Passage BIO, Inc.

1. Nature of Operations

Passage Bio, Inc., referred to herein collectively with its wholly-owned subsidiary as the Company, a Delaware corporation incorporated in July 2017, is a clinical stage genetic medicines company that historically focused on improving the lives of patients with neurodegenerative diseases through the development and advancement of cutting-edge, one-time therapies designed to target critical underlying pathologies in these conditions. The Company has determined to wind-down its gene therapy programs and, as described in the section titled “Recent Developments,” on June 24, 2026, the Company entered into an Agreement and Plan of Merger and Reorganization, which was subsequently amended and restated on September 2, 2026, or, as amended, the Merger Agreement, with Remix Therapeutics, Inc., or Remix, a Delaware corporation. In connection with the wind-down, the Company terminated its development services and clinical supply arrangements with Catalent Maryland, Inc., or Catalent, and terminated the Company’s collaboration agreement with Gemma Biotherapeutics, Inc., or Gemma, and the Company’s license with the Trustees of the University of Pennsylvania, or Penn, with respect to PBFT02, the Company’s former lead product candidate.

Recent Developments

On June 24, 2026 and subsequently amended and restated on September 2, 2026, the Company entered into a Merger Agreement with Remix, Peregrine Merger Sub, Inc., or the Merger Sub, a Delaware corporation and wholly-owned subsidiary of the Company, and Peregrine Merger Sub II, LLC, or Merger Sub II, a Delaware limited liability company and wholly-owned subsidiary of the Company. Upon the terms and subject to the satisfaction or waiver of the conditions described in the Merger Agreement, Merger Sub will be merged with and into Remix, with Remix surviving as a wholly-owned subsidiary of the Company and immediately following thereof, Remix will be merged with and into Merger Sub II, with Merger Sub II surviving as a wholly-owned subsidiary of the Company (such transaction, the Merger). The Merger is intended to qualify as a tax-free reorganization for U.S. federal income tax purposes and is expected to close in the fourth quarter of 2026, assuming satisfaction or waiver of all of the conditions of the Merger Agreement.

If the Merger is completed, the Company will continue as the surviving corporation after the Merger, but will change its name to Remix Therapeutics, Inc., and the management of Remix is expected to become the management of the surviving corporation. The surviving company is expected to pursue the business activities of Remix following the closing of the Merger. If the Merger Agreement were to be terminated under specified circumstances, the Company may be required to make a payment to Remix equal to $1.5 million in cash.

On July 21, 2026, the Company filed with the SEC a registration statement on Form S-4, as amended, or the Registration Statement, that includes a proxy statement/prospectus relating to the Merger and the related transactions, including the issuance of shares of Passage Bio Common Stock in the Merger and the matters to be submitted to the Company’s stockholders for their approval. The Registration Statement was declared effective by the SEC on October 9, 2026, and on October 9, 2026, the Company filed the definitive proxy statement/prospectus with the SEC and commenced mailing it to the Company’s stockholders. A special meeting of the Company’s stockholders to vote on the proposals described in the proxy statement/prospectus was held on November 5, 2026, at which the Company’s stockholders voted to approve all proposals included in the proxy statement/prospectus. The Merger remains subject to satisfaction or waiver of the other conditions to the closing of the Merger.

2. Risks, Liquidity, and Going Concern

The Company has incurred recurring losses and negative cash flows from operations since inception and had an accumulated deficit of $724.9 million as of September 30, 2026. The Company expects to continue to incur net losses and negative cash flows from operations for the foreseeable future.

The Company’s operations have historically consisted primarily of conducting preclinical studies, developing licensed technology, conducting clinical trials, and developing and manufacturing of clinical supply to support clinical trials. The

Company faces risks associated with early-stage biotechnology companies whose product candidates are in development. Product candidates require significant additional research and development efforts and establishing manufacturing capacity and regulatory approval prior to commercialization. These efforts would require significant amounts of additional capital for the Company and even if the Company’s efforts are successful, it is uncertain when, if ever, the Company will realize revenue from product sales.

On March 5, 2021, the Company entered into a Sales Agreement, or the Sales Agreement, with Cowen and Company, LLC, or Cowen, relating to the applicable terms of at-the-market equity offerings, or the ATM Facility, pursuant to which the Company may, but is not obligated to, offer and sell, from time to time, shares of its common stock with an aggregate offering price up to $125.0 million through Cowen, as sales agent in the ATM Facility. The Company is currently limited in its capacity to offer and sell shares of its common stock under the Sales Agreement pursuant to the prospectus supplement to its shelf registration statement on Form S-3, filed on March 4, 2024. As of September 30, 2026, $15.8 million of capacity remains available to be sold under the ATM Facility.

These consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles, or GAAP, assuming the Company will continue as a going concern. The going concern assumption contemplates the realization of assets and satisfaction of liabilities in the normal course of business. In accordance with the Financial Accounting Standards Board’s, or FASB, Accounting Standards Codification, or ASC, Subtopic 205-40,Presentation of Financial Statements - Going Concern, the Company has evaluated whether there are certain conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the consolidated financial statements are issued. The Company incurred net losses of approximately $4.7 million and $7.7 million for the three months ended September 30, 2026 and 2025, respectively, and $20.1 million and $32.5 million for the nine months ended September 30, 2026 and 2025, respectively. As of September 30, 2026, the Company had cash and cash equivalents totaling $20.2 million, which may not be sufficient to fund the Company’s operating expense and capital expenditure requirements for at least the twelve months following the date these consolidated financial statements are issued. The Company’s ability to continue as a going concern will depend on its ability to complete the Merger (including Remix’s related sale of common stock and pre-funded warrants) or otherwise obtain substantial additional funding. There can be no assurance that the Company will be able to complete the Merger or that Remix will be able to complete its sale of common stock and pre-funded warrants on a timely basis, on acceptable terms, or at all.

If the Company does not complete the proposed transaction with Remix and until such time, if ever, as the Company can generate substantial product revenue, the Company expects to finance its operations through a combination of equity offerings, debt financings, collaborations, strategic alliances, reverse merger or other business combination transactions, and marketing, distribution or licensing arrangements. To the extent that the Company raises additional capital through the sale of equity or convertible debt securities, existing stockholders’ ownership interest will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect existing stockholders’ rights as common stockholders. Debt financing and preferred equity financing, if available, may involve agreements that include covenants limiting or restricting its ability to take specific actions, such as incurring additional debt, making acquisitions or capital expenditures or declaring dividends. If the Company raises additional funds through collaborations, strategic alliances or marketing, distribution or licensing arrangements with third parties, the Company may have to relinquish valuable rights to its technologies, future revenue streams, research programs or drug candidates, or grant licenses on terms that may not be favorable to the Company. If the Company pursues another reverse merger or other business combination transaction similar to the proposed Merger, the Company may be subject to significant transaction costs, stockholders may experience substantial dilution, management team may change, and the Company may not achieve the anticipated benefits of such a transaction.

