The Company leases real estate, primarily laboratory, office and manufacturing space. The Company’s leases have remaining terms ranging from approximately two to ten years. Certain leases include one or more options to renew, exercisable at the Company’s sole discretion, with renewal terms that can extend the lease from approximately one year to five years. The Company evaluated the renewal options in its leases to determine if it was reasonably certain that the renewal option would be exercised, given the Company’s current business structure, uncertainty of future growth, and the associated impact to real estate, the Company concluded that it is not reasonably certain that any renewal options would be exercised. Therefore, the operating lease assets and operating lease liabilities only contemplate the initial lease terms. All the Company’s leases qualify as operating leases.

In July 2021, the Company entered into a lease agreement for a donor collection facility in Tempe, Arizona with a lease term of ten years, commencing in March 2022, subject to certain renewal options, which are not deemed reasonably certain. Minimum lease payments total $4,052, net of tenant improvement allowance of $770, through the lease term. At lease commencement, the Company recorded a right-of-use asset of $5,900, which consists of the lease liability of $2,327 and $3,573 of leasehold improvements that revert back to the lessor at the termination of the lease.

In August 2021, the Company entered into a lease for additional office and laboratory space in Waltham, Massachusetts with a lease term of ten years, commencing in two phases in October 2021 and March 2022, respectively, with a third and final phase for laboratory space, not yet commenced at December 31, 2022. Minimum lease payments for the two phases that commenced in 2022 total $12,125 and $2,449, respectively, net of tenant improvement allowance of $767 for the laboratory space, through the lease term. At each lease commencement, the Company recorded right-of-use assets of $7,602 and $2,662, respectively, which consist of the lease liability of $7,602 for the office space, and the lease liability of $1,273 and $1,389 of leasehold improvements that revert back to the lessor at the termination of the lease for the laboratory space. The lease is subject to certain renewal options, which are not deemed reasonably certain at commencement of the first two phases.

In September 2021, the Company entered into a lease for additional laboratory and office space in Cambridge, Massachusetts with a lease term of ten years and a renewal option for an additional seven-year term. The lease commenced in December 2022, and the

renewal option was not deemed reasonably certain of exercise. Minimum lease payments total $101,548 throughout the lease term. At lease commencement, the Company recorded a right-of-use asset of $56,065, which consists of the lease liability of $54,206 and $1,859 of leasehold improvements that revert back to the lessor at the termination of the lease.

In April 2022, the Company entered into a lease for additional laboratory and office space in Spring House, Pennsylvania, with a lease term of ten years and a renewal option, subject to certain conditions, for an additional five-year term. The undiscounted minimum lease payments are $2,980, net of a tenant improvement allowance of $1,223, over the original ten-year term. As of December 31, 2022, the lease has not yet commenced, and accordingly the Company has not recorded a right-of-use asset or a lease liability with respect thereto.

In December 2022, the Company amended its lease of its corporate headquarters in Cambridge, Massachusetts (the "Lease Amendment"). The Lease Amendment reduced the office space subject to the lease while maintaining the laboratory and manufacturing space and extended the term to begin in November 2023, when the term of the original lease concludes, and continue through January 2030. The Company accounted for the Lease Amendment as a modification to the existing lease and not a new contract separate from the existing contract, and accordingly increased the associated lease liability and right-of-use asset by $32,837. Minimum lease payments total $60,022 throughout the term of the Lease Amendment, net of a tenant improvement allowance of $1,000.

The Company has committed to restore the leased space subject to the Lease Amendment to the condition specified in the original lease, and the Company updated its estimate of the costs required to fulfill this obligation in accordance with ASC 410, Asset Retirement Obligations, at the effective date of the modification. Based on current estimates, the Company recorded an additional asset retirement obligation of $452 in December 2022.

The following table summarizes the presentation in the Company’s consolidated balance sheets of its operating leases:


	December 31,
	2022		2021
Assets:
Operating lease assets	$	110,984	$	18,208

Liabilities:
Operating lease liabilities	$	3,601	$	6,610
Operating lease liabilities, net of current portion		107,942		17,958
Total operating lease liabilities	$	111,543	$	24,568

The following table summarizes the effect of lease costs in the Company’s consolidated statement of operations and comprehensive loss:


	Year Ended December 31,
	2022		2021			2020
Operating lease costs	$	8,830	$	5,170		$	4,163
Short-term lease costs		1,375		1,452			1,457
Variable lease costs		4,547		3,300			2,890
Sublease income		—		(1,575	)		(1,813	)
Total lease costs	$	14,752	$	8,347		$	6,697

During the years ended December 31, 2022, 2021, and 2020, the Company made cash payments for operating leases of $7,809, $6,821 and $6,302, respectively.

As of December 31, 2022, future payments of operating lease liabilities are as follows (in thousands):


	As of December 31, 2022
2023	$	16,815
2024		19,055
2025		21,164
2026		21,755
2027 and thereafter		108,383
Total future payments of operating lease liabilities	$	187,172
Less: imputed interest		(75,629	)
Present value of operating lease liabilities	$	111,543