8. LEASES

Lease Arrangements

The Company enters into lease arrangements for its facilities. A summary of the arrangements is as follows:

Operating Leases

Lexington

On September 26, 2016, and as amended on December 31, 2016, the Company entered into a 10 year and 9-month lease, which includes two successive five-year renewal options, for its facility in Lexington, Massachusetts, which the Company uses primarily for its current good manufacturing practices (“cGMP”) manufacturing, as well as for additional laboratory and office space. As there is not reasonable certainty that the renewal options will be exercised, the lease liabilities and the right-of-use assets pertaining to the Lexington Lease do not account for the two successive five-year renewal options. Throughout the term of the lease, 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. As required under the terms of the lease agreement, the Company has placed restricted cash of approximately $2.7 million in a separate bank account as of December 31, 2023 and 2022.

Cambridge

In April 2015, the Company entered into a lease agreement for an office and laboratory facility in Cambridge, Massachusetts (the “Cambridge Lease”), which commenced in October 2015 with a term of 7.5 years with a five-year renewal option to extend the lease. Throughout the term of the lease, 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. As required under the terms of the lease agreement, the Company has placed restricted cash of $1.0 million in a separate bank account as of December 31, 2023 and 2022.

In December 2020, the Company exercised its option under the Cambridge Lease to lease the additional office and laboratory space at the existing facility. The combined space constitutes the entire building. The lease for the additional space commenced on October 1, 2021, with a term of five years and is considered a separate lease from the Cambridge Lease. On the commencement date, the Company utilized the operating lease classification and recorded a right-of-use asset and corresponding operating lease liability of $4.5 million and began recognizing straight-line rent expense under ASC 842. Throughout the term of the lease, 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.

In June 2022, the Company exercised the five-year renewal option under the Cambridge Lease to extend the lease term through March 2028 (the “Cambridge Lease Extension”). Therefore, as required by ASC 842, the Company calculated an incremental borrowing rate of 10.53% and remeasured the right-of-use asset and the lease liabilities related to the Cambridge Lease Extension. As a result, an

additional $12.0 million of operating right-of-use asset and corresponding operating lease liabilities were recorded relating to the Cambridge Lease Extension.