Balance Sheet Components - Summary of Accrued and Other Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued employee related costs	$ 3,804	$ 4,359
Accrued research and development costs	2,213	1,715
Accrued professional fees	1,252	774
Operating lease liabilities	$ 408	$ 207
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	us-gaap:OtherLiabilitiesCurrent	us-gaap:OtherLiabilitiesCurrent
Other	$ 104	$ 93
Total accrued and other liabilities	$ 7,781	$ 7,148