Segment Reporting - Schedule of Segment Reporting Information, by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Segment Reporting [Line Items]
Collaboration revenue - related party	$ 17	$ 0	$ 33	$ 0
Research and development	7,767	10,029	13,048	19,310
General and administrative	6,739	6,769	12,972	13,885
Gain on lease modification	0	0	(6,882)	0
Total operating expenses	14,506	16,798	19,138	33,195
Loss from operations	(14,489)	(16,798)	(19,105)	(33,195)
Change in fair value of convertible notes - related party	271	0	271	0
Net loss	(12,750)	(14,733)	(16,971)	(28,845)
Related And Nonrelated Parties
Segment Reporting [Line Items]
Sublease income	1,418	1,794	1,747	3,685
Reportable Segment
Segment Reporting [Line Items]
Collaboration revenue - related party	17	0	33	0
Depreciation and amortization	667	915	1,355	1,840
Gain on lease modification	0	0	(6,882)	0
Total operating expenses	14,506	16,798	19,138	33,195
Loss from operations	(14,489)	(16,798)	(19,105)	(33,195)
Interest income	55	270	156	664
Net loss	(12,750)	(14,733)	(16,971)	(28,845)
Reportable Segment | Related And Nonrelated Parties
Segment Reporting [Line Items]
Sublease income	1,418	1,794	1,747	3,685
Reportable Segment | Nonrelated Party
Segment Reporting [Line Items]
Other income (expense), net	(5)	1	(40)	1
External services and supplies | Reportable Segment
Segment Reporting [Line Items]
Research and development	4,877	6,317	7,113	12,514
General and administrative	2,889	1,298	4,402	3,492
Personnel-related expenses, including stock-based compensation | Reportable Segment
Segment Reporting [Line Items]
Research and development	1,699	2,176	3,514	3,920
General and administrative	2,361	3,184	5,055	5,769
Facilities and other | Reportable Segment
Segment Reporting [Line Items]
Research and development	990	1,311	2,001	2,427
General and administrative	$ 1,023	$ 1,597	$ 2,580	$ 3,233