The Company leases corporate office and laboratory space in South San Francisco, California under a sub-sublease that expires in December 2023. The sub-sublease contains scheduled rent increases over the lease term. Prior to moving into the South San Francisco office and laboratory space in February 2019, the Company leased office and laboratory space in San Francisco, California, under a sublease that expired in February 2019. The Company also leases office space for administrative functions in Carmel, Indiana under a lease agreement that expires in August 2023. In February 2021, the Company subleased substantially all of the office space under the Carmel, Indiana lease. The Company also leases office and laboratory space in Groton, Connecticut that supports the Microbiome program under a lease that expires in March 2021. Due to the wind-down of the Microbiome program, the lease will not be renewed. The Company’s China subsidiary leases office space and lab space in Shanghai. The lab space expired in December 2020 and the office space expires March 2021, neither of which are being renewed. Additionally, the Company’s China subsidiary leases office space in Beijing under a lease agreement that expires in December 2021. Certain lease contracts contain renewal clauses that the Company assesses on a case by case basis. The Company also leases certain laboratory equipment accounted for as operating leases expiring at various dates, with the final lease expiring in 2023. In February 2021, the Company purchased substantially all of the leased equipment used for the Microbiome program from its leasing agency and sold them to a third party. The loss on the sale is equal to the impairment loss the Company recognized on these assets for the year ended December 31, 2020 of $0.7 million.

When the Company cannot determine the implicit rate in its leasing arrangements, the Company uses its incremental borrowing rate as the discount rate when measuring operating lease liabilities. The incremental borrowing rate represents an estimate of the interest rate the Company would incur at lease commencement to borrow an amount equal to the lease payments on a collateralized basis over the term of a lease within a particular currency environment.

At December 31, 2020, the Company had operating lease liabilities of $10.1 million and right-of-use assets of $9.1 million.

The following summarizes quantitative information about the Company’s operating leases (in thousands):

	Year Ended December 31,
	2020		2019
Lease cost
Operating lease cost	$	5,214	$	4,454
Short-term lease cost		401		609
Variable lease cost		1,468		1,193
Total lease cost	$	7,083	$	6,256

	Year Ended December 31,
	2020		2019
Operating cash flows from operating leases	$	4,513	$	4,269
Right-of-use assets exchanged for new operating lease liabilities	$	1,302	$	15,261

As of December 31, 2020, the weighted-average remaining lease term for operating leases was 2.7 years and the weighted-average discount rate for operating leases was 9.2%.

As of December 31, 2020, the maturities of the Company’s operating lease liabilities were as follows (in thousands):

2021	$	4,369
2022		3,905
2023		3,502
Total		11,776
Less: present value discount		(1,647	)
Operating lease liabilities	$	10,129

Operating lease costs were $7.1 million, $6.3 million and $4.2 million for the years ended December 31, 2020, 2019 and 2018, respectively.