12.  Related Party Transactions

Asset Purchase and Related Agreements with Johnson & Johnson Innovative Medicine

On December 20, 2023, the Company entered into the Asset Purchase Agreement with Johnson & Johnson Innovative Medicine pursuant to which the Company sold and assigned to Johnson & Johnson Innovative Medicine, and Johnson & Johnson Innovative Medicine purchased and assumed, the UCLB RPGR License Agreement relating to the research, development, manufacture and exploitation of the RPGR Product, and other related assets as described in the Asset Purchase Agreement. Simultaneously, the Company and Johnson & Johnson Innovative Medicine also entered into a Supply Agreement pursuant to which the Company agreed to manufacture and supply the RPGR Product for Johnson & Johnson Innovative Medicine. Under the Supply Agreement, Meira UK II, together with its affiliates, will manufacture commercial supply of the RPGR Product for Johnson & Johnson

Innovative Medicine for an initial term of four years, with Johnson & Johnson Innovative Medicine having an option to extend the Supply Agreement for a fifth year upon written notification. Johnson & Johnson Innovative Medicine may terminate the Supply Agreement for convenience upon 90 days’ written notice with payment of a termination fee. Under the Asset Purchase Agreement, Johnson & Johnson Innovative Medicine paid the Company a non-refundable upfront fee of $65.0 million in December 2023 and the Company is eligible to receive fees from commercial supply of the RPGR Product and in addition, milestones of up to $350.0 million, as follows: (i) a milestone payment of $50.0 million in connection with the achievement of the initiation of the extension study for the Phase 3 LUMEOS clinical trial for the RPGR Product; (ii) $10.0 million upon completion of certain specified development services for the drug substance for the RPGR Product; (iii) $5.0 million upon completion of certain specified development services for the drug product for the RPGR Product; (iv) $175.0 million upon the first commercial sale of an RPGR Product in the United States; (v) $75.0 million upon the first commercial sale of an RPGR Product in at least one of the United Kingdom, France, Germany, Spain and Italy; (vi) $25.0 million upon completion of the transfer of certain manufacturing technology for drug substance and drug product from the Company to Johnson & Johnson Innovative Medicine; and (vii) $10.0 million upon regulatory approval of a Johnson & Johnson Innovative Medicine-selected manufacturing facility in each of the United States and European Union for commercial manufacture of the RPGR Product. During 2024, the Company received $60.0 million in milestone payments from Johnson & Johnson Innovative Medicine. Johnson & Johnson Innovative Medicine is also responsible for any royalty or milestone amounts that become payable on the RPGR Product under the UCLB RPGR License Agreement.

Revenue Recognition under the Asset Purchase and Related Agreements

The agreements entered into in December 2023 were executed at the same time and were negotiated with a single commercial objective; therefore, the contracts were combined and accounted for as a single contract. These agreements were accounted for as a termination of the existing Collaboration Agreement and the creation of a new contract where the transaction price includes the remaining deferred revenue – related party from the terminated agreement of $30.6 million, the fixed upfront payment of $65.0 million under the Asset Purchase Agreement, and an aggregate of $1.8 million estimated variable consideration for transition services, offset by a credit of $5.1 million for pre-funded inventory, totaling $92.3 million. The transaction price was allocated to four performance obligations on a relative SSP basis, subject to certain exceptions for discounts and variable consideration. As the SSPs are not directly observable for any of the distinct goods and services, the SSPs were estimated based on a valuation. The total transaction price of $92.3 million was allocated to the performance obligations with respect to SSPs as follows: process performance qualification (“PPQ”) services in the amount of $2.9 million, net of future billings, material rights representing the commercial supply of RPGR Product and an in-substance contract renewal option in the amount of $6.9 million, manufacturing technology transfer in the amount of $28.7 million, and the sale of nonfinancial assets representing the sale and transfer of all the Company’s right, title, and interest in the intellectual property related to the RPGR Product and the assignment of the UCLB RPGR License Agreement to Johnson & Johnson Innovative Medicine in the amount of $53.8 million.

