Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Cash flows from operating activities:
Net loss	$ (140,718)	$ (95,020)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,956	999
Stock-based compensation expense	30,615	17,629
Amortization of operating lease right-of-use assets	1,918	2,092
Net accretion of discounts on investments	(4,913)	(10,991)
Unrealized foreign exchange loss	(6,617)	0
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(1,499)	(4,958)
Operating lease right-of-use assets	(17,575)	0
Other assets	(6,554)	(8,581)
Operating lease liabilities	15,999	(1,804)
Accounts payable	(29,163)	5,672
Accrued compensation	(14,418)	(7,968)
Accrued contract manufacturing expenses	8,088	(51,840)
Accrued expenses	(4,393)	(4,354)
Net cash used in operating activities	(166,274)	(159,124)
Cash flows from investing activities:
Purchases of property and equipment	(5,424)	(5,678)
Purchases of manufacturing facility build-out and equipment construction-in-progress	(21,327)	(6,394)
Purchases of investments	(314,485)	(687,697)
Maturities of investments	438,488	242,318
Sales of investments	26,065	6,378
Net cash provided (used) in investing activities	123,317	(451,073)
Cash flows from financing activities:
Proceeds from exercise of common stock options	6,049	5,024
Proceeds from issuance of common stock from follow-on offerings, net of issuance costs	0	816,478
Taxes paid related to the net share settlement of equity awards	(5,290)	(3,306)
Net cash provided by financing activities	759	818,196
Effect of exchange rate changes on cash and cash equivalents	1,172	6,062
Net increase (decrease) in cash, cash equivalents and restricted cash	(41,026)	214,061
Cash, cash equivalents and restricted cash, beginning of period	389,195	398,554
Cash, cash equivalents and restricted cash, end of period	348,169	612,615
Cash and cash equivalents	346,850	611,512
Restricted cash	1,319	1,103
Cash, cash equivalents and restricted cash	348,169	612,615
Supplemental disclosure of non-cash investing activities:
Purchases of property and equipment recorded in accounts payable and accrued expenses	$ 3,889	$ 13,719