In February 2025, the Company entered into a Second Amendment (the “Winter Street Amendment”) which will terminate the lease entered into by the Company in 2022 for space at 840 Winter Street, Waltham, Massachusetts (the “840 Winter Lease”) on or before June 30, 2028. In connection with the Winter Street Amendment, the Company paid the landlord lease modification payments totaling $78.0 million in three installments, with $34.0 million paid in February 2025, $30.0 million paid in April 2025 and $14.0 million paid in January 2026. In conjunction with the Winter Street Amendment, also in February 2025, the Company entered into a lease agreement (the “Tech Square Lease”) with the same landlord as the 840 Winter Lease, for office and laboratory space located at 400 Technology Square, Cambridge, Massachusetts (“400 Tech Square”).

Under the terms of the Tech Square Lease and subsequent amendments, the Company will lease approximately 125,000 square feet of office and laboratory space at 400 Tech Square. In addition, the Tech Square Lease will expand to include an additional 23,000 square feet of office and laboratory space at 400 Tech Square representing the 5th floor (the “Additional Tech Square Premises”) when such space becomes available.

The initial term of the Tech Square Lease is twelve years and three months beginning in September 2026 (the “Rent Commencement Date”). The Company’s obligation to pay rent will start in December 2026. The Company has an option to extend the Tech Square Lease for an additional term of five years. As of the Rent Commencement Date, the base rent under the Tech Square Lease will be $108.00 per square foot per year, plus certain operating expenses, and taxes. The base rent is subject to scheduled annual increases of 3% in July of each rent year. In addition, the Company is entitled to receive up to $410.00 per square foot of tenant improvement allowances. The Company has recorded $52.5 million of prepaid rent related to the Tech Square Lease within “Prepaid expenses and other current assets” in the condensed consolidated balance sheet as of March 31, 2026.

The table below reconciles the undiscounted cash flows for each of the next five years and total of the remaining years to the operating lease liabilities recorded in the condensed consolidated balance sheet as of March 31, 2026:


Future Operating Lease Payments
	(in thousands)
Remainder of 2026	$	17,818
2027		24,125
2028		15,637
2029		12,666
2030		13,043
Thereafter		13,550
Total lease payments	$	96,839
Less: imputed interest		(16,349	)
Total operating lease liabilities at March 31, 2026	$	80,490

Excluded from the Future Operating Lease Payments table above is $189.1 million related to the Tech Square Lease, which has not yet commenced as of March 31, 2026.