Prepaid expenses and other current assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Prepaid expenses and other current assets
Prepaid clinical	$ 4,693	$ 6,052
Prepaid insurance	1,122	1,177
Prepaid Manufacturing Cost	2,241	613
Other prepaid expenses and current assets	366	298
Total prepaid expenses and other current assets	$ 8,422	$ 8,140