As a result, there is substantial doubt about the Company’s ability to continue as a going concern within one year after the date that these consolidated financial statements are issued. The consolidated financial statements do not include any adjustments to the carrying amounts and classification of assets, liabilities, and reported expenses that may be necessary if the Company were unable to continue as a going concern.

3. Summary of Significant Accounting Policies

The Company’s complete summary of significant accounting policies can be found in “Note 3. Summary of Significant Accounting Policies” in the audited consolidated financial statements included in the Company’s Annual Report filed on Form 10-K for the year ended December 31, 2025.

Basis of Presentation

The accompanying unaudited consolidated financial statements have been prepared in accordance with GAAP and include accounts of Passage Bio, Inc. and its wholly-owned subsidiary, which are collectively referred to herein as the Company. All intercompany balances and transactions have been eliminated in consolidation. Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the ASC and Accounting Standards Updates, or ASUs, promulgated by the FASB.

Interim Consolidated Financial Statements

The accompanying unaudited interim consolidated financial statements have been prepared from the books and records of the Company in accordance with GAAP for interim financial information and Rule 10-01 of Regulation S-X promulgated by the SEC, which permits reduced disclosures for interim periods. All adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of the accompanying consolidated balance sheets, consolidated statements of operations and comprehensive loss, consolidated stockholders’ equity, and consolidated cash flows have been made. Although these interim consolidated financial statements do not include all of the information and notes required for complete annual consolidated financial statements, management believes the disclosures are adequate to make the information presented not misleading. Unaudited interim consolidated results of operations and cash flows are not necessarily indicative of the results that may be expected for the full year. Unaudited interim consolidated financial statements and notes should be read in conjunction with the audited consolidated financial statements and notes included in the Company’s 2025 Annual Report filed on Form 10-K.

Use of Estimates

The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and contingent liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Estimates and assumptions are periodically reviewed, and the effects of the revisions are reflected in the accompanying consolidated financial statements in the period they are determined to be necessary.

Fair Value of Financial Instruments

Management believes that the carrying amounts of the Company’s financial instruments, including cash equivalents, prepaid expenses, and accounts payable, approximate fair value due to the short-term nature of those instruments.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents. The Company maintains a deposit account in a federally insured financial institution in excess of federally insured limits. The Company also maintains a portfolio of money market funds, which is diversified to limit exposure related to counterparty and industry risks. The Company maintains an investment policy which dictates the allocation of funds within its portfolio of money market funds. The Company has not experienced any losses in such accounts and believes it is not exposed to significant risk on its cash and cash equivalents beyond the normal credit risk associated with commercial banking relationships and money market funds.

Cash and Cash Equivalents

The Company considers all highly-liquid investments that have maturities of three months or less when acquired to be cash equivalents. Cash equivalents as of September 30, 2026 consisted of money market funds. Cash consists of cash deposits at banking institutions. As of June 30, 2025, all of the Company’s marketable securities matured and the proceeds were invested into money market funds, which are included in cash and cash equivalents on the Company’s consolidated balance sheet.

The Company had cash and cash equivalents of$20.2 million and$46.3 million as of September 30, 2026 and December 31, 2025, respectively.

Marketable Securities

The Company classifies its marketable securities with original maturities of greater than three months as available-for-sale. These securities are carried at fair market value, with unrealized gains and losses reported in comprehensive loss and accumulated other comprehensive income (loss) within stockholders’ equity. Any premium or discount arising at purchase of debt securities is amortized and/or accreted over the term of the security to other income (expense), net. Gains or losses on marketable securities sold are recognized as a component of other income (expense), net in the consolidated statement of operations and comprehensive loss on the specific identification method. All marketable securities are available for use, as needed, to fund operations and therefore, the Company classifies all marketable securities as current assets within the consolidated balance sheet. As of September 30, 2026, the Company hadno marketable securities.

Property and Equipment, Net

Property and equipment, net consists of laboratory equipment, office equipment, computer hardware and software, furniture and fixtures, and leasehold improvements and is initially recorded at cost. Maintenance and repairs that do not improve or extend the lives of the respective assets are expensed as incurred. Property and equipment are depreciated on a straight-line basis over their estimated useful lives. The Company estimates useful life on an asset-by-asset basis, which generally consists ofthree years for computer hardware and software, five years for office equipment, five years for laboratory equipment, andseven years for furniture and fixtures. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful life of the asset.

When property and equipment are retired or otherwise disposed of, the costs and accumulated depreciation and amortization are removed from the respective accounts, with any resulting gain or loss recognized concurrently.

The Company reviews long-lived assets, such as property and equipment, for impairment when events or changes in circumstances indicate the carrying amount of the assets may not be recoverable. The Company did not recognize any impairment expenses for long-lived assets for the nine months ended September 30, 2026. The Company recognized impairment expenses for laboratory equipment and certain other assets of $2.6 million for the nine months ended September 30, 2025.

Leasing

The Company evaluates leases at their inception to determine if they are an operating lease or a finance lease. During the nine months ended September 30, 2026 and 2025, the Company classified all leases with terms greater than one year, as operating leases.

The Company recognizes assets and liabilities for operating leases at their inception, based on the present value of all payments due under the lease agreement. The Company uses its incremental borrowing rate to determine the present value of operating leases, which is determined by referencing collateralized borrowing rates for debt instruments with terms similar to the respective lease. The Company utilizes the accounting policy election to not separate lease and non-lease components and the accounting policy election to not apply the recognition requirement to leases with a term of 12 months or less.

When assets and liabilities for operating leases are written off, the balances are removed from the respective accounts, with any resulting gain or loss recognized concurrently.

The Company reviews long-lived assets, such as right of use assets, or ROU assets, for impairment when events or changes indicate the carrying amount of the ROU assets may not be recoverable. The Company didnot recognize any impairment expenses for ROU assets for the three and nine months ended September 30, 2026 or 2025.

