Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net loss	$ (463,927)	$ (402,266)	$ (223,485)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	7,003	3,156	2,834
Stock-based compensation expense	84,822	48,760	23,650
Non-cash payments for acquired manufacturing rights	0	0	7,995
Amortization of operating lease right-of-use assets	8,842	7,015	6,619
Net accretion of discounts on investments	(38,704)	(34,775)	(947)
Unrealized foreign exchange loss	4,232	0	0
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(5,827)	17,870	433
Operating lease right-of-use assets	(49,948)	(16,724)	0
Other assets	(26,511)	(33,007)	(465)
Operating lease liabilities	41,886	11,284	1,151
Accounts payable	34,584	11,225	2,896
Accrued compensation	9,517	9,876	(2,275)
Accrued contract manufacturing expenses	(22,943)	44,501	3,826
Accrued expenses	(35,653)	36,295	7,171
Net cash used in operating activities	(452,627)	(296,790)	(170,597)
Cash flows from investing activities:
Purchases of property and equipment	(22,427)	(16,062)	(5,841)
Purchases of manufacturing facility build-out and equipment construction-in-progress	(96,732)	(51,815)	0
Purchases of investments	(3,086,701)	(1,329,896)	(102,745)
Maturities of investments	1,133,235	611,876	168,691
Sales of investments	66,959	12,586	14,480
Net cash (used in) provided by investing activities	(2,005,666)	(773,311)	74,585
Cash flows from financing activities:
Proceeds from issuance of common stock and pre-funded warrants from follow-on offerings, net of issuance costs	2,239,713	545,302	759,181
Proceeds from issuance of common stock under at-the-market offering, net of issuance costs	195,943	90,741	97,299
Proceeds from issuance of shares through employee equity incentive plans	27,144	7,646	5,928
Taxes paid related to the net share settlement of equity awards	(14,292)	(3,876)	(861)
Net cash provided by financing activities	2,448,508	639,813	861,547
Effect of exchange rate changes on cash and cash equivalents	426	(6,686)	137
Net (decrease) increase in cash, cash equivalents and restricted cash	(9,359)	(436,974)	765,672
Cash, cash equivalents and restricted cash, beginning of period	398,554	835,528	69,856
Cash, cash equivalents and restricted cash, end of period	389,195	398,554	835,528
Cash and cash equivalents	387,878	397,451	834,657
Restricted cash	1,317	1,103	871
Cash, cash equivalents and restricted cash	389,195	398,554	835,528
Supplemental disclosures of non-cash investing and financing activities:
Purchases of property and equipment recorded in accounts payable and accrued expenses	13,179	8,510	110
Issuance of common stock for acquired manufacturing rights	$ 0	$ 0	$ 7,995