Income taxes - Schedule of Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Tax computed at the federal statutory rate	$ (22,361)	$ (20,034)
State income taxes, net of federal tax benefit	(6)	0
Deferred impact of conversion to C Corporation		(2,131)
Nondeductible executive compensation	685	4,145
Stock-based compensation	1,132	(1,021)
Research and development and orphan drug credits	(3,692)	(3,091)
Uncertain tax positions	910	757
Other, net	(23)	793
Valuation allowance	23,355	20,582
Income tax expense	$ 0	$ 0