA’s Accelerated Approval Program prior to September 30, 2029, we would become eligible to receive a Priority Review Voucher under the Rare Pediatric Disease Designation Program.

Upon success in gaining regulatory approval from the FDA with OST-HER2 in Osteosarcoma, we intend to evaluate OST-HER2’s potential use, both alone and in combination with HER2 targeting antibodies such as Herceptin®, in other solid tumors including breast, esophageal and lung cancers. OST-HER2 has potential uses in both the prevention of metastases in solid tumors, and therapeutically against HER2-expressing solid tumors treated with HER targeting antibodies.

We also own rights to an OST-Tunable Drug Conjugate (OST-tADC) platform, a next generation antibody-drug conjugate (ADC) silicone dioxide linker technology. “Tunable” is a term used in drug development that refers to the properties that can be influenced by chemical modifications, and “antibody-drug conjugate” or ADC is a term used to describe a drug made up of a monoclonal antibody attached to a cytotoxic payload, or a highly active and toxic pharmaceutical molecule, through chemical linkers. The ADC links an antibody that can home in on a targeted tumor to deploy the cytotoxic payload or toxic agent against the tumor. Furthering our founding mission, we intend to investigate clinical indications for OST-tADC in Osteosarcoma and other solid tumors.

Pipeline of Our Product Candidates

We have built a pipeline of product candidates targeting multiple indications for solid cancers. Our pipeline includes two drug technologies: (i) OST-HER2, an off-the-shelf immunotherapy, which is a type of cancer treatment that helps one’s immune system fight cancer, comprised of a genetically weakened and modified strain ofListeria monocytogenes, a species of bacteria that causes the infection listeriosis, that expresses HER2 peptides, and (ii) OST-tADC, a next generation tunable ADC with a plug-and-play platform that features tunable pH sensitive silicone linkers (SiLinkers™). The payloads may include antibodies, chemotherapeutics, cytotoxins and potentially mRNA treatments directly into and in the vicinity of solid tumors.

***OST-HER2 (OST31-164).*Our most advanced product candidate, OST-HER2, is a genetically engineered strain ofListeria monocytogenes, attenuated for reduced virulence, increased antibiotic susceptibility and the expression of three HER2 protein epitopes fused to immune-enhancing peptides on the membrane of the bacteria.

OST-HER2 has received an orphan drug designation in the United States. The FDA may designate a biologic product as an orphan product if it is intended to treat a rare disease or condition, which generally is defined as having a patient population of fewer than 200,000 individuals in the United States. Osteosarcoma has an incidence rate of approximately 1,000 individuals affected per year in the United States. Orphan product designation, subject to limited exceptions, can provide a period of market exclusivity for a product that is the first to receive marketing approval for the designated indication. Other potential indications may include breast, esophageal, lung and other solid tumors. In August 2021, OST-HER2 was awarded rare pediatric disease designation and previously received fast track designation by the FDA. Such designations by the FDA do not convey any advantages in, or shorten the duration of, the regulatory review or approval process.

***OST-tADC.***Our tunable drug conjugate (tADC) platform is currently in preclinical development. Each tADC contains four main components: ligand, payload cassette adaptor, linker and payload. In addition, tADCs contain units to optimize physicochemical properties. The ligands are selected to bind to receptors overexpressed on cancer cells. Upon binding, the tADC construct gets internalized into the cancer cell, where the payload is released, to cause cell death. The payload cassette adapters enable the stoichiometrical attachments of linkers and payloads. The SiLinkers represent a novel and pH-sensitive linker system. The SiLinker release profile can be tuned with proximal functional groups, resulting in payload release in the endosome, lysosome or the slightly acidic tumor microenvironment. The SiLinker system is compatible with a variety of payloads and not limited to the employment of cytotoxic drug delivery. The first set of internal programs focus on the use of SiLinker and conditionally active payloads (CAPs™) drug products. CAPs are cytotoxic drugs which on their own, due to their functional groups, cannot readily permeate cells at physiological pH; however, at the slightly acidic pH of the tumor-microenvironment, after some linker cleavage, these payloads readily permeate into cancer cells, resulting in an enhanced bystander effect. Our lead program targets folate receptor alpha, a protein expressed on the surface of cells that participates in cell signaling, as well as cellular replication and division, and is overexpressed in multiple cancers such as ovarian and endometrial cancers. The lead compound employs folic acid, a small molecule, as the targeting ligands and contains six exatecan-silanols, which is a type of silanol-based cytotoxic payload. This discovery work is being carried out at Syngene International Limited, an integrated contract research organization (CRO) based in Bangalore, India.

From time to time, we may evaluate collaboration opportunities for our product candidates. We expect to work opportunistically with pharmaceutical and biotechnology companies, as we have done with BlinkBio, Inc. by in-licensing the OST-tADC technology, seeking to utilize our technology and know-how for developing additional oncologic drug products. The following table summarizes information regarding our product candidates and development programs.

In addition to our development of OST-HER2 for multiple indications of solid cancers in humans, OST-HER2 is a product candidate for veterinary use in canines. As part of our growth strategies, we intend to consider potentially out-licensing OST-HER2 to animal health companies for such use. See “OS-Focused Clinical Trials and Studies — Preclinical Animal Study” for more information.

Our Acquisition of HER2 andLm-Related Assets

On April 9, 2025, pursuant to the terms of an Asset Purchase Agreement, dated as of January 28, 2025 (the “HER2 Purchase Agreement”), between us and Ayala Pharmaceuticals, Inc. (formerly known as Advaxis, Inc. (“Ayala”)), we completed the acquisition of theLm-based immune-oncology programs and related intellectual property assets (the “HER2 Assets”) from Ayala. The HER2 Assets include two investigational new drug applications (“IND”) with the FDA: (i) ADXS-503 for non-small cell lung cancer; and (ii) ADXS-504 for prostate cancer.

Our OS-Focused Clinical Trials and Studies

We and our former licensors have conducted a number of clinical trials and studies in the field of Osteosarcoma and Tunable Drug Conjugates to date.

***Phase IIb Clinical Trial.***In July 2021, we initiated a Phase IIb clinical trial to evaluate the safety and efficacy of our OST-HER2 product candidate in patients following complete surgical resection of recurrent pulmonary metastatic Osteosarcoma. The study was sponsored by us and conducted by George Clinical, Inc. A total of 41 eligible patients between the ages of 12 and 39 were enrolled, with full enrollment completed in October 2023. Patients received a total of 16 intravenous infusions of OST-HER2 administered over a 48-week treatment period. The trial was conducted at major hospitals across 21 clinical sites in 18 U.S. states. The treatment phase has been completed, and patients continue to be followed prospectively for long-term survival.

The primary endpoint of the study was 12-month event-free survival (“EFS”), defined as the proportion of patients who remained recurrence-free at 12 months following surgical resection. EFS outcomes were compared to a best available historical control derived from published U.S. literature (the “Published Control”), with recurrence assessments conducted every three months in accordance with standard of care. In the first quarter of 2025, we announced that the study met its primary endpoint with statistical significance. Specifically, 33% of OST-HER2-treated patients (n=41) were event-free at 12 months compared to 20% in the Published Control population, representing a 13-percentage point absolute improvement over historical outcomes.

