Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2019
Cash flows used in operating activities:
Net loss		$ (44,540)	$ (24,076)
Adjustments to reconcile net loss to cash provided by (used in) operating activities:
Depreciation and amortization		1,252	1,173
Stock-based compensation expense		713	913
Loss on disposal of fixed assets			9
Unrealized loss on short-term investments		(53)
Accretion of discount on investments		8
Reduction in carrying amount of right-of-use assets		910	850
Amortization of debt discount	$ 203	229
Change in fair value of warrant liability	3,141	3,141
Changes in operating assets and liabilities:
Accounts receivable		482	83,846
Prepaid expenses, other current assets and other assets		(1,798)	(655)
Accounts payable		(132)	3,071
Accrued expenses and other liabilities		3,157	1,729
Operating lease liability		(651)	(544)
Deferred revenue		(8,425)	(398)
Net cash provided by (used in) operating activities		(45,710)	65,918
Cash flows used in investing activities:
Purchases of property and equipment		(359)	(1,422)
Purchase of short-term investments		(135,926)	(14,902)
Proceeds received from maturities of short-term investments			14,902
Net cash used in investing activities		(136,284)	(1,422)
Cash flows provided by financing activities:
Proceeds from the issuance of Series B convertible preferred stock, net of issuance costs of $4,473		145,525
Proceeds from the issuance of common stock		764	206
Financing costs paid in connection with initial public offering		(2,446)
Vested stock option settlement		(727)
Repurchase of common stock		(210)	(40)
Proceeds from long-term debt, net of issuance costs of $527		11,973
Net cash provided by financing activities		154,879	166
Net increase (decrease) in cash, cash equivalents and restricted cash		(27,115)	64,662
Cash, cash equivalents and restricted cash at beginning of period		93,126	38,888
Cash, cash equivalents and restricted cash at end of period	66,011	66,011	103,550
Reconciliation of cash, cash equivalents and restricted cash:
Cash, cash equivalents and restricted cash at end of period	66,011	66,011	103,550
Less restricted cash	(2,577)	(2,577)	(2,577)
Cash and cash equivalents at end of the period	$ 63,434	63,434	100,973
Supplemental disclosures of non-cash investing and financing activities:
Capital expenditures in accounts payable		10	98
Accrued deferred initial public offering costs		474
Stock option exercises included in prepaid and other current assets		33	$ 53
Fair value of warrants issued in connection with debt issuance		$ 5,465