Research and Development

Research and development costs are expensed as incurred and consist primarily of expenses incurred with the University of Pennsylvania’s Gene Therapy Program, or GTP, and Gemma, contract research organizations, contract manufacturing organizations, internal analytical and testing activities, and employee-related expenses, including salaries, benefits, and share-based compensation. Management makes estimates of the Company’s external accrued research and development expenses, which primarily relate to contract research organizations and contract manufacturing organizations, as of each consolidated balance sheet date in the Company’s consolidated financial statements based on an estimate of progress to completion of specific tasks using facts and circumstances known to the Company at that time. The Company determines the estimates by reviewing contracts, vendor agreements, change orders, and through discussions with the Company’s internal clinical personnel and external service providers as to the progress to completion of services and the agreed-upon fee to be paid for such services. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual and related expenses accordingly.

Other Income (Expense), Net

Other income (expense), net consists of interest earned on cash equivalents and marketable securities, amortization of premium and discount on marketable securities, and income from subleases.

The Company recorded $0.2 million to other income (expense), net for the three months ended September 30, 2026, which consisted of $0.2 million attributable to interest income and de minimis related to income from subleases.

The Company recorded $0.9 million to other income (expense), net for the three months ended September 30, 2025, which consisted of $0.5 million attributable to interest income and $0.4 million related to income from subleases.

The Company recorded $1.4 million to other income (expense), net for the nine months ended September 30, 2026, which consisted of $0.8 million attributable to interest income and $0.6 million related to income from subleases.

The Company recorded $2.9 million to other income (expense), net for the nine months ended September 30, 2025, which consisted of $1.8 million attributable to interest income and the amortization of premium and discount on the Company’s marketable securities and $1.1 million related to income from subleases.

Share-Based Compensation

The Company measures share-based awards at grant-date fair value and records compensation expense on a straight-line basis over the vesting period of the awards. The Company’s share-based compensation consists of restricted stock units, or RSUs, and options to purchase common stock, or stock option awards.

The Company uses the Black-Scholes option pricing model to value its stock option awards.

Estimating the fair value of stock option awards requires the input of assumptions, including the expected term of stock options and stock price volatility. The assumptions used in estimating the fair value of share-based awards represent management’s estimate and involve inherent uncertainties and the application of management’s judgment. As a result, if factors change and management uses different assumptions, share-based compensation expense could be materially different for future awards.

Prior to 2026, the Company estimated the expected term of the stock options using the “simplified method,” as the Company had limited historical information from which to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior for its stock option grants. The Company now has sufficient historical exercise data and has determined it is no longer appropriate to use the “simplified method”. Additionally, the Company no longer uses comparable public company data to estimate expected volatility and instead bases its expected volatility assumption on the historical volatility of its own stock price. The Company will apply this methodology prospectively and the change in estimates did not have a material impact for the three and nine months ended September 30, 2026.

The Company accounts for forfeitures of RSUs and stock option awards as they occur.

License and Other Revenue

The Company may enter into license agreements and transition services agreements (see Note 7) under which it may license rights to research, develop, manufacture, and commercialize its product candidates to third parties and provide transition services for such licenses. Payments under these arrangements may include non-refundable, upfront fees, reimbursement of certain costs, payments upon the achievement of certain milestones, and royalties on product sales.

The Company applies FASB ASC Topic 606,* Revenue from Contracts with Customer*s, or ASC 606, when all of the following criteria are met, to determine a valid contract exists: (i) the parties have approved the contract and are committed to perform their respective obligations; (ii) the Company can identify each party’s rights regarding the goods or services to be transferred; (iii) the Company can identify the payment terms for the goods or services to be transferred; (iv) the contract has commercial substance; and (v) the Company will collect substantially all of the consideration to which it will be entitled in exchange for the goods or services that will be transferred to the customer. Once it is determined that a valid contract exists, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including consideration of the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations on a relative stand-alone selling price basis; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. As part of the accounting for these arrangements, the Company must use its judgment to determine the number of performance obligations, the transaction price, the stand-alone selling price for each performance obligation identified in the contract for the allocation of transaction price, the contract term and pattern of satisfaction of the performance obligations. The Company uses judgment to determine whether milestones or other variable consideration, except for certain sales-based milestone payments and royalties, should be included in the transaction price as described further below.

At the inception of each arrangement that includes milestone payments, the Company evaluates whether the milestones are considered probable of being achieved and estimates the amount to be included in the transaction price using the most likely amount method set forth in ASC 606. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as those subject to regulatory approvals, are not considered probable of being achieved until those approvals are received. The Company evaluates factors such as the scientific, clinical, regulatory, commercial and other risks that must be overcome to achieve the particular milestone in making this assessment. There is considerable judgment involved in determining whether it is probable that a significant revenue reversal would not occur. At the end of each subsequent reporting period, the Company reevaluates the probability of achievement of all milestones subject to constraint and, if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis in the consolidated statements of operations and comprehensive loss in the period of adjustment.

For customer contracts in the scope of ASC 606, amounts due to the Company are recorded as accounts receivable on the Company’s consolidated balance sheet when the Company’s right to consideration is unconditional. Amounts received prior to satisfying the related performance obligations are classified on the Company’s consolidated balance sheet as current deferred revenue if expected to be recognized as revenue within 12 months following the consolidated balance sheet date and as deferred revenue, net of current portion, if amounts are not expected to be recognized as

revenue within the 12 months following the consolidated balance sheet date. The Company does not evaluate a contract for a significant financing component if payment is expected within one year or less from the transfer of promised items to the customer.

Net Loss Per Share

Basic net loss per share of common stock is computed by dividing net loss by the weighted average number of shares of common stock outstanding during each period. Diluted loss per share of common stock includes the effect, if any, from the potential exercise or conversion of securities, such as stock options, which would result in the issuance of incremental shares of common stock. For diluted net loss per share, the weighted-average number of shares of common stock is the same for basic net loss per share due to the fact that when a net loss exists, dilutive securities are not included in the calculation as the impact is anti-dilutive.

The following potentially dilutive securities have been excluded from the computation of diluted weighted-average shares of common stock outstanding, as they would be anti-dilutive:

Recently Issued Accounting Pronouncements

In November 2024, the FASB issued ASU No. 2024-03,Income Statement – Reporting Comprehensive Income – Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses, or ASU 2024-03, which requires entities to provide disclosures to disaggregate operating expenses into specific categories, such as salaries and wages, depreciation, and amortization, to provide enhanced transparency into the nature and function of expenses. ASU 2024-03 is effective for the Company’s first fiscal year beginning after December 15, 2026, and for interim periods within the Company’s first fiscal year beginning after December 15, 2027, with early adoption permitted. ASU 2024-03 may be applied retrospectively or prospectively. The Company is currently evaluating the impact of this guidance on its disclosures.

