The Company has contractual arrangements with research and development organizations and suppliers; however, these contracts are generally cancelable on 30 days’ notice and the obligations under these contracts are largely based on services performed.

The Company leases office space in Hayward, California under non-cancelable operating leases with expiration in 2025. Rent expense was $1.6 million, $0.9 million and $0.6 million for the years ended December 31, 2018, 2017 and 2016, respectively. Future minimum lease payments under non-cancelable operating leases as of December 31, 2018 are as follows (in thousands):

Year ending December 31:	Operating Leases
2019	$	2,041
2020		2,105
2021		2,195
2022		2,265
2023		2,339
2024 and beyond		4,487
Total	$	15,432

Total minimum lease payments have not been reduced by minimum sublease rent income of approximately $0.6 million under a future noncancelable sublease.

The Company has provided deposits for letters of credit totaling $0.2 million to secure its obligations under its lease, which have been classified as long-term assets on the Company’s consolidated balance sheet as of December 31, 2018.

As permitted under Delaware law and in accordance with the Company’s bylaws, the Company is required to indemnify its officers and directors for certain events or occurrences while the officer or director is or was serving in such capacity. The Company is also party to indemnification agreements with its directors and officers. The Company believes the fair value of the indemnification rights and agreements is minimal. Accordingly, the Company has not recorded any liabilities for these indemnification rights and agreements as of December 31, 2018, 2017 and 2016.