Pierre Fabre Agreements

In October 2021, we entered into the Pierre Fabre Commercialization Agreement, pursuant to which, we granted to Pierre Fabre an exclusive, field-limited license to commercialize and distribute Ebvallo in Europe and select emerging markets in the Initial Territory following regulatory approval. In September 2022, we entered into Amendment No. 1 to the Pierre Fabre Commercialization Agreement (PF Amendment No. 1). Under the terms of PF Amendment No. 1, following European Commission approval of Ebvallo for EBV+ PTLD and subsequent filing of the Marketing Authorization Application (MAA)

transfer to Pierre Fabre, we received an additional $30 million milestone payment in exchange for, among other things, a reduction in: (i) royalties we are eligible to receive as a percentage of net sales of tab-cel (Ebvallo) in the Territory, and (ii) the supply price mark up on tab-cel purchased by Pierre Fabre. Additionally, we agreed to extend the time period for provision of certain services to Pierre Fabre in the Initial Territory at our cost pursuant to the Pierre Fabre Commercialization Agreement. In December 2022, we sold a portion of our right to receive royalties and certain milestone payments related to Ebvallo in the Initial Territory under the Pierre Fabre Commercialization Agreement to HCRx for a total investment amount of $31.0 million, subject to a repayment cap between 185% and 250% of the total investment amount by HCRx. See Note 6 for further information related to the agreement with HCRx.

In October 2023, we entered into the A&R Commercialization Agreement with Pierre Fabre. Pursuant to the A&R Commercialization Agreement, Pierre Fabre’s exclusive rights to research, develop, manufacture, commercialize and distribute tab-cel were expanded to include all other countries in the world (Additional Territory) in addition to the Initial Territory (together, the Territory), subject to our performance of certain obligations as described below.

In August 2024, we sold certain intermediates used in the manufacture of Ebvallo to Pierre Fabre for $15.5 million, transferring title and risk of loss to these intermediates in advance of the Manufacturing Transition Date (as defined below), which guarantees Pierre Fabre supply and control of intermediates to be used in the production of Ebvallo. We received payment for these intermediates in September 2024.

We also entered into a separate manufacturing and supply agreement with Pierre Fabre for us to manufacture Ebvallo for Pierre Fabre to use in the Initial Territory based on a fixed price through December 31, 2023 and at a price equal to cost plus a margin for orders placed after December 31, 2023, subject to a maximum annual increase. In March 2025, we completed the transfer of all manufacturing responsibility to Pierre Fabre and Pierre Fabre is, at its cost, responsible for manufacturing and supplying tabelecleucel for development and commercialization worldwide under an amendment to the A&R Commercialization Agreement (A&R Commercialization Agreement Amendment). The A&R Commercialization Agreement Amendment defined the Manufacturing Transition Date as March 31, 2025 (the Manufacturing Transition Date). At the Manufacturing Transition Date, we sold to Pierre Fabre certain unreleased batches and intermediate inventory used in the production of tab-cel. We also sold to Pierre Fabre certain materials that support tab-cel manufacturing at no cost. Pursuant to the A&R Commercialization Agreement Amendment, Pierre Fabre has also agreed to pay certain liabilities owed to our CMOs that were incurred as of December 31, 2024. In exchange for accelerating the transfer of all manufacturing responsibility and assumption of such costs by Pierre Fabre, among other things, we agreed to reduce the amount of certain potential future regulatory and commercial milestone payments under the A&R Commercialization Agreement.

Cell selection is the process of identifying the appropriate cell line from available tab-cel inventory to be used for a patient. In February 2025, we transferred commercial cell selection in the Initial Territory and the Additional Territory to Pierre Fabre. Prior to the transfer of commercial cell selection, we were responsible for the performance of commercial cell selection services in the Initial Territory at our cost, and we were responsible for the performance of commercial cell selection services in the Additional Territory at the sole expense of Pierre Fabre. Without transfer of the cell selection technology, no other party can provide such services. In July 2025, we transferred clinical cell selection to Pierre Fabre.

