Segment information (Details) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2025 USD ($)	Mar. 31, 2025 USD ($)	Jun. 30, 2024 USD ($)	Mar. 31, 2024 USD ($)	Jun. 30, 2025 USD ($) Segment	Jun. 30, 2024 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | Segment					1
Number of reportable segments | Segment					1
Collaboration revenue	$ 4,015		$ 2,364		$ 6,941	$ 3,393
Less:
In-process research and development	0		6,312		0	118,266
General and administrative	10,042		6,978		20,732	12,983
Total operating expenses	50,493		42,373		98,055	175,701
Loss from operations	(46,478)		(40,009)		(91,114)	(172,308)
Interest income	3,081		3,887		6,077	6,694
Net loss	(43,397)	$ (41,640)	(36,122)	$ (129,492)	(85,037)	(165,614)
Single reportable segment
Segment Reporting Information [Line Items]
Collaboration revenue	4,015		2,364		6,941	3,393
Less:
In-process research and development			6,312			118,266
Other product candidates	11,206		8,206		18,049	14,501
Indirect research and development	13,772		5,484		25,314	9,612
General and administrative	10,042		6,978		20,732	12,983
Total operating expenses	50,493		42,373		98,055	175,701
Loss from operations	(46,478)		(40,009)		(91,114)	(172,308)
Interest income	3,081		3,887		6,077	6,694
Net loss	(43,397)		(36,122)		(85,037)	(165,614)
Single reportable segment | Varegacestat
Less:
Direct research and development expenses	12,733		4,526		27,120	4,776
Single reportable segment | IM-1021
Less:
Direct research and development expenses	1,728		7,685		4,795	10,409
Single reportable segment | IM-3050
Less:
Direct research and development expenses	$ 1,012		$ 3,182		$ 2,045	$ 5,154