Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Accrued Expenses and Other Current Liabilities
Accrued employee compensation and benefits	$ 2,752	$ 1,482
Accrued external research and development expenses	1,004	125
Accrued issuance costs	495
Accrued general and administrative professional service expenses	301	35
Other	328	115
Total	$ 4,880	$ 1,757