In September 2025, the FASB issued ASU No. 2025-06,Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software, or ASU 2025-06. ASU 2025-06 is intended to increase the operability of the accounting for internal-use software costs by removing all references to software development project stages. ASU 2025-06 requires capitalization of software costs to start when management has authorized and committed to funding the software project, it is probable that the project will be completed and the software will be used to perform the function intended. ASU 2025-06 is effective for the Company’s first fiscal year beginning after December 15, 2027, and for interim periods within that year with early adoption permitted. The Company is currently evaluating the impact of this guidance on its consolidated financial statements.

In December 2025, the FASB issued ASU No. 2025-11,Interim Reporting (Topic 270): Narrow-Scope Improvements, or ASU 2025-11. The amendments reorganize and clarify the interim disclosure requirements in U.S. GAAP and establish a single, principles based framework for determining the information that should be disclosed in interim periods. ASU 2025-11 is effective for the Company for interim periods within annual periods beginning after December 15, 2027, with early adoption permitted. The guidance can be applied prospectively or retrospectively. The Company is currently evaluating the impact of ASU 2025-11 on its interim consolidated financial statement disclosures.

4. Fair Value of Financial Instruments and Non-Financial Instruments

Financial Instruments

Fair value is the price that could be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. Fair value determination in accordance with applicable accounting guidance requires that a number of significant judgments be made. Additionally, fair value is used on a nonrecurring basis to evaluate assets for impairment or as required for disclosure purposes by applicable accounting guidance on disclosures about fair value of financial instruments. Depending on the nature of the assets and liabilities, various valuation techniques and assumptions are used when estimating fair value. The carrying amounts of certain of the Company’s financial instruments, including prepaid expenses and accounts payable are shown at cost, which approximates fair value due to the short-term nature of these instruments. The Company follows the provisions of FASB ASC Topic 820,Fair Value Measurement, for financial assets and liabilities measured on a recurring basis. The guidance requires fair value measurements be classified and disclosed in one of the following three categories:

The Company considers all highly liquid investments that have maturities of three months or less when acquired to be cash equivalents. Cash equivalents include money market funds that are carried at cost, which approximates their fair value. The fair values are based on quoted market prices in active markets for identical assets and therefore are classified within Level 1 of the fair value hierarchy.

Non-Financial Instruments

Long-lived non-financial assets are measured at fair value on a nonrecurring basis for purposes of calculating impairment using Level 3 inputs as defined in the fair value hierarchy. The fair value of long-lived assets using Level 3 inputs is determined by estimating the amount and timing of net future cash flows (which are unobservable inputs) and discounting them using a risk-adjusted rate of interest. Significant increases or decreases in actual cash flows may result in valuation changes. There were no assets remeasured in the three and nine months ended September 30, 2026. Assets remeasured in the nine months ended September 30, 2025 included laboratory equipment and certain other assets which were sold prior to September 30, 2025 and were not included in the consolidated balance sheet as of September 30, 2025. The impairment related to the remeasurement of $2.6 million is included in the consolidated statement of operations for the nine months ended September 30, 2025. There were no assets remeasured in the three months ended September 30, 2025.

5. Property and Equipment, Net

Property and equipment, net, consists of the following:

On May 22, 2026, the Company entered into an agreement to terminate its lease agreement for office space in Philadelphia, Pennsylvania, or the 2005 Market Street Lease Termination Agreement. Pursuant to the 2005 Market Street Lease Termination Agreement, the Company agreed to pay the landlord a termination fee of $2.3 million. As a result of the 2005 Market Street Lease Termination Agreement, the Company recognized a net gain of $1.9 million on the lease termination for the nine months ended September 30, 2026. The net gain is comprised of a $2.7 million gain on the write-off of assets and liabilities for operating leases offset by a $0.8 million net loss on disposal of property and equipment. The assets disposed of as part of the termination primarily included leasehold improvements.

On March 4, 2026, the Company entered into an agreement to terminate its lease agreement for laboratory space in Hopewell, New Jersey, or the Hopewell Lease Termination Agreement. Pursuant to the Hopewell Lease Termination Agreement, the Company agreed to pay the landlord a termination fee of $4.8 million as well as accrued rent through February 14, 2026. As a result of the Hopewell Lease Termination Agreement, the Company recognized a net gain of $0.6 million on the lease termination for the nine months ended September 30, 2026. The net gain is comprised of a $3.8 million gain on the write-off of assets and liabilities for operating leases offset by a $3.2 million net loss on disposal of property and equipment. The assets disposed of as part of the termination included office equipment, leasehold improvements, furniture and fixtures, and computer hardware and software.

There wasno depreciation and amortization expense for the three months ended September 30, 2026. Depreciation and amortization expense was $0.2 million for the three months ended September 30, 2025.

Depreciation and amortization expense was $0.2 million and $0.6 million for the nine months ended September 30, 2026 and 2025, respectively.

6. Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following:

7. Gemma License Agreement

On July 31, 2024, the Company entered into a series of sublicense agreements with Gemma in connection with the outlicense of PBGM01 for the treatment of GM1 gangliosidosis, or GM1, PBKR03 for the treatment of Krabbe disease, or Krabbe, and PBML04 for the treatment of metachromatic leukodystrophy, or MLD, collectively the Outlicensed Programs, and such agreements, the Gemma Sublicenses. On May 7, 2025, the Company agreed to amend each of the Gemma Sublicenses to revise certain financial terms related to the Outlicensed Programs, or the Amended Gemma

Sublicenses. Pursuant to the Amended Gemma Sublicenses, the Company is entitled to receive (i) an aggregate total of $15.0 million in initial payments for licenses and clinical product supply, of which $10.0 million has been received, and $5.0 million of which was due in March 2026, and has not yet been received; (ii) an additional $5.0 million contingent on Gemma completing certain business milestones; (iii) up to an additional $114.0 million in development and commercial milestone payments; and (iv) single digit royalties as a percentage of annual worldwide net sales, in exchange for sublicenses to relevant intellectual property, transfer of regulatory dossiers and transfer of clinical trial materials and product supply related to the Outlicensed Programs. Gemma will be responsible for all payments due to the Trustees of the University of Pennsylvania’s, or Penn, under the Company’s research, collaboration and licensing agreement with Penn, or the Penn License Agreement, related to the Outlicensed Programs. On July 31, 2024, the Company also entered into a transition services agreement with Gemma, or the Transition Services Agreement, as amended by the First Amendment to the Transition Services Agreement, dated January 31, 2025, pursuant to which, the Company provided transitional services at cost to Gemma through May 31, 2025, and is entitled to reimbursement for transitional services performed retroactively from March 1, 2024, related to the transfer of the Outlicensed Programs.

