Neurogene Inc.

Previous wording

Despite recent scientific advances in genetics, most neurological diseases, particularly those with devastating consequences to patients, are left untreated. Conventional gene therapy is an attractive potential treatment approach for only a limited number of monogenic diseases due to the challenges caused by the complex biology of neurological diseases and by inherent variable transgene uptake and expression. We are a clinical-stage biotechnology company committed to overcoming these limitations and turning today’s complex devastating neurological diseases into treatable conditions. By harnessing our proprietary transgene regulation technology, EXACTTM (Expression Attenuation via Construct Tuning), we are developing a differentiated product portfolio of genetic medicines for rare neurological diseases with high unmet need not otherwise addressable by conventional gene therapy. Our EXACT approach leverages key scientific breakthroughs, including gene transfer technology, microRNA-based genetic circuits, and adeno-associated virus (“AAV”) delivery, and is designed to deliver therapeutic levels of transgene to key areas of the brain that underlie neurological disease pathology.

Current wording

Despite recent scientific advances in genetics, most neurological diseases, particularly those with devastating consequences to patients, are left untreated. Conventional gene therapy is an attractive potential treatment approach for only a limited number of monogenic diseases due to the challenges caused by the complex biology of neurological diseases and by inherent variable transgene uptake and expression. We are a clinical-stage biotechnology company committed to overcoming these limitations and turning today’s complex devastating neurological diseases into treatable conditions. We are building a robust and differentiated product portfolio of genetic medicines for rare neurological diseases with high unmet need not otherwise addressable by conventional gene therapy. One approach we are taking harnesses our proprietary transgene regulation technology, EXACTTM (Expression Attenuation via Construct Tuning), that utilizes microRNA-based genetic circuits designed to deliver therapeutic levels of transgene to key areas of the brain that underlie neurological disease pathology.

Previous wording

Our first clinical-stage program to utilize the EXACT platform is NGN-401, which is in development for the treatment of Rett syndrome, a disease with a patient population that has a significant unmet need, and that ultimately progresses to substantial neurological and physical impairment and premature death. Our ongoing registrational trial of NGN-401, Embolden TM, is a single-arm, open-label, baseline-controlled trial evaluating the 1E15 vg dose of NGN-401 in 20 females with Rett syndrome. The Embolden trial is designed to evaluate NGN-401 in females ages three and above with potential to support a broad label in a single study and enable an efficient path to market. The first participant was dosed during the fourth quarter of 2025. We completed dosing in a Phase 1/2 open-label, multi-center clinical trial of NGN-401 gene therapy for Rett syndrome, with ten participants receiving the 1E15 vg dose. Clinical grade NGN-401 is manufactured at our manufacturing facility and was used for dosing in the Phase 1/2 clinical trial and is being used for the Embolden trial. NGN-401 is delivered using a one-time intracerebroventricular (“ICV”) procedure, which we believe is the most suitable route of administration to achieve optimal biodistribution in key regions of the brain and other parts of the nervous system that underlie Rett syndrome pathophysiology.

Current wording

Our first clinical-stage program, NGN-401, is in development for the treatment of Rett syndrome, a severe and progressive neurodevelopmental disease with substantial neurological and physical impairments and significant unmet need. NGN-401 is purposefully designed to utilize the EXACT platform and adeno-associated virus (“AAV”) delivery viaintracerebroventricular (“ICV”) administration, and to deliver the full-length MECP2 gene which preserves the complete set of endogenous regulatory elements to restore functional MeCP2 protein. Our ongoing registrational trial of NGN-401, Embolden TM, is a single-arm, open-label, baseline-controlled trial evaluating the 1E15 vg dose of NGN-401 in females with Rett syndrome. The Embolden trial is designed to evaluate NGN-401 in females ages three and above with potential to support a broad label in a single study and enable an efficient path to market. Approximately 90% of participants have been dosed in Embolden, and we are on track to complete dosing in the second quarter of 2026. We completed dosing in a Phase 1/2 open-label, multi-center clinical trial of NGN-401 gene therapy for Rett syndrome, with ten participants receiving the 1E15 vg dose. NGN-401 is delivered using a one-time ICV procedure, which we believe is the most suitable route of administration to achieve optimal biodistribution in key regions of the brain and other parts of the nervous system that underlie Rett syndrome pathophysiology. Clinical grade NGN-401 manufactured at our fully operational current good manufacturing practices (“cGMP”) facility in Houston, Texas was used for dosing in the Phase 1/2 clinical trial and is being used for the Embolden trial. We believe that our in-house manufacturing capabilities better enable control of product quality and development timelines, strategic pipeline and financial flexibility, and clinical-to-commercial continuity.

Previous wording

We received clearance of our Investigational New Drug (“IND”) application by the U.S. Food and Drug Administration (“FDA”) in January 2023.

Current wording

We received clearance of our Investigational New Drug (“IND”) application by the U.S. Food and Drug Administration (“FDA”) in January 2023. We completed enrollment in the Phase 1/2 open-label, multi-center clinical trial evaluating NGN-401 for the treatment of female patients with classic Rett syndrome in the second quarter of 2025. The trial is assessing the safety, tolerability, and efficacy of NGN-401 at a dose of 1E15 vg in eight participants in an ages 4-10 years cohort and two participants in an ages 11 years and older cohort.

