9. Leases

Operating Lease

In November 2019, the Company entered into a lease of office and laboratory space at 301 Binney Street in Cambridge, Massachusetts to be used as its new corporate headquarters (the “Lease”). The expiration date of the Lease was

originally in August 2025 and included an option to extend the term by two years. The base rent under the original Lease was $6.9 million per year, subject to an annual increase of 3.5%. Variable lease payments include the Company’s allocated share of costs incurred and expenditures made by the landlord in the operation and management of the building. The Lease included incentives of $14.1 million in the form of an allowance for tenant improvements related to the design and build out of the space. In connection with the Lease, the Company has secured a letter of credit for $2.3 million which renews automatically each year.

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In May 2024, the Company entered into the First Amendment (the “Lease Amendment”) to the Lease to extend the term for approximately two years, commencing on August 19, 2025 (the “First Extension Term”) with the base rent to start at approximately $6.2 million per year, followed by a 3% annual increase. Pursuant to the Lease Amendment, the Company also has an option to extend the term of the Lease by five years, upon the expiration of the First Extension Term.

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Other information related to the Lease is as follows (in thousands, except lease term and discount rate):

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