Accrued expenses and other current liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Accrued expenses and other current liabilities
Accrued employee compensation and benefits	$ 2,670	$ 6,429
Accrued external research and development expenses	5,150	3,980
Accrued professional fees	1,065	882
Current portion of operating lease liabilities	2,996	2,383
Other	384	570
Accrued expenses and other current liabilities	$ 12,265	$ 14,244