CONDENSED STATEMENT OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities
Net loss		$ (73,464)	$ (10,589)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense		2,657	382
Depreciation and amortization		503	272
Accretion and amortization of investments, net		116
Non-cash lease expense		220	124
Change in fair value of preferred stock purchase right liability	$ (3,383)	40,163	(3,383)
Change in fair value of derivative liability			(858)
Non-cash loss from extinguishment of debt	752		752
Non-cash interest expense on convertible notes	283		472
Others		(15)
Changes in operating assets and liabilities:
Prepaid expenses and other assets		(3,355)	28
Accounts payable and accrued and other liabilities		2,523	1,069
Net cash used in operating activities		(30,652)	(11,731)
Cash flows from investing activities
Purchases of property and equipment		(6,442)	(1,306)
Purchases of short-term investments		(144,916)
Maturities of short-term investments		20,000
Net cash used in investing activities		(131,358)	(1,306)
Cash flows from financing activities
Proceeds from issuance of convertible preferred stock, net of issuance costs		64,321	38,417
Proceeds from initial public offering, net of issuance costs		265,461
Proceeds from stock option exercises		322
Proceeds from early exercise of stock options		12	42
Proceeds from issuance of convertible notes, net of issuance costs			5,986
Net cash provided by financing activities		330,116	44,445
Net increase in cash and cash equivalents		168,106	31,408
Cash, cash equivalents, and restricted cash beginning of period		20,875	7,956
Cash, cash equivalents, and restricted cash end of period	39,364	188,981	39,364
Reconciliation of cash, cash equivalents and restricted cash to the balance sheet:
Cash and cash equivalents	39,095	188,568	39,095
Restricted cash	269	413	269
Total cash, cash equivalents and restricted cash	$ 39,364	188,981	39,364
Non-cash investing activities:
Property and equipment included in accounts payable and accrued liabilities		825	$ 329
Non-cash financing activities:
Deferred offering costs included in accounts payable and accrued liabilities		$ 331