Previous wording

In November 2025, we announced updated positive interim clinical data from the Phase 1/2 NGN-401 clinical trial in the pediatric cohort (ages 4-10) of participants receiving the 1E15 vg dose (n=8 for efficacy data; n=10 for safety data which includes both pediatric and adolescent/adult participants) with a data cut-off date of October 30, 2025.

Current wording

In November 2025, we announced updated positive interim clinical data from the Phase 1/2 NGN-401 trial in the pediatric cohort (ages 4-10)receiving the 1E15 vg dose (n=8 for efficacy data; n=10 for safety data, including pediatric and adolescent/adult participants) with a data cutoff date of October 30, 2025.

Previous wording

We believe that a successful best-in-class gene therapy treatment for Rett syndrome should be purposefully built to deliver: (1) multi-domain improvements across hand function, gross motor function and communication - the key domains impacting Rett syndrome, (2) progressive gains of developmental milestones/skills over time and (3) durability of gains sustained over time. Updated interim data showed that all pediatric participants, regardless of baseline disease severity, experienced functional gains, with an aggregate 35 developmental milestones/skills gained across core clinical domains of Rett syndrome – hand function/fine motor, language/communication and ambulation/gross motor. Participants with longer term follow-up continued to gain developmental milestones/skills and those more recently dosed with six months of follow-up also gained developmental milestones/skills. All developmental milestones/skills gained have been durable, with multidomain improvements observed in the core domains. All CGI-I improvements reported in November 2024 were durable, with no changes in any participant.

Current wording

All pediatric participants, regardless of baseline disease severity, experienced functional gains, with an aggregate 35 developmental milestones gained across core clinical domains of Rett syndrome, including hand function/fine motor, language/communication and ambulation/gross motor. Participants with longer term follow-up continued to gain developmental milestones and those more recently dosed with six months of follow-up also demonstrated milestone gains. All developmental milestones and CGI‑I improvements reported as of November 2024 were durable as of the data cutoff date, with no changes observed.

Previous wording

Four out of five participants with 12 months or longer follow-up in the Phase 1/2 trial met the responder definition of the primary endpoint that will be assessed at Month 12 for the Embolden trial.

Current wording

As of October 30, 2025, four out of five participants with at least 12 months of follow-up met the responder definition of the primary endpoint planned for assessment at Month 12 in the Embolden trial. The three participants with six months of follow-up have also showed early clinical activity, consistent with previously dosed participants.

Previous wording

We also announced safety and tolerability data from the 10 participants in the Phase 1/2 clinical trial who received the 1E15 vg dose of NGN-401 as of the data cut-off date of October 30, 2025. We believe that NGN-401 has been generally well-tolerated at the 1E15 vg dose, and there has been no evidence of hemophagocytic lymphohistiocytosis (“HLH”) in any participant at this dose. All treatment-related adverse events (“AEs”) have been Grade 1 (mild) or Grade 2 (moderate) in severity, and the majority are known potential risks of AAV and have resolved or are resolving. Participant 5 experienced two Grade 2 serious adverse events (“SAEs”) related to abnormal nerve conduction findings - areflexia and related elective inpatient diagnostic testing. The nerve conduction findings have returned to the normal range. Unrelated to NGN-401, Participant 5 also experienced a leg fracture confounding her Month 12 gross motor assessment

Current wording

We also reported safety and tolerability data from the ten participants in the Phase 1/2 clinical trial who received the 1E15 vg dose of NGN-401 as of the data cutoff date of October 30, 2025. We believe that NGN-401 has been generally well-tolerated at the 1E15 vg dose, with no cases of hemophagocytic lymphohistiocytosis (“HLH”) in any participant at this dose. All treatment-related adverse events (“AEs”) have been Grade 1 (mild) or Grade 2 (moderate) in severity, and the majority are known potential risks of AAV and have resolved or are resolving. Participant 5 experienced two Grade 2 serious adverse events (“SAEs”) related to an abnormal nerve conduction finding - areflexia and related elective inpatient diagnostic testing. The nerve conduction finding has returned to the normal range. Unrelated to NGN-401, Participant 5 also experienced a leg fracture confounding her Month 12 gross motor assessment.

Previous wording

The Phase 1/2 trial previously included a cohort evaluating a 3E15 vg dose of NGN-401. In November 2024, the third participant receiving the 3E15 vg dose died following complications from a rare hyperinflammatory syndrome associated with systemic exposure to high doses of AAV, and we discontinued use of that dose level. Hyperinflammatory syndromes can include HLH and multisystem inflammatory syndrome. Based on research we conducted related to hyperinflammatory syndromes and AAV gene therapy, HLH has only been reported following doses of AAV that are generally in the 1E14 vg/kg range or higher. The 1E15 vg dose level we moved forward in the Phase 1/2 trial and are evaluating in the Embolden registrational trial translates into the E13 vg/kg range, and we are not aware of any case of HLH ever being reported at this dose level.

Current wording

The Phase 1/2 trial previously included a cohort evaluating a 3E15 vg dose of NGN-401. In November 2024, the third participant receiving the 3E15 vg dose died following complications from a rare hyperinflammatory syndrome associated with systemic exposure to high doses of AAV, and we discontinued use of that dose. Hyperinflammatory syndromes can include HLH and multisystem inflammatory syndrome.

