Accrued and Other Current Liabilities - Schedule of Accrued and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued employee compensation costs	$ 3,496	$ 4,123
Accrued professional costs	518	593
Accrued research and development costs	5,434	3,689
Current portion of operating lease liabilities	1,425
Accrued other	28	82
Other current liabilities	328	1,443
Total accrued and other current liabilities	$ 11,229	$ 9,930