As Gemma has a limited history of operations, the Company will not recognize revenue under ASC 606 until the Company either (i) has received payment and there are no remaining obligations to transfer goods and services under the Amended Gemma Sublicenses and Transition Services Agreement (as payments received by Gemma are nonrefundable), or (ii) concludes that substantially all of the transaction price is collectible. As of September 30, 2026, the Company has received initial payments of $10.0 million associated with the aggregate $15.0 million of initial payments to be made under the Amended Gemma Sublicenses for licenses and clinical product supply and $4.8 million associated with the Transition Services Agreement and applied $2.2 million in amounts owed to Gemma for the Company’s Huntington’s disease program against amounts due to the Company for transition services under these agreements. The Company recorded these amounts ($17.0 million) as non-refundable sublicense and transition services payments on the consolidated balance sheet as of September 30, 2026, as the criteria set forth above have not yet been met.

8. Severance

In April 2026, in connection with the Company’s review of strategic alternatives, the Company announced a restructuring of its workforce, or the Restructuring Plan, to decrease operating expenses by reducing the workforce by approximately 75%. In accordance with ASC 420,Exit and Disposal Activities, the Company recorded severance and termination-related costs of $1.6 million in general and administrative expenses and $1.8 million in research and development expenses for the nine months ended September 30, 2026. As of September 30, 2026, there wereno unpaid severance and termination-related costs.

In January 2025, the Company announced a workforce reduction to reduce operating expenses and to extend its cash runway. In connection with the announcement, the Company reduced headcount by approximately 55%. In accordance with ASC 420,Exit and Disposal Activities, the Company recorded severance and termination-related costs of $0.4 million in general and administrative expenses and $1.3 million in research and development expenses for the nine months ended September 30, 2025.

9. Leases

2005 Market Street Lease Agreement

The Company was party to a lease agreement for office space, or the 2005 Market Street Lease Agreement, in Philadelphia, Pennsylvania. Under the 2005 Market Street Lease Agreement, the Company leased approximately 37,000 square feet. The 2005 Market Street Lease Agreement commenced in February 2021 and was expected to expire in December 2031 with an option toextend the term of the 2005 Market Street Lease Agreement bytwo additional terms offive years each. On May 22, 2026, the Company entered into the 2005 Market Street Lease Termination Agreement. Pursuant to the 2005 Market Street Lease Termination Agreement, the Company agreed to pay the landlord a termination fee of$2.3 million. As a result of the 2005 Market Street Lease Termination Agreement, the Company recognized a net gain of $1.9 million on the lease termination for the three months ended June 30, 2026. The net gain is comprised of a $2.7 million gain on the write-off of assets and liabilities for operating leases offset by a $0.8 million net

loss on disposal of property and equipment. The assets disposed of as part of the termination primarily included leasehold improvements. As a result of the 2005 Market Street Lease Termination Agreement, ROU assets decreased $0.7 million and lease liabilities for operating leases decreased $5.8 million during the nine months ended September 30, 2026.

Sublease Agreement A

On August 7, 2023, the Company entered into a sublease agreement with a counterparty, or Sublessee A, to sublease approximately 8,000 square feet of the 2005 Market Street Lease Agreement, or Sublease Agreement A. This sublease term began on November 1, 2023, and was to continue through March 31, 2029. The base sublease rent was $0.1 million per year and increased by 2.75% annually through the expiration of the agreement. Additionally, Sublessee A was required to pay the portion of the common area maintenance expenses, operating expenses and use and occupancy taxes which the Company was required to pay under the 2005 Market Street Lease Agreement. In connection with the 2005 Market Street Lease Termination Agreement on May 22, 2026, the Sublease Agreement A was concurrently terminated.

Sublease Agreement B

On September 29, 2023, the Company entered into a sublease agreement with a counterparty, or Sublessee B, to sublease approximately 29,000 square feet of the 2005 Market Street Lease Agreement, or Sublease Agreement B. This sublease term began on March 1, 2024 and Sublessee B elected the option toextend the term of the sublease agreement through March 31, 2029. The base sublease rent was $0.9 million per year for the entire term of the sublease. Additionally, Sublessee B was required to pay applicable use and occupancy taxes but was not obligated to make payments for operating expenses and common area maintenance expenses which the Company was required to pay under the 2005 Market Street Lease Agreement. In connection with the 2005 Market Street Lease Termination Agreement on May 22, 2026, the Sublease Agreement B was concurrently terminated.

Laboratory Lease Agreement

The Company was also party to a lease agreement for laboratory space, or the Laboratory Lease Agreement, in Hopewell, New Jersey. The Laboratory Lease Agreement commenced in March 2021 and was expected to expire in March 2036 with an option to extend the term of the Laboratory Lease Agreement by up totwo five-year terms. On March 4, 2026, the Company entered into the Hopewell Lease Termination Agreement with the Landlord. Pursuant to the Hopewell Lease Termination Agreement, the Company agreed to pay the Landlord a termination fee of $4.8 million as well as accrued rent through February 14, 2026. The Company has no further obligations under the Laboratory Lease Agreement subsequent to the effective date of the Hopewell Lease Termination Agreement. As of March 4, 2026, the Company recognized a net gain of $0.6 million on the lease termination comprised of a $3.8 million gain on the write-off of assets and liabilities for operating leases offset by a $3.2 million net loss on disposal of property and equipment, which was primarily leasehold improvements. As a result of the Hopewell Lease Termination Agreement, ROU assets decreased $9.4 million and lease liabilities for operating leases decreased $18.0 million during the nine months ended September 30, 2026.