Previous wording

Despite our research related to hyperinflammatory syndromes and AAV gene therapy showing that HLH has only been reported following doses of systemic AAV that are higher than the 1E15 vg dose level, in an abundance of caution, we incorporated into our Phase 1/2 and Embolden protocols additional monitoring for markers using the HLH diagnostic criteria, such as ferritin, and a treatment algorithm to be used in the event HLH is detected. When administered early, this treatment algorithm has been used successfully to treat cases of HLH both in other AAV gene therapy and other known causes of HLH. There has been no evidence of HLH or hyperinflammatory syndrome in any participant at the 1E15 vg dose level in the NGN-401 clinical trial as of the date of this report.

Current wording

Based on research we conducted in 2025 related to hyperinflammatory syndromes and AAV gene therapy, HLH has only been reported following doses of AAV that are generally in the 1E14 vg/kg range or higher. The 1E15 vg dose used in the Phase 1/2 trial and in the Embolden registrational trial translates into the E13 vg/kg range, and we are not aware of any case of HLH ever being reported at this dose. Out of an abundance of caution, we incorporated enhanced monitoring into our Phase 1/2 and Embolden protocols for HLH markers, including ferritin, and a treatment algorithm that when administered early, has been used successfully to treat cases of HLH both in other AAV gene therapies and other known causes of HLH.

Previous wording

In June 2025, we first announced written agreement from the FDA on key elements of the NGN-401 Embolden registrational trial design, and we confirmed these elements and the trial design in September 2025. The primary endpoint is a responder-based composite endpoint that will assess an improvement in the Clinical Global Impression–Improvement Scale (“CGI-I”) with Rett syndrome anchors and the gain of a developmental milestone/skill, compared to the participant’s own baseline. Responders are defined as participants who attain a CGI-I score less than or equal to three (“minimally improved”) and gain any one developmental milestone/skill from a list of 28, as captured through standardized video recordings and independently verified by blinded central raters at the 12-month endpoint. A response rate of 35% (or 7 out of 20 patients) is the minimum threshold for success to reject the null hypothesis in the Embolden trial.

Current wording

The primary endpoint is a responder-based composite endpoint that will assess an improvement in the Clinical Global Impression–Improvement Scale (“CGI-I”) with Rett syndrome anchors and the gain of a developmental milestone, compared to the participant’s own baseline. Responders are defined as participants who attain a CGI-I score less than or equal to three (“minimally improved”) and gain any one developmental milestone from a list of 28, as captured through standardized video recordings and independently verified by blinded central raters at the 12-month endpoint. A response rate of 35% is the minimum threshold for success to reject the null hypothesis in the Embolden trial.

Previous wording

In June 2024, we announced that NGN-401 was one of four programs selected by the Center for Biologics Evaluation and Research at the FDA to participate in the FDA’s Support for clinical Trials Advancing Rare disease Therapeutics (“START”) Pilot Program based on potential for clinical benefits and clinical development program readiness. As part of the START Program, we have opportunities for enhanced communications with the FDA, with the aim to further accelerate the pace of NGN-401’s development. These opportunities are designed to provide frequent advice and regular ad-hoc conversations to address product-specific development issues, including, but not limited to, clinical study design, choice of control group and fine-tuning the choice of patient population. In August 2024, we announced that NGN-401 also received Regenerative Medicine Advanced Therapy (“RMAT”) designation from the FDA. RMAT designation is granted for regenerative medicines intended to treat, modify, reverse, or cure a serious or life-threatening disease or condition, and with preliminary clinical evidence that indicates that the drug has the potential to address unmet medical needs. Benefits of the RMAT designation program include all the benefits of Fast Track and Breakthrough Therapy designation programs, including early and frequent communications with FDA senior managers, intensive guidance on efficient drug development and eligibility for an Accelerated Approval pathway and Priority Review.

Current wording

In June 2024, we announced that NGN-401 was one of four sponsors selected by the Center for Biologics Evaluation and Research at the FDA to participate in the FDA’s Support for clinical Trials Advancing Rare disease Therapeutics (“START”) pilot program based on potential for clinical benefits and clinical development program readiness. As part of the START program, we have opportunities for enhanced communications with the FDA, with the aim to further accelerate the pace of NGN-401’s development. These opportunities are designed to provide frequent advice and regular ad-hoc conversations to address product-specific development issues, including, but not limited to, clinical study design, choice of control group and fine-tuning the choice of patient population.

Previous wording

We believe that our EXACT platform has broad applicability in complex neurological diseases not otherwise easily addressable by conventional gene therapy. In addition to our Rett syndrome program, we are in the early discovery stage for other potential programs.

Current wording

We believe that our EXACT platform has broad applicability in complex neurological diseases not otherwise easily addressable by conventional gene therapy. In addition to NGN‑401, we are advancing early‑stage discovery programs leveraging our EXACT platform for other potential indications. These programs are in the discovery stage, and we have not yet selected a clinical development candidate.

Previous wording

In addition to NGN-401, we were pursuing a conventional gene therapy program for the treatment of CLN5 Batten disease. We completed enrollment in a Phase 1/2 clinical trial of NGN-101 in patients with CLN5 Batten disease and in November 2024 announced that we do not expect to move forward with the program at this time. Given the rarity of the disease, continued investment in the program was predicated on alignment on a streamlined registrational pathway with the FDA. To support a streamlined pathway, we submitted an RMAT application to the FDA. Despite our belief that we met the standard of preliminary clinical evidence required to obtain an RMAT designation, the RMAT application was denied. We are currently evaluating options for the program.

