Neurogene (NGNE) deepens Rett gene therapy push with 2025 loss and long cash runway

Rhea-AI Filing Summary

Neurogene Inc. reported a full year 2025 net loss of $90.4 million, widening from $75.1 million in 2024, as it increased investment in its Rett syndrome gene therapy program NGN-401.

Research and development expenses rose to $75.0 million from $60.9 million, and general and administrative expenses increased to $28.3 million from $22.6 million, mainly due to higher clinical trial and employee-related costs. The company ended 2025 with $269.0 million in cash, cash equivalents and short-term investments, which it expects to fund operations through the first quarter of 2028.

Clinically, Neurogene fully enrolled its Embolden registrational trial for NGN-401 in Rett syndrome, with more than half of participants dosed and dosing completion targeted for the second quarter of 2026. Interim Phase 1/2 data at the 1E15 vg dose showed multidomain, durable functional gains across motor and communication domains, with NGN-401 generally well-tolerated and no cases of hemophagocytic lymphohistiocytosis.

NGN-401 received FDA Breakthrough Therapy designation based on interim Phase 1/2 data, and the FDA confirmed commercial manufacturing scale will match clinical scale, avoiding comparability studies. Neurogene plans to begin a Process Performance Qualification campaign and present updated Phase 1/2 data, including at least 12 months of follow-up for all 10 participants, in mid-2026, while continuing early commercial-readiness and payor engagement activities.

Positive

• Strong cash runway: Cash, cash equivalents and short-term investments of $269.0 million as of December 31, 2025 are expected to fund planned operations through the first quarter of 2028.
• Regulatory de-risking for NGN-401: NGN-401 received FDA Breakthrough Therapy designation based on interim Phase 1/2 data, and the FDA confirmed commercial manufacturing scale matches clinical scale, removing the need for comparability studies.
• Advancing toward registration in Rett syndrome: The Embolden registrational trial is 100% enrolled with more than 50% of participants dosed, using a single trial designed to support a Biologics License Application for patients aged three years and older.
• Encouraging clinical data: Interim Phase 1/2 results as of October 30, 2025 showed multidomain, durable functional gains and a generally well-tolerated safety profile at the 1E15 vg dose, with no cases of hemophagocytic lymphohistiocytosis.

Negative

• Increasing losses with higher operating expenses: Net loss widened to $90.4 million for 2025 from $75.1 million in 2024, as R&D expenses rose to $75.0 million and G&A expenses to $28.3 million, reflecting growing clinical and corporate spending ahead of potential commercialization.

Insights

Biotech equity analyst

Neurogene deepens NGN-401 investment, gains key FDA support and extends cash runway.

Neurogene is clearly pivoted toward late-stage development of NGN-401 for Rett syndrome. R&D spending increased to $75.0 million in 2025 from $60.9 million, largely from higher Rett trial and headcount costs, while G&A rose to $28.3 million as the company builds infrastructure ahead of potential commercialization.

Operationally, the company has fully enrolled the Embolden registrational trial, dosed more than half of participants and aligned with the FDA on a single trial design for patients aged three and older. Interim Phase 1/2 data as of October 30, 2025 showed multidomain, durable functional gains with NGN-401 at the 1E15 vg dose and a generally well-tolerated profile, with no hemophagocytic lymphohistiocytosis reported.

Regulatory and manufacturing de‑risking are notable: NGN-401 received FDA Breakthrough Therapy designation, and the agency agreed that commercial manufacturing scale matches clinical scale, eliminating comparability studies. With $269.0 million in cash and investments at December 31, 2025, Neurogene expects funding through the first quarter of 2028, covering key 2026 milestones such as completion of Embolden dosing in the second quarter, mid‑2026 Phase 1/2 data updates and initiation of Process Performance Qualification activities.

0001404644FALSE00014046442024-03-182024-03-18

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934

Date of Report (date of earliest event reported): March 24, 2026

Neurogene Inc.

(Exact name of registrant as specified in its charter)

Delaware			001-36327			98-0542593
(State or other jurisdiction of incorporation or organization)			(Commission File Number)			(I.R.S. Employer Identification No.)

535 W 24th Street, 5th Floor

New York, NY 10011

(Address of principal executive offices, including zip code)

Registrant's telephone number, including area code: (877) 237-5020

N/A

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class

Trading Symbol(s)

Name of each exchange on which registered

Common Stock, $0.000001 par value

NGNE

The Nasdaq Global Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. o

Item 2.02 Results of Operations and Financial Condition

On March 24, 2026, Neurogene Inc. (the “Company”) issued a press release announcing financial results for the quarter and year ended December 31, 2025. A copy of the press release announcing such results is attached as Exhibit 99.1 to this Current Report on Form 8-K. Also on March 24, 2026, the Company posted an updated corporate presentation on its website. A copy of the corporate presentation is furnished as Exhibit 99.2 to this Current Report on Form 8-K.

