11. Leases

Property Leases

The Company leases approximately 230,000 square feet of real estate, including laboratory and office space in Cambridge, Massachusetts, and the surrounding areas. The Company’s leases have remaining terms ranging from approximately one to twelve years. Certain leases include options to renew, exercised at the Company’s sole discretion, with varying renewal terms that can extend the lease term for an additional three to five years. All of the Company’s leases qualify as operating leases.

Throughout the term of its leases, the Company is responsible for paying certain costs and expenses, in addition to the rent, as specified in the lease, including a proportionate share of applicable taxes, operating expenses and utilities. The variable portion of these costs are expensed as incurred and are disclosed as variable lease costs.

In February 2022 and subsequently amended in June 2023, the Company entered into an agreement to lease approximately 140,000 square feet of office, general laboratory and manufacturing space at 840 Winter Street in Waltham, Massachusetts (the “840 Winter Lease”). In November 2024 the Company determined, in accordance with ASC 842, that the criteria for commencement of the lease had been met as the lessor had made the space available for the Company’s use. The Company recorded a right of use asset of $125.7 million and a lease liability of $113.1 million related to the 840 Winter Lease. The difference between the right-of-use asset and the lease liability of $12.6 million relates to prepaid rent. The initial term of the 840 Winter Lease was twelve years, ending in September 2036. The Company had options to extend the lease for two five-year terms, which were not reasonably certain of exercise as of the commencement date. The 840 Winter Lease is subject to 3% fixed rate rent escalations and requires the Company to make monthly payments for operating costs such as real estate taxes, maintenance costs, and utilities. These costs are variable in nature and have therefore been excluded from consideration in the contract. Refer to Note 16 for further information regarding the 840 Winter Lease.

In January 2023, the Company executed a sublease for approximately 13,000 square feet of laboratory and office space in Cambridge, Massachusetts for a term of approximately three years. The sublease agreement grants an option to renew the term for one additional year.