STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net loss	$ (44,224)	$ (36,889)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	1,219	390
Stock-based compensation	7,486	3,601
(Increase) decrease in:
Receivables	(2,961)	(742)
Prepaid expenses and other current assets	5,820	6,838
Right of use asset	(721)	389
Other noncurrent assets	493	(634)
Increase (decrease) in:
Accounts payable	22	176
Accrued expenses	(4,742)	3,320
Lease liabilities	843	(361)
Net cash used in operating activities	(36,765)	(23,912)
Cash flows from investing activities:
Purchases of property and equipment	(2,594)	(4,000)
Net cash used in investing activities	(2,594)	(4,000)
Cash flows from financing activities:
Proceeds from exercise of stock options	1,036	16
Issuance of common stock in connection with a public offering, net	0	88,661
Issuance of common stock in connection with at the market offerings, net	0	13,015
Net cash provided by financing activities	1,036	101,692
Net increase in cash and cash equivalents, and restricted cash	(38,323)	73,780
Cash and cash equivalents, and restricted cash, beginning of period	115,069	79,741
Cash and cash equivalents, and restricted cash, end of period	76,746	153,521
Supplementary disclosure of cash flow information:
Accounts included in accrued expenses and accounts payable related to property and equipment	$ 258	$ 1,026