Segment information (Details) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2025 USD ($)	Jun. 30, 2025 USD ($)	Mar. 31, 2025 USD ($)	Sep. 30, 2024 USD ($)	Jun. 30, 2024 USD ($)	Mar. 31, 2024 USD ($)	Sep. 30, 2025 USD ($) Segment	Sep. 30, 2024 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | Segment							1
Number of reportable segments | Segment							1
Collaboration revenue	$ 0			$ 2,910			$ 6,941	$ 6,303
Less:
In-process research and development	0			6,706			0	124,972
General and administrative	10,945			9,526			31,677	22,509
Total operating expenses	60,138			53,432			158,193	229,133
Loss from operations	(60,138)			(50,522)			(151,252)	(222,830)
Interest income	2,681			3,422			8,758	10,116
Net loss	(57,457)	$ (43,397)	$ (41,640)	(47,100)	$ (36,122)	$ (129,492)	(142,494)	(212,714)
Single reportable segment
Segment Reporting Information [Line Items]
Collaboration revenue				2,910			6,941	6,303
Less:
In-process research and development				(6,706)				(124,972)
Other product candidates	(17,623)			(10,917)			(35,672)	(25,418)
Indirect research and development	(14,097)			(8,126)			(39,411)	(17,738)
General and administrative	(10,945)			(9,526)			(31,677)	(22,509)
Total operating expenses	(60,138)			(53,432)			(158,193)	(229,133)
Loss from operations	(60,138)			(50,522)			(151,252)	(222,830)
Interest income	2,681			3,422			8,758	10,116
Net loss	(57,457)			(47,100)			(142,494)	(212,714)
Single reportable segment | Varegacestat
Less:
Direct research and development expenses	(12,495)			(9,621)			(39,615)	(14,397)
Single reportable segment | IM-1021
Less:
Direct research and development expenses	(2,874)			(4,456)			(7,669)	(14,865)
Single reportable segment | IM-3050
Less:
Direct research and development expenses	$ (2,104)			$ (4,080)			$ (4,149)	$ (9,234)