Leases
Our building leases are comprised of office and laboratory space under non-cancelable operating leases. These lease agreements have remaining lease terms of two years and contain various clauses for renewal at our option. The renewal options were not included in the calculation of the operating lease assets and the operating lease liabilities as the renewal options are not reasonably certain of being exercised. The lease agreements do not contain residual value guarantees.
We currently lease approximately 146,000 square feet at 88 Sidney Street, 43,000 square feet at 64 Sidney Street, and 13,000 square feet at 38 Sidney Street, Cambridge, Massachusetts. All leases, as amended, expire on February 29, 2028. At the end of the initial lease period, we have the option to extend the leases at all facilities for two consecutive five-year periods at the fair market rent at the time of the extension.
The components of lease expense and other information related to leases were as follows: | | | | | | | | | | | | | | | | | |
| (In thousands) | 2025 | | 2024 | | 2023 |
| Operating lease costs | $ | 15,227 | | | $ | 15,227 | | | $ | 15,227 | |
| Cash paid for amounts included in the measurement of operating lease liabilities | 19,583 | | | 18,705 | | | 18,170 | |
We have not entered into any material short-term leases or financing leases as of December 31, 2025.
In arriving at the operating lease liabilities as of December 31, 2025, we applied the weighted-average incremental borrowing rate of 5.7% from inception over a weighted-average remaining lease term of 2.2 years. In arriving at the operating lease liabilities as of December 31, 2024, we applied the weighted-average incremental borrowing rate of 5.7% over a weighted-average remaining lease term of 3.2 years.
As of December 31, 2025, undiscounted minimum rental commitments under non-cancelable leases, for each of the next five years and total thereafter, were as follows: | | | | | |
| (In thousands) | |
| 2026 | $ | 18,511 | |
| 2027 | 20,755 | |
| 2028 | 3,479 | |
| |
| Undiscounted minimum rental commitments | 42,745 | |
| Interest | (2,538) | |
| Total operating lease liabilities | $ | 40,207 | |
We provided our landlord a security deposit of $2.9 million as security for our leases, which is included within other non-current assets on our consolidated balance sheet.
In August 2021, we entered into a long-term sublease agreement for 13,000 square feet of the office space at 38 Sidney Street, Cambridge, Massachusetts, which expired on December 31, 2024.
In April 2022, we entered into a long-term sublease agreement for 27,000 square feet of the office space at 64 Sidney Street, Cambridge, Massachusetts, which expired on April 30, 2025.
In May 2023, we entered into a long-term sublease agreement for 7,407 square feet of office space on the first floor of 64 Sidney Street, Cambridge, Massachusetts, which expired on July 31, 2025. In July 2025, we entered into a long-term sublease
agreement with a new tenant for the same space, which began in November 2025 with the term of the lease running through February 2028.
We recorded operating sublease income of $1.9 million and $6.4 million for the years ended December 31, 2025 and December 31, 2024, respectively, in other income, net in the consolidated statements of operations. We hold security deposits from our sublessee of approximately $0.1 million which is recorded within other non-current assets on our consolidated balance sheet.
As of December 31, 2025, the future minimum lease payments to be received under the long-term sublease agreement was as follows: | | | | | |
| (In thousands) | |
| 2026 | $ | 386 | |
| 2027 | 394 | |
| 2028 | 67 | |
| Total | $ | 847 | |