Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Statement of Comprehensive Income [Abstract]
Revenue		$ 8	$ 13	$ 15	$ 16
Operating expenses:
Research and development		34,857	40,261	78,304	83,435
General and administrative		9,786	12,256	23,832	25,750
Other operating loss (income), net		1,062	(976)	943	(2,066)
Impairment of long-lived assets		1,443	0	1,443	0
Total operating expenses		47,148	51,541	104,522	107,119
Loss from operations		(47,140)	(51,528)	(104,507)	(107,103)
Interest income, net		3,276	6,364	7,138	13,183
Other income (expense), net		1,180	(645)	2,490	445
Impairment of other investments		0	0	0	(13,001)
Total other income, net		4,456	5,719	9,628	627
Net loss		(42,684)	(45,809)	(94,879)	(106,476)
Other comprehensive loss:
Net unrealized (loss) gain on marketable securities		(101)	7	(234)	(303)
Comprehensive loss		$ (42,785)	$ (45,802)	$ (95,113)	$ (106,779)
Net loss per common share, basic (in dollars per share)	[1]	$ (2.89)	$ (3.59)	$ (6.42)	$ (8.36)
Net loss per common share, diluted (in dollars per share)	[1]	$ (2.89)	$ (3.59)	$ (6.42)	$ (8.36)
Weighted-average shares used to compute net loss per common share, basic (in shares)	[1]	14,793	12,770	14,774	12,741
Weighted-average shares used to compute net loss per common share, diluted (in shares)	[1]	14,793	12,770	14,774	12,741

[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.