Secondary endpoints included overall survival and safety. In October 2025, we announced final two-year overall survival data. Among 36 evaluable patients, 75% (27 of 36) were alive two years following their most recent pulmonary resection compared to 40% in the Published Control population (p < 0.0001). Earlier interim analyses demonstrated 12-month overall survival of 91% for OST-HER2-treated patients compared to 80% in the Published Control, and 24-month overall survival of 61% compared to 40%, respectively. Survival assessments were conducted at three-month intervals. The study was not powered as a randomized controlled trial, and comparisons were made against published historical data rather than a contemporaneous control arm.

Safety was assessed throughout the treatment period and follow-up using the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE). OST-HER2 was generally well tolerated. No treatment-emergent adverse events classified as CTCAE Grade 5 (death) were reported. Adverse events were monitored during the 48-week treatment period, with ongoing follow-up for survival and long-term safety.

In January 2026, we announced results from exploratory biomarker analyses evaluating immune activation markers in peripheral blood. Activation of biomarkers within the interferon gamma pathway was observed to correlate with overall survival outcomes and distinguished long-term survivors (≥ two years) from short-term survivors (< one year). These biomarker analyses were exploratory in nature, were not pre-specified as primary or secondary endpoints, and have not been validated as surrogate endpoints for clinical benefit.

Although the Phase IIb trial met its primary endpoint and demonstrated favorable overall survival outcomes relative to historical controls, the study was conducted as an open-label trial and did not include a randomized, contemporaneous control arm. Comparisons to historical controls are subject to inherent limitations, including potential differences in patient populations, standards of care, supportive therapies and assessment methodologies, and such comparisons may not be predictive of results in a randomized controlled trial. We intend to continue engaging with the FDA regarding potential regulatory pathways for OST-HER2. However, there can be no assurance that the FDA will determine that the results of the Phase IIb trial are sufficient to support submission or approval of a BLA. The FDA may require additional clinical data, including data from a randomized Phase III clinical trial, prior to approval. The necessity, scope and design of any additional trials will depend on future regulatory interactions and formal FDA determinations.

***Phase Ib Clinical Trial.*From September 2015 through May 2017, Advaxis, Inc. (“Advaxis”) sponsored and conducted a Phase Ib clinical trial evaluating ADXS-HER2 (also known as ADXS31-164), the intellectual property rights to which we subsequently acquired from Ayala for further development and commercialization as our OST-HER2 product candidate. The Phase Ib study was a multicenter, open-label, dose-escalation trial designed to evaluate safety and tolerability, determine the maximum tolerated dose (“MTD”), and establish a recommended Phase II dose. The study enrolled 12 adult patients with advanced, HER2-expressing solid tumors. Patients received escalating intravenous doses of ADXS-HER2 administered every three weeks during a 12-week treatment cycle. Clinical sites were located at hospitals in Colorado, Michigan, North Carolina, Pennsylvania and Texas. Following completion of study treatment, all 12 patients entered a three-year surveillance period to monitor for potentialListeria monocytogenes-related complications.

The primary endpoints were safety and tolerability, including the incidence of dose-limiting toxicities (“DLTs”) during the first four months of treatment and the frequency and severity of adverse events, assessed using the CTCAE, including Grade 4 events (life-threatening consequences). Secondary endpoints included (i) objective tumor response rate (complete or partial response) as assessed by Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 and immune-related RECIST (ir-RECIST), and (ii) immunologic response parameters measured through serial peripheral blood collection and analysis of peripheral blood mononuclear cells and serum biomarkers.

No dose-limiting toxicities were observed at the highest dose level evaluated (1 × 109 colony-forming units (“CFU”)), and no maximum tolerated dose was reached. ADXS-HER2 administered intravenously at 1 × 109 CFU appeared to be generally well tolerated in the 12 treated and evaluable subjects. No objective tumor responses (complete or partial responses) were observed in this late-stage, heavily pre-treated patient population. Based on the observed safety and tolerability profile, 1 × 109 CFU was selected as the recommended Phase II dose.

This Phase Ib study was primarily designed to assess safety and dose selection and was not powered or intended to evaluate clinical efficacy. Accordingly, the absence of objective tumor responses in this small, heterogeneous patient population should be interpreted in the context of the study’s dose-escalation design and safety-focused objectives.

***Preclinical Animal Study.***From July 2012 through September 2015, a prior licensee of Advaxis sponsored and conducted a preclinical study evaluating ADXS-HER2 in 18 companion canines with HER2-positive appendicular Osteosarcoma following standard-of-care treatment (amputation and chemotherapy). This study is sometimes referred to as a Phase I veterinary clinical study. We subsequently acquired the intellectual property rights to ADXS-HER2 constructs for further development and commercialization as OST-HER2.

Canine appendicular Osteosarcoma is recognized in scientific literature as a spontaneous large-animal model with biological and clinical similarities to pediatric Osteosarcoma. In this study, ADXS-HER2 was administered in the setting of minimal residual disease following definitive surgical and chemotherapeutic management. Outcomes were compared to a historical control cohort treated with amputation and chemotherapy alone.

Results published in 2016 in Clinical Cancer Research (Mason, N. et al., “Immunotherapy with a HER2-Targeting Listeria Induces HER2-Specific Immunity and Demonstrates Potential Therapeutic Effects in a Phase I Trial in Canine Osteosarcoma”) reported improvements in overall survival and metastatic disease progression relative to the historical control group. Reported overall survival rates at one, two and three years were 77.8%, 67% and 56%, respectively, for ADXS-HER2-treated dogs, compared to 55%, 28% and 22%, respectively, for historical controls. Median survival time was 956 days in the ADXS-HER2-treated group compared to 423 days in the historical control group (hazard ratio 0.33; 95% confidence interval 0.136–0.802; p = 0.014). A reduction in the incidence of metastatic disease was also reported relative to historical controls. The study also noted the important translational relevance of the findings for children with Osteosarcoma. This study for canine Osteosarcoma indications constituted preclinical work as it relates to our development of OST-HER2 to treat Osteosarcoma in humans. These findings were generated in a small, non-randomized veterinary study using historical controls. Animal study results are not necessarily predictive of clinical outcomes in humans.

Following completion of the study, an application for conditional licensure of ADXS-HER2 for the treatment of canine Osteosarcoma was submitted to the United States Department of Agriculture (“USDA”). In December 2017, ADXS-HER2 was granted a conditional license for veterinary use in dogs one year of age and older diagnosed with Osteosarcoma. As the current owner of the ADXS-HER2 constructs, we held the conditional license for OST-HER2. The conditional license permitted limited commercial distribution while additional data was to be generated to support full licensure. We subsequently allowed the conditional license to lapse in connection with manufacturing process improvements and a strategic reassessment of our development priorities. We may seek a new conditional license in the future following engagement with a USDA-licensed contract manufacturer. Full USDA licensure would require submission of additional data, including studies addressing safety, purity, potency, effectiveness, metabolism and shedding in canines. We are currently evaluating potential future development strategies with respect to the veterinary indication. There can be no assurance that we will seek or obtain future USDA licensure.

