Right-of-Use Assets and Liabilities

9 Months Ended

Sep. 30, 2025

Operating lease liabilities and their corresponding right-of-use ("ROU") assets are recorded based on the present value of lease payments over the expected remaining lease term. The interest rate implicit in lease contracts is typically not readily determinable. As a result, the Company utilizes its incremental borrowing rate, which reflects the fixed rate at which it could borrow on a collateralized basis the amount of the lease payments in the same currency, for a similar term, in a similar economic environment. The Company's weighted average incremental borrowing rate at September 30, 2025 totaled 7.0%. Lease expense is recognized on a straight-line basis over the lease term.

In August 2024, the Company entered into a Lease Termination Agreement with 101 College Street LLC (the "Landlord"). Under the terms of the Lease Termination Agreement, the lease, by and between the Company and the Landlord, dated May 4, 2021 (as amended, the "Terminated Lease"), was terminated in full, effective August 15, 2024. In connection with the Lease Termination Agreement and as consideration for the Landlord’s agreement to terminate the lease for its laboratory and office space at 101 College Street in full, the Company agreed to pay to the Landlord a one-time cash termination fee in the amount of $41.5 million and wrote-off $1.9 million of prepaid rent, both of which were recognized in general and administrative expenses on the condensed consolidated statement of operations.

The Company has operating leases for its corporate office, laboratories and certain equipment, which expire no later than December 2029. The leases have a weighted average remaining term of approximately 4.2 years.

The components of lease expense were as follows:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in millions)	2025		2024		2025		2024
Operating lease cost	$	0.7	$	0.5	$	2.2	$	1.5

Supplemental cash flow information related to leases was as follows:


	Nine Months Ended September 30,
(dollars in millions)	2025		2024
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	1.6	$	1.6
Supplemental non-cash information:
Right-of-use assets obtained in exchange for new lease obligations	$	1.5	$	—

In December 2024, the Company, entered into a Seventh Amendment and an Eighth Amendment, and in February 2025, the Company entered into a Ninth Amendment to its lease (collectively the “Building 5 Lease Amendments") with Science Park Development Corporation for certain premises in New Haven, Connecticut (the “Building 5 Premises”). The Building 5 Lease Amendments extended the term of the original lease to December 31, 2029, and expanded the Building 5 Premises to include approximately 10,900 square feet of additional laboratory and office space in the first quarter of 2025, resulting in an increase in the Company's ROU assets of $1.5 million.

Maturities of operating lease liabilities as of September 30, 2025, were as follows:


(dollars in millions)
Remainder of 2025	$	0.6
2026	2.3
2027	2.4
2028	2.5
2029	2.6


Total lease payments	10.4
Less: imputed interest	(1.5)
Total	$	8.9