Hopewell Sublease Agreement

On September 4, 2024, the Company entered into a sublease agreement with a counterparty, or Sublessee C, to sublease approximately 3,200 square feet, or 5% of its approximately 62,000 square feet of leased laboratory space under the Laboratory Lease Agreement, or Hopewell Sublease Agreement. This sublease term began on September 11, 2024 and was scheduled to expire on December 31, 2029, with an option for Sublessee C to extend the term of the sublease through December 2032. The base sublease rent was $0.1 million per year and increased by 2.5% annually through the expiration of the Hopewell Sublease Agreement. Additionally, Sublessee C was required to pay the portion of the common area maintenance expenses, operating expenses, and use and occupancy taxes that the Company was required to pay under the Laboratory Lease Agreement. In connection with the Hopewell Lease Termination Agreement on March 4, 2026, the Hopewell Sublease Agreement was concurrently terminated. The Company has no ongoing sublease arrangements related to the Hopewell, New Jersey laboratory space.

As of September 30, 2026, the Company has been relieved of all its operating lease obligations.

The following table summarizes lease expense by lease type that was recognized during the three and nine months ended September 30, 2026 and 2025:

The following table shows the weighted average discount rate and weighted average remaining lease term of the operating leases:

The cash paid for amounts included in the measurement of the Company’s operating lease liabilities for the nine months ended September 30, 2026 and 2025 were $0.8 million and $3.0 million, respectively, recorded in operating cash flows.

The following table summarizes sublease income that was recognized in other income (expense), net during the three and nine months ended September 30, 2026 and 2025:

10. Commitments and Contingencies

Amended and Restated Research, Collaboration and License Arrangement with Penn

In connection with the transfer of the Outlicensed Programs (GM1, Krabbe, and MLD), the Company restructured its research, collaboration and license agreement with Penn, as amended, previously the Penn Agreement and now referred to as the Penn License Agreement. Pursuant to the Penn License Agreement, as of July 31, 2024, the Company (i) terminated the funding of discovery research programs; (ii) terminated the research and exploratory research programs; (iii) terminated the remaining eight options it had for future central nervous system, or CNS, indications; (iv) terminated the transaction fee payable to Penn in the event of certain corporate transactions; and (v) retained its current exclusive and non-exclusive licenses to its programs in FTD, GM1, Krabbe and MLD and certain platform technologies resulting from the discovery programs that it funded.

For the Company’s licensed programs in GM1, Krabbe and MLD, the Penn License Agreement requires that it make payments of up to $16.5 million per product candidate. Each payment will be due upon the achievement of specific development milestone events by such licensed product for a first indication, reduced development milestone payments for the second and third indications and no development milestone payments for subsequent indications. In addition, on a product-by-product basis, the Company is obligated to make up to $55.0 million in sales milestone payments on each licensed product based on annual worldwide net sales of the licensed product in excess of defined thresholds. Pursuant to the Amended Gemma Sublicenses, Gemma is responsible for the payments to Penn related to the Outlicensed Programs.

Upon successful commercialization of a product using the licensed technology, the Company is obligated to pay to Penn, on a licensed product-by-licensed product and country-by-country basis, tiered royalties (subject to customary reductions) in the mid-single digits percentage on annual worldwide net sales of such licensed product. In addition, other

than the Amended Gemma Sublicenses, the Company is obligated to pay to Penn a percentage of sublicensing income, ranging from the mid-single digits to low double digits, for sublicenses under the Penn License Agreement. The agreement will expire on a licensed product-by-licensed product and country-by-country basis upon the later of (i) the expiration of the last valid claim of the licensed patent rights that covers the exploitation of such licensed product in such country, and (ii) the expiration of the royalty period. Pursuant to the Amended Gemma Sublicenses, Gemma is responsible for the payments to Penn related to the Outlicensed Programs.

On June 23, 2026, the Company delivered written notice to Penn to terminate the Penn License Agreement, solely with respect to its product candidate referred to as PBFT02 for all indications licensed to the Company thereunder for such product candidate, including frontotemporal dementia with granulin mutations, or the PBFT02 Termination. The PBFT02 Termination became effective on September 23, 2026, and the Company no longer has any rights under the Penn License Agreement to develop or commercialize PBFT02. The Penn License Agreement will remain in effect with respect to all non-terminated licensed products.

Gemma - Research, Collaboration and License Agreement

In connection with the transfer of the Outlicensed Programs, on July 31, 2024, the Company entered into a research, collaboration and license agreement with Gemma, or the Gemma Collaboration Agreement. Pursuant to the Gemma Collaboration Agreement, (i) Gemma will conduct certain preclinical and Investigational New Drug, or IND, enabling work for the Company’s active research program in Huntington’s disease and a currently paused research program in Temporal Lobe Epilepsy, or TLE, which were previously being conducted by Penn under the Penn Agreement and (ii) Gemma will grant the Company options to conduct mutually-agreed research programs in four new CNS indications.

Upon successful commercialization of a product using the licensed technology, the Company is obligated to pay to Gemma, on a licensed product-by-licensed product and country-by-country basis, tiered royalties (subject to customary reductions) in the mid-single digits percentage on annual worldwide net sales of such licensed product. In addition, the Company is obligated to pay to Gemma a percentage of sublicensing income, ranging from the mid-single digits to low double digits, for sublicenses under the Gemma Collaboration Agreement. The agreement will expire on a licensed product-by-licensed product and country-by-country basis upon the later of (i) the expiration of the last valid claim of the licensed patent rights that covers the exploitation of such licensed product in such country, and (ii) the expiration of the royalty period.

If the Company was to exercise any of the four options under the Gemma Collaboration Agreement, it would owe Gemma a non-refundable aggregate fee of $1.0 million per product indication, with $0.5 million due upfront and another $0.5 million fee owed upon a further developmental milestone.

The Company has also entered into the Amended Gemma Sublicenses and Transition Services Agreement as described in Note 7.

The Amended Gemma Sublicenses, the Transition Services Agreement, and the Gemma Collaboration Agreement are collectively referred to as the Outlicense Transaction Agreements.

On May 21, 2026, the Company provided written notice to Gemma to terminate the Gemma Collaboration Agreement, which terminated on August 21, 2026. Upon termination, the Company no longer has any rights to the research programs or the options for new CNS indications previously available to it under the Gemma Collaboration Agreement.

As of September 2026, the services under the Transition Services Agreement have been completed and the Amended Gemma Sublicenses remain in effect.