***Preclinical Development.***Our OST-HER2 product candidate is also being evaluated for potential development in additional HER2-expressing solid tumor indications, including breast, esophageal and lung cancers. These programs are currently in the preclinical stage. The scope of additional preclinical development required, if any, will depend on multiple factors, including the totality of available clinical and nonclinical data, the specific tumor indication pursued, the design of any subsequent clinical protocol (including whether additional cohorts are incorporated into a follow-on or master protocol) and feedback from the FDA and other regulatory authorities. While OST-HER2 has been evaluated clinically in Osteosarcoma, regulatory authorities may require additional preclinical pharmacology, toxicology, biodistribution or other nonclinical studies to support initiation of clinical trials in different tumor types. The extent of any such requirements will depend on regulatory determinations regarding the sufficiency and applicability of existing data to the proposed indications. There can be no assurance that additional preclinical studies will not be required prior to initiating clinical trials in breast, esophageal, lung or other solid tumor indications, or that existing clinical data will be deemed sufficient to support expansion into those indications.

Our OST-tADC product candidate for all indications is also currently in preclinical development. We will need to conduct further preclinical trials for OST-tADC prior to the submission of an IND in order to pursue clinical trials with these candidates. Such preclinical trials are expected to include pharmacokinetics and pharmacodynamics, two-week dose finding toxicology studies in vivo (on living cell lines or in living animals), as well as good laboratory practice (GLP) trials ensuring stability, potency and purity of the IND product candidate.

Our Technology Platform

We are in the process of building a fully integrated platform technology to accelerate the development of a range of product candidates across multiple therapeutic areas. Our platform technology is intended to leverage our management’s in-depth experience in immunotherapy research, development and manufacturing to enable us to pursue multiple therapeutic targets. Our scientists and scientific advisors have accumulated decades of collective experience in the field of immunotherapy, oncology and small-molecule drug production, contributing key insights and significant achievement in our clinical development process.

Our Growth Strategies

Our goal is to enrich and lengthen the lives of patients by being a leading, fully integrated biotechnology company. We are seeking to develop, manufacture and commercialize multiple product candidates targeting orphan and non-orphan oncologic diseases across multiple tissue types and therapeutic areas. To achieve our goal, we are pursuing the following growth strategies:

Through these strategies, we aim to leverage our OST-HER2 and OST-tADC platforms to develop a diversified oncology pipeline across multiple tumor types, while maintaining flexibility to pursue both human and veterinary indications, and to capture value through partnerships, out-licensing and clinical expansion.

Expansion Opportunities

We may seek to expand our business through acquisitions, in-licensing of complementary products or technologies, or the acquisition of companies with complementary capabilities. While we have current collaborative agreements in place, we believe in an opportunistic approach to collaboration and licensing; thus, we expect to operate in a manner that is customary in the pharmaceutical industry, including potential acquisitions and partnerships.

We believe there is continued interest from larger pharmaceutical companies in biotechnology firms developing next-generation therapies, including ADCs, due in part to the potential of these therapies to address unmet medical needs in oncology. Advances in ADC technology, including combinations with immunotherapies and other targeted agents, have broadened the potential applications for these modalities, which we may consider as part of our expansion strategy.

Our Scientific Collaborations

***Scientific Collaborators.***We collaborate with experts and physicians to help advance our programs and, together, we are focused on translational strategies to support the clinical study of our new therapy candidates. These collaborations support our goals to translate deep expertise in structure-based drug design into a novel portfolio of precisely targeted therapies. We strive to address medical needs for patients with cancer harboring resistance mutations in driver kinases using technology originally developed at the University of Pennsylvania under the guidance of Dr. Robert G. Petit, our Chief Medical and Scientific Officer. Our partnering approach with physician-scientists allows us to understand the limitations of existing therapies, which we believe will lead to product candidates that address the dual needs of treatment resistance and kinase selectivity. OST-HER2’s compositions and methods of use are covered by two granted U.S. utility patents and one granted Japanese patent. These patents were originally developed at the University of Pennsylvania and were owned either solely by the University or jointly with Advaxis. We acquired all rights, title and interest in these patents from Advaxis pursuant to an assignment, which enables us to develop, manufacture and commercialize OST-HER2 without reliance on in-licensing from Advaxis. See “Our Licensing Obligations — Advaxis” and “Our Intellectual Property” below.

We have also established collaborations through service agreements with global CROs to provide scale and expertise in research chemistry, chemical manufacturing, biology, pharmacology and toxicology, and clinical studies.

***Scientific Advisory Board.***We have established a scientific advisory board comprised of six members with extensive experience in the field of oncology. Our scientific advisors include researchers who publish widely cited research on topics relevant to the study and treatment of cancer, lead clinical units at experienced precision medicine cancer centers in the United States and are actively involved in our drug development process and programs. Our scientific advisory board meets periodically with our board of directors and management to discuss matters relating to our business activities and to establish commercial business alliances. Members of our scientific advisory board are reimbursed by us for out-of-pocket expenses incurred in connection with serving on our advisory board.

Our scientific advisory board currently includes the following physicians and their professional affiliations:

***Patient Advocacy Advisory Board.***We have established a patient advocacy advisory board comprised of four members with experience dealing with the effects of Osteosarcoma. This board is responsible for reviewing and establishing our patient advocacy philosophy and policy. This board also develops procedures for patient care evaluation while adhering to regulatory standards. This board identifies gaps in patient care and represents patient interests at FDA meetings, ensuring that patient voices are heard in regulatory discussions. Members of our patient advocacy advisory board are reimbursed by us for out-of-pocket expenses incurred in connection with serving on such board and sign customary non-disclosure agreements.

Our patient advocacy advisory board currently includes the following individuals and their affiliations:

***ADC Advisory Board.***We have established an ADC advisory board comprised of two members with extensive experience with ADC technologies. This board is responsible for reviewing and establishing our strategy and policies related to ADCs and helps to design and implement procedures for evaluating the efficacy and safety of our ADC technologies, ensuring compliance with regulatory standards. This board identifies opportunities to enhance ADC technology and address challenges in development, contributing to the advancement of innovative therapies in the field. Members of our ADC advisory board are reimbursed by us for out-of-pocket expenses incurred in connection with serving on such board and sign customary non-disclosure agreements.

Our ADC advisory board currently includes the following professionals and their affiliations:

Some of the members of our advisory boards may serve as consultants under consulting agreements for which they will receive compensation. To date, however, none of our advisory board members has served as consultants to us, and we have not entered into any consulting agreements with any of them. To our knowledge, none of our advisory board members has any conflict of interest between their obligations to us and their obligations to others. Hospitals, medical centers and companies with which advisory board members are involved may in the future have commercial relationships with us.

Our Licensing Obligations

***Advaxis.***In November 2020, we entered into an amended and restated development, license and supply agreement with Advaxis, pursuant to which Advaxis granted a license to us that allowed us to utilize Advaxis’ ADXS-HER2 construct patents to develop and commercialize ADXS-HER2, our lead product candidate (OST-HER2). On April 9, 2025, we acquired from Ayala (formerly Advaxis) the HER2 Assets. In connection with such acquisition, the amended and restated development, license and supply agreement was terminated.