The information in this Item 2.02 and Exhibits 99.1 and 99.2 attached hereto are being furnished and shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall such information or Exhibits 99.1 and 99.2 be deemed incorporated by reference into any filing under the Exchange Act or the Securities Act of 1933, as amended, except as expressly set forth by specific reference to such filing.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

Exhibit Number						Description
99.1						Press Release dated March 24, 2026
99.2						Corporate Presentation (March 2026)
104						Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

			NEUROGENE INC.
Date: March 24, 2026			By:			/s/ Christine Mikail
						Name: Christine Mikail
						Title: President, Chief Financial Officer

Neurogene Reports Full Year 2025 Financial Results and Highlights Recent Updates

100% of participants enrolled in Embolden™ registrational trial and >50% of participants dosed; on track to complete dosing in second quarter of 2026

NGN-401 has been generally well-tolerated in Phase 1/2 trial and Embolden, with no cases of HLH at the 1E15 vg dose; additional interim Phase 1/2 data expected mid-2026

FDA Breakthrough Therapy designation granted to NGN-401 based on positive interim safety and efficacy data from Phase 1/2 trial

PPQ campaign planned to begin mid‑2026, supporting BLA readiness

Strong cash position provides runway through first quarter of 2028

NEW YORK – March 24, 2026 – Neurogene Inc. (Nasdaq: NGNE), a clinical-stage company founded to bring life-changing genetic medicines to patients and families affected by rare neurological diseases, today announced full year 2025 financial results and highlighted recent corporate updates.

“We continue to demonstrate strong execution, with completion of enrollment in the Embolden registrational trial, dosing more than half of participants, and receipt of Breakthrough Therapy designation for NGN-401,” stated Rachel McMinn, Ph.D., Founder and Chief Executive Officer of Neurogene. “NGN-401 continued to be generally well-tolerated at the 1E15 vg dose, and we remain on track to complete dosing in the second quarter of 2026. With PPQ planned to begin mid-year and early commercial-readiness activities well underway, we believe NGN-401 is increasingly de-risked as we advance toward a BLA submission and potential launch of NGN-401.”

Recent Corporate and NGN-401 Program Highlights

NGN-401 Gene Therapy for the Treatment of Rett Syndrome

•Announced today 100% of participants are enrolled in the Embolden™ registrational trial and >50% of participants have been dosed, and the Company is on track to complete dosing in the second quarter of 2026

•NGN-401 at the 1E15 vg dose has been generally well-tolerated, with no cases of hemophagocytic lymphohistiocytosis (HLH) in the Phase 1/2 trial or Embolden as of March 23, 2026

•Received Breakthrough Therapy designation for NGN-401 from the U.S. Food and Drug Administration (FDA), which was based on the FDA’s review of interim efficacy and

safety data from the Phase 1/2 trial as of the data cutoff date of October 30, 2025, including patient-level data and supporting video documentation

•In preparation for the planned NGN-401 Biologics License Application (BLA) submission, confirmed with the FDA that commercial manufacturing scale is the same as current clinical manufacturing scale, removing the need for comparability studies

•Initiated all 13 U.S. clinical trial sites conducting Embolden, with ongoing activities to convert these sites to commercial sites at launch

•Completed rigorous market payor research confirming strong reimbursement potential of NGN-401

•Reported positive interim data from the pediatric cohort (ages 4-10 cohort) of the Phase 1/2 trial, which demonstrated multidomain, durable gains with continued developmental milestone acquisition as of the data cutoff date of October 30, 2025

Key Anticipated Milestones in 2026

•Complete dosing of participants in the Embolden registrational trial in the second quarter of 2026

•Present updated interim safety and efficacy data on the pediatric cohort and the adolescent/adult cohort from the Phase 1/2 trial in mid-2026, including at least 12 months of follow-up for all 10 participants

•Initiate Process Performance Qualification (PPQ) campaign in mid-2026

•Initiate additional early commercial-readiness activities

Full Year 2025 Financial Results

•Cash, Cash Equivalents and Short-Term Investments: Cash, cash equivalents and short-term investments as of December 31, 2025 were $269.0 million and are expected to fund planned operations through the first quarter of 2028.

•Research & Development (R&D) Expenses: R&D expenses were $75.0 million for the twelve months ended December 31, 2025, compared to $60.9 million for the twelve months ended December 31, 2024. The increase in R&D expenses for the twelve months ended December 31, 2025 was primarily driven by an increase in Rett syndrome clinical trial costs and employee-related expenses due to an increase in R&D headcount, and it was partially offset by decreases in spending on the CLN5 Batten disease program and early discovery.

•General & Administrative (G&A) Expenses: G&A expenses were $28.3 million for the twelve months ended December 31, 2025, compared to $22.6 million for the twelve months ended December 31, 2024. The increase in G&A expenses for the twelve months ended December 31, 2025 was primarily driven by an increase in employee-related expenses due to an increase in non-cash stock-based compensation and headcount.

•Net Loss: Net loss was $90.4 million for the twelve months ended December 31, 2025, compared to $75.1 million for the twelve months ended December 31, 2024.

About Neurogene

Neurogene (NASDAQ: NGNE) is a clinical-stage biotechnology company focused on developing life-changing genetic medicines for people and their families impacted by devastating neurological diseases. The Company is using a biology-first approach paired with optimized delivery to develop purpose-built genetic medicines, including programs powered by its novel and proprietary EXACT™ transgene regulation technology. Neurogene is advancing its lead gene therapy program, NGN-401, as a potential best-in-class, one-time treatment for Rett syndrome. For more information, visit neurogene.com or follow on LinkedIn.

About NGN-401

NGN-401 is an investigational AAV9 gene therapy in late-stage clinical development as a potential best-in-class, one-time treatment for Rett syndrome. It is the only clinical candidate to deliver the full-length human MECP2 gene and includes Neurogene’s EXACT™ transgene regulation technology, which is designed to deliver consistent, tightly controlled MeCP2 protein expression on a cell-by-cell basis. NGN-401 is delivered through intracerebroventricular administration to achieve the broadest targeting directly to the brain and nervous system based on nonclinical biodistribution data. NGN-401 is being evaluated in the Embolden™ registrational clinical trial. Interim data from the Phase 1/2 trial (as of October 30, 2025) have shown that participants experienced multidomain, durable gains with continued skill acquisition observed over time, and NGN-401 at the 1E15 vg dose has been generally well-tolerated. NGN-401 has received Breakthrough Therapy, Regenerative Medicine Advanced Therapy, Fast Track, Orphan Drug and Rare Pediatric Disease designations and selection for the START Pilot Program from the U.S. Food and Drug Administration, Advanced Therapy Medicinal Product, Orphan and Priority Medicines designations from the European Medicines Agency and Innovative Licensing and Application Pathway designation from the United Kingdom Medicines and Healthcare products Regulatory Agency.