As part of the Pierre Fabre Commercialization Agreement, we formed a joint steering committee (JSC) with Pierre Fabre that provides oversight, decision making and implementation guidance regarding the commercialization activities, the responsibilities of which have been expanded to cover the incremental scope of the A&R Commercialization Agreement.

During the applicable period specified in the A&R Commercialization Agreement, we are responsible for various development, safety, process science, and regulatory activities, including obtaining regulatory approval in the United States for tab-cel for EBV-associated post-transplant lymphoproliferative disease. Pierre Fabre will pay us for these services in accordance with the A&R Commercialization Agreement. Pierre Fabre is responsible, at its cost, for obtaining and maintaining all other required regulatory approvals and for commercialization and distribution of tab-cel in the Additional Territory, including conducting any other clinical study required. We will own any intellectual property rights developed solely by us under the A&R Commercialization Agreement. As described above, in March 2025, we transferred all process science services and manufacturing responsibilities to Pierre Fabre. In July 2025, we further amended the A&R Commercialization Agreement and completed the transfer of all development, clinical (including sponsorship of the ALLELE and tab-cel multi-cohort study) and safety activities for tab-cel to Pierre Fabre. In October 2025, we further amended the A&R Commercialization Agreement to transfer all regulatory activities (including sponsorship of the tab-cel BLA) to Pierre Fabre. Pierre Fabre is, at its cost, responsible for all regulatory activities (including sponsorship of the tab-cel BLA) for tab-cel worldwide, and Pierre Fabre is to use commercially reasonable efforts to obtain BLA approval as soon as possible. We will, at Pierre Fabre’s expense, continue to observe the regulatory activities and support Pierre Fabre in its efforts to obtain BLA approval. In December 2025, we further amended the A&R Commercialization Agreement to, among other things, mitigate the impact of the cost of rebuilding commercial inventory in the United States. We agreed to reduce the milestone payment due upon BLA approval of tab-cel to

$31.0 million in exchange for the right to receive an additional $15.0 million potential milestone payment upon achieving a certain commercial milestone. Under the terms of the A&R Commercialization Agreement, as amended by the A&R Commercialization Agreement Amendment, we are entitled to receive an aggregate of up to $308.0 million in remaining milestone payments upon achieving certain regulatory and commercial milestones relating to tab-cel in the Initial Territory, and an aggregate of up to $556.0 million in additional potential milestone payments upon achieving certain regulatory and commercial milestones relating to tab-cel in the Additional Territory, including up to $31.0 million in potential regulatory milestones in connection with the approval by the FDA of a BLA for tab-cel. We are also eligible to receive significant double-digit tiered royalties as a percentage of net sales of tab-cel (Ebvallo) in the Territory until the later of 12 years after the first commercial sale in each such country, the expiration of specified patent rights in each such country, or the expiration of all regulatory exclusivity for tab-cel in each such country. Royalty payments may be reduced in certain specified customary circumstances. Royalties and milestones from the commercialization of Ebvallo in the Initial Territory remain subject to the HCRx Agreement.

Accounting Analysis

Identification of the Contract

We assessed this arrangement in accordance with ASC 606 and concluded that the promises in the A&R Commercialization Agreement represent transactions with a customer.

Identification of the Promises and Performance Obligations

We identified five performance obligations under the A&R Commercialization Agreement, as amended, which consist of the following material promises:

Determination of the Transaction Price

Under the Pierre Fabre Commercialization Agreement, we determined that the $45.0 million upfront payment constituted the entire consideration to be included in the transaction price at the outset of the arrangement, and the $40.0 million in regulatory milestones achieved in December 2022 were added to the transaction price upon meeting the related milestone criteria. The remaining $308.0 million of potential regulatory and commercial milestone payments that we are eligible to receive associated with the Initial Territory were excluded from the transaction price, as the milestone amounts were fully constrained based on the probability of achievement or have not been earned. None of the future royalty and sales-based milestone payments were included in the transaction price, as the potential payments represent sales-based consideration.

