The Company leases office and laboratory space in Austin, Texas under operating leases that commenced in January 2015 and February 2017, respectively. The office lease was amended in September 2016 to increase office space and extend the term to December 31, 2020. In addition, the amended office lease provides for tenant improvement allowances on both the original space and expansion space totaling $0.2 million.

The Company signed a new laboratory lease agreement in October 2017 for the original laboratory space, which commenced on January 1, 2018. The laboratory lease was subsequently amended in October 2018 to increase the space and extend the lease term to September 30, 2021.

As provided in the office and laboratory leases, monthly lease payments are subject to annual increases through the lease term. The Company recognizes rent expense on a straight-line basis over the non-cancellable term of each lease.

The Company is subject to security deposit requirements under the terms of the amended office lease and laboratory lease agreements, totaling $48,000, until the expiration of the lease. The lessor is entitled to retain all or any part of the security deposit for payment in the event of any uncured default by the Company under the terms of the lease.

Future annual minimum lease payments due under non-cancellable operating leases at December 31 of each year are as follows (in thousands):

2019	$	397
2020		409
2021		83
Thereafter		—
Total minimum lease payments	$	889

For the years ended December 31, 2018, 2017, and 2016, the Company incurred $0.4 million, $0.4 million, and $0.2 million in rent expense under non-cancellable operating leases.