***BlinkBio.***In August 2020, we entered into a licensing agreement with BlinkBio, Inc., pursuant to which BlinkBio granted a license to us that allows us to utilize BlinkBio’s proprietary technology to develop, manufacture and commercialize certain of our products. BlinkBio granted us an exclusive license for tADC’s that are directed towards, binds to or modifies the folate receptor alpha and a co-exclusive license for tADC’s that are directed towards, binds to or modifies any target other than the folate receptor alpha, such as HER2. In connection with the license agreement, we also agreed to issue a convertible note to BlinkBio.

Biolacuna Ltd. We have contracted with Biolacuna Ltd, a global life sciences advisory firm, to assist with the following agencies requirements to register OST-HER2 and gain approval of its use in the respective regions:

University of Pennsylvania. On April 9, 2025, we acquired from Ayala the HER2 Assets. Pursuant to the terms of the HER2 Purchase Agreement, the amended and restated development, license and supply agreement with Advaxis terminated. In connection with the acquisition of the HER2 Assets, we were assigned by Ayala a license agreement with the Trustees of the University of Pennsylvania covering the use of HER2 construct patents. Under the terms of the license agreement, we are required to pay an annual license fee to the Trustees of the University of Pennsylvania. We are obligated to pay a royalty equal to 1.5% of net sales related to:

See “Management’s Discussion and Analysis of Financial Condition and Results of Operations” for more information on our licensing obligations and the BlinkBio convertible note.

Our Intellectual Property

Our commercial success depends in part on our ability and the ability of those third parties from whom we in-license patents to obtain and maintain intellectual property protection in the United States and other countries for our current or future product candidates, including our lead core product candidate OST-HER2, our other core product candidate OST-tADC, our non-core product candidates, our proprietary compound library and other know-how. We seek to protect our proprietary and intellectual property position by, among other methods, in-licensing, owning, co-owning and filing patents and patent applications in the United States and abroad related to our proprietary technology, inventions and improvements that are important to the development and implementation of our business. We also rely on trade secrets, know-how and continuing technological innovation to develop and maintain our proprietary and intellectual property position.

Following our acquisition of the HER2 Assets from Ayala, we now own or co-own certain patents covering our lead product candidates. We also in-license patents and patent applications for our other core candidate, OST-tADC, from BlinkBio, Inc. We co-own with the University of Pennsylvania the intellectual property related to OST-HER2, which includes two granted U.S. utility patents, one granted Japanese patent, and two additional foreign patents and pending applications, with expected expiration between 2029 and 2035, excluding any potential patent term extensions. We hold exclusive rights to patents and patent applications covering the commercial manufacturing of OST-HER2 and our broaderListeria-based immunotherapy platform, including two granted U.S. utility patents, one pending U.S. patent application, 11 granted foreign patents and 12 pending foreign applications. These patents are expected to expire in 2038, with one U.S. patent expiring in 2040 after patent term adjustment. The intellectual property licensed from BlinkBio, Inc. includes six granted U.S. utility patents and multiple foreign patents and pending applications covering methods of use for silicon-based drug conjugates and silanol-based therapeutic payloads, with expected expiration between 2036 and 2037, excluding any potential patent term extensions.

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 in the field of oncology. Our future plans also include reliance on data exclusivity, market exclusivity and patent term extensions when available.

The degree of patent protection we require to successfully commercialize our current or future product candidates may be unavailable or severely limited in some cases and may not adequately protect our rights or permit us to gain or keep any competitive advantage. We cannot provide any assurances that any of the patents that we own, co-own or in-license have, or that any of such pending patent applications that mature into issued patents will include, claims with a scope sufficient to protect OST-HER2 and OST-tADC or our other current or future product candidates. In addition, if the breadth or strength of protection provided by such patent applications or any patents we may own, co-own or in-license is threatened, it could dissuade companies from collaborating with us to license, develop or commercialize current or future product candidates.

Our ability to stop third parties from making, using, selling, offering to sell or importing products identical or similar to ours will depend on the extent to which we have rights under valid and enforceable patents, trade secrets or other intellectual property rights that cover these activities. The patent rights of biotechnology and pharmaceutical companies like ours are generally uncertain and can involve complex legal, scientific and factual issues. Our and any future licensor’s current and future patent applications may not result in the issuance of any patent in any particular jurisdiction, and the claims of any current or future issued patents, even if those claims are valid and enforceable, may not provide sufficient protection from competitors. Any owned or in-licensed patent rights we may obtain may not enable us to prevent others from replicating, manufacturing, using or administering our product candidates for any indication. Moreover, the coverage initially claimed in a patent application may be significantly reduced before a patent is issued, and a patent’s scope can be reinterpreted after issuance. In addition, any patent we may own, co-own or in-license may be challenged, circumvented or invalidated by third parties. As a result, we cannot ensure that any of our product candidates will be protected by valid and enforceable patents. See “Risk Factors — Risks Related to Our Intellectual Property” for a more comprehensive description of risks related to our intellectual property.

Our Commercialization Strategy

We intend to retain significant development and commercial rights to our product candidates and, if marketing approval is obtained, to commercialize our product candidates on our own, or potentially with a partner, in the United States and other regions. We currently have no sales, marketing or commercial product distribution capabilities. We intend to build the necessary infrastructure and capabilities over time for the United States, and potentially other regions, following further advancement of our product candidates. We believe that such a focused sales and marketing organization will be able to address the community of oncologists who are the key specialists in treating the patient populations for which our product candidates are being developed. Clinical data, the size of the addressable patient population and the size of the commercial infrastructure and manufacturing needs may all influence or alter our commercialization plans. The responsibilities of the marketing organization would include developing educational initiatives with respect to approved products and establishing relationships with researchers and practitioners in relevant fields of medicine.

Our Future 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 pre-clinical and clinical testing, as well as for commercial manufacturing if any of our product candidates obtain marketing approval. We also rely, and expect to continue to rely, on third parties to package, label, store and distribute our investigational product candidates, as well as 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 development of our product candidates.

All of our product candidates are biopharmaceuticals and are manufactured in synthetic processes from available starting materials. The chemistry appears amenable to scale-up and does not currently require unusual equipment in the manufacturing process. We expect to continue to develop product candidates that can be produced cost-effectively at contract manufacturing facilities.

Currently, the OST-HER2 active pharmaceutical ingredients (API) (e.g., clinical drug substance) are manufactured in accordance with GMPs. The drug product formulation is being developed with the goal of producing lyophilized therapeutics with consistent and immediate release dissolution profiles that can be reproducibly manufactured using automated equipment. All manufacturing activities for the OST-HER2 drug product are performed in accordance with GMPs. We currently rely on these vendors as single-source contract manufacturing organizations.

We are in the process of developing our supply chain for each of our product candidates and intend to put in place framework agreements under which third party ReciBioPharma, a chemical manufacturer, will generally provide us with necessary quantities of API and drug product on a project-by-project basis based on our development needs.

As we advance our product candidates through development, we will explore adding backup suppliers for the OST-tADC and drug product for each of our product candidates to protect against any potential supply disruptions.

