The Company has operating leases for its current corporate offices, laboratory space, manufacturing facility, and dedicated space in a vivarium in South San Francisco, California, as well as for an additional facility in South San Francisco that the Company plans to use for corporate offices, laboratories and manufacturing.

The components of lease expense were as follows (in thousands):


	Year Ended December 31,
	2022		2021
Operating lease expense	$	11,220	$	2,581
Variable lease expense (1)		462		302
Short-term lease expense		45		92
Total lease expense	$	11,727	$	2,975

(1) Variable lease expense for the periods presented primarily included common area maintenance charges.

Supplemental information related to operating leases were as follows (in thousands):


	Year Ended December 31,
	2022		2021
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows used for operating leases	$	6,887	$	2,239

The weighted-average remaining lease term was 10.8 years for the corporate office and laboratory space leases as of December 31, 2022. The corporate office lease includes an option to renew for an additional seven years. However, the renewal option was not included in the lease term for calculating the lease liability, as the renewal option allows the Company to maintain operational flexibility, and the Company was not reasonably certain

that it would exercise the renewal option at the time of the lease commencement. The weighted-average discount rate was 9.8% as of December 31, 2022.

There were $59.5 million and $18.7 million in right-of-use assets obtained in exchange for operating lease liabilities resulting from new leases and from modifications of existing leases, respectively, for the year ended December 31, 2022.

Maturities of operating lease liabilities under existing operating leases as of December 31, 2022 were as follows (in thousands):


Year ending December 31,	Amount
2023	$	11,206
2024		12,671
2025		13,033
2026		13,467
2027		13,917
2028 and thereafter		87,290
Total undiscounted future minimum lease payments		151,584
Less imputed interest		(60,813	)
Less tenant improvement receivable		(7,837	)
Total operating lease liabilities	$	82,934
Operating lease liabilities:
Current		4,249
Non-current		78,685
Total lease liability	$	82,934

In May 2018, the Company entered into a lease agreement for its corporate office and laboratory space located in South San Francisco, California with an expiration date in May 2025 (the "Initial Lease Agreement"). In April 2019, the Company executed the first amendment to the Initial Lease Agreement for additional corporate space, laboratory space and manufacturing capabilities and an extension to the lease term through April 2026.

In May 2020, the Company signed a second amendment to the Initial Lease Agreement. The amended lease provides for an eight-year non-cancelable lease of additional office and laboratory space in the same building. The lease amendment for additional office and laboratory space provided for abatement of rent during the first three months of the lease and contains rent escalations during the term of the lease. The lease for this additional space commenced in January 2021 and expires in January 2029. The lease amendment also includes an extension of the lease term for the existing office and laboratory space beginning on May 1, 2020 and expiring in January 2029. The amendment to the Initial Lease Agreement also includes an option to extend the lease for an additional seven-year term.

In January 2021, the Company signed a third amendment to the Initial Lease Agreement which provides for the lease of additional space in the same building. The lease amendment for this additional space commenced in April 2021 and expires in March 2024.

In October 2021, the Company signed a fourth amendment to the Initial Lease Agreement which provides for the lease of additional space in the same building. The lease for additional office and laboratory space provides for abatement of rent during the first two months of the lease and contains rent escalations during the term of the lease. The lease amendment of this additional space commenced in April 2022 and expires in January 2029. The lease amendment also includes this additional space in the Company’s option to extend the amended Initial Lease Agreement for an additional seven-year term. The other terms of the Initial Lease Agreement, as amended, remain unchanged.

In July 2021, the Company entered into a lease agreement for corporate office, manufacturing and laboratory space located in South San Francisco, California with an expiration date approximately twelve years after the lease's legal commencement date (the "Additional Lease Agreement"). The lease for this additional space and the

Company's obligation to pay rent commenced in January 2022. In addition to base rent, the Company is responsible for payment of direct expenses, which include operating, insurance and tax expenses. The lease also provides for certain tenant improvement allowances of up to approximately $25.2 million for tenant improvements and certain infrastructure upgrades in connection with the initial buildout of the premises, approximately $4.4 million of which, if utilized, would need to be repaid by the Company over the lease term. In 2021, the Company delivered a security deposit in the form of a letter of credit of $1.6 million to the Landlord in connection with the Additional Lease Agreement.

In November 2021, the Company entered into an amendment to the Additional Lease Agreement. The lease amendment expressly includes manufacturing as a permitted use at the facility, clarifies that Silicon Valley Bank is an acceptable bank for purposes of issuing a letter of credit under the lease, revises the letter of credit transferability terms and replaces the form of letter of credit attached to the lease.

In August 2022, the Company entered into fifth amendment to the Initial Lease Agreement and a second amendment to the Additional Lease Agreement for its existing facilities in South San Francisco, California. The fifth amendment to the Initial Lease Agreement includes an extension of the lease term for certain of the Company's existing facilities through July 31, 2030. The second amendment to the Additional Lease Agreement provides for approximately $15.0 million of additional tenant improvement allowances, in addition to the tenant improvement allowances of $25.2 million included in the original Additional Lease Agreement, and increases the base rent payments over the existing term of the lease.