Leases	9 Months Ended
Sep. 30, 2021
Leases [Abstract]
Leases	. Leases In March 2020, the Company entered into an agreement to lease approximately 39,000 square feet of office and laboratory space at 281 Albany Street in Cambridge, Massachusetts under an operating lease agreement (the “281 Albany Lease”). The Company’s obligation to pay rent will start on the date that is six months after the commencement date or the date on which the Company occupies the premises, whichever occurs earlier (the “Rent Commencement Date”). The initial term of the 281 Albany Lease is ten years following the Rent Commencement Date. In March 2021 the Company determined, in accordance with ASC 842, “Leases (Topic 842)” (“ASC 842”), that the commencement date of the lease had been met as the facility was substantially complete and available for use and, accordingly, the Company recognized a right-of-use asset and a lease liability of approximately $40.4 million and $34.8 million, respectively, in the first quarter of 2021 related to the 281 Albany Lease. In determining the lease liability, the Company used an incremental borrowing rate of 5.52% based on a number of factors including the Company’s credit rating and the lease term. Included in the recognized right-of-use asset at the inception of the lease was approximately $5.6 million in lease payments that were prepaid under the terms of the lease. The base rent under the 281 Albany Lease is $99.00 per square foot per year during the first year of the term, which is subject to scheduled annual increases up to $128.87 per square foot per year during the last year of the initial term, plus certain operating expenses and taxes. In addition, the landlord agreed to contribute an aggregate of $4.4 million toward the cost of construction and tenant improvements for the premises. In accordance with the 281 Albany Lease, the Company is required to maintain a letter of credit in the amount of $1.9 million that is restricted for the term of the lease. These restricted cash equivalents are reported in “Other Assets” in the Company’s condensed consolidated balance sheets. The Company has the option to extend the 281 Albany Lease for two successive five-year terms. The option for this extension is not included as part of the lease liability and right-of-use asset at September 30, 2021, as it is not reasonably certain that it will be exercised. In July 2021, the Company entered into an agreement to lease 13,662 square feet of office space at 17 Tudor Street in Cambridge, Massachusetts under an operating lease agreement (the “17 Tudor Lease”). The Company’s obligation to pay rent will start on November 1, 2021. The initial term of the 17 Tudor Lease is five years and the Company has an option to extend the 17 Tudor Lease for one three-year term. The option for this extension is not included as part of the lease liability and right-of-use asset at September 30, 2021, as it is not reasonably certain that it will be exercised. The base rent under the 17 Tudor Lease is $74.00 per square foot during the first year of the term, which is subject to scheduled annual increases throughout the term, resulting in a base rent of $83.29 per square foot during the last year of the initial term, plus certain operating expenses and taxes. In September 2021 the Company determined, in accordance with ASC 842, that the commencement date of the lease had been met as the Company had gained access to the facility in order to begin work on lessee-owned tenant improvements and, accordingly, the Company recognized a right-of-use asset and a lease liability of approximately $4.9 million in the third quarter of 2021 related to the 17 Tudor Lease. In determining the lease liability, the Company used an incremental borrowing rate of 4.15% based on a number of factors including the Company’s credit rating and the lease term. In accordance with the 17 Tudor Lease, the Company is required to maintain a letter of credit in the amount of $0.2 million that is restricted for the term of the lease. These restricted cash equivalents are reported in “Other Assets” in the Company’s condensed consolidated balance sheet. In July 2021, the Company entered into an agreement to extend an existing lease for a clean room located in Waltham, Massachusetts under an operating lease agreement (the “Waltham Lease”) for an additional two years. The Company determined, in accordance with ASC 842, that the extension should be accounted for as a lease modification and, accordingly, recorded an adjustment to the right-of-use asset and lease liability of approximately $2.5 million in the third quarter of 2021 related to the Waltham Lease.

Leases

9 Months Ended

Sep. 30, 2021

. Leases

In March 2020, the Company entered into an agreement to lease approximately 39,000 square feet of office and laboratory space at 281 Albany Street in Cambridge, Massachusetts under an operating lease agreement (the “281 Albany Lease”). The Company’s obligation to pay rent will start on the date that is six months after the commencement date or the date on which the Company occupies the premises, whichever occurs earlier (the “Rent Commencement Date”). The initial term of the 281 Albany Lease is ten years following the Rent Commencement Date. In March 2021 the Company determined, in accordance with ASC 842, “Leases (Topic 842)” (“ASC 842”), that the commencement date of the lease had been met as the facility was substantially complete and available for use and, accordingly, the Company recognized a right-of-use asset and a lease liability of approximately $40.4 million and $34.8 million, respectively, in the first quarter of 2021 related to the 281 Albany Lease. In determining the lease liability, the Company used an incremental borrowing rate of 5.52% based on a number of factors including the Company’s credit rating and the lease term. Included in the recognized right-of-use asset at the inception of the lease was approximately $5.6 million in lease payments that were prepaid under the terms of the lease. The base rent under the 281 Albany Lease is $99.00 per square foot per year during the first year of the term, which is subject to scheduled annual increases up to $128.87 per square foot per year during the last year of the initial term, plus certain operating expenses and taxes. In addition, the landlord agreed to contribute an aggregate of $4.4 million toward the cost of construction and tenant improvements for the premises. In accordance with the 281 Albany Lease, the Company is required to maintain a letter of credit in the amount of $1.9 million that is restricted for the term of the lease. These restricted cash equivalents are reported in “Other Assets” in the Company’s condensed consolidated balance sheets. The Company has the option to extend the 281 Albany Lease for two successive five-year terms. The option for this extension is not included as part of the lease liability and right-of-use asset at September 30, 2021, as it is not reasonably certain that it will be exercised.

In July 2021, the Company entered into an agreement to lease 13,662 square feet of office space at 17 Tudor Street in Cambridge, Massachusetts under an operating lease agreement (the “17 Tudor Lease”). The Company’s obligation to pay rent will start on November 1, 2021. The initial term of the 17 Tudor Lease is five years and the Company has an option to extend the 17 Tudor Lease for one three-year term. The option for this extension is not included as part of the lease liability and right-of-use asset at September 30, 2021, as it is not reasonably certain that it will be exercised. The base rent under the 17 Tudor Lease is $74.00 per square foot during the first year of the term, which is subject to scheduled annual increases throughout the term, resulting in a base rent of $83.29 per square foot during the last year of the initial term, plus certain operating expenses and taxes. In September 2021 the Company determined, in accordance with ASC 842, that the commencement date of the lease had been met as the Company had gained access to the facility in order to begin work on lessee-owned tenant improvements and, accordingly, the Company recognized a right-of-use asset and a lease liability of approximately $4.9 million in the third quarter of 2021 related to the 17 Tudor Lease. In determining the lease liability, the Company used an incremental borrowing rate of 4.15% based on a number of factors including the Company’s credit rating and the lease term. In accordance with the 17 Tudor Lease, the Company is required to maintain a letter of credit in the amount of $0.2 million that is restricted for the term of the lease. These restricted cash equivalents are reported in “Other Assets” in the Company’s condensed consolidated balance sheet.

In July 2021, the Company entered into an agreement to extend an existing lease for a clean room located in Waltham, Massachusetts under an operating lease agreement (the “Waltham Lease”) for an additional two years. The Company determined, in accordance with ASC 842, that the extension should be accounted for as a lease modification and, accordingly, recorded an adjustment to the right-of-use asset and lease liability of approximately $2.5 million in the third quarter of 2021 related to the Waltham Lease.