We generally expect to rely on third parties for the manufacture of any companion diagnostics that we may develop.

Government Regulation

Our current or future product candidates and the activities associated with their development and commercialization, including their design, testing, manufacture, safety, efficacy, recordkeeping, labeling, storage, approval, advertising, promotion, sale, distribution, import and export are subject to comprehensive regulation by the FDA and other regulatory agencies in the United States and by comparable authorities in other countries.

Preclinical Studies and IND

Before initiating clinical trials in humans, a sponsor must complete preclinical development activities, which generally include laboratory evaluations of product chemistry, manufacturing, formulation and stability, as well asin vitro and animal studies designed to assess pharmacology, toxicology and potential safety risks. Nonclinical safety studies intended to support an IND application are required to comply with applicable GLP regulations.

To initiate human clinical trials in the United States, a sponsor must submit an IND to the FDA. An IND contains, among other things, results of preclinical studies, manufacturing and analytical data, any available clinical data or relevant literature, and a proposed clinical trial protocol. The IND submission process is intended to allow the FDA to assess whether the investigational product is reasonably safe to evaluate in humans and whether the proposed clinical trial protocol is appropriate.

An IND becomes effective 30 days after receipt by the FDA unless the FDA, within that 30-day period, places the proposed clinical trial on full or partial clinical hold due to safety concerns or deficiencies in the submission. If a clinical hold is imposed, the sponsor must address the FDA’s concerns to the agency’s satisfaction before the clinical trial may proceed. Accordingly, submission of an IND does not guarantee that the FDA will permit a clinical trial to begin. Certain long-term nonclinical studies, such as reproductive toxicity or carcinogenicity studies, may continue after an IND becomes effective.

Clinical Trials

Clinical trials must be conducted in accordance with applicable federal statutes and regulations governing drug development and human subject research, as well as in compliance with Good Clinical Practice (“GCP”) requirements, which are international ethical and scientific quality standards intended to protect the rights, safety and welfare of human subjects and to ensure the integrity and reliability of clinical trial data. Clinical trials must also be conducted pursuant to protocols that detail, among other things, the study objectives, inclusion and exclusion criteria, dosing regimen, safety monitoring procedures, and statistical analysis plans designed to evaluate efficacy and safety endpoints.

Clinical trials are typically conducted at multiple geographically dispersed sites to support generalizability of the data and to enable the FDA to evaluate the overall benefit-risk profile of the investigational product and determine whether it satisfies the applicable statutory standard for approval. Clinical data generated in these trials form the basis for the product labeling, if approved.

In the United States, each clinical trial must be reviewed and approved by an Institutional Review Board (“IRB”) prior to initiation. An IRB is a duly constituted body established to review and monitor biomedical research involving human subjects and has authority to approve, require modifications to, or disapprove research in order to protect the rights and welfare of trial participants. In foreign jurisdictions, clinical trials are subject to review and approval by independent ethics committees or similar regulatory authorities in accordance with applicable local laws and regulations.

The FDA may impose a clinical hold at any time before or during a clinical trial if it identifies safety concerns or determines that the investigation is not being conducted in accordance with applicable statutory or regulatory requirements. A clinical hold may delay or suspend a trial until the identified deficiencies are satisfactorily addressed. Similarly, an IRB may suspend or terminate a trial at its institution for non-compliance with applicable legal or regulatory requirements or IRB determinations, or if it determines that the research presents an unexpected serious risk to subjects.

Investigational products used in clinical trials must be manufactured in accordance with applicable current good manufacturing practice (“cGMP”) requirements under federal law and related regulations. While full commercial-scale validation is not required during early development, manufacturing controls must be sufficient to ensure product identity, strength, quality and purity appropriate for the stage of development. As clinical development progresses, regulatory expectations for manufacturing controls and validation generally increase.

Marketing Approval

Before we can commercialize any of our current or future product candidates, we must obtain marketing approval from the applicable regulatory authorities. We have not received approval to market any of our current product candidates. We expect to rely on third-party contract research organizations and regulatory consultants to assist us in preparing and submitting marketing applications and navigating the regulatory review process. Securing regulatory approval requires the submission of extensive preclinical and clinical data, as well as supporting information, to the relevant regulatory authorities for each therapeutic indication and line of treatment to establish the product candidate’s safety, efficacy, and, in the case of biologics, purity and potency. Securing regulatory approval also requires the submission of detailed information regarding the drug manufacturing process and, in most cases, inspection of manufacturing facilities by the applicable regulatory authority.

The process required by the FDA before a drug or biologic product may be marketed in the United States generally involves the following:

We are not permitted to market our current or future product candidates in the United States until we receive approval of an NDA or BLA from the FDA, as applicable. In the European Economic Area, we must receive a marketing authorization from the European Commission following review by the European Medicines Agency, and in other foreign jurisdictions, we must obtain approval from comparable regulatory authorities prior to commercialization.

Post-Market Requirements

If the FDA or comparable foreign regulatory authorities approve any of our current or future product candidates, the manufacturing processes, labeling, packaging, distribution, adverse event reporting, storage, advertising, promotion, and recordkeeping for the drug will be subject to extensive and ongoing regulatory requirements. These requirements include submissions of safety and other post-marketing information and reports, registration, continued compliance with cGMPs, and compliance with GCPs for any clinical trials conducted post-approval. Regulatory approvals may also be subject to limitations on the approved indications, conditions of approval, or requirements for additional post-marketing studies, including Phase IV clinical trials and ongoing safety surveillance.

Later discovery of previously unknown problems with a product, including adverse events of unanticipated severity or frequency, or issues with our manufacturing processes or third-party manufacturers, or failure to comply with regulatory requirements, may result in, among other things:

To produce our product candidates for clinical trials and any products for commercial purposes, either at our own facilities or at third-party facilities, we and our third-party vendors must comply with applicable cGMP requirements. As part of our ongoing quality and process improvement efforts, we routinely assess our quality systems and implement enhancements as necessary to maintain compliance with applicable regulations. Regulatory authorities, including the FDA and comparable foreign authorities, may inspect our facilities to confirm compliance.

Animal Health Products

Certain U.S. federal agencies oversee the regulation of animal health products, including the FDA, the USDA and, as applicable, the U.S. Environmental Protection Agency (“EPA”). The FDA Center for Veterinary Medicine regulates animal pharmaceuticals under the Federal Food, Drug, and Cosmetic Act. The EPA regulates certain pesticidal products intended for use in or on animals.

The USDA, through the Animal and Plant Health Inspection Service (“APHIS”) and the Center for Veterinary Biologics (“CVB”), regulates veterinary biologics, including vaccines, diagnostics and immunomodulators, under the Virus-Serum-Toxin Act. APHIS oversees the importation, interstate movement and environmental release of veterinary biologics, while the CVB evaluates the safety, purity, potency and efficacy of these products prior to licensure.

The CVB’s licensure process for veterinary biologics generally includes:

Conditional licenses may be granted for veterinary biologics in special circumstances, such as limited markets or unmet needs, if the product demonstrates a reasonable expectation of safety and efficacy. Products with conditional licensure may be marketed under specific restrictions and are subject to follow-up studies to support full licensure. The CVB continues to monitor licensed products, enforce manufacturing standards, and may require additional data, inspections, or post-marketing studies as needed to ensure ongoing safety and efficacy.