Cautionary Note Regarding Forward-Looking Statements

Statements in this press release are made as of the date of this press release. Neurogene does not undertake any obligation to make any updates to these statements to reflect events that occur or circumstances that arise after the date of this press release, except as may be required under applicable U.S. securities law.

Statements in this press release which are not historical in nature are intended to be, and hereby are identified as, forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These statements may discuss goals, intentions and expectations as to future plans, trends, events, results of operations or financial condition, or otherwise, based on current expectations and beliefs of the management of Neurogene, as well as assumptions made by, and information currently available to, management of Neurogene, including, but not limited to, statements regarding: the therapeutic potential and utility, efficacy and clinical benefits of NGN-401; the safety and tolerability profile of NGN-401; the applicability of reported interim results from the NGN-401 Phase 1/2 clinical trial to other participants or potential participants, including adolescent or adult patients; the potential for NGN-401 to be a best-in-class gene therapy for Rett syndrome; trial designs and clinical development plans for the

Company’s EmboldenTM registrational clinical trial of NGN-401 for Rett syndrome; trial designs and clinical development plans for the Company’s Embolden registrational clinical trial of NGN-401 for Rett syndrome, including timing of anticipated dosing and completion of participant dosing in our clinical trial and the expected timeline of our process performance qualification (PPQ) activities for our chemistry, manufacturing and controls (CMC) requirements; the response rate, expected durability and deepening of clinical data results from our NGN-401 clinical trial; the potential for future approval for commercialization of NGN-401 as a treatment for Rett syndrome, including the potential for third-party payor approval of reimbursement as well as the potential to convert existing clinical trial sites to commercial sites in the event NGN-401 does receive commercial approval; expected timing for release of additional data from our Phase 1/2 clinical trial of NGN-401; the potential for success of the Embolden registrational clinical trial of NGN-401 for Rett syndrome; the clinical benefit of delivering NGN-401 via intracerebroventricular administration; expected future interactions with or positions of the FDA, including the timing and outcome of any such interactions and anticipated benefits of any regulatory designation for NGN-401, including the FDA’s Breakthrough Therapy designation, Rare Pediatric Disease designation, RMAT designation and participation in the FDA’s START program; and the time period over which existing cash resources may be sufficient to fund the Company’s operations. Forward-looking statements generally include statements that are predictive in nature and depend upon or refer to future events or conditions, and include words such as “may,” “will,” “should,” “would,” “expect,” “anticipate,” “plan,” “likely,” “believe,” “estimate,” “project,” “intend,” “on track,” and other similar expressions or the negative or plural of these words, or other similar expressions that are predictions or indicate future events or prospects, although not all forward-looking statements contain these words. Forward-looking statements are based on current beliefs and assumptions that are subject to risks, uncertainties and assumptions that are difficult to predict with regard to timing, extent, likelihood, and degree of occurrence, which could cause actual results to differ materially from anticipated results and many of which are outside of Neurogene’s control. Such risks, uncertainties and assumptions include, among other things: the potential for negative impacts to participants in the Phase 1/2 clinical trial of NGN-401 for the treatment of Rett syndrome; the risk that the Company may not be able to report data on the predicted timeline; risks related to the Company’s ability to obtain regulatory approval for, and ultimately commercialize, its product candidates, including NGN-401; risks related to timing of completing enrollment in the Embolden trial of NGN-401 for Rett syndrome; and other risks and uncertainties identified under the heading "Risk Factors" included in Neurogene’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2025, filed with the Securities and Exchange Commission (“SEC”) on November 13, 2025, and other filings that the Company has made and may make with the SEC in the future. Nothing in this communication should be regarded as a representation by any person that the forward-looking statements set forth herein will be achieved or that the contemplated results of any such forward-looking statements will be achieved. Forward-looking statements in this communication speak only as of the day they are made and are qualified in their entirety by reference to the cautionary statements herein. Except as required by applicable law, Neurogene undertakes no obligation to revise or update any forward-looking statement, or to make any other forward-looking statements, whether as a result of new information, future events or otherwise.

This communication contains hyperlinks to information that is not deemed to be incorporated by reference into this communication.

- Financial Tables Follow -

Neurogene Inc. Unaudited Condensed Consolidated Balance Sheet Data (In thousands of U.S. dollars)

Neurogene Inc. Unaudited Condensed Consolidated Statements of Operations (In thousands of U.S. dollars, except per share information)