Current wording

We also pursued a gene therapy program for the treatment of CLN5 Batten disease. We completed enrollment in a Phase 1/2 clinical trial of NGN-101, and in November 2024, we announced that we do not expect to advance the program at this time. Given the rarity of the disease, continued investment in the program was predicated on alignment with the FDA on a streamlined registrational pathway. To support this objective, we submitted an RMAT application, which was denied. We are currently evaluating options for the program.

Previous wording

We were founded in 2018, and have devoted substantially all of our resources to conducting research and development activities (including with respect to the NGN-401 and NGN-101 programs) and undertaking preclinical studies, establishing our manufacturing facility, conducting clinical trials and the manufacturing of product used in our clinical trials and preclinical studies, business planning, developing and maintaining our intellectual property portfolio, hiring personnel, raising capital, and providing general and administrative support for these activities.

Current wording

We were founded in 2018, and have devoted substantially all of our resources to conducting research and development activities and undertaking preclinical studies, establishing our manufacturing facility, conducting clinical trials and the manufacturing of product used in our clinical trials and preclinical studies, business planning, developing and maintaining our intellectual property portfolio, hiring personnel, raising capital, and providing general and administrative support for these activities.

Previous wording

Since our inception, we have funded our operations primarily with outside capital (e.g., proceeds from the sale of preferred stock and common stock), we have raised aggregate net proceeds of approximately$552.3 million. However, we have incurred significant recurring losses, including a net loss of$65.6 million and$55.6 million for thenine months ended September 30, 2025 and 2024, respectively. In addition, as of September 30, 2025, we had an accumulated deficit of$327.9 million and cash, cash equivalents and short-term investments totaling$265.4 million. In order to continue our operations, we must achieve profitable operations and/or obtain additional equity or debt financing. Until we achieve profitability, management plans to fund our operations and capital expenditures with cash on hand and the sale and issuance of securities. There can be no assurance that we will be successful in raising additional capital or that such capital, if available, will be on terms that are acceptable to us. If we are unable to raise sufficient additional capital, we may be compelled to consider actions such as reducing the scope of our operations and planned capital expenditures or selling certain assets, including intellectual property assets.

Current wording

Since our inception, we have funded our operations primarily with outside capital (e.g., proceeds from the sale of preferred stock, common stock and pre-funded warrants) and have raised aggregate net proceeds of approximately$552.1 million. However, we have incurred significant recurring losses, including a net loss of$30.9 million and$22.6 million for thethree months ended March 31, 2026 and 2025, respectively. In addition, as of March 31, 2026, we had an accumulated deficit of$383.6 million and cash, cash equivalents and short-term investments totaling$243.2 million. In order to continue our operations, we must achieve profitable operations and/or obtain additional equity or debt financing. Until we achieve profitability, management plans to fund our operations and capital expenditures with cash on hand and the sale and issuance of securities. There can be no assurance that we will be successful in raising additional capital or that such capital, if available, will be on terms that are acceptable to us. If we are unable to raise sufficient additional capital, we may be compelled to consider actions such as reducing the scope of our operations and planned capital expenditures or selling certain assets, including intellectual property assets.

Previous wording

•advance the NGN-401 program through clinical development;

Current wording

•advance the NGN-401 program through clinical development and, if successful, seek regulatory approvals;

Previous wording

•seek regulatory approvals for any product candidates that successfully complete clinical trials;

Current wording

•seek regulatory approvals for any other product candidates that successfully complete clinical trials;

Previous wording

•incur additional legal, accounting and other expenses related to operating as a public company.

Current wording

•incur legal, accounting and other expenses related to operating as a public company.

Previous wording

We do not have any products approved for commercial sale and have not generated any commercial revenue from product sales. Our ability to generate product revenue sufficient to achieve and maintain profitability will depend upon the successful development and eventual commercialization of one or more of our product candidates, which we expect, if it ever occurs, will take many years. We expect to spend a significant amount in development and marketing costs prior to such time. We will therefore require substantial additional capital to develop our product candidates and support our continuing operations. We may never succeed in achieving regulatory and marketing approval for our product candidates. We may obtain unexpected results from our preclinical and clinical trials. For example, in November 2024 we decided not to move forward with the NGN-101 gene therapy program for CLN5 Batten disease, given the rarity of the disease and the lack of a streamlined registrational pathway with the FDA following denial of our RMAT application for that program. We may in the future elect to discontinue, delay, or modify additional preclinical and clinical trials of our other product candidates. A change in the outcome of any of these variables with respect to the development of a product candidate could mean a significant change in the costs and timing associated with the development of that product candidate. Accordingly, until such time that we can generate a sufficient amount of revenue from product sales or other sources, if ever, management expects to finance our operations through private or public equity or debt financings, loans or other capital sources, which could include income from collaborations, partnerships or other marketing, distribution, licensing or other strategic arrangements with third parties, or from grants. However, we may be unable to raise additional capital from these sources on favorable terms, or at all, which could have a material adverse effect on our business. Our management cannot provide assurance that we will ever generate positive cash flow from operating activities. Please see the section below entitled Liquidity and Capital Resources for additional details on our substantial capital requirements.

