Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows used in operating activities:
Net loss	$ (43,551)	$ (22,705)
Adjustments to reconcile net loss to cash provided by (used in) operating activities:
Stock-based compensation expense	9,073	277
Depreciation expense	839	832
Reduction in carrying amount of right-of-use asset	647	600
Accretion of discount on marketable securities	474
Amortization of debt discount − related party	360	25
Changes in operating assets and liabilities:
Accounts receivable	(1,729)	(3,923)
Prepaid expenses and other current and long-term assets	(1,181)	(1,651)
Accounts payable	(1,338)	462
Accrued expenses and other current liabilities	316	(628)
Operating lease liability	(508)	(429)
Deferred revenue	(6,338)	(4,120)
Net cash used in operating activities	(42,936)	(31,260)
Cash flows used in investing activities:
Proceeds from maturities of marketable securities	209,494
Purchases of marketable securities	(237,622)	(103,942)
Purchases of property and equipment	(1,168)	(75)
Net cash used in investing activities	(29,296)	(104,017)
Cash flows provided by financing activities:
Proceeds from follow-on offering, net of issuance costs paid of $10.8 million (Note 10)	169,934
Proceeds from exercises of stock options	705	232
Payment of initial public offering costs	(286)
Proceeds from the issuance of Series B shares, net of issuance costs of $4.5 million		141,026
Proceeds from long-term debt and warrant − related party, net of issuance costs of $0.5 million		11,973
Repurchase of common stock		(124)
Vested stock option settlement		(727)
Other	(3)
Net cash provided by financing activities	170,350	152,380
Net change in cash, cash equivalents and restricted cash	98,118	17,103
Cash, cash equivalents and restricted cash at beginning of period	184,304	93,126
Cash, cash equivalents and restricted cash at end of period	282,422	110,229
Reconciliation of cash, cash equivalents and restricted cash:
Cash, cash equivalents and restricted cash at end of period	282,422	110,229
Less: restricted cash	(1,276)	(2,577)
Cash and cash equivalents at end of the period	281,146	107,652
Supplemental disclosures of cash flow information:
Cash paid for interