The aggregate future minimum lease payments for operating leases as of September 30, 2021, are as follows.


	Operating Leases (1)		Sublease Income
2021 (remaining 3 months)	$	587	$	(462	)
2022		2,381		(1,901	)
2023		2,458		(1,964	)
2024		2,537		(2,029	)
2025		1,953		(1,569	)
Total payments	$	9,916	$	(7,925	)

(1) Future minimum lease payments include repayment of outstanding restructuring liabilities.

In April 2015, PNAi entered a lease for approximately 3,800 square feet of office and laboratory space for a term of 39 months in Woburn, Massachusetts. In January 2018, the Company elected to renew this lease for three years, beginning in August 2018. This lease expired in July 2021.

In April 2018, the Company entered into a lease for approximately 24,606 square feet of office and life science research space, which commenced on October 1, 2018, when the Company obtained control of the rented space for a term of 84 months in South San Francisco, California (“the South San Francisco Lease”). In connection with the South San Francisco Lease, the Company maintains a letter of credit issued to the lessor in the amount of $293, which is secured by restricted cash that is classified as noncurrent based on the term of the underlying lease.

The Company’s total future minimum commitment due pursuant to the South San Francisco Lease is $9,916 as of September 30, 2021. In November 2020, the Company entered into a non-cancellable sublease agreement for the facility, under the terms of which the Company is entitled to receive $7,925 in sublease payments over the term of the sublease, which ends concurrently with the original lease in September 2025. As tenant, the Company remains responsible for the $9,916 minimum lease commitment on the facilities.

The Company recorded rent expense totaling $535 and $1,605 for the three and nine months ended September 30, 2020. No rent expense was recorded for the three and nine months ended September 30, 2021.

The Company had certain leases on research and laboratory equipment which were assigned to a certain third party as of September 30, 2021. The Company recorded no rent expense for the three months ended September 30, 2020 and rent expense totaling $256 for the nine months ended September 30, 2020. No rent expense was recorded for the three and nine months ended September 30, 2021.