Condensed Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities
Net loss	$ (16,641)	$ (7,665)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation	157	181
Stock-based compensation expense	1,136	33
Amortization of discounts and loan issuance costs	29	30
Noncash interest expense	110	1,399
Change in fair value of preferred warrant liability	75	(1)
Changes in operating assets and liabilities:
Prepaid and other assets	(392)	(195)
Accounts payable and accrued liabilities	1,908	(199)
Accrued compensation	5	(50)
Operating lease right-of-use assets and liabilities, net	2	(39)
Deferred revenue	(1,320)	19,900
Net cash (used in) provided by operating activities	(14,931)	13,394
Cash flows from investing activities
Purchases of property and equipment	(10)	(130)
Net cash used in investing activities	(10)	(130)
Cash flows from financing activities
Proceeds from issuance of common stock in initial public offering, gross	298,080	0
Payment of issuance costs related to initial public offering	(22,680)	0
Proceeds from exercise of stock options/units, net of repurchases	16	63
Payments on long-term debt	(4,683)	(1,400)
Proceeds from issuance of Series C convertible preferred stock, net of issuance costs	2,200	0
Proceeds from issuance of convertible notes, net of issuance costs	0	19,458
Net cash provided by financing activities	272,933	18,121
Net increase in cash, cash equivalents and restricted cash	257,992	31,385
Cash, cash equivalents and restricted cash at beginning of period	94,578	3,090
Cash, cash equivalents and restricted cash at end of period	352,570	34,475
Supplemental disclosure of cash flow information:
Cash paid for interest	571	225
Supplemental schedule of noncash investing and financing activities:
Right-of-use assets obtained in exchange for operating lease liabilities	676	807
Costs incurred, but not paid, in connection with IPO included in accounts payable and accrued liabilities	1,346	0
Costs incurred, but not paid, in connection with purchases of property and equipment included in accounts payable and accrued liabilities	287	0
Conversion of convertible preferred stock into common stock upon completion of initial public offering	136,920	0
Reclassification of warrant liability to equity due to adjustment from preferred stock warrant to common stock warrant upon completion of initial public offering	$ 120	$ 0