Other Healthcare Laws

If we begin commercializing any of our current or future product candidates, our operations will be subject to a variety of U.S. federal, state and foreign healthcare laws and regulations. These laws govern, among other things, the recommendation, prescribing, marketing, distribution and reimbursement of biopharmaceutical products. Healthcare providers, including physicians, play a central role in prescribing and recommending drugs for which we obtain marketing approval. Our arrangements with healthcare providers, payors and other customers are subject to requirements designed to ensure the integrity of these interactions.

U.S. federal laws include, among others, the Anti-Kickback Statute, which prohibits offering or receiving remuneration to induce or reward the referral or recommendation of products reimbursable under federal healthcare programs, and the False Claims Act, which imposes penalties for submitting, or causing the submission of, false or fraudulent claims to the federal government. Analogous state laws may impose similar requirements, including reporting obligations for payments or other transfers of value to healthcare providers.

Healthcare reform legislation also influences coverage, pricing and reimbursement for biopharmaceutical products. In the United States, statutes such as the Affordable Care Act and the Inflation Reduction Act, as well as other federal and state programs, establish requirements for Medicaid and Medicare drug rebates, coverage determinations, pricing transparency and other programmatic matters. States may also adopt regulations affecting pricing, reimbursement and product access, including measures that encourage importation, bulk purchasing or competitive bidding. Similar legislative and regulatory frameworks exist in other countries, where foreign authorities regulate drug approval, reimbursement and healthcare coverage.

Compliance with these laws and regulations informs our commercial programs, interactions with healthcare providers and payors, product labeling and pricing strategies. Government authorities may update, amend or reinterpret these laws, which can affect operational requirements for biopharmaceutical companies.

Privacy and Data Protection Laws

Our operations may involve the collection, use, storage and transmission of personal information, including health-related data obtained in connection with clinical trials, research activities and other business operations. As a result, we are subject to a variety of federal, state, and foreign privacy and data protection laws and regulations.

***HIPAA and HITECH.***In the United States, the Health Insurance Portability and Accountability Act of 1996 (“HIPAA”), as amended by the Health Information Technology for Economic and Clinical Health Act of 2009 (“HITECH”), establishes standards for the privacy and security of protected health information maintained by healthcare providers, health plans and healthcare clearinghouses, as well as their business associates. These laws impose requirements relating to the use, disclosure and safeguarding of individually identifiable health information, including administrative, physical, and technical safeguards and breach notification obligations. HIPAA and HITECH also provide for civil and criminal penalties for violations and authorize enforcement by the U.S. Department of Health and Human Services and, in certain circumstances, state attorneys general.

***International Data Protection Laws.***Outside the United States, privacy and data protection laws regulate the processing of personal information, including health-related data. For example, the European Union’s General Data Protection Regulation (“GDPR”) establishes requirements governing the collection, processing, storage and transfer of personal data and imposes obligations on organizations that process such data. The GDPR includes restrictions on cross-border data transfers and provides individuals with certain rights regarding their personal data. The United Kingdom has adopted a similar regulatory framework under the UK GDPR and the Data Protection Act 2018. Compliance with these frameworks may affect how we collect, process, and transfer personal data in connection with our operations in Europe and other jurisdictions.

***U.S. State Privacy Laws.***Several U.S. states have enacted comprehensive privacy laws that regulate the collection and use of personal information. For example, the California Consumer Privacy Act (“CCPA”), as amended by the California Privacy Rights Act (“CPRA”), provides California residents with rights regarding their personal information and imposes obligations on covered businesses relating to disclosures, consumer rights requests, and limitations on certain uses or sharing of personal data. These laws are enforced by state authorities and may provide private rights of action in certain circumstances. Additional states have adopted or are considering similar privacy legislation.

Compliance with these privacy and data protection requirements may affect how we design our clinical trial activities, information systems, data processing practices and contractual arrangements with third parties that process personal information on our behalf.

Environmental Regulations

Our operations, facilities and product development activities are subject to a variety of U.S. federal, state, local and foreign environmental, health and safety laws and regulations. These requirements govern, among other things, air emissions, wastewater discharges, the use and storage of hazardous substances, the generation and disposal of hazardous and non-hazardous waste, and the remediation of environmental contamination.

Our research and development and manufacturing-related activities involve the use of hazardous and flammable materials, including chemicals and biological and radioactive materials, and may generate hazardous waste. We typically rely on third-party contractors for the transport, treatment and disposal of these materials and wastes.

Environmental regulatory authorities, including the EPA and comparable state and foreign agencies, administer laws and regulations relating to pollution control, environmental protection and workplace health and safety. These requirements address, among other matters, emissions to air, discharges to land or water, and the handling, storage, transportation and disposal of regulated materials. Compliance with these laws and regulations is an ongoing component of our operations and facility management.

Pricing Regulations and Third-Party Coverage and Reimbursement

The requirements governing regulatory approval, pricing and reimbursement for pharmaceutical and biologic products vary significantly among countries. In some jurisdictions, governmental authorities regulate or approve the price of a drug before it can be marketed, while in others pricing reviews occur after marketing authorization. In many foreign markets, prescription drug pricing remains subject to ongoing governmental oversight even after initial approval. As a result, the timing of commercial launch and the price at which products may be marketed can be influenced by regulatory review and reimbursement determinations.

The commercial success of any of our current or future product candidates will depend, in part, on the availability of coverage and reimbursement from government healthcare programs, private health insurers and other third-party payors. These payors determine whether a product will be covered under a particular health plan and establish reimbursement levels. In making these determinations, payors typically consider factors such as the product’s safety and efficacy, clinical value, medical necessity and cost-effectiveness.

Healthcare systems in the United States and other countries increasingly emphasize cost containment. Government authorities and third-party payors employ a range of mechanisms to manage pharmaceutical expenditures, including coverage limitations, formulary controls, negotiated discounts and rebates, and utilization management tools. These policies may influence product pricing, prescribing practices and reimbursement levels.

In the United States, coverage and reimbursement decisions for many medicines under the Medicare program are administered by the Centers for Medicare & Medicaid Services (“CMS”), a component of the U.S. Department of Health and Human Services. CMS policies often inform reimbursement approaches adopted by private payors and other healthcare programs.

Trade Laws

Our global operations are subject to various U.S. and foreign laws and regulations relating to anti-corruption, anti-money laundering, export controls, economic sanctions and other international trade matters (collectively, “Trade Laws”). These laws generally prohibit companies and their employees, agents and other representatives from offering, authorizing or providing improper payments or other benefits to government officials or private parties in order to obtain or retain business or secure an improper advantage.

In the course of our business, we may interact with government agencies, government-affiliated hospitals, universities and other public institutions, including in connection with clinical trials, regulatory approvals and research collaborations. We may also engage third parties, such as contract research organizations, consultants and other service providers, to support these activities. Trade Laws may apply to our activities and to those conducted on our behalf by such third parties.

Compliance with applicable Trade Laws informs our internal policies, procedures and contractual arrangements with third parties engaged in our operations in the United States and internationally.

