Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flow from operating activities
Net loss	$ (134,625)	$ (148,563)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	32,218	26,128
Depreciation and amortization	2,962	1,620
Noncash lease expense	4,000	1,117
Amortization of premiums on investments	2,380	1,412
Acquired in-process research and development	2,500
Effective interest on liability for sale of future royalties	902
Changes in operating assets and liabilities:
Receivable from collaboration partners ($708,296 and ($381) from a related party)	708,764	(526)
Prepaid expenses and other current assets	4,028	(9,086)
Other long-term assets (($1,322) and $0 to a related party)	(1,442)	471
Accounts payable	12,102	(3,569)
Accrued research and development	8,432	10,449
Other accrued liabilities	(10,220)	163
Deferred revenue (($41,264) and ($15,422) to a related party)	(44,764)	(18,922)
Operating lease liabilities	(1,184)	(1,003)
Other long-term liabilities	2,645	(2)
Net cash provided by (used in) operating activities	588,698	(140,311)
Cash flow from investing activities
Purchases of short-term and long-term investments	(763,131)	(370,690)
Proceeds from maturities of short-term and long-term investments	262,824	438,733
Sales of short-term and long-term investments	26,852	7,500
Purchases of property and equipment	(4,302)	(9,714)
Purchases of in-process research and development	(5,500)
Net cash (used in) provided by investing activities	(483,257)	65,829
Cash flow from financing activities
Proceeds from issuance of common stock ($0 and $220,235 from a related party)		220,235
Proceeds from sale of future royalties	5,000
Proceeds from issuance of common stock pursuant to equity award plans	14,274	4,122
Repurchase of unvested shares of stock		(6)
Net cash provided by financing activities	19,274	224,351
Net increase in cash and cash equivalents	124,715	149,869
Cash, cash equivalents and restricted cash at beginning of period	150,919	173,618
Cash, cash equivalents and restricted cash at end of period	275,634	323,487
Supplemental disclosure of cash flow information
Income taxes paid	2,743
Non-cash investing and financing activities:
Unpaid portion of property and equipment purchases included in accounts payable and accrued liabilities	617	6,488
Vesting of early exercised stock options and restricted stock	$ 52	$ 358