Catalent Agreements

The Company had previously entered into a collaboration agreement, and a development services and clinical supply agreement, or the Amended Catalent Agreements, with Catalent Maryland, a unit of Catalent, Inc. acquired by Novo Holdings A/S, or Catalent, to secure clinical scale manufacturing capacity for batches of active pharmaceutical

ingredients for the Company’s gene therapy product candidates. Under the terms of the Amended Catalent Agreements, Catalent agreed to manufacture batches of drug product for the Company’s gene therapy product candidates.

The Amended Catalent Agreements were expected to remain in effect until November 6, 2030, and established a limited exclusive relationship between the Company and Catalent for the manufacture of bulk drug substance and drug product for the Company’s adeno-associated virus delivery therapeutic product candidates for the treatment of FTD and GM1. Under the Amended Catalent Agreements, the limited exclusive relationship would convert to a non-exclusive relationship (i) in the event Catalent failed to meet certain performance standards and (ii) following certain conditional events related to the divestiture by the Company of either FTD or GM1, in which case the Company would pay Catalent certain fees. In the event of certain transactions, the Company may terminate the Amended Catalent Agreements for convenience with respect to such products, in which case, the Company would pay Catalent a certain termination fee. During the nine months ended September 30, 2026, the Company paid Catalent $0.9 million related to the Amended Catalent Agreements, which had been accrued as of and during the three months ended December 31, 2025.

On June 23, 2026, the Company delivered written notice to Catalent to terminate the amended and restated development services and clinical supply agreement in their entirety, effective as of June 23, 2026. The Company determined to terminate these agreements in connection with the wind-down of its gene therapy programs and the proposed Merger, and the Company is not obligated to pay Catalent any termination fee in connection with the termination.

Litigation

In the normal course of business, the Company from time to time is named as a party to legal claims and actions. The Company records a loss contingency reserve for a legal proceeding when the potential loss is considered probable and can be reasonably estimated. The Company hasnot recorded any amounts for loss contingencies as of September 30, 2026.

The Company is the defendant in litigation with a former employee, who filed a lawsuit in the Court of Common Pleas of Philadelphia County asserting claims for breach of contract and violation of the Pennsylvania Wage Payment and Collection Law. The plaintiff, who was terminated from their employment in 2019, contended that the Company entered into a binding settlement agreement in February 2020 under which he was to receive shares of company stock and additional compensation. Specifically, he contended that before the announcement of the Company’s initial public offering in February 2020, he was promised 150,000 shares of stock as part of the settlement, and that those shares were not subject to the reverse stock split that was implemented for all shareholders. The Company responded that the shares offered in settlement negotiations in 2020 were to be subject to the reverse split, and that had the settlement been finalized, the plaintiff would have been entitled to 33,836 shares (1,692 shares adjusted for the Reverse Stock Split effected in 2025). A trial in this case was held in October 2024. The jury found that an agreement was reached, but it agreed with the Company that any shares to be awarded to the plaintiff were subject to the reverse split. The jury awarded damages in an amount that was roughly equal to what the Company contended had been offered to the plaintiff before the initial public offering. Both sides then challenged the verdict, and on December 12, 2024, the judge who presided over the trial delivered a judgment in the Company’s favor, finding that no binding agreement was reached and that the plaintiff was not entitled to recover any damages. On December 23, 2024, the plaintiff filed an appeal with the Superior Court of Pennsylvania. On September 25, 2025, the appellate court affirmed the entry of judgment in favor of the Company and on October 7, 2025, the plaintiff filed an Application for Reargument to the Superior Court of Pennsylvania. In December 2025, the plaintiff petitioned for review of their appeal to the Pennsylvania Supreme Court. In July 2026, the Pennsylvania Supreme Court denied the petition for review with respect to the plaintiff’s challenge to the post-trial rulings in favor of the Company, but it agreed to hear the question of whether certain communications between lawyers and the mediator were appropriately excluded from evidence at trial under Pennsylvania’s mediation privilege. The Pennsylvania Supreme Court timing for this hearing is currently pending. The Company intends to continue to defend against this claim.

Other than the above, the Company is not presently a party to any legal proceedings that, in the opinion of management, would, if decided against the Company, have a material adverse effect on the Company’s business. Regardless of outcome, litigation can have an adverse impact on the Company due to defense and settlement costs, diversion of management resources, negative publicity and reputational harm, and other factors.

Employment Agreements

The Company has employment agreements with certain key personnel providing for up to 18 months of salary continuation, up to 150% of target annual bonus amounts, and acceleration of vesting in stock-based compensation awards in certain circumstances. As of September 30, 2026, the Merger had not been consummated and no amounts related to change in control severance benefits were payable under the employment agreements. Therefore, no liability has been recorded. Upon closing of the Merger, the Company expects to make payments related to change in control severance benefits of approximately $2.4 million.

11. Stockholders’ Equity and Share-Based Compensation

Equity Incentive Plan

The Company hasthree equity incentive plans: the 2018 Equity Incentive Plan, as amended, or the 2018 Plan, the 2020 Equity Incentive Plan, or the Incentive Plan, and the 2021 Equity Inducement Plan, or the Inducement Plan. New awards can only be granted under the Incentive Plan and the Inducement Plan.

The total number of shares authorized under the Incentive Plan as of September 30, 2026 was 1,106,739. Additionally,220,122 shares previously issued under the 2018 Plan which were forfeited are available for issuance under the Incentive Plan. As of September 30, 2026,738,743 shares were available for future grants under the Incentive Plan. The number of shares of the Company’s common stock that may be issued pursuant to rights granted under the Incentive Plan shall automatically increase on January 1st of each year, commencing on January 1, 2021 and continuing forten years, in an amount equal tofive percent of the total number of shares of the Company’s common stock outstanding on December 31st of the preceding calendar year, subject to the discretion of the board of directors to determine a lesser number of shares shall be added for such year. As a result, the number of shares reserved for issuance under the Incentive Plan increased by 159,141 and 155,155 shares in January 2026 and 2025, respectively.

The Incentive Plan provides for the granting of common stock, incentive stock options, nonqualified stock options, restricted stock awards, and/or stock appreciation rights to employees, directors, and other persons, as determined by the Company’s board of directors. The Company’s stock options awarded to date under the Incentive Plan vest based on a requisite service period, generally over four-year periods, and have a term often years.

The Inducement Plan was approved by the Company’s board of directors in July 2021. The total number of shares authorized under the Inducement Plan as of September 30, 2026 was 125,000. Of this amount,90,896 shares were available for future grants as of September 30, 2026. The Inducement Plan provides for the granting of nonqualified stock options and restricted stock awards to employees hired by the Company, as determined by the Company’s board of directors. The Company’s stock options awarded to date under the Inducement Plan vest based on requisite service period and have a term often years. The Company’s restricted stock units awarded to date under the Inducement Plan vest based on requisite service period and have a term based on each award agreement.