Our Competition

The biotechnology and pharmaceutical industries are highly competitive and characterized by rapid technological advancement, evolving regulatory requirements, and significant research and development efforts. We face competition from large pharmaceutical companies, biotechnology companies, academic institutions, government agencies and other research organizations that are developing or commercializing therapies for cancer and rare diseases, including Osteosarcoma.

While we are not currently aware of any adjuvant therapy for Osteosarcoma intended for use in pediatric patients that is further advanced in development than OST-HER2, a number of organizations are developing therapies that may compete with our product candidates. These include product candidates under development by companies such as AstraZeneca and Y-mAbs Therapeutics, as well as programs being pursued by academic and research institutions, including MD Anderson Cancer Center.

Competition in this industry is based on a number of factors, including the ability to successfully develop product candidates, demonstrate safety and efficacy in clinical trials, obtain regulatory approvals, secure intellectual property protection, establish manufacturing capabilities, obtain reimbursement from third-party payors and successfully commercialize approved products.

Human Capital and Employees

As of March 26, 2026, we had four full-time employees and one part-time employee. We also utilize the services of a limited number of consultants as needed to perform specialized regulatory and medical-related services. Our employees are not represented by labor unions or covered by collective bargaining agreements. We consider our relationship with our employees to be good. All of our employees have entered into agreements with our company requiring them not to disclose our proprietary information and assigning to us all rights to inventions made during their employment.

Facilities

Our corporate address is 115 Pullman Crossing Road, Suite 103, Grasonville, Maryland 21638. This space is the accounting office of our Chief Financial Officer and provided to us rent free. We believe that suitable additional or alternative space would be available in the future on commercially reasonable terms, if necessary. As of the date of this annual report, all our operations are conducted remotely.

Recent Developments

PIPE Financing

On December 24, 2024, we entered into a Securities Purchase Agreement (the “PIPE Purchase Agreement”) with certain institutional and accredited investors, substantially all of whom were existing stockholders, to issue immediately separable units (the “Units”), each consisting of one share of Series A senior convertible preferred stock (“Series A Preferred Stock”) and one warrant to purchase one share of common stock (each, a “Series A Warrant”). The Units were sold at $4.00 per Unit (the “PIPE Financing”). At two closings on December 31, 2024 and January 14, 2025, we issued an aggregate of 1,775,750 shares of Series A Preferred Stock and Series A Warrants exercisable into 1,775,750 shares of common stock, generating gross proceeds of approximately $7.1 million before fees and expenses.

Brookline Capital Markets, a division of Arcadia Securities, LLC, acted as exclusive placement agent for the issuance and sale of the securities in the PIPE Financing. Brookline Capital Markets, a division of Arcadia Securities, LLC, acted as exclusive placement agent. In connection with the PIPE Financing, we paid Brookline cash fees totaling $159,685 and $79,723 to Brookline and Brookline’s selected dealer, respectively, plus warrants to purchase an aggregate of 59,848 shares of common stock (the “Agent Warrants”).

The PIPE Purchase Agreement required stockholder approval under NYSE American rules for issuances that could exceed 20% of common stock outstanding as of December 24, 2024. On April 9, 2025, we held a Special Meeting of Stockholders, at which the issuance of shares upon (i) conversion of the Series A Preferred Stock, (ii) exercise of the Series A Warrants, and (iii) exercise of the Agent Warrants, in each case without regard to any limits on conversion or exercise therein and in amounts collectively equal to or exceeding 20% of our common stock outstanding as of December 24, 2024 (including upon the operation of applicable price reset and anti-dilution provisions and/or the reduction of conversion prices and exercise prices), was approved by our stockholders.

Acquisition of HER2 Assets

On April 9, 2025, we completed the acquisition of the HER2 Assets from Ayala. The HER2 Assets include two INDs with the FDA: (i) ADXS-503 for non-small cell lung cancer; and (ii) ADXS-504 for prostate cancer. In consideration for the purchase of the HER2 Assets, we agreed to assume certain specified liabilities and to pay an aggregate purchase price of $8,000,000, which was paid as follows: (i) $400,000 to Ayala ($150,000 of which was transferred upon signing of the HER2 Purchase Agreement and the remainder on the closing date); (ii) $100,000 to a third party on behalf of Ayala on the closing date; and (iii) $7,500,000 worth of shares of our common stock, or 4,774,637 shares based on the volume-weighted average price of our common stock over the 30 trading days immediately preceding the closing date.

ATM Equity Offering Program and Sales

On August 8, 2025, we entered into an at market issuance sales agreement (the “Sales Agreement”) with B. Riley Securities, Inc. and JonesTrading Institutional Services LLC (each, a “Sales Agent” and, together, the “Sales Agents”) relating to shares of our common stock. Pursuant to the Sales Agreement, we may offer and sell shares of our common stock from time to time having an aggregate offering price of up to $18,000,000 through or to the Sales Agents. We will pay each of the Sales Agents a total commission for its services in acting as agent in the sale of common stock up to 3.0% of the gross sales price per share of all shares sold through it as agent under the Sales Agreement. The amount of proceeds we will receive will depend upon the actual number of shares of our common stock sold and the market price at which such shares are sold. Because there is no minimum offering amount required as a condition to close a sale, the actual total public offering amount, commissions and proceeds to us are not determinable at this time. Sales of our common stock under the Sales Agreement are being made pursuant to a prospectus supplement filed with the SEC on August 25, 2025. As of March 26, 2026, we have sold an aggregate of 282,679 shares of our common stock for aggregate gross proceeds of $530,162 pursuant to the Sales Agreement.

Warrant Exercise Inducement and Exchange Offers

On July 11, 2025, we completed a final closing of a warrant exercise inducement and exchange offer (the “First Inducement Offering”). On September 2, 2025, we closed on a second warrant exercise inducement and exchange offer (the “Second Inducement Offering”). On January 14, 2026, we closed on a third warrant exercise inducement and exchange offer (the “Third Inducement Offering” and, collectively with the First Inducement Offering and Second Inducement Offering, the “Inducement Offerings”). The First Inducement Offering and Second Inducement Offering were made to holders of certain of our Series A Warrants to purchase shares of our common stock having a then current exercise price of $1.12 per share.

Pursuant to certain inducement offer letter agreements, holders of Series A Warrants exercised for cash their Series A Warrants to purchase an aggregate of 7,154,338 shares of our common stock at the then current exercise price of $1.12 per share and in exchange we issued to such holders new warrants (the “New Warrants”) to purchase up to an aggregate of 7,154,338 shares of our common stock at an exercise price of $3.00 per share, subject to adjustment as provided therein. The New Warrants are immediately exercisable from the date of issuance and have a term of exercise of five years from such date.

The Third Inducement Offering was made to less than 10 accredited investors that held New Warrants to purchase up to an aggregate of 5,382,148 shares of our common stock having a then current exercise price of $3.00 or $2.10 per share. Pursuant to certain inducement offer letter agreements, such holders of New Warrants exercised for cash their New Warrants to purchase 2,499,558 shares of our common stock at a reduced exercise price of $1.40 per share and in exchange we issued to such holders new warrants (the “2026 Warrants”) to purchase up to an aggregate of 2,499,558 shares of our common stock at an exercise price of $1.40 per share, subject to adjustment as provided therein. The 2026 Warrants are immediately exercisable from the date of issuance and have a term of exercise of five years from such date.