Since the commencement of the Asset Purchase Agreement and related agreements, the Company received a $50.0 million milestone payment in connection with the achievement of the initiation of the extension study for the Phase 3 LUMEOS clinical trial for the RPGR Product. The milestone payment was allocated to the four performance obligations on the same basis noted above increasing the value of each performance obligation as follows: PPQ services in the amount of $1.6 million, material rights representing the commercial supply of RPGR Product and an in-substance contract renewal option in the amount of $3.8 million, manufacturing technology transfer in the amount of $15.6 million, and the sale of nonfinancial assets representing the sale and transfer of all the Company’s right, title, and interest in the intellectual property related to the RPGR Product and the assignment of the UCLB RPGR License Agreement to Johnson & Johnson Innovative Medicine in the amount of $29.0 million. Additionally, the Company received a $10.0 million milestone payment in connection with the completion of certain specified development services for the drug substance for the RPGR Product which was allocated to the PPQ services performance obligation. The Company also entered into additional agreements to provide additional services under the Asset Purchase Agreement and related agreements amounting to an aggregate of $5.8 million which was

included in the transaction price and allocated to each of the respective performance obligations. Furthermore, the Company recorded certain changes in estimates related to the valuation of its performance obligations.

The transaction price allocated to PPQ services will be recognized over time using an inputs method measure of progress. The transaction price allocated to the material right for the commercial supply of RPGR Product will be recorded as deferred revenue – related party until Johnson & Johnson Innovative Medicine exercises its option to purchase supply and the Company transfers control of such supply to Johnson & Johnson Innovative Medicine. The transaction price allocated to the in-substance renewal option (material right) will be recorded as deferred revenue – related party until Johnson & Johnson Innovative Medicine exercises the option and the Company transfers control of the underlying goods or services to Johnson & Johnson Innovative Medicine. The Company will account for the exercise of the in-substance renewal option (material right) as a continuation of the existing contract (i.e., a change in the transaction price). The transaction price allocated to the technology transfer will be recognized over time using an inputs method measure of progress. The Company will recognize a gain for the difference between the carrying amount of the nonfinancial assets and the consideration allocated to that unit of account when control of the nonfinancial assets transfers in accordance with ASC 610-20, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets.

During the year ended December 31, 2024, the Company recognized a gain of $28.4 million related to the sale of nonfinancial assets which is included in other income in the consolidated statement of operations and comprehensive loss.

As of December 31, 2025, the aggregate transaction price allocated to unsatisfied performance obligations was $66.9 million which the Company expects to recognize over an estimated period of approximately 2.0 years.

A summary of the deferred revenue recognition is as follows (in thousands):

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During the year ended December 31, 2025 and 2024, the Company recognized $2.6 million and $14.0 million, respectively, of deferred revenue – related party as service revenue in connection with PPQ services under the Asset Purchase Agreement and related agreements.

During the years ended December 31, 2025 and 2024, $6.4 million and $33.3 million of service revenue, inclusive of the $2.6 million and $14.0 million, respectively, of deferred revenue – related party recognized as service revenue, was recognized based on cumulative progress of PPQ services under the Asset Purchase Agreement and related agreements.

Debt Financing

On August 2, 2022 the Company, as borrower, and Meira UK II and Meira Ireland, as guarantors (the “Subsidiary Guarantors”), entered into a senior secured financing arrangement (the “Financing Agreement”) by and among the Company, the Subsidiary Guarantors, the lenders and other parties from time to time party thereto and Perceptive Credit Holdings III, LP, as administrative agent and lender (“Perceptive”). On December 19, 2022, the Financing Agreement was converted to a notes purchase agreement and guaranty (the “Notes Purchase Agreement”) between the same parties and under substantially the same terms and conditions as the Financing Agreement, subject to certain customary note constitution terms. Perceptive Advisors, LLC, an affiliate of Perceptive, is a greater than 10.0% holder of the ordinary shares of the Company. Additionally, Ellen Hukkelhoven, Ph.D., a director of the

Company, is an employee of Perceptive Advisors, LLC. Refer to the discussion in Note 14 for further information related to the accounting for the debt financing.

On December 31, 2025, the Company entered into a share purchase agreement to repurchase 2,300,000 of its ordinary shares from Perceptive Life Sciences Master Fund, Ltd., an affiliate of Perceptive Advisors LLC, at a purchase price of $7.91 per share. The aggregate purchase price of $18.2 million was subject to satisfaction of certain conditions precedent to settlement, therefore no liability was recognized as of December 31, 2025. The Company considered the obligation to be a contingent commitment, as the repurchase was contingent upon the conditions being met on settlement date. The transaction was settled on January 5, 2026