Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (66,959)	$ (68,144)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	13,882	22,028
Impairment of other investments	10,000	0
Depreciation and amortization expense	5,027	4,187
Net amortization and accretion on marketable securities	(1,850)	475
Change in fair value of success payment liabilities	(1,708)	(3,851)
Non-cash lease income	(293)	(214)
Loss on property and equipment disposals	0	84
Change in fair value of equity warrant	0	(28)
Changes in operating assets and liabilities:
Prepaid expenses, other current assets and other assets	(408)	(397)
Accounts payable	2,069	2,937
Accrued liabilities and other current liabilities	(5,860)	(6,393)
Deferred revenue	0	(558)
Operating lease liabilities, non-current	0	2,135
Other non-current liabilities	(112)	(113)
Net cash used in operating activities	(46,212)	(47,852)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of property and equipment	(1,533)	(9,733)
Purchases of marketable securities	(108,560)	(96,196)
Sales and maturities of marketable securities	142,247	79,807
Net cash provided by (used in) investing activities	32,154	(26,122)
CASH FLOWS FROM FINANCING ACTIVITIES
Taxes paid related to net share settlement of equity awards	(69)	0
Proceeds from exercise of stock options	0	2,555
Net cash (used in) provided by financing activities	(69)	2,555
Net decrease in cash, cash equivalents and restricted cash	(14,127)	(71,419)
Cash, cash equivalents and restricted cash at beginning of period	123,834	294,294
Cash, cash equivalents and restricted cash at end of period	109,707	222,875
Represented by:
Cash and cash equivalents	109,426	222,596
Restricted cash	281	279
Total	109,707	222,875
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid for amounts included in the measurement of lease liabilities	2,406	2,672
Cash received for amounts related to tenant improvement allowances	0	2,042
Non-cash investing and financing activities:
Purchases of property and equipment included in accounts payable and accrued liabilities	$ 395	$ 107