Our leases consist of a Lease Agreement (the Mission Bay Lease) with ARE-San Francisco No. 19, LLC (ARE) for our 155,215 square foot corporate office and R&D facility located at 455 Mission Bay Boulevard South, San Francisco, California (the Mission Bay Facility) and a Lease Agreement (the Third Street Lease) with Kilroy Realty Finance Partnership, L.P. (Kilroy) for an additional 135,936 square foot of office space at 360 Third Street, San Francisco, California (the Third Street Facility). Both leases terminate on January 31, 2030, subject to two consecutive five year renewal options for the Mission Bay Facility and one five year renewal option for the Third Street Facility. Other key terms include the following:

Due to our 2022 and 2023 Restructuring Plans, during the years ended December 31, 2024, and December 31, 2023, we recorded impairment charges of $7.3 million and $30.6 million, respectively, for our right-of-use assets which we are seeking to sublease. See Note 10 for additional information.

We generally recognize lease expense for our operating leases on a straight-line basis over the lease term. For spaces where we have recognized an impairment charge, the aggregate lease expense recognized over the remaining term is reduced by the amount of the impairment charge, but we recognize the remaining lease expense on an accelerated basis. The components of lease expense, which we include in operating expenses in our Consolidated Statements of Operations, were as follows (in thousands):


	Year Ended December 31,
	2024		2023
Operating lease expense	$	8,723	$	12,116
Variable lease expense		9,000		7,027
Total lease expense	$	17,723	$	19,143

During the years ended December 31, 2024 and 2023, we paid $21.6 million and $21.0 million, respectively, of operating lease payments related to our lease liabilities, which we include in net cash used in operating activities in our Consolidated Statements of Cash Flows.

As of December 31, 2024, the maturities of our operating lease liabilities were as follows (in thousands):


Year ending December 31,
2025	$	20,450
2026		22,958
2027		23,682
2028		24,427
2029		25,195
2030 and thereafter		2,108
Total lease payments		118,820
Less: portion representing interest		(16,256	)
Operating lease liabilities		102,564
Less: current portion		(19,868	)
Operating lease liabilities, less current portion	$	82,696

As of December 31, 2024, the weighted-average remaining lease term is 5.1 years and the weighted-average discount rate was 5.8%.

We have entered into subleases for approximately 29,000 square feet of space in our Mission Bay Facility that provide for fixed lease payments, as well as full recovery of the subtenants’ share of operating expenses under our master lease agreement, subject to certain free rent periods. We record the total sublease income as a reduction of general and administrative expense, which totaled $3.2 million and $2.2 million for the years ended December 31, 2024 and December 31, 2023, respectively.

As of December 31, 2024, maturities of our operating lease receivables from subleases for each of the next five years and thereafter were as follows:


Year ending December 31,
2025	$	1,480
2026		1,670
2027		1,729
2028		1,788
2029		1,846
2030 and thereafter		—
Gross Lease Receivable	$	8,513