The Company leases office and laboratory space under various non-cancelable operating leases. The Company’s significant lease agreements are disclosed in Note 9, Leases, in the audited consolidated financial statements for the year ended December 31, 2024, and notes thereto, included in the Company’s Annual Report on Form 10-K that was filed with the SEC on February 28, 2025. Since the date of those financial statements, there have been no changes to the Company’s significant agreements except as described below.

In November 2021, the Company entered into a lease for three floors of office and laboratory space in Cambridge, Massachusetts, with rent commencing in March 2024, subject to any credits pursuant to the terms of the lease (the “60 First Street Lease”). Subsequent to the initial non-cancelable term of the lease of ten years, the Company has an option to extend the lease for an additional period of ten years with the rent during the extension term being the then fair market rent. The Company secured the lease with a $13.1 million security deposit, which was recorded as restricted cash on the condensed consolidated balance sheets as of June 30, 2025 and December 31, 2024.

The Company determined that the lease contained three separate lease components, each of which represents a right of use that the Company can benefit from on its own and neither of which are highly dependent nor highly related to each other. The Company allocated the consideration among the three lease components based on their relative fair market values.

In accordance with ASC 842, Leases, the lease commenced for one of the lease components in March 2024 and the Company recorded a right-of-use asset of $44.9 million, and a corresponding lease liability of $33.6 million on the lease commencement date; this included a reclass of $11.3 million from prepaid expenses to right-of-use asset related to build out costs which were determined to be owned by the lessor. In March 2025, the Company determined that the lease commenced on the remaining two lease components and recorded right-of-use assets of $76.8 million, and a corresponding lease liability of $78.6 million on the lease commencement date. As the exercise of the option to extend the lease term is not reasonably certain, the Company will recognize lease expense for all lease components through February 2034.

In June 2024, the Company filed a complaint in Massachusetts Superior Court against NW Cambridge Property Owner, LLC (“NWC”), the Company’s landlord at 60 First Street, alleging that NWC had breached the 60 First Street Lease by, among other reasons, refusing to provide the Company with certain rental credits for the late delivery of the leased space. While this lawsuit is pending, the Company continued to make the disputed payments under the 60 First Street Lease under protest. The disputed payments are recorded within other current assets on the Company’s condensed consolidated balance sheets. Total payments made under dispute was $13.9 million, and $10.8 million as of June 30, 2025 and December 31, 2024, respectively.

In August 2024, the Company entered into the third amendment to its existing lease for approximately 16,000 square feet of combined laboratory and office space at 480 Arsenal Street, Watertown, Massachusetts (the “480 Arsenal Amendment”). In September 2024, the Company entered into a new lease for approximately 48,500 square feet of combined laboratory and office space at 500 Arsenal Street, Watertown, Massachusetts (the “500 Arsenal Lease”). The landlords of the spaces at 480 Arsenal Street and 500 Arsenal Street are affiliates.

The 480 Arsenal Amendment provides the Company with an additional 9,400 square feet of combined laboratory and office space (the “Expansion Space”) at no additional cost and also provides an early termination date for the existing space and the Expansion Space. The lease for space at 480 Arsenal Street, including the Expansion Space, terminated on April 30, 2025.

The 500 Arsenal Lease term commenced in December 2024 with a base term of 11 months. In December 2024, the Company began constructing improvements to the space, the construction for which was completed in 2025. Subsequent to the base term, the Company has an option to extend the lease through August 2028, which it exercised in February 2025. The Company secured the lease with a $0.6 million security deposit, which is recorded as restricted cash on the condensed consolidated balance sheets as of June 30, 2025. The 500 Arsenal Lease also provides a tenant improvement allowance of $2.4 million and an additional tenant improvement allowance of $1.2 million, which the Company would be obligated to repay to the landlord. The Company did not use the additional tenant improvement allowance.

As the 480 Arsenal Amendment and the 500 Arsenal Lease meet the criteria for combining contracts under ASC 842, the Company determined that both 480 Arsenal Amendment and the 500 Arsenal Lease are modifications to its existing lease at 480 Arsenal Street. Within the combined contract the Company identified two separate lease components, each of which represents a right of use that the Company can benefit from on its own and none which are neither highly dependent nor highly related to the other. The Company allocated the consideration under the combined contract among the two lease components based on their relative fair market value. In calculating the allocable consideration and the fair market value of each lease component, the Company determined it is probable that it will exercise the option to extend the lease term provided under the 500 Arsenal Lease.

For accounting purposes, as the construction of the lessor assets were completed, the Company determined that the 500 Arsenal Lease commenced in March 2025 and recorded right-of-use assets of $7.0 million, and a corresponding lease liability of $5.5 million on the lease commencement date. Concurrently, the Company also determined that the termination of its leased space at 480 Arsenal Street was reasonably certain, and the Company recorded a $3.1 million reduction to the Company’s operating lease liability and its operating lease right-of-use asset on the condensed consolidated balance sheet.

The table below reconciles the undiscounted future annual lease payments to the total operating lease liabilities recorded in the condensed consolidated balance sheet as of June 30, 2025:


(in thousands)	Undiscounted Amounts
Undiscounted lease payments:
Remaining in 2025	$	10,494
2026	21,703
2027	22,355
2028	22,294
2029	21,478
Thereafter	96,601
Total undiscounted lease payments	194,925

Less: imputed interest	(75,189)
Total operating lease liability	$	119,736