Company Contact:
Mike Devine

Executive Director, Corporate Communications
michael.devine@neurogene.com

Investor Contact:
Argot Partners
Neurogene@argotpartners.com

###

EVERY BREAKTHROUGH BEGINS WITH BELIEF March 2026 Corporate Presentation

Forward Looking Statements This communication contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These statements may discuss goals, intentions and expectations as to future plans, trends, events, results of operations or financial condition, or otherwise, based on current expectations and beliefs of the management of Neurogene, as well as assumptions made by, and information currently available to, management of Neurogene, including, but not limited to, statements regarding: the therapeutic potential and utility, efficacy and clinical benefits of its programs, including its EXACTTM technology and NGN-401; the potential for commercial approval of NGN-401 and the speed with which any such approval might be obtained; market opportunities for Neurogene's product candidates, including the estimated prevalence of Rett syndrome and expected levels of demand for NGN-401; the safety and tolerability profile of NGN-401; the applicability of reported interim results from the NGN-401 Phase 1/2 clinical trial to other participants or potential participants, including adolescent or adult participants; any extrapolation of interim trial results on the likelihood of gaining approval of NGN-401 from the FDA or any other regulator; trial designs and clinical development plans for the EmboldenTM registrational clinical trial of NGN-401 for Rett Syndrome, including timing of anticipated enrollment and completion of the enrollment in this clinical trial and the timing and the expected timeline of our Process Performance Qualification (PPQ) activities for our chemistry, manufacturing and controls (CMC) requirements; the response rate, expected durability and deepening of clinical data results from the NGN-401 clinical trials; expected timing for release of additional data from the Phase 1/2 clinical trial of NGN-401; the potential superiority of ICV administration and delivery of a full MECP2 gene as against other potential gene therapies; the potential for NGN-401 to be a best-in- class or first-in-class gene therapy for Rett syndrome; patient, caregiver and KOL sentiments relating to priorities on selecting potential gene therapy treatments; expectations related to payer reimbursement for NGN-401 if approved, including estimates related to potential reimbursement rates, the ease of obtaining reimbursement and the sentiments of payers with respect to value placed on certain outcomes and any impact of potentially implementing an outpatient regimen for NGN-401; the ability to and speed with which Neurogene could convert existing clinical trial sites to commercial sites if it is successful in obtaining regulatory approval for the commercialization of NGN-401; the potential for success of the Embolden registrational clinical trial of NGN-401 for Rett Syndrome; expected future interactions with or positions of the FDA or foreign regulatory authorities, including the timing and outcome of any such interaction and anticipated benefits of any regulatory designation for Neurogene's product candidates, including the FDA’s Breakthrough Therapy designation and RMAT designation, the EMA's PRIME designation and participation in the FDA's START program with respect to NGN-401; the benefits of Neurogene's in-house manufacturing capabilities; anticipated early-stage discovery and expectations regarding the initiation of future clinical trials for programs in development; the timing and achievement of any catalyst for value creation for Neurogene; and Neurogene's cash runway, including the time period over which existing cash resources may be sufficient to fund the Company’s operations. Forward-looking statements generally include statements that are predictive in nature and depend upon or refer to future events or conditions, and include words such as “may,” “will,” “should,” “would,” “expect,” “anticipate,” “plan,” “likely,” “believe,” “estimate,” “project,” “intend,” and other similar expressions or the negative or plural of these words, or other similar expressions that are predictions or indicate future events or prospects, although not all forward-looking statements contain these words. Statements that are not historical facts are forward-looking statements. Forward-looking statements are based on current beliefs and assumptions that are subject to risks and uncertainties and are not guarantees of future performance. Actual results could differ materially from those contained in any forward-looking statement as a result of various factors, including, without limitation: uncertainties regarding interactions with and feedback received from FDA staff regarding the Embolden registrational trial including the risk that the FDA could change its requirements for the Embolden trial; the ability to raise additional capital to finance operations; the ability of Neurogene to report its data on the predicted timeline; the ability of Neurogene to effectively use the RMAT designation, Breakthrough Therapy designation, PRIME designation or START program to accelerate development of NGN-401; the potential for negative impacts to patients dosed in the ongoing clinical trials for NGN-401; the ability to advance product candidates through non-clinical and clinical development; the ability to obtain regulatory approval for, and ultimately commercialize, Neurogene's product candidates; Neurogene’s limited experience in designing and conducting clinical trials; the ability to identify and pivot to other programs, product candidates that may be more profitable or successful than Neurogene's current product candidates; expectations regarding the potential tolerability, safety or efficacy for NGN-401; the ability to attract, hire, and retain skilled executive officers and employees; reliance on third parties, contract manufacturers, and contract research organizations; the ability of Neurogene to protect its intellectual property and proprietary technologies; risks related to Neurogene’s ability to correctly estimate its operating expenses, including its projected cash runway; and legislative, regulatory, political and economic developments and general market conditions. The foregoing review of important factors that could cause actual events to differ from expectations should not be construed as exhaustive and should be read in conjunction with statements that are included herein and elsewhere, including the risk factors included in the Company’s most recent Annual Report on Form 10-K and Quarterly Reports on Form 10-Q filed with the Securities and Exchange Commission, as well as risk factors associated with companies, such as Neurogene, that operate in the biopharma industry. These forward-looking statements involve a number of risks, uncertainties (some of which are beyond Neurogene’s control) or other assumptions that may cause actual results or performance to be materially different from those expressed or implied by these forward-looking statements. Nothing in this communication should be regarded as a representation by any person that the forward-looking statements set forth herein will be achieved or that the contemplated results of any such forward-looking statements will be achieved. Forward-looking statements in this communication speak only as of the day they are made and are qualified in their entirety by reference to the cautionary statements herein. Except as required by applicable law, Neurogene undertakes no obligation to revise or update any forward-looking statement, or to make any other forward-looking statements, whether as a result of new information, future events or otherwise. Industry and Market Data Certain information contained in this Presentation relates to or is based on studies, publications, surveys and Neurogene’s own internal estimates and research. In this Presentation, Neurogene relies on, and refers to, publicly available information and statistics regarding market participants in the sector in which Neurogene competes and other industry data. Any comparison of Neurogene to any other entity assumes the reliability of the information available to Neurogene. Neurogene obtained this information and statistics from third-party sources, including reports by market research firms and company filings. In addition, all of the market data included in this Presentation involve a number of assumptions and limitations, and there can be no guarantee as to the accuracy or reliability of such assumptions. Finally, while Neurogene believes its internal research is reliable, such research has not been verified by any independent source and Neurogene has not independently verified the information. Trademarks This Presentation may contain trademarks, service marks, trade names and copyrights of other companies, which are the property of their respective owners. Solely for convenience, some of the trademarks, service marks, trade names and copyrights referred to in this Presentation may be listed without the TM, SM © or ® symbols, but Neurogene will assert, to the fullest extent under applicable law, the rights of the applicable owners, if any, to these trademarks, service marks, trade names and copyrights. Disclaimer 2

