The Company has operating leases for its corporate office and laboratory space and dedicated space in a vivarium in South San Francisco, California. Rent expense, which is recognized on a straight-line basis over the term of each lease, were $0.5 million and $1.4 million for the three and nine months ended September 30, 2020, respectively, and $0.4 million and $0.8 million for the three and nine months ended September 30, 2019, respectively. The total cash paid for operating leases included in the operating cash flows were $0.4 million and $1.3 million for the three and nine months ended September 30, 2020, respectively, and $0.4 million and $0.8 million for the three and nine months ended September 30, 2019, respectively. The weighted-average remaining lease term was 8.3 years for the corporate office and laboratory space leases, and 0.5 years for the vivarium lease as of September 30, 2020. The weighted-average discount rate was 10% as of September 30, 2020.

In May 2020, the Company signed an amendment to its office and laboratory facilities lease. The amended lease provides for an eight-year non-cancelable lease of additional office and laboratory space in the same building. The lease for additional office and laboratory space provides 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 is expected to commence in the first quarter of 2021 and expires in 2029. The lease amendment also includes an extension of the lease term for the existing office and laboratory space beginning on May 1, 2020 through the first quarter of 2029. The lease agreement includes an option to extend the lease for an additional seven-year term.

Maturities of operating lease liabilities under existing operating leases as of September 30, 2020 were as follows (in thousands):

Year ending December 31,	Amount
2020 (remaining 3 months)	$	430
2021		1,461
2022		1,452
2023		1,503
2024		1,556
2025 and thereafter		6,981
Total future minimum lease payments		13,383
Less imputed interest		(4,248	)
Present value of net minimum lease payments	$	9,135
Operating lease liabilities:
Current		1,476
Non-current		7,659
Total lease liability	$	9,135

Total minimum lease payments of $4.5 million related to the lease of additional space under the amendment were excluded from the table above as the lease agreement had not yet commenced as of September 30, 2020.