The Company’s lease portfolio is primarily comprised of operating leases for office, laboratory, non-good manufacturing practices (GMP) pilot plant manufacturing, and industrial space located in Seattle, WA, Cambridge, MA, South San Francisco, CA, Fremont, CA, and Rochester, NY. These leases contain various rent abatement periods, after which they require monthly lease payments that may be subject to annual increases throughout the lease term. The Seattle and South San Francisco lease agreements each provide the Company with the option to renew for an additional period of five years. The Company is not reasonably certain it will renew these leases, and therefore the renewal options are not considered in the remaining lease term for these leases. The industrial space located in Fremont, CA will be used for the construction of a GMP manufacturing facility. The lease agreement initial term is ten years and includes the option to extend for up to two additional five-year terms. The lease for the Company’s Rochester facility includes the option to extend for up to two additional two-year terms. The Company anticipates that it will exercise all options to extend for both the Fremont and Rochester facilities. Certain leases provide the Company with the right to make tenant improvements, including the addition of laboratory space or build-out of manufacturing capabilities, and include a lease incentive allowance.

The following table contains additional information related to the Company’s operating leases:

Location	Approximate Square Footage	Commencement Dates	Expiration Dates
Seattle, WA	48,086	March 2019 to September 2020	December 2026 to April 2028
Cambridge, MA	59,639	March 2019 to May 2020	November 2025 to February 2028
South San Francisco, CA	66,075	December 2019 to November 2021	April 2024 to April 2030
Fremont, CA	163,193	July 2021	November 2031
Rochester, NY	3,309	January 2022	January 2025

Throughout the term of the lease agreements, the Company is responsible for paying certain operating costs in addition to rent, such as common area maintenance, taxes, utilities, and insurance. These additional charges are considered variable lease costs and are recognized in the period in which the costs are incurred.

		Three Months Ended March 31,
		2022		2021
	(in thousands)
Operating lease cost		$	5,480	$	2,898
Short-term lease cost			-		512
Variable lease cost			1,489		1,087
Total lease cost		$	6,969	$	4,497

As of March 31, 2022, the weighted-average remaining lease term was 9.6 years and the weighted-average incremental borrowing rate was 8.95%.

The following table reconciles the Company’s undiscounted operating lease cash flows by fiscal year, to the present value of the operating lease liabilities as of March 31, 2022 (in thousands):

2022 (remaining 9 months)		14,964
2023		22,273
2024		21,387
2025		21,236
2026		18,199
2027 and thereafter		81,998
Total undiscounted lease payments		180,057
Less: imputed interest		(64,549	)
Less: tenant improvement allowances		(3,355	)
Present value of operating lease liabilities	$	112,153