3 To develop life-changing genetic medicines for people and their families impacted by devastating neurological diseases OUR MISSION Biology-first design Precision delivery for maximum drug distribution EXACT platform for precise transgene expression Driven by patients and families in need OUR APPROACH

NGN-401 is Rapidly Advancing Towards Commercialization as a Potential Transformative One-Time Treatment for Rett Syndrome 4 Clear Path to Registration with Single Registrational Trial for Broadest Age Range • Key elements of Embolden registrational trial aligned with FDA, including a single trial for ages ≥ 3 years • 100% of participants enrolled in Embolden and >50% of participants dosed High-Value Rare Disease with Significant Opportunity to Improve Patient Lives Early commercial-readiness activities underway to transform multi-billion-dollar market burdened by lifelong, high-intensity medical care Upcoming Milestones • Complete dosing of Embolden on track for 2Q’26 • Presentation of 12+ months Phase 1/2 data for all 10 participants planned for mid-2026 • Process Performance Qualification (PPQ) campaign planned to begin mid-2026 Neurogene is Positioned for Significant Value Inflection with Multiple Catalysts in 2026 Potential Best-in-Class Treatment for Rett Syndrome • Compelling clinical evidence showing durable multidomain improvements demonstrated across full spectrum of disease severity • Received FDA Breakthrough Therapy designation, in addition to START Pilot Program, RMAT and other regulatory designations

NGN-401 for Rett Syndrome

6 Cause: Variants in the MECP2 gene on the X chromosome lead to deficiency of functional MeCP2 protein MeCP2 is a DNA-binding protein essential for normal brain and nervous system function Onset: Developmental delay occurs at 6-18 months, followed by loss of previously acquired milestones during regression and subsequent developmental plateau at ~3 years Hallmark features: Loss of expressive and receptive communication Loss of purposeful hand function with repetitive movements Gait abnormalities and mobility challenges Seizures, breathing irregularities, severe constipation Rett Syndrome: Rare, Debilitating, Progressive, Neurodevelopmental Disorder

7 Multi-Billion-Dollar Market Opportunity for Disease-Modifying Gene Therapy for Rett Syndrome 1 Major market prevalence based on internal estimates; U.S. prevalence estimate based on published incidence rates; Laurvick CL, et al. J Pediatr 2006;148(3):347–35. 2 WW incidence estimate based on published incidence rates; Pini G, et al. Orphanet Journal of Rare Diseases (2016) 11:132. 3 Internal market research ~15,000 – 20,000 patients Major market prevalence US, EU and UK1 1:10,000 females Worldwide incidence2 Rett Syndrome is One of the More Prevalent Rare Diseases Clear Unmet Need No disease-modifying treatment available Only treatment options are limited to symptom management High burden on families and healthcare system Lifelong, constant care is required Payors value functional changes that are clinically meaningful and show improvements in activities of daily living Payors are familiar with Rett syndrome Decades-long survival supports premium-priced durable gene therapy Payors are Receptive to Reimbursement3

8 NGN-401: Purposefully Designed to Be the Best-in-Class Gene Therapy for Rett Syndrome Full-length MECP2 to translate functional MeCP2 protein NGN-401 Construct Only Gene Therapy Designed to Safely Deliver Full-length Protein to Key Areas of the Brain and Nervous System to Maximize Benefit ICV delivery to achieve the broadest targeting of brain and nervous system EXACT transgene regulation technology designed to safely achieve target levels

9 ICV Delivery Achieves Greater Expression in the Brain Compared to IT-L ICV = Intracerebroventricular IT-L = intrathecal lumbar ESGCT 2025 ICV route of delivery has been shown in preclinical models to have greater targeting of brain and nervous system regions underlying Rett syndrome pathophysiology compared to IT-L An estimated 30,000 ICV procedures are performed by neurosurgeons annually in the U.S. and require minimal downtime/recovery

NGN-401 PHASE 1/2 TRIAL

11 Dosing Completed in NGN-401 Phase 1/2 Clinical Trial in Females with Rett Syndrome Trial evaluating 1E15 vg dose of NGN-401 n=8 Ages 4-10 n=2 Ages > 11 Open-label, multicenter trial designed to assess the safety, tolerability and efficacy of NGN-401 Key Eligibility Criteria: Females with Classic Rett syndrome in post-regression stage of illness Clinical diagnosis and genetic confirmation of pathogenic MECP2 variant Clinical Global Impression-Severity (CGI-S) score of 4-6 Trial Overview

Baseline Characteristics of the Pediatric Participants in Phase 1/2 12 Pediatric Cohort (n=8) Pt:1 Pt:2 Pt:3 Pt:4 Pt:5 Pt:6 Pt:7 Pt:8 Age at Dosing (Years) 7 4 6 7 6 4 6 8 Baseline CGI-S Score 4 Moderately Ill 5 Markedly Ill 5 Markedly Ill 5 Markedly Ill 5 Markedly Ill 5 Markedly Ill 4 Moderately Ill 4 Moderately Ill Genetic Variant Severity Mild Severe Severe Severe Severe Moderate Mild-Moderate Mild-Moderate Time Post-Dosing (Months) 24 18 18 15 12 6 6 6 As of data cutoff date of October 30, 2025 Evaluating the Impact of NGN-401 Across Full Spectrum of Disease Severity

