Segment Information - Schedule of Segment expenses reviewed by the CDMO (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Collaboration and other revenue	$ 11,000	$ 0
Total research and development expenses	63,095	103,731
Total general and administrative expenses	21,848	25,956
Net Income (Loss)	(69,776)	(123,462)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Collaboration and other revenue	11,000	0
Total research and development expenses	63,095	103,731
Total general and administrative expenses	21,848	25,956
Interest and other income/(expense)	4,167	6,225
Net Income (Loss)	(69,776)	(123,462)
Operating Segments [Member] | Total program expenses
Segment Reporting Information [Line Items]
Total research and development expenses	43,022	81,369
Operating Segments [Member] | Personnel and related
Segment Reporting Information [Line Items]
Total research and development expenses	12,082	12,552
Total general and administrative expenses	7,213	7,553
Operating Segments [Member] | Equity-based compensation
Segment Reporting Information [Line Items]
Total research and development expenses	4,238	5,462
Total general and administrative expenses	4,683	8,082
Operating Segments [Member] | Facilities And other
Segment Reporting Information [Line Items]
Total research and development expenses	3,753	4,348
Total general and administrative expenses	9,952	10,321
Operating Segments [Member] | Mecbotamab vedotin, BA3011 | Total program expenses
Segment Reporting Information [Line Items]
Total research and development expenses	12,934	24,533
Operating Segments [Member] | Ozuriftamab vedotin, BA3021 | Total program expenses
Segment Reporting Information [Line Items]
Total research and development expenses	8,962	13,530
Operating Segments [Member] | Evalstotug, BA3071 | Total program expenses
Segment Reporting Information [Line Items]
Total research and development expenses	9,103	17,099
Operating Segments [Member] | BA3182 | Total program expenses
Segment Reporting Information [Line Items]
Total research and development expenses	5,111	4,048
Operating Segments [Member] | Other CAB Programs | Total program expenses
Segment Reporting Information [Line Items]
Total research and development expenses	$ 6,912	$ 22,159