Segment reporting (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2026 USD ($) segment	Mar. 31, 2025 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment	1
Number of reportable segments | segment	1
Revenue from collaboration agreements	$ 6,152	$ 7,238
General and administrative	9,331	9,330
Total operating expenses	33,937	36,402
Non-operating income	(2,656)	(2,842)
Net loss	(25,129)	(26,322)
Reportable Segment
Segment Reporting Information [Line Items]
Revenue from collaboration agreements	0	0
Reportable Segment | Operating Segments
Segment Reporting Information [Line Items]
Development expenses	12,589	14,550
Research expenses	8,710	7,724
General and administrative	9,967	8,621
Total operating expenses	31,266	30,895
Non-operating income	(2,656)	(2,842)
Adjustments or reconciling items	(3,481)	(1,731)
Net loss	$ (25,129)	$ (26,322)