We engaged a SEC-registered broker dealer and FINRA member (the “Solicitation Agent”) to act as our exclusive warrant solicitation agent in connection with the Inducement Offerings and paid the Solicitation Agent a cash fee equal to 5.0%, 1.5% and 8.0% of the total gross cash proceeds received from the exercise by the holders of their respective warrants in connection with the First Inducement Offering, Second Inducement Offering and Third Inducement Offering, respectively. We also paid the Solicitation Agent $15,000 and $25,000 for its reasonable legal and other expenses in connection with the First Inducement Offering and Third Inducement Offering, respectively.

The gross proceeds to us from the Inducement Offerings, before deducting transaction fees and other offering expenses, were approximately $11.5 million. We are using the net proceeds from the Inducement Offerings to support U.S. and international regulatory and pre-commercial efforts aimed at securing marketing authorizations for OST-HER2 in the prevention or delay of recurrent, fully resected, pulmonary metastatic Osteosarcoma, provide funding for our wholly owned subsidiary OS Animal Health’s proposed spin-off transaction preparations, and for general corporate purposes.

The shares of common stock underlying the New Warrants have been registered for resale under the Securities Act. We agreed to file a registration statement on Form S-3 (or other appropriate form, including on Form S-1, if we are not then eligible to register securities on Form S-3) providing for the resale of the shares of common stock issued or issuable upon exercise of the 2026 Warrants within 30 calendar days of March 2, 2026, and to use commercially reasonable efforts to have such registration statement declared effective by the SEC within 60 calendar days (or within 90 calendar days in case of “full review” by the SEC) following its initial filing and to keep such registration statement effective at all times until the earlier of (i) the time no holder owns any 2026 Warrants or shares of common stock issuable upon exercise thereof and (ii) the Delegend Date (as defined in the inducement offer letter agreements entered into in connection with the Third Inducement Offering).

Privately Negotiated Warrant Exercise Inducement and Exchange Agreements

From January 10, 2026 through February 2026, we entered into privately negotiated inducement offer letters, pursuant to which certain remaining holders of our New Warrants exercised for cash their New Warrants to purchase an aggregate of 123,216 shares of our common stock at a reduced exercise price of $1.40 per share and in exchange we issued new warrants to purchase up to an aggregate of 123,216 shares of our common stock at an exercise price of $1.40 per share, subject to adjustment as provided therein. Such new warrants are immediately exercisable from the date of issuance and have a term of exercise of five years from such date. We received gross proceeds of approximately $172,502 from the exercise of these New Warrants.

We agreed to file a registration statement on Form S-3 (or other appropriate form, including on Form S-1, if we are not then eligible to register securities on Form S-3) providing for the resale of the shares of common stock issued or issuable upon exercise of these warrants on or before March 30, 2026, and to use commercially reasonable efforts to have such registration statement declared effective by the SEC within 60 calendar days (or within 90 calendar days in case of “full review” by the SEC) following its initial filing and to keep such registration statement effective at all times until the earlier of (i) the time no holder of these warrants owns any such warrants or shares of common stock issuable upon exercise thereof and (ii) the Delegend Date (as defined in the privately negotiated inducement offer letters).

2026 Bridge Financing

On March 4, 2026, pursuant to a securities purchase agreement (the “Bridge SPA”), we issued to certain accredited investors in a private placement transaction (i) 10.0% original issue discount unsecured convertible promissory notes in an aggregate principal amount of $2,200,000 (the “Bridge Notes”) and (ii) warrants to purchase up to an aggregate of 1,666,667 shares of our common stock (the “Bridge Warrants” and such private placement transaction, the “Bridge Financing”), for aggregate gross proceeds of $2,000,000, before deducting placement agent fees and other Bridge Financing expenses. The Bridge Notes mature on March 4, 2027 and accrue interest at a rate of 4.0% per annum. The Bridge Warrants were immediately exercisable upon issuance, expire five years from the date of issuance and have an exercise price of $1.40 per share, subject to adjustment as provided therein.

The Bridge Notes were sold at a 10% original issue discount, such that for each $100,000 invested by a purchaser, such purchaser received a Bridge Note in the principal amount of $110,000. The Bridge Notes are convertible into shares of our common stock under certain circumstances. If we complete a “Qualified Offering,” defined as a registered public offering or registered direct offering resulting in at least $2.5 million in gross proceeds from new money investments, the outstanding principal, together with all accrued and unpaid interest, will automatically convert into the securities sold in such offering at the offering price. Additionally, prior to any such Qualified Offering or repayment of the Bridge Notes, holders may elect to convert the Bridge Notes, in whole or in part, into shares of our common stock at a conversion price equal to 90% of the average daily volume-weighted average price of our common stock during the 10 trading days immediately preceding the holder’s conversion notice, subject to adjustment.

We intend to use the net proceeds of the Bridge Financing to fund clinical development activities, including ongoing and planned clinical trials, and advance our research and development programs, as well as for working capital and general corporate purposes.

We engaged a SEC-registered broker dealer and FINRA member to act as the exclusive placement agent for the Bridge Financing. In connection with the Bridge Financing, we paid to the placement agent (a) a cash fee equal to 7.0% of the aggregate gross cash proceeds received by us in connection with the Bridge Financing and (b) a one-time expense reimbursement of $25,000 for its legal and other expenses incurred in connection with the Bridge Financing.

We agreed to file a registration statement on Form S-3 (or Form S-1 if we are not then eligible to register securities for Form S-3) by April 3, 2026 to register for resale the shares of our common stock issuable upon conversion of the Bridge Notes and exercise of the Bridge Warrants, and to use commercially reasonable efforts to cause such registration statement to become effective within 60 calendar days (or 90 calendar days in the case of a “full review” by the SEC) following its initial filing and to keep such registration statement effective at all times until the earlier of (i) the time that no investor owns any Bridge Notes, Bridge Warrants or shares underlying such Bridge Notes and Bridge Warrants or (ii) the Legend Removal Date (as defined in the Bridge SPA).

We were formed as a Delaware limited liability company on April 12, 2018 under the name OS Therapies, LLC. On June 24, 2019, we converted from a limited liability company to a Delaware corporation and changed our name to OS Therapies Incorporated. We completed our initial public offering in August 2024 and our common stock is currently listed on NYSE American under the symbol “OSTX.”

We presently conduct all of our operations remotely. Our registered corporate address is 115 Pullman Crossing Road, Suite #103, Grasonville, Maryland 21638, and our telephone number is (410) 297-7793. Our website address is www.ostherapies.com. We make available on this website, free of charge, our annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K and amendments to those reports pursuant to Section 13(a) or 15(d) of the Exchange Act as soon as reasonably practicable after we electronically file such material with, or furnish such information to, the SEC. Reports and other information we file with the SEC may also be viewed at the SEC’s website at www.sec.gov. The information contained on, or that can be accessed through, our website is not incorporated by reference into this report.