The Company leases real estate, primarily laboratory, office and manufacturing space. The Company’s leases have remaining terms ranging from approximately one to nine 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 ten 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 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 were $3,029, net of a tenant improvement allowance of $1,184, over the original ten-year term. The lease

commenced in April 2023, at which point, the Company recorded a right-of-use asset of $3,546, which consists of the lease liability of $1,210, and $2,336 of leasehold improvements that revert back to the lessor at the termination of the lease.

In June 2023, the Company entered into a lease for a donor collection facility in Irvine, California, with a lease term of approximately six years and a renewal option, subject to certain conditions, for an additional five-year term. The undiscounted minimum lease payments are $1,079 over the original term. The lease commenced in December 2023, at which point, the Company recorded a right-of-use asset of $1,830, which consists of the lease liability of $768, and $1,062 of leasehold improvements that revert back to the lessor at the termination of the lease.

In January 2024, the Company entered into a sublease agreement with an unrelated third party to sublease a portion of its office and laboratory space in Cambridge, Massachusetts. The term of the sublease agreement commenced in March 2024 and ends on January 13, 2030. The Company will receive lease payments over the sublease term totaling $10,400. The sublessee is obligated to pay all real estate taxes and costs related to the subleased premises, including cost of operations, maintenance, repair, replacement and property management.

As of March 31, 2024, the Company identified an indicator of impairment of its donor collection facility in Cambridge, Massachusetts, as the facility is no longer being used by the Company as a result of operational efficiencies implemented related to the production process and is being marketed for sublease. The Company determined that this represents a significant adverse change in the extent in which the long-lived asset was being used. The Company determined that the location contains multiple asset groups for the purpose of the long-lived asset impairment assessment. The Company concluded that the carrying value of each asset group was not recoverable as it exceeded the future net undiscounted cash flows that are expected to be generated from the assets within the asset group. For the three months ended March 31, 2024, the Company recognized an impairment loss of $3,267, consisting of $1,731 on the operating lease right-of-use asset and $1,536 on the leasehold improvements. $2,727 of the total impairment loss is included in research and development expenses and the remaining $540 is included in general and administrative expenses in the accompanying condensed consolidated statements of operations and comprehensive loss.

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


	March 31, 2024		December 31, 2023
Assets:
Operating lease assets	$	105,669	$	109,793

Liabilities:
Operating lease liabilities	$	8,833	$	6,677
Operating lease liabilities, net of current portion		103,341		105,715
Total operating lease liabilities	$	112,174	$	112,392

The following table summarizes the effect of lease costs in the Company’s condensed consolidated statements of operations and comprehensive loss (in thousands):


	Three Months Ended March 31,
	2024			2023
Operating lease costs	$	5,771		$	5,410
Short-term lease costs		374			368
Variable lease costs		1,967			1,763
Sublease income		(376	)		—
Total lease costs	$	7,736		$	7,541

During the three months ended March 31, 2024 and 2023, the Company made cash payments for operating leases of $3,596 and $3,413 respectively.

As of March 31, 2024, future payments of operating lease liabilities are as follows (in thousands):


	As of March 31, 2024
2024 (remaining 9 months)	$	16,273
2025	$	22,062
2026	$	22,674
2027	$	23,347
2028	$	23,580
2029 and thereafter	$	65,819
Total future minimum lease payments	$	173,755
Less: interest		(61,581	)
Present value of operating lease liabilities	$	112,174

As of March 31, 2024, the weighted average remaining lease term was 7.70 years and the weighted average incremental borrowing rate used to determine the operating lease liability was 13%. As of March 31, 2023, the weighted average remaining lease term was 8.68 years and the weighted average incremental borrowing rate used to determine the operating lease liability was 13%.