The Company measures share-based awards at their grant-date fair value and records compensation expense on a straight-line basis over the vesting period of the awards. The Company recorded share-based compensation expense in the following expense categories in its accompanying consolidated statements of operations and comprehensive loss for the period presented:

The following table summarizes stock option activity for the nine months ended September 30, 2026:

The weighted average grant date fair value of options granted was $5.31 and $6.02 for the nine months ended September 30, 2026 and 2025, respectively. As of September 30, 2026, the total unrecognized compensation expense related to unvested stock option awards was $1.2 million, which the Company expects to recognize over a weighted average period of 2.1 years.

There wasno aggregate intrinsic value of options outstanding, options exercised, and options exercisable for the three and nine months ended September 30, 2026. The aggregate intrinsic value of options outstanding was $0.1 million at September 30, 2025 and the aggregate intrinsic value of options exercised and options exercisable were each de minimis during the three and nine months ended September 30, 2025.

The fair value of each option was estimated on the date of grant using the weighted average assumptions in the table below:

Restricted Stock Units

The Company issues RSUs to employees that vest over periods of time as determined by the board of directors. Any unvested shares are forfeited upon termination of services. The fair value of the RSUs is equal to the fair market value of the Company’s common stock on the date of grant. Compensation expense is recognized on a straight-line basis over the vesting period of the RSUs.

The following table summarizes activity related to RSU awards during the nine months ended September 30, 2026:

As of September 30, 2026, the total unrecognized expense related to all RSUs was de minimis, which the Company expects to recognize over a weighted-average period of 0.3 years.

Employee Stock Purchase Plan

The Company’s 2020 Employee Stock Purchase Plan, or the ESPP, became effective on February 28, 2020. The ESPP authorizes the issuance of up to 99,088 shares of the Company’s common stock. Of this amount,59,103 were available for future grants as of September 30, 2026. The number of shares of the Company’s common stock that may be issued pursuant to rights granted under the ESPP shall automatically increase on January 1st of each year and continuing forten years, in an amount equal toone percent of the total number of shares of the Company’s common stock outstanding on December 31st of the preceding calendar year, subject to the discretion of the board of directors to determine a lesser number of shares shall be added for such year. As a result, on January 1, 2026 and 2025, subject to the discretion of the board of directors, the shares authorized for issuance under the ESPP were not increased.

Under the ESPP, eligible employees can purchase the Company’s common stock through accumulated payroll deductions at such times as are established by the board of directors’ Compensation Committee. Eligible employees may purchase the Company’s common stock at 85% of the lower of the fair market value of the Company’s common stock on the first day of the offering period or on the last day of the offering period. The offering periods under the ESPP have a duration of six months, with periods ending in May and November of each calendar year. Eligible employees may contribute up to 15% of their eligible compensation. Under the ESPP, a participant may not accrue rights to purchase more than $25,000 worth of the Company’s common stock for each calendar year in which such right is outstanding or purchase more than 200 shares of the Company’s common stock in any single offering period. In May 2026, the board of directors approved the termination of the current offering period and suspended future offering periods going forward. All amounts contributed which have not been used to purchase shares of the Company’s common stock have been returned to employees as of September 30, 2026.

In accordance with the guidance in ASC Topic 718-50,* Compensation – Stock Compensation*, the ability to purchase shares of the Company’s common stock at 85% of the lower of the price on the first day of the offering period or the last day of the offering period (i.e. the purchase date) represents an option and, therefore, the ESPP is a compensatory plan under this guidance. Accordingly, share-based compensation expense is determined based on the option’s grant-date fair value as estimated by applying the Black-Scholes option-pricing model and is recognized over the withholding period. No share-based compensation expense related to the ESPP was recorded during the three and nine months ended September 30, 2026 and 2025.

12. Segment Reporting

Operating segments are defined as components of an enterprise which engages in business activities from which it may recognize revenues and incur expenses about which separate discrete information is available for evaluation by the chief operating decision maker, or CODM, in deciding how to allocate resources and in assessing performance. The Company operates in asingle reportable segment, developing and advancing genetic medicines designed to target critical underlying pathology of neurodegenerative diseases.

The accounting policies of the single segment are the same as those described in the summary of significant accounting policies in the Company’s 2025 Annual Report filed on Form 10-K. The Company’s CODM is its chief executive officer. The measure of segment assets is reported on the consolidated balance sheet as total assets. All assets are located within the United States.

The CODM uses net loss as reported on the Company’s consolidated statement of operations to assess the Company’s performance. The CODM also uses cash forecasts in deciding where to invest or expand operations within the business. In these cash forecasts, research and development expenses and general and administrative expenses exclude certain non-cash items such as share-based compensation and depreciation and amortization expenses.

The following table summarizes significant segment expenses:

The components of Other income (expense), net are further described in Note 3 to the consolidated financial statements.

13. Subsequent Events

Prior to the closing of the proposed transaction with Remix, the Company expects to declare a distribution of one contingent value right, or CVR, for each outstanding share of Passage Bio Common Stock to holders of record as of the close of business on the last business day prior to the closing of the Merger, and to enter into a Contingent Value Rights Agreement, or the CVR Agreement, with Computershare Trust Company, N.A., as rights agent. Each CVR entitles the holder to receive its pro rata share of 100% of the Legacy Asset Payments (as defined in the CVR Agreement) actually received by the Company or its subsidiaries during the applicable CVR period, less Permitted Deductions (as defined in the CVR Agreement). Legacy Asset Payments consist of certain payments received from Gemma under the Company’s MLD and GM1 exclusive license agreements, and the applicable CVR periods end on December 31, 2027 with respect to MLD Payments and July 31, 2028 with respect to GM1 Payments.

On October 5, 2026, the parties to the Merger Agreement entered into an amendment to the Merger Agreement to amend certain terms of the form of CVR Agreement.

On October 9, 2026, the Registration Statement was declared effective by the SEC, and the Company filed the definitive proxy statement/prospectus with the SEC and commenced mailing it to the Company’s stockholders. A special meeting of the Company’s stockholders to vote on the proposals described in the proxy statement/prospectus was held on November 5, 2026, at which the Company’s stockholders voted to approve all proposals included in the proxy statement/prospectus.