Current wording

We do not have any products approved for commercial sale and have not generated any commercial revenue from product sales. Our ability to generate product revenue sufficient to achieve and maintain profitability will depend upon the successful development and eventual commercialization of one or more of our product candidates, which we expect, if it ever occurs, will take many years. We expect to spend a significant amount in development and marketing costs prior to such time. We will therefore require substantial additional capital to develop our product candidates and support our continuing operations. We may never succeed in achieving regulatory and marketing approval for our product candidates. We may obtain unexpected results from our preclinical and clinical trials. For example, in November 2024 we decided not to move forward with the NGN-101 gene therapy program for CLN5 Batten disease, given the rarity of the disease and the lack of a streamlined registrational pathway with the FDA following denial of our RMAT application for that program. We may in the future elect to discontinue, delay, or modify additional preclinical and clinical trials of our other product candidates. A change in the outcome of any of these variables with respect to the development of a product candidate could mean a significant change in the costs and timing associated with the development of that product candidate. Accordingly, until such time that we can generate a sufficient amount of revenue from product sales or other sources, if ever, management expects to finance our operations through private or public equity or debt financings, loans or other capital sources, which could include income from collaborations, partnerships or other marketing, distribution, licensing or other strategic arrangements with third parties, or from grants. However, we may be unable to raise additional capital from these sources on favorable terms, or at all, which could have a material adverse effect on our business. Our management cannot provide assurance that we will ever generate positive cash flow from operating activities. See “Liquidity and Capital Resources”.

Previous wording

Uncertainty in the global economy presents significant risks to our business. We are subject to continued risks and uncertainties related to the current macroeconomic environment, including high inflation, high interest rates, changes in foreign currency exchange rates, changes in trade policies, including the implementation of tariffs, sanctions, export or import controls and other actions or the threat of such actions that restrict international trade by the United States, China or other countries, changes in domestic and global monetary and fiscal policy, volatility in financial markets, rapid changes in our regulatory landscape in the United States, including significant staffing reductions, unexpected shifts in leadership of certain federal agencies, and an uncertain legislative environment, recent bank failures, proposed or adopted federal U.S. legislation seeking to limit the provision of services in our sector by certain non-U.S. entities, geopolitical factors, including the ongoing conflicts between Russia and Ukraine and in the Middle East and the responses thereto, the impacts of climate change, and supply chain disruptions. While management is closely monitoring the impact of the current macroeconomic conditions on aspects of our business, including the impacts on our participants in our clinical trials, employees, suppliers, vendors and business partners, the ultimate extent of the direct and indirect impacts on our business remains highly uncertain and will depend on future developments and factors that continue to evolve. Most of these developments and factors are outside of our control and could exist for an extended period of time. Management will continue to evaluate the nature and extent of the potential impacts to our business, results of operations, liquidity and capital resources. Please see the section entitled Risk Factors for additional risks associated with global economic events.

Current wording

Uncertainty in the global economy presents significant risks to our business. We are subject to continued risks and uncertainties related to the current macroeconomic environment, including persistent inflation, changing interest rates, changes in foreign currency exchange rates, changes in trade policies, including tariffs or other trade restrictions or the threat of such actions, changes in domestic and global monetary and fiscal policy, the enactment of the BIOSECURE Act in December 2025, which mandates a transition away from “biotechnology companies of concern,” rapid changes in the regulatory and legislative landscape in the United States, geopolitical factors, including the ongoing conflicts between Russia and Ukraine and in the Middle East and significant volatility in commodity prices, including the price of oil, and the responses thereto, the impacts of climate change, and supply chain disruptions. While management is closely monitoring the impact of the current macroeconomic conditions on aspects of our business, including the impacts on our participants in our Phase 1/2 and Embolden clinical trials, employees, suppliers, vendors and business partners, the ultimate extent of the direct and indirect impacts on our business remains highly uncertain and will depend on future developments and factors that continue to evolve. Most of these developments and factors are outside of our control and could exist for an extended period of time. Management will continue to evaluate the nature and extent of the potential impacts to our business, results of operations, liquidity and capital resources. For additional information, see the section entitled “Risk Factors.”

Previous wording

Interest income consists primarily of interest earned on our cash equivalents and short-term investments. We expect our interest income to fluctuate depending on interest rates and the amount of cash that is invested.

Current wording

Interest income consists primarily of interest earned on our cash, cash equivalents and short-term investments. We expect our interest income to fluctuate depending on interest rates and the amount of cash that is invested.

Previous wording

As of December 31, 2024, we had federal and state NOL carryforwards in the amount of$319.8 million and$39.6 million, respectively, which may be available to offset future taxable income. The state NOL carryforwards will begin to expire in 2038, unless previously utilized. Most federal NOL carryforwards were generated subsequent to January 1, 2018, and therefore are able to be carried forward indefinitely. As of December 31, 2024, we also had federal research tax credit and federal orphan drug tax credit carryforwards of$7.9 million and$4.8 million, respectively, which may be used to offset future tax liabilities. These tax and orphan drug credit carryforwards begin to expire in 2039 and 2043, respectively, unless previously utilized.

Current wording

As of December 31, 2025, we had federal and state NOL carryforwards in the amount of$372.2 million and$43.5 million, respectively, which may be available to offset future taxable income. The state NOL carryforwards will begin to expire in 2038, unless previously utilized. Most federal NOL carryforwards were generated subsequent to January 1, 2018, and therefore are able to be carried forward indefinitely. As of December 31, 2025, we also had federal research tax credit and federal orphan drug tax credit carryforwards of$8.5 million and$10.0 million, respectively, which may be used to offset future tax liabilities. These tax and orphan drug credit carryforwards begin to expire in 2039 and 2043, respectively, unless previously utilized.