NGN-401 Drove Clinically Meaningful and Durable Improvement Across Key Rett Syndrome Domains 13As of data cutoff date of October 30, 2025; Neurogene press release (November 12, 2025) 100% showed functional improvements across core disease domains – fine motor/hand function, gross motor/ambulation and communication 35 total developmental milestones gained No plateau, including out to 24 months Multidomain gains enable increasingly complex activities, enhancing independence and health-related quality of life 88% achieved improved CGI-I score 1E15 vg dose continues to be generally well-tolerated, consistent with AAV-based gene therapy Key Findings from Interim Phase 1/2 Data

14 Caregivers Seek Treatment that Improves Daily Living and Leads to Durable, Multidomain Improvements Fine Motor/Hand Function Improvements Enables self-feeding, quicker meals, family/social dining and independence E.g., Transferring/grasping objects, finger feeding, drinking from a cup, using utensils Expressive & Receptive Communication Improvements Expressing needs, following instructions simplifying daily routines and strengthening connections E.g., Making choices, using words with meaning Gross Motor/Ambulation Improvements Enhances mobility and reduce caregiver burden E.g., Sitting w/support, standing while holding on, climbing up/down stairs Caregivers Consistently Highlight Improvements in Core Domains are the Priority Quantitative research conducted in 2024 with 30 Rett syndrome caregivers to daughters aged 3-22 years old; Follow-up qualitative research conducted in 2024 and 2025 with 27 Rett syndrome caregivers (sub-set of quantitative respondents) to daughters aged 3-22 years old

15 NGN-401 Drove Durable Accumulation of Multidomain Milestones Across Core Domains That Matter Most to Caregivers 3 4 5 7 92 6 4 7 8 4 8 12 12 14 3 Mos. 6 Mos. 9 Mos. 12 Mos. >12 Mos. Interim Phase 1/2 Data Showed Developmental Milestones Increased by Domain Over Time Post-NGN-401 Treatment n=8 n=8 n=6 n=5 n=4 18 9 21 26 31 As of data cutoff date of October 30, 2025 # o f D ev el o p m en ta l M ile st o n es A ch ie ve d Fine Motor/Hand Function Expressive & Receptive Communication Gross Motor/Ambulation

16 NGN-401 Delivers Durable, Multidomain Improvements that Translate to Real Life Impact Can communicate needs & wants, and foster greater social connections Says words with meaning Follows daily routines, e.g., getting ready for school Communicates needs and wants; can ID colors Engages with friends and family; shows affection Starting/ improved communication with use of assisted device Enhanced comfort and reduced distress Improvements in constipation Drinks clear liquids, eats solids for first time Absent aspiration pneumonia events Sleeps through the night Reduced physical burden for caregivers for activities of daily living Sits without support Walks up and down stairs unassisted Bends at waist and stands back up Bears more weight for ease of transfer Can get on/off furniture, out of bathtub, into car unassisted Less dependence on caregivers for basic needs Uses hands to self-feed, drink, play with toys, self-soothe Decreased to no stereotypies Uses utensils to self-feed New Functional Abilities and Improvements Post-Treatment with NGN-401 Improvements in Key Domains Lead to: Multidomain improvements Participation in activities of daily living Improvements in health-related quality of life Fine Motor/Hand Function Gross Motor/Ambulation Communication Autonomic

17 Phase 1/2 Caregiver Testimonials Following Treatment with NGN-401 Highlight Improvements Important to Families As of data cutoff date of October 30, 2025 “Sleep improved significantly as she is able to sleep all through the night without any issue.” “Her understanding has improved, especially with me when I ask her to do small tasks, then she will do it immediately almost every time…” “The other day she...ran a couple steps while out…” “She uses both hands to grab her blanket...She holds a banana and takes bites.” “She is paying attention, and even at school with decision- making…she knows what we are asking of her.” “She reacts to…[the] puppy. We have never seen that…nothing going on before, nothing was worth her attention. Now she is enjoying day-to-day.” “She is happier.” “I am grateful [NGN-401] has seemed to benefit [her] health and life…” “She is so happy all the time and calm.” “Before, she was really stuck a lot. Her gait has improved a lot.” “Walking and standing are so much better. Before she would fall all the time and now she doesn’t. She is so much stronger and rarely falls.” “She holds onto things longer…she is eating pieces of fruit using a fork, a new skill.” “She kissed me for the first time ever.”

18 NGN-401 Remains Generally Well Tolerated at the1E15 vg Dose Level As of data cutoff date of October 30, 2025 TEAE = Treatment emergent adverse event • All TEAEs related to NGN-401 have been Grade 1 (mild) or Grade 2 (moderate) in severity; the majority are known potential risks of AAV and have resolved or are resolving • Most participants experienced mild liver enzyme elevations • SAEs (Grade 2) related to abnormal nerve conduction findings occurred in Pt:5: • Areflexia and related elective inpatient diagnostic testing • Nerve conduction findings have returned to normal range • Unrelated to NGN-401, Pt:5 also experienced a leg fracture confounding her Month 12 gross motor assessment • No evidence of hemophagocytic lymphohistiocytosis (HLH) in any participant • Seizures have remained well controlled following NGN-401 • No intracerebroventricular (ICV) procedure-related AEs • No signs or symptoms indicative of MeCP2 overexpression 1E15 vg Dose Total n=10 N Events TEAEs related to NGN-401 9 59 Serious TEAEs Unrelated to NGN-401 3 4 Serious TEAEs Related to NGN-401 1 2

