Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Statement of Comprehensive Income [Abstract]
Revenue		$ 36	$ 61	$ 130
Operating expenses:
Research and development		158,675	171,603	182,945
General and administrative		45,135	52,041	66,983
Other operating income, net		(2,145)	(3,309)	(2,790)
Acquired in-process research and development		66,332	87,184	0
Impairment of long-lived assets		1,443	51,297	0
Total operating expenses		269,440	358,816	247,138
Loss from operations		(269,404)	(358,755)	(247,008)
Interest income, net		13,080	24,068	23,453
Other (expense) income, net		(18,124)	4,694	1,846
Impairment of other investments		0	(13,001)	(12,923)
Total other (loss) income, net		(5,044)	15,761	12,376
Net loss		(274,448)	(342,994)	(234,632)
Other comprehensive loss:
Net unrealized (loss) gain on marketable securities		(49)	385	7,505
Comprehensive loss		$ (274,497)	$ (342,609)	$ (227,127)
Net loss per common share, basic (in dollars per share)	[1]	$ (16.06)	$ (26.23)	$ (18.70)
Net loss per common share, diluted (in dollars per share)	[1]	$ (16.06)	$ (26.23)	$ (18.70)
Weighted-average shares used to compute net loss per common share, basic (in shares)	[1]	17,093	13,074	12,549
Weighted-average shares used to compute net loss per common share, diluted (in shares)	[1]	17,093	13,074	12,549

[1] 1. Amounts previously reported have been retroactively adjusted to reflect the 1-for-20 reverse stock split effected on May 30, 2025. See Note 2.