Previous wording

Comparison of the Three and Nine Months Ended September 30, 2025 and 2024

Current wording

Comparison of the Three Months Ended March 31, 2026 and 2025

Previous wording

Expenses related to the Rett syndrome program increased primarily due to a $0.2 million increase in preclinical costs, a $1.0 million increase in clinical trial costs related to the Phase 1/2 and pivotal clinical trial of NGN-401, and a $0.6 million increase in CMC costs. The decrease in expenses related to the Batten disease program was primarily driven by a $1.5 million decrease in clinical trial costs for the Phase 1/2 clinical trial of NGN-101 and a $0.2 million decrease in clinical development costs, due to the de-prioritization of the program. The decrease in expenses related to the Early Discovery program was primarily driven by a $0.7 million decrease in preclinical costs.

Current wording

Expenses related to the Rett syndrome program increased primarily due to a $5.1 million increase in clinical trial costs related to the Phase 1/2 and pivotal clinical trial of NGN-401, a $2.4 million increase in chemistry, manufacturing and controls (“CMC”) costs primarily related to CDMO support for NGN-401 and a $1.0 million decrease in preclinical costs. The decrease in expenses related to the Batten disease program was primarily driven by a $0.6 million decrease in clinical trial costs for the Phase 1/2 clinical trial of NGN-101, due to the de-prioritization of the program. The decrease in expenses related to the Early Discovery program was driven by a $0.6 million decrease in preclinical costs primarily due to lower costs of preclinical development for the Early Discovery program.

Previous wording

As noted above, the increase in unallocated internal expenses was driven primarily by higher salaries, benefits, and stock-based compensation costs due to an increase in research and development headcount, as well as an increase in consumables expense related to CMC.

Current wording

The increase in unallocated internal expenses was primarily driven by higher salaries, benefits, and stock-based compensation costs due to an increase in research and development headcount, as well as an increase in laboratory consumables expense related to CMC.

Previous wording

The change in other income was insignificant for the three months ended September 30, 2025 and three months ended September 30, 2024.

Current wording

The change in other income was not material for the three months ended March 31, 2026 and three months ended March 31, 2025.

Previous wording

The change in other expenses was insignificant for the three months ended September 30, 2025 as compared to the three months ended September 30, 2024.

Current wording

The change in other expenses was not material for the three months ended March 31, 2026 as compared to the three months ended March 31, 2025.

Previous wording

As of September 30, 2025, we had cash, cash equivalents and short-term investments totaling$265.4 million. Since inception and through the issuance of these financial statements, we have funded our operations primarily through the sales of convertible preferred stock and common stock for net proceeds of approximately$552.3 million, including net proceeds from sale of common stock pursuant to our ATM Sales Agreement.

Current wording

As of March 31, 2026, we had cash, cash equivalents and short-term investments totaling$243.2 million. Since inception and through the issuance of these financial statements, we have funded our operations primarily through the sales of convertible preferred stock and common stock for net proceeds of approximately$552.1 million, including net proceeds from sale of common stock pursuant to our ATM Sales Agreement.

Previous wording

For the nine months ended September 30, 2024, we used $53.1 million of cash in operating activities. Cash used in operating activities reflected our net loss of $55.6 million, a $5.1 million net decrease in our operating assets and liabilities, and noncash charges of $7.6 million, which consisted primarily of $5.8 million in stock-based compensation, $2.4 million in depreciation and $0.5 million in non-cash operating lease expense, partially offset by $1.5 million in accretion on the held-to-maturity investments. The primary use of cash was to fund our operations related to the development of our product candidates, costs associated with the Reverse Merger (as defined below) and the associated financing (the “Pre-Closing Financing”), and related severance and retention payments to former Neoleukin employees.

Current wording

For the three months ended March 31, 2026, we used $26.1 million of cash in operating activities. Cash used in operating activities reflected our net loss of $30.9 million, a $1.2 million decrease in our net operating assets and non-cash charges of $3.6 million, which consisted primarily of $3.6 million of stock-based compensation, $0.8 million in depreciation and impairment expense and $0.2 million in non-cash operating lease expense partially offset by $0.4 million in accretion on the held-to-maturity investments and $0.7 million change in the contingent value rights liability. The primary use of cash was to fund our operations related to the development of our product candidates.

Previous wording

For the nine months ended September 30, 2025, we used $59.7 million of cash in operating activities. Cash used in operating activities reflected our net loss of $65.6 million, a $3.1 million net decrease in our operating assets and liabilities and noncash charges of $9.0 million, which consisted primarily of $10.8 million of stock-based compensation and $2.3 million in depreciation, partially offset by $4.0 million in accretion on the held-to-maturity investments. The primary use of cash was to fund our operations related to the development of our product candidates.

Current wording

For the three months ended March 31, 2025, we used $20.8 million of cash in operating activities. Cash used in operating activities reflected our net loss of $22.6 million, a $1.4 million net increase in our operating assets and liabilities, and non-cash charges of $3.3 million, which consisted primarily of $4.0 million in stock-based compensation, $0.7 million in depreciation and $0.2 million in non-cash operating lease expense, partially offset by $1.7 million in accretion on the held-to-maturity investments. The primary use of cash was to fund our operations related to the development of our product candidates.

Previous wording

For thenine months ended September 30, 2024, net cash flows used in investing activities consisted of purchases of short-term investments of $80.2 million and purchases of property and equipment of $0.7 million, partially offset by proceeds from maturities of short-term investments of $58.3 million.

