7. Leases

In November 2018, we entered into a lease agreement for office space in Thousand Oaks, California, that expired in February 2026 and for which we had the option to extend the lease for an additional period of five years after the initial term.

In February 2025, we vacated this office space prior to the termination of the lease, resulting in the abandonment of the right-of-use asset. When a lease right-of-use asset has been abandoned, the estimated useful life of the asset is updated to reflect the cease use date, and the remaining carrying value of the asset is amortized ratably over the period between the commitment date and the cease use date. In February 2025, with the abandonment of the lease, we recognized accelerated amortization expense on the abandoned right-of-use asset in the amount of $1.0 million within general and administrative expenses. The lease associated with the Thousand Oaks office ended in February 2026, and no lease liability remained on our balance sheet as of June 30, 2026.

In March 2021, we entered into a lease agreement for the 33,659 square feet of office, lab and warehouse space at the Atara Research Center (ARC). During the third quarter of 2021, the initial 10.5-year lease term commenced, upon substantial completion of the landlord’s work as defined under the agreement. Base rent is subject to annual increases of 3% with each annual anniversary of the rent commencement date. In March 2025, we announced a pause on our CAR T research and development activities and initiated the wind-down of the ARC facility. We considered this to be a triggering event and performed an impairment analysis on the right-of-use asset. In April 2025, we recorded a non-cash impairment of the right-of-use asset of $4.1 million, representing the amount by which the carrying value of the right-of-use asset exceeded its estimated fair value. We recorded the impairment loss within research and development expenses on the accompanying consolidated statements of operations and comprehensive income (loss). In August 2025, we executed an amendment to the ARC lease that reduced our leased premises to 12,750 square feet and terminated our option to extend the lease. We determined that this amendment constituted a triggering event resulting in a partial lease termination modification. In 2025, we recorded a non-cash reduction of $3.4 million to the right-of-use asset to reflect the decrease in the asset’s value following the lease modification. The modification also reduced the related lease liability, generating a $6.0 million gain. Overall, these changes resulted in a net gain of $2.6 million recorded within research and development expenses in 2025. The remaining right-of-use asset and lease liability associated with the ARC facility continue to be reflected on our balance sheet.

In February 2017, we entered into a lease agreement (the ATOM Lease) for approximately 90,580 square feet of office, lab and cellular therapy manufacturing space in Thousand Oaks, California (the ATOM Facility). The initial 15-year term of the headlease commenced on February 15, 2018, upon the substantial completion of landlord’s work as defined under the agreement. In April 2022, we assigned the ATOM Lease to FDB in connection with the closing of the sale of the ATOM Facility to FDB. Under ASC 842, we are considered to be the sub-lessor of the ATOM Lease. We have not received novation from the landlord and therefore have not been relieved of our primary obligations under the headlease. Therefore, the right-of-use asset and lease liability for the ATOM Facility remain on our balance sheet. Given the continued use of the ATOM lease by another party, we did not consider there to be a trigger for valuation considerations following our restructuring activities.

We evaluated our vendor contracts to identify embedded leases and determined that the Master Services and Supply Agreement (Fujifilm MSA) we entered into with FUJIFILM Diosynth Biotechnologies California, Inc. (FDB) contained items that constituted a lease under ASC 842, Leases, as Atara has the right to substantially all of the economic benefits from the use of the asset and can direct the use of the asset. We concluded that the Fujifilm MSA contains an embedded operating lease for certain dedicated processing rooms for the manufacturing of Atara product and an embedded finance lease for certain freezers dedicated for our use. The Fujifilm MSA includes contractual obligations in the form of payments for the processing rooms and the freezers, each over a term of five years. As a result, we added right-of-use assets and lease liabilities for the processing rooms and freezers for the initial term of the lease in the amounts of $50.8 million and $4.8 million, respectively. In November 2023, we agreed to forego the use of one processing room for approximately one year in return for a reduction in contractual obligations under the Fujifilm MSA, and in November 2024, we exercised the option to release the processing room to FDB for the remainder of the initial term. The Fujifilm MSA was novated to Pierre Fabre in March 2025 as part of the A&R Commercialization Agreement Amendment. As of June 30, 2025, we were relieved of our primary obligations under the Fujifilm MSA. Therefore, the right-of-use assets and lease liabilities for the processing rooms and the freezers have been removed from our consolidated balance sheet as of June 30, 2025. At the time of this release in June 2025, we recognized a gain on derecognition of the operating lease liability of $0.7 million and a gain on derecognition of the finance lease liability of $0.5 million within research and development expenses.

Additionally, in 2021, we entered into an amended lease agreement (Aurora Lease) for our office and lab space in Aurora, Colorado, to add additional lab space and in November 2023, we further amended the Aurora Lease to extend the term to April 2025. The lease agreement expired on April 30, 2025, and the right-of-use asset and lease liability for the Aurora Lease are no longer on our balance sheet.

We originally leased office space in South San Francisco, California under a non-cancellable lease agreement. In December 2021, we entered into a second amendment with the landlord to extend the lease term through May 2025. The amended lease agreement does not include an option to extend the lease term. In connection with the amended lease, we were required to maintain a letter of credit in the amount of $0.1 million to the landlord. In October 2022, we entered into a sub-lease agreement with a third party for this office space. The sub-lease term commenced in November 2022 and expired in May 2025. At the expiration of the lease in May 2025 our right-of-use asset and lease liability for the South San Francisco office were removed from our balance sheet and the requirement to maintain a letter of credit was released.