6. Lease obligation

Operating Leases

As of June 30, 2026, the Company has a lease for laboratory and office space at 75 Hayden Avenue in Lexington, Massachusetts (the “Lexington Facility”) through January 31, 2031, and a lease for additional office and laboratory space at 64 Sidney Street in Cambridge, Massachusetts (the “Cambridge Facility”) through November 30, 2026.

In August 2023, the Company entered into a first amendment (the “First Amendment”) to its existing lease for the Lexington Facility, pursuant to which the Company agreed to lease approximately 61,307 square feet of additional office and laboratory space. The commencement date for the First Amendment occurred on February 1, 2024. The expected contractual obligation under the First Amendment to the Company’s existing lease for the Lexington Facility is approximately $35.4 million, to be paid over the 7-year term of the lease.

The Company’s lease agreements require the Company to maintain a cash deposit or irrevocable letter of credit in the aggregate amount of $2.7 million payable to its landlords as security for the performance of its obligations under the leases. These amounts are recorded as restricted cash in the accompanying condensed consolidated balance sheets.

In August 2024, the Company executed the sublease of the Cambridge Facility (the “Sublease Agreement”). Payments received under the Sublease Agreement are included in other income in the condensed consolidated statements of operations and comprehensive (loss) income. Subject to certain conditions set forth therein, the Sublease Agreement terminates simultaneously with the Company’s lease for the Cambridge Facility.

Operating lease cost was $1.8 million and $1.9 million during the three months ended June 30, 2026 and 2025, respectively. Operating lease cost was $3.7 million and $3.8 million during the six months ended June 30, 2026 and 2025, respectively. As of June 30, 2026, the weighted-average remaining lease term was 3.2 years and the weighted-average incremental borrowing rate used to determine the operating lease liability was 6.5%.