Current wording

For thethree months ended March 31, 2026, net cash flows provided by investing activities consisted of proceeds from maturities of short-term investments of $130.0 million, partially offset by purchases of short-term investments of $83.5 million and purchases of property and equipment of $0.3 million.

Previous wording

For thenine months ended September 30, 2025, net cash flows used in investing activities consisted of purchases of short-term investments of $226.8 million and purchases of property and equipment of $1.1 million, partially offset by proceeds from maturities of short-term investments of $212.2 million.

Current wording

For thethree months ended March 31, 2025, net cash flows used in investing activities consisted of purchases of short-term investments of $89.0 million and purchases of property and equipment of $0.8 million, partially offset by proceeds from maturities of short-term investments of $44.7 million.

Previous wording

For the nine months ended September 30, 2025, net cash flows provided by financing activities primarily consisted of $9.8 million of open market sales of common stock pursuant ATM Sales Agreement.

Current wording

For the three months ended March 31, 2026, net cash flows provided by financing activities primarily consisted of proceeds of $0.2 million from the exercise of stock options.

Previous wording

We sub-lease approximately 6,000 square feet of office space for our corporate headquarters in New York, New York, with a term expiring in January 2028.

Current wording

We sub-lease approximately 6,000 square feet of office space for our corporate headquarters in New York, New York. In November 2025, we extended the lease by an additional 19 months at a lower cost per square foot which now expires in January 2028.

Previous wording

Each contingent value right (“CVR”) distributed pursuant to the CVR Agreement, dated December 18, 2023, by and between us and the Rights Agent (the “CVR Agreement”) contains the contractual right to receive certain net savings, if any, realized by June 30, 2029 in connection with certain legacy lease obligations related to our business prior to the Reverse Merger (the “Lease CVR”). As of September 30, 2025, approximately$0.7 million was recorded as a component of the contingent value rights liability arising from the Lease CVR on our condensed consolidated balance sheet. The commitment relates to Neoleukin’s sublease agreement, effective October 31, 2023, for one of its properties with an unrelated third party for the remainder of the lease term. For more information on the Lease CVR, see Note 9, Commitments and Contingencies—Lease CVR, in the notes to the financial statements included in Part I, Item 1 of this Quarterly Report on Form 10-Q.

Current wording

Each contingent value right (“CVR”) distributed pursuant to the CVR Licensing Agreement, dated December 18, 2023, by and between us and the rights agent (the “CVR Agreement”) contains the contractual right to receive certain net savings, if any, realized by June 30, 2029 in connection with certain legacy lease obligations related to our business prior to the reverse merger with Neoleukin (the “Lease CVR”). As of March 31, 2026, approximately$0.4 million was recorded as a component of the contingent value rights liability arising from the Lease CVR on our condensed consolidated balance sheet. The commitment relates to Neoleukin’s sublease agreement, effective October 31, 2023, for one of its properties with an unrelated third party for the remainder of the lease term. For more information on the Lease CVR, see Note 9, Commitments and Contingencies—Lease CVR, in the notes to the financial statements included in Part I, Item 1 of this Quarterly Report on Form 10-Q.

Previous wording

The December 2023 CVR Licensing Agreement and April 2024 CVR Agreement collectively account for the total Intellectual Property CVR. As of September 30, 2025, approximately $0.3 million was recorded within the contingent value rights liability as an offset arising from the Intellectual Property CVR on our condensed consolidated balance sheet due to deductions permitted under the Merger Agreement. For more information on the Intellectual Property CVR, see Note 9, Commitments and Contingencies—Intellectual Property CVR, in the notes to the financial statements included in Part I, Item 1 of this Quarterly Report on Form 10-Q.

Current wording

The December 2023 CVR Licensing Agreement and April 2024 CVR Licensing Agreement collectively account for the total Intellectual Property CVR. As of March 31, 2026, no other development and sales milestones were achieved nor deemed probable of achievement under the December 2023 CVR Licensing Agreement. For more information on the Intellectual Property CVR, see Note 9, Commitments and Contingencies—Intellectual Property CVR, in the notes to the financial statements included in Part I, Item 1 of this Quarterly Report on Form 10-Q.

Previous wording

In December 2020, we entered into the MCA with the University of Edinburgh. Under the MCA, we and the University of Edinburgh agreed to collaborate oncertain research and development projects (“Projects”), and we agreed to provide funding for such Projects for a 40-month initial term, which term was extended in November 2023 for an additional 33 months and may be further extended by mutual agreement. In exchange for such funding, the University of Edinburgh granted us the option to exclusively license any intellectual property arising from such Projects. Under the MCA, we are obligated to pay semi-annual installment payments relating to funding of costs for personnel and lab consumables for the 40-month period. Either party may terminate the MCA for convenience upon 90 days’ notice. If we terminate the MCA, we would be responsible for all non-cancellable costs and commitments related to any particular Project and any and all funding costs for any person working on such Project.

Current wording

In December 2020, we entered into a Master Collaboration Agreement (the “MCA”) with the University of Edinburgh (the “University of Edinburgh”). Under the MCA, we and the University of Edinburgh agreed to collaborate on certain research and development projects (“Projects”), and we agreed to provide funding for such Projects for a 40-month initial term, which was extended in November 2023 for an additional 33 months and may befurther extended by mutual agreement. Under the MCA, we are obligated to pay semi-annual installment payments relating to funding of costs for personnel and lab consumables for the duration of the MCA. Either party may terminate the MCA for convenience upon 90 days’ notice. If we were to terminate the MCA, we would be responsible for all non-cancellable costs and commitments related to any particular Project and any and all funding costs for any person working on such Project.

