Leases	9 Months Ended
Sep. 30, 2022
Leases [Abstract]
Leases	10. Leases In January 2022, the Company entered into an agreement to lease approximately 38,000 square feet of office and laboratory space at 730 Main Street, Cambridge, Massachusetts under an operating lease agreement (the “730 Main Lease”). The initial term of the 730 Main Lease is for ten years following the Rent Commencement Date and the Company has the option to extend the 730 Main Lease for one five-year term. The base rent under the 730 Main Lease is $130.00 per square foot per year during the first year of the term, which is subject to scheduled 3% annual increases, plus certain operating expenses and taxes. The Company determined that in accordance with ASC 842, Leases (Topic 842)(“ASC 842”) the commencement date of the lease had not been met as of September 30, 2022. Therefore, the Company did not record a right of use asset or liability related to the 730 Main Lease during the nine months ended September 30, 2022. The Company anticipates that the lease will commence in the fourth quarter of 2022. In accordance with the 730 Main Lease, the Company is required to maintain a letter of credit in the amount of $2.4 million that is restricted for the term of the lease. The restricted cash equivalents are reported in “Investments and other assets” on the Company's condensed consolidated balance sheet. In February 2022, the Company entered into an agreement to lease approximately 140,000 square feet of manufacturing space located at 840 Winter Street, Waltham, Massachusetts (the “840 Winter Lease”), which will provide the Company with the ability to manufacture its own products in a good manufacturing practice (“GMP”) compliant facility as well as to supplement the Company’s current leased premises in Cambridge, Massachusetts. The 840 Winter Lease, including the obligation to pay rent, is expected to commence in the second half of 2024 for an initial term of twelve years. The Company did not record a right of use asset or liability related to the 840 Winter Lease under ASC 842 during the nine months ended September 30, 2022, as the Company had not taken control of the premises. The base rent under the 840 Winter Lease is $73.50 per square foot per year during the first year of the term, which is subject to scheduled 3% annual increases, plus certain operating expenses and taxes. In accordance with the 840 Winter Lease, the Company is required to maintain an initial letter of credit in the amount of $2.6 million. On or before January 1, 2023, the Company will replace the initial letter of credit with a replacement letter of credit in the amount of $6.0 million. As of September 30, 2022, the restricted cash equivalents related to the initial letter of credit are reported in “Investments and other assets” on the Company's condensed consolidated balance sheet. The Company has the option to extend the 840 Winter Lease for two five-year terms. In June 2022, the Company entered into an agreement to lease approximately 62,000 square feet of office and laboratory space located at 640 Memorial Drive, Cambridge, Massachusetts under an operating lease agreement (the “640 Memorial Drive Lease”). The term of the lease is five years, ending in August 2027. The Company does not have an option to extend the 640 Memorial Drive Lease. The base rent under the 640 Memorial Drive Lease is approximately $97 per square foot per year during the first year of the term, which is subject to scheduled 4% annual increases, plus certain operating expenses and taxes. In September 2022 the Company determined, in accordance with ASC 842, that the commencement date for the lease had been met as the lessor had made the space available for the Company's use. During the period ended September 30, 2022 the Company recorded a right of use asset of $30.7 million and a lease liability of $30.2 million related to the 640 Memorial Drive Lease under ASC 842. The difference between the right of use asset and the lease liability of $0.5 million relates to prepaid rent. In determining the lease liability, the Company used an incremental borrowing rate of 7.99% based on a number of factors including the Company's credit rating and the lease term. In accordance with the 640 Memorial Drive Lease, the Company is required to maintain a letter of credit in the amount of $1.8 million that is restricted for the term of the lease. The restricted cash equivalents are reported in “Investments and other assets” on the Company's condensed consolidated balance sheet. The landlord will also contribute approximately $1.2 million toward the cost of tenant improvements for the premises.

Leases

9 Months Ended

Sep. 30, 2022

10. Leases

In January 2022, the Company entered into an agreement to lease approximately 38,000 square feet of office and laboratory space at 730 Main Street, Cambridge, Massachusetts under an operating lease agreement (the “730 Main Lease”). The initial term of the 730 Main Lease is for ten years following the Rent Commencement Date and the Company has the option to extend the 730 Main Lease for one five-year term. The base rent under the 730 Main Lease is $130.00 per square foot per year during the first year of the term, which is subject to scheduled 3% annual increases, plus certain operating expenses and taxes. The Company determined that in accordance with ASC 842, Leases (Topic 842)(“ASC 842”) the commencement date of the lease had not been met as of September 30, 2022. Therefore, the Company did not record a right of use asset or liability related to the 730 Main Lease during the nine months ended September 30, 2022. The Company anticipates that the lease will commence in the fourth quarter of 2022. In accordance with the 730 Main Lease, the Company is required to maintain a letter of credit in the amount of $2.4 million that is restricted for the term of the lease. The restricted cash equivalents are reported in “Investments and other assets” on the Company's condensed consolidated balance sheet.

In February 2022, the Company entered into an agreement to lease approximately 140,000 square feet of manufacturing space located at 840 Winter Street, Waltham, Massachusetts (the “840 Winter Lease”), which will provide the Company with the ability to manufacture its own products in a good manufacturing practice (“GMP”) compliant facility as well as to supplement the Company’s current leased premises in Cambridge, Massachusetts. The 840 Winter Lease, including the obligation to pay rent, is expected to commence in the second half of 2024 for an initial term of twelve years. The Company did not record a right of use asset or liability related to the 840 Winter Lease under ASC 842 during the nine months ended September 30, 2022, as the Company had not taken control of the premises. The base rent under the 840 Winter Lease is $73.50 per square foot per year

during the first year of the term, which is subject to scheduled 3% annual increases, plus certain operating expenses and taxes. In accordance with the 840 Winter Lease, the Company is required to maintain an initial letter of credit in the amount of $2.6 million. On or before January 1, 2023, the Company will replace the initial letter of credit with a replacement letter of credit in the amount of $6.0 million. As of September 30, 2022, the restricted cash equivalents related to the initial letter of credit are reported in “Investments and other assets” on the Company's condensed consolidated balance sheet. The Company has the option to extend the 840 Winter Lease for two five-year terms.

In June 2022, the Company entered into an agreement to lease approximately 62,000 square feet of office and laboratory space located at 640 Memorial Drive, Cambridge, Massachusetts under an operating lease agreement (the “640 Memorial Drive Lease”). The term of the lease is five years, ending in August 2027. The Company does not have an option to extend the 640 Memorial Drive Lease. The base rent under the 640 Memorial Drive Lease is approximately $97 per square foot per year during the first year of the term, which is subject to scheduled 4% annual increases, plus certain operating expenses and taxes. In September 2022 the Company determined, in accordance with ASC 842, that the commencement date for the lease had been met as the lessor had made the space available for the Company's use. During the period ended September 30, 2022 the Company recorded a right of use asset of $30.7 million and a lease liability of $30.2 million related to the 640 Memorial Drive Lease under ASC 842. The difference between the right of use asset and the lease liability of $0.5 million relates to prepaid rent. In determining the lease liability, the Company used an incremental borrowing rate of 7.99% based on a number of factors including the Company's credit rating and the lease term. In accordance with the 640 Memorial Drive Lease, the Company is required to maintain a letter of credit in the amount of $1.8 million that is restricted for the term of the lease. The restricted cash equivalents are reported in “Investments and other assets” on the Company's condensed consolidated balance sheet. The landlord will also contribute approximately $1.2 million toward the cost of tenant improvements for the premises.