As of December 31, 2020, we had an operating lease for 73,328 square feet of laboratory and office space in San Diego, California, with a lease term that expires on December 31, 2025. We have one 5-year option to renew this lease on expiration. During the year ended December 31, 2020, we paid $3.6 million for our operating lease.

We leased 26,067 square feet of laboratory, office and warehouse space in Redwood City, California. The lease for the Redwood City space expired in May 2019. In March 2018, we entered into a sublease agreement for the Redwood City property. The sublease agreement expired in May 2019. We also leased 1,898 square feet of office space in Jersey City, New Jersey. The lease for the Jersey City office space expired in December 2019.

Annual future minimum lease payments as of December 31, 2020 are as follows (in thousands):

Year ended December 31:
2021	$	3,942
2022		4,058
2023		4,178
2024		4,274
2025		4,379
Thereafter		—
Total future minimum lease payments		20,831
Less: discount		(3,273	)
Total lease liabilities	$	17,558

Rent expense under all operating leases totaled $3.9 million, $3.1 million and $3.2 million for the years ended December 31, 2020, 2019 and 2018, respectively.

We enter into agreements with clinical sites and clinical research organizations for the conduct of our clinical trials and contract manufacturing organizations for the manufacture and supply of preclinical, clinical and commercial materials and drug product. We make payments to these clinical sites and clinical research organizations based in part on the number of eligible patients enrolled and the length of their participation in the clinical trials. In some of our agreements with contract manufacturing organizations, we are required to meet minimum purchase obligations. Under certain of these agreements, we may be subject to penalties in the event that we prematurely terminate these agreements. At this time, due to the variability associated with clinical site agreements, contract research organization agreements and contract manufacturing agreements, we are unable to estimate with certainty the future costs we will incur. We intend to use our current financial resources to fund our obligations under these commitments.