Previous wording

In March 2022, we exercised our option through the collaboration under the MCA, and entered into a License Agreement (the “March 2022 Edinburgh License Agreement”) with the University of Edinburgh, pursuant to which we licensed certain patents and know-how related to the EXACT technology and optimized MECP2 cassettes on an exclusive basis. Under the March 2022 Edinburgh License Agreement, we obtained an exclusive, worldwide license to the licensed patents to develop, manufacture, supply, sell, and commercialize any products that utilize the licensed patents (the “Licensed Products”) in exchange for low single-digit percentage royalties on future commercial net sales of the Licensed Products. Royalties are payable on a Licensed Product-by-Licensed Product and country-by-country basis until the later of the expiration of the last licensed patent covering such Licensed Product in the country where the Licensed Product is sold, or, if no licensed patent exists or has expired in such country, then ten years from first commercial sale of such Licensed Product in such country (the “Royalty Term”). The term of the March 2022 Edinburgh License Agreement continues until the end of the Royalty Term and the expiration of all of the payment obligation thereunder. We may terminate the March 2022 Edinburgh License Agreement for convenience upon 90 days’ notice. In connection with the license, we are also obligated to pay the University of Edinburgh up to $5.3 million in regulatory-related milestones and up to $25.0 million in sales-related milestones based on annual net sales of Licensed Products in excess of defined thresholds.

Current wording

In March 2022, we exercised our option under the MCA with respect to certain Projects and entered into a License Agreement with the University of Edinburgh (the “March 2022 Edinburgh License Agreement”), pursuant to which we licensed certain patents and know-how related to the EXACT technology and optimized MECP2 cassettes on an exclusive basis. Under the March 2022 Edinburgh License Agreement, we obtained an exclusive, worldwide license to the licensed patents to develop, manufacture, supply, sell, and commercialize any products that utilize the licensed patents (the “Licensed Products”) in exchange for low single-digit percentage royalties on future commercial net sales of the Licensed Products. Royalties are payable on a Licensed Product-by-Licensed Product and country-by-country basis until the later of the expiration of the last licensed patent covering such Licensed Product in the country where the Licensed Product is sold, or, if no licensed patent exists or has expired in such country, then 10 years from first commercial sale of such Licensed Product in such country (the “Royalty Term”). The term of the March 2022 Edinburgh License Agreement continues until the end of the Royalty Term and the expiration of all of the payment obligations under that license. We may terminate the March 2022 Edinburgh License Agreement for convenience upon 90 days’ notice. In connection with the license, we are also obligated to pay the University of Edinburgh up to $5.3 million in regulatory-related milestones, of which $0.3 million has been paid in connection with the Phase 1/2 study. The remaining regulatory milestone payments consist of $2.0 million payable upon achievement of the first regulatory approval (FDA or EMA) and $3.0 million payable upon achievement of the second regulatory approval (FDA or EMA). In addition, we may be obligated to make up to $25.0 million of sales-related milestone payments based on annual net sales of Licensed Products in excess of defined thresholds.

Previous wording

In August 2024, we entered into a Nonexclusive License Agreement with the Board of Trustees of Leland Stanford Junior University (the “Stanford License Agreement”) to license, on a non-exclusive basis, certain biological materials used in the manufacturing process of our product candidates, including NGN-401. Over the 10-year term of the Stanford License Agreement, we are obligated to pay an annual license maintenance fee. We may terminate this agreement for convenience upon 30 days’ notice.

Current wording

In August 2024, we entered into a Non-exclusive License Agreement with the Board of Trustees of Leland Stanford Junior University (the “Stanford License Agreement”) to license, on a non-exclusive basis, certain biological materials used in the manufacturing process of our product candidates, including NGN-401. Over the 10-year term of the Stanford License Agreement, we are obligated to pay an annual license maintenance fee. We may terminate this agreement for convenience upon 30 days’ notice.

Previous wording

Our financial statements are prepared in accordance with U.S. GAAP. The preparation of the financial statements and related disclosures requires management to make estimates and judgments that affect the reported amounts of assets, liabilities, costs and expenses, and the disclosure of contingent assets and liabilities in our financial statements. We base our estimates on historical experience, known trends and events and various other factors that management believes are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Management evaluates estimates and assumptions on a periodic basis. Our actual results may differ from these estimates. A summary of our significant accounting policies is presented in Part II, Item 8 of our Annual Report on Form 10-K for the year ended December 31, 2024. There have been no material changes to our significant accounting policies during thenine months ended September 30, 2025.

Current wording

Our financial statements are prepared in accordance with U.S. GAAP. The preparation of the financial statements and related disclosures requires management to make estimates and judgments that affect the reported amounts of assets, liabilities, costs and expenses, and the disclosure of contingent assets and liabilities in our financial statements. We base our estimates on historical experience, known trends and events and various other factors that management believes are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Management evaluates estimates and assumptions on a periodic basis. Our actual results may differ from these estimates. A summary of our significant accounting policies is presented in Part II, Item 8 of our Annual Report on Form 10-K for the year ended December 31, 2025. There have been no material changes to our significant accounting policies during thethree months ended March 31, 2026.