Upon the effective date of the A&R Commercialization Agreement, the $20.0 million additional upfront payment was received and estimated revenue for the development, safety, regulatory and process science services were added to the transaction price, and the $20.0 million regulatory milestone achieved in March 2024 and the $20.0 million regulatory milestone achieved in July 2024 were added to the transaction price upon meeting the related milestone criteria. The remaining $556.0 million of potential regulatory and commercial milestone payments that we are eligible to receive associated with the Additional Territory were excluded from the transaction price, as the milestone amounts were fully constrained based on the probability of achievement or have not been earned. None of the future royalty and sales-based milestone payments were

included in the transaction price, as the potential payments represent sales-based consideration. Upon the effective date of the A&R Commercialization Agreement Amendment, the liabilities owed to the CMOs that were relieved by Pierre Fabre were added to the transaction price.

We reevaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, and, as necessary, we adjust our estimate of the transaction price.

Allocation of the Transaction Price to Performance Obligations

The transaction price was allocated to each performance obligation based on their relative standalone selling price. We developed the estimated standalone selling price for each of the A&R Commercialization Agreement performance obligations with the objective of determining the price at which we would sell such an item if it were to be sold regularly on a standalone basis.

Recognition of Revenue

Commercialization revenue associated with the Initial Territory Obligation was recognized over the period during which the material right existed, which ended on March 31, 2025, the Manufacturing Transition Date. Commercialization revenue associated with sales of Ebvallo and intermediate inventory to Pierre Fabre was deferred until we performed the associated manufacturing of finished Ebvallo product inventory and cell selection services, or until the transfer of manufacturing and cell selection technology to Pierre Fabre. All revenue associated with the Initial Territory Obligation was recognized as of March 31, 2025. As of March 31, 2025, Pierre Fabre was able to utilize the inventory it had purchased from us on its own.

Commercialization revenue associated with the Additional Territory Obligation and the Process Sciences Obligation is recognized using a cost-based input method based on the amount of actual costs incurred relative to the total budgeted costs expected to be incurred for the respective performance obligations. A cost-based input method of revenue recognition requires us to make estimates of costs to complete our performance obligation. In making such estimates, significant judgment is required to evaluate assumptions related to cost estimates. The cumulative effect of revisions to estimated costs to complete our performance obligation will be recorded in the period in which changes are identified and amounts can be reasonably estimated. The Process Sciences Obligation was completed on the Manufacturing Transition Date. All revenue associated with the Process Sciences Obligation was recognized as of March 31, 2025. As of June 30, 2026, there is approximately $0.8 million of deferred revenue remaining associated with the Additional Territory Obligation to be recognized upon completion of certain regulatory obligations. The transfer of control occurs over the respective time period and, in our judgment, is the best measure of progress towards satisfying the performance obligation. A significant change in these assumptions and estimates could have a material impact on the timing and amount of revenue recognized in future periods. We recognized all revenue associated with the Intermediate Inventory Obligation and the Manufacturing Materials Obligation at a point in time, upon the Manufacturing Transition Date, which is when title and risk of loss, and thus, control, of the intermediate inventory and materials transferred to Pierre Fabre.

During the six months ended June 30, 2026, we recognized approximately $60,000 of revenue that was included in the deferred revenue balance as of December 31, 2025.

Costs incurred relating to performing the services within the Additional Territory Obligation and Process Sciences Obligation consist of third party expenses and time incurred by our employees to satisfy requirements set forth by the A&R Commercialization Agreement. These costs are included in research and development expenses in the condensed consolidated statements of operations and comprehensive income (loss). Such costs were $0.2 million for both the three and six months

ended June 30, 2026, and such costs were $4.0 million and $11.1 million for the three and six months ended June 30, 2025, respectively.