Segment Information - Schedule of Operating Segments (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Operating expenses:
External research and development costs	[1]	$ 214,712	$ 167,865	$ 68,424
General and administrative operations		70,883	49,005	24,579
Depreciation expense		1,418	189
Provision for income taxes		278	18	0
Consolidated net loss		(255,843)	(182,146)	(83,985)
Reportable Segment
Operating expenses:
Research and development personnel-related (excluding equity-based compensation)	[2]	68,490	39,013	9,387
External-discovery related costs and other	[2]	22,469	11,064	15,019
General and administrative personnel-related (excluding equity-based compensation)	[2]	26,740	16,935	8,047
General and administrative operations	[2],[3]	19,117	18,690	12,002
Equity-based compensation	[2]	46,277	23,332	6,103
Depreciation expense	[2]	1,418	189
Interest income		(30,030)	(34,742)	(9,018)
Provision for income taxes		278	18
Consolidated net loss		255,843	182,146	83,985
Reportable Segment | Zumilokibart (APG777)
Operating expenses:
External research and development costs	[2]	76,441	49,241	21,644
Reportable Segment | APG990 / APG279
Operating expenses:
External research and development costs	[2]	16,250	20,000
Reportable Segment | APG333 / APG273
Operating expenses:
External research and development costs	[2]	5,257	28,095
Reportable Segment | APG808
Operating expenses:
External research and development costs	[2]	$ 3,136	$ 10,311	$ 20,801

[1] Includes related party amounts of $2,186 for the year ended December 31, 2025, $19,179 for the year ended December 31, 2024 and $26,285 for the year ended December 31, 2023.

[2] The significant expense categories and amounts align with the segment-level information that is regularly provided to the CODM

[3] General and administrative operations are comprised of finance, investor relations, business development, human resources, legal, facilities & IT, and certain other overhead expenses