EMBOLDEN REGISTRATIONAL TRIAL OVERVIEW

20 Alignment with FDA on Single Registrational Trial to Support BLA Submission; Enrollment Underway in Embolden Trial Immunosuppression: Steroid prophylaxis during first 90 days, followed by taper Developmental Milestones • CGI-I score of ≤ 2 • Gain from baseline of at least 2 developmental milestones Single Arm, Baseline-Controlled, Open-Label Trial of NGN-401 in Females with Rett Syndrome Responder-based composite endpoint defined as: • CGI-I of ≤ 3 and • Gain from baseline of any one developmental milestone 35% response rate, or 7 of 20 participants, needed for success Primary Endpoint at 12 Months Key Secondary Endpoints • Pre-specified from a list of 28 • Captured through standardized video recordings and rated by independent, central, blinded raters Screening Period (Up to 45 days) NGN-401 One-time 1E15 vg dose Patients ≥ 3 years n=20 Primary Observation (12 Months)

28 Pre-Specified Developmental Milestones From Natural History Database Aligned with FDA, KOLs and Caregivers as Meaningful 21 Fine Motor/ Hand Function Gross Motor/Ambulation Communication 1.2% - 3% 0.3 – 6.6% Reached for toy Taken a drink from a cup held without assistance Used raking grasp to retrieve an object Used a pincer grasp (either refined or modified) Finger fed Transferred an object from one hand to the other Used a spoon/fork to eat without assistance Sat with support when placed Sat without support when placed Come to sitting Pulled to standing Stood while holding on Stood independently Cruised around furniture or holding on to someone Walked independently Climbed up stairs with help Climbed up stairs without help Climbed down stairs with help Climbed down stairs without help Ran 10 feet without falling Responded to familiar names/words Followed a command with a gesture Followed a command without a gesture Pointed for something they want Waved bye-bye Babbled Used words with meaning Spoken in phrases (2 words or more with meaning)

22 35% (7 of 20) Pre-Specified Minimum Response Rate for Success 80% Response Rate (4 of 5) % R es p o n d er s at 1 2 m o n th s Phase 1/2 Responders in Phase 1/2 Trial Exceed the Bar for Success Established as the Primary Endpoint in the Embolden Trial As of data cutoff date of October 30, 2025 Phase 1/2 Embolden 1E15 vg dose Steroid-only immunosuppression regimen Trial sites at Rett Centers of Excellence Standardized CGI-I training at all sites Independent, central review of video-based milestone assessments based on pre-specified definitions Independent, central, blinded review of video- based milestone assessments based on pre-specified definitions Key Design Elements Carried Into Embolden Interim Phase 1/2 Data and Key Trial Design Elements Carried Into the Registrational Trial De-risk Embolden Outcomes

COMMERCIAL READINESS & KEY ANTICIPATED MILESTONES

24 Building a Strong Foundation for Commercialization Internal CMC capabilities and manufacturing facility to produce commercial product Positioning Embolden clinical trial sites for rapid conversion to commercial sites at launch Payor research confirms strong reimbursement potential for NGN-401 Embolden Clinical Trial Sites at Rett Centers of Excellence Separate payment to be issued for NGN-401, enabling hospitals to secure reimbursement without inpatient bundling constraints Outpatient pathway optionality intended to further simplify reimbursement

Wholly Owned and Fully Integrated In-House AAV Manufacturing 25 GMP Manufacturing Toxicology Batch Manufacturing Process Development Quality Assurance Quality Control Analytical Development Flexibility to manufacture AAV product at low cost Own product quality and development timelines Process development expertise supports both HEK293 and Sf9/rBV manufacturing platforms Flexibility to rapidly adapt CMC execution to program needs Process and scale are consistent between clinical and commercial; avoids potential future comparability challenges 42,000 sq ft facility in Houston, with 6,000 sq ft of cleanrooms

Compelling Interim Clinical Data: Multidomain, durable improvements across spectrum of disease severity 26 Single Registrational Trial Enrolling: Enables approval for broad population NGN-401 is Positioned for Leadership in Rett Syndrome with Multiple Value-Creating Catalysts Expected in 2026 and Beyond Early Commercial- Readiness Underway: Robust payor and market research to support future product launch Present Phase 1/2 Data: 12+ month data for all 10 participants Expected Timing: Mid-2026 Start PPQ campaign Expected Timing: Mid-2026 Expected to fund operations through Embolden data readout, BLA submission and key pre-launch activities 2025 ANTICIPATED 2026 MILESTONES Complete Dosing in Embolden Registrational Trial Expected Timing: 2Q’26 Strong Cash Balance (1Q’28) Initiation of Additional Commercial-Readiness Activities

APPENDIX: INTERIM PHASE 1/2 DATA UPDATE PARTICIPANT VIGNETTES

28 Pt:1 Gained 11 Developmental Milestones Across All Core Domains with Durability out to 24 Months Walking, ataxic gait, no ability to climb stairs Raking, no ability to hold objects Severe impairment, unable to follow commands, indicate wishes Pt:1 Developmental Milestones Post-NGN-401 Months Post-NGN-401 3 6 9 12 15 18 24 Fine Motor/Hand Function Used a pincer grasp (either refined or modified)       Taken a drink from a cup held without assistance       Used a spoon/fork to eat without assistance    Transferred an object from one hand to the other    Gross Motor/Ambulation Climbed up stairs without help       Heel-to-toe walking*      Climbed down stairs without help     Come to sitting  Communication Followed a command without a gesture       Waves bye bye     Pointed for something they want     Pt:1 Baseline: 7 Yrs Old Post Treatment with NGN-401 As of data cutoff date of October 30, 2025 *Not included in Embolden developmental milestones list; previously reported developmental milestones from other validated scales Images are representative of developmental milestones

