Segment Reporting - Summary of Revenue Significant Expenses and Net Loss for Segment (Details) - USD ($)	3 Months Ended				6 Months Ended		12 Months Ended		15 Months Ended
	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024	Dec. 31, 2023	Jun. 30, 2025
Segment Reporting Information [Line Items]
Collaboration revenue	$ 183,000		$ 598,000		$ 366,000	$ 1,130,000
Research and development costs	5,110,000		13,264,000		9,986,000	31,502,000
Impairment of property and equipment	0		1,883,000		0	1,883,000	$ 1,900,000	$ 1,600,000
Impairment of right-of-use assets	0		22,836,000		0	22,836,000	22,800,000
Restructuring and other related charges	398,000		6,450,000		1,283,000	6,450,000	$ 10,900,000		$ 12,200,000
Total operating expenses	9,009,000		49,572,000		18,033,000	73,628,000
Loss from operations	(8,826,000)		(48,974,000)		(17,667,000)	(72,498,000)
Interest income	410,000		855,000		708,000	1,941,000
Other income:	981,000		0		981,000	0
Total other income	1,391,000		855,000		1,689,000	1,941,000
Loss before income tax expense	(7,435,000)		(48,119,000)		(15,978,000)	(70,557,000)
Income tax expense	(2,000)		(12,000)		(6,000)	(26,000)
Net Income (Loss)	(7,437,000)	$ (8,547,000)	(48,131,000)	$ (22,452,000)	(15,984,000)	(70,583,000)
Clinical Related Costs
Segment Reporting Information [Line Items]
Research and development costs	1,346,000		5,058,000		2,632,000	11,019,000
Employee Related Costs
Segment Reporting Information [Line Items]
Research and development costs	3,074,000		5,451,000		6,149,000	14,926,000
Product Development and Manufacturing Costs
Segment Reporting Information [Line Items]
Research and development costs	176,000		1,415,000		309,000	2,898,000
Facilities, Support Costs and Depreciation
Segment Reporting Information [Line Items]
Research and development costs	2,669,000		3,708,000		5,341,000	7,773,000
Professional, Consulting and Public Company Costs
Segment Reporting Information [Line Items]
Research and development costs	$ 1,346,000		$ 2,771,000		$ 2,319,000	$ 5,843,000