Condensed Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating Activities
Net loss	$ (81,489)	$ (59,115)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and other expense	24	108
Amortization of premium and discounts on investment securities	918	115
Share-based compensation	6,997	6,044
Changes in operating assets and liabilities:
Income tax receivable	1,765	0
Prepaid expense and other assets	726	542
Accrued interest receivable	449	(112)
Accrued research and development expenses	(916)	6,007
Accounts payable and accrued expenses	(4,662)	1,383
Change in working capital	63	0
Net cash used in operating activities	(76,125)	(45,028)
Investing Activities
Purchase of marketable securities	(56,245)	(108,305)
Maturities of marketable securities	136,447	0
Net cash provided by (used in) investing activities	80,202	(108,305)
Financing Activities
Proceeds from employee stock plan purchases	1,672	333
Net cash provided by financing activities	109,429	150,453
Net increase (decrease) in cash and cash equivalents	113,506	(2,880)
Cash and cash equivalents
Beginning of period	66,373	125,699
End of period	179,879	122,819
Supplemental disclosure of cash paid
Income tax refunds received	1,765	3,327
Underwritten Offering
Financing Activities
Proceeds from issuance of common stock	107,757	116,883
Private Placement
Financing Activities
Proceeds from issuance of common stock	$ 0	$ 33,237