29 Pt:2 Gained 10 Developmental Milestones Across All Core Domains with Durability out to 18 Months As of data cutoff date of October 30, 2025 *Not included in Embolden developmental milestones list; previously reported developmental milestones from other validated scales Images are representative of developmental milestones Impaired, ataxic, help to stand Severe impairment, unable to use hands Severe impairment, unable to follow commands, non-verbal Pt:2 Developmental Milestones Post-NGN-401 Months Post-NGN-401 3 6 9 12 15 18 Fine Motor/Hand Function Reached for toy       Used raking grasp to retrieve an object     Finger fed     Taken a drink from a cup held without assistance     Gross Motor/Ambulation Pulled to standing       Bent down, touched floor, and recovered*     Stepped off curb with help*    Climbed up stairs with help   Communication Followed a command without a gesture       Used words with meaning       Pt:2 Baseline: 4 Yrs Old Post Treatment with NGN-401

30 Pt:3 Gained 6 Developmental Milestones Across All Core Domains with Durability out to 18 Months As of data cutoff date of October 30, 2025 Images are representative of developmental milestones Pt:3 Baseline: 6 Yrs Old Cannot sit, stand or walk independently Raking grasp Post Treatment with NGN-401 Cannot follow commands Pt:3 Developmental Milestones Post-NGN-401 Months Post-NGN-401 3 6 9 12 15 18 Fine Motor/Hand Function Used a pincer grasp (either refined or modified)      Finger fed     Transferred an object from one hand to the other     Gross Motor/ Ambulation Sat without support when placed       Communication Followed command without gesture    Followed command with gesture  Severe Dysphagia

31 Pt:4 Gained 4 Developmental Milestones Across 2 Core Domains with Durability out to 15 Months Pt:4 Baseline: 7 Yrs Old Raking grasp, unable to hold objects Post Treatment with NGN-401 Unable to follow commands Pt:4 Developmental Milestones Post-NGN-401 Months Post-NGN-401 3 6 9 12 15 Fine Motor/Hand Function Used a pincer grasp (either refined or modified)      Used a spoon/fork to eat without assistance      Taken a drink from a cup held without assistance      Communication Followed command without a gesture     As of data cutoff date of October 30, 2025 Images are representative of developmental milestones

32 Pt:7 Gained 1 Developmental Milestone at Early Timepoint Pt:7 Developmental Milestones Post-NGN-401 Months Post-NGN-401 3 6 Fine Motor/Hand Function Used a spoon/fork to eat without assistance  Pt:7 Baseline: 6 Yrs Old Post Treatment with NGN-401 Could not use utensils As of data cutoff date of October 30, 2025 Images are representative of developmental milestones

33 Pt:8 Gained 3 Developmental Milestones Across 2 Core Domains at Early Timepoint Pt:8 Baseline: 8 Yrs Old Unable to bend at waist Pt:8 Developmental Milestones Post-NGN-401 Months Post-NGN-401 3 6 Gross Motor/ Ambulation Bent down, touched floor, and recovered*   Communication Followed command with a gesture  Used words with meaning  Unable to follow commands, cannot use words with meaning Hi! How are you? Hey!.. Good! Post Treatment with NGN-401 As of data cutoff date of October 30, 2025 *Not included in Embolden developmental milestones list; previously reported developmental milestones from other validated scales Images are representative of developmental milestones

FAQ

What were Neurogene (NGNE) key financial results for full year 2025?

Neurogene reported a 2025 net loss of $90.4 million, compared with $75.1 million in 2024. R&D expenses rose to $75.0 million and G&A expenses to $28.3 million, reflecting higher Rett syndrome clinical trial and employee-related costs.

How much cash does Neurogene (NGNE) have and how long is its runway?

As of December 31, 2025, Neurogene held $269.0 million in cash, cash equivalents and short-term investments. The company expects this balance to fund planned operations through the first quarter of 2028, covering key NGN-401 development and pre-launch activities.

What progress has Neurogene made with its NGN-401 Embolden registrational trial?

Neurogene has fully enrolled the Embolden registrational trial for NGN-401, with more than half of participants already dosed. The company remains on track to complete dosing in the second quarter of 2026, using a single trial design aligned with the FDA.

What do interim Phase 1/2 data show about NGN-401 for Rett syndrome?

Interim Phase 1/2 data as of October 30, 2025 showed multidomain, durable functional gains across motor and communication domains in NGN-401-treated participants. At the 1E15 vg dose, NGN-401 was generally well-tolerated, with no cases of hemophagocytic lymphohistiocytosis reported.

What regulatory designations has NGN-401 received from the FDA?

NGN-401 has received Breakthrough Therapy, Regenerative Medicine Advanced Therapy, Fast Track, Orphan Drug and Rare Pediatric Disease designations, as well as selection for the FDA’s START Pilot Program, supporting its development as a potential treatment for Rett syndrome.

What manufacturing and commercialization steps is Neurogene taking for NGN-401?

Neurogene confirmed with the FDA that commercial manufacturing scale will match clinical scale, avoiding comparability studies. It plans to begin a Process Performance Qualification campaign mid‑2026 and is preparing to convert Embolden trial sites into commercial sites while conducting extensive payor research.

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