Share-based compensation - Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 5,347	$ 3,227	$ 11,050	$ 5,386
Unrecognized compensation cost	62,900		$ 62,900
Recognition period			2 years 10 months 24 days
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	2,233	1,041	$ 4,667	1,424
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 3,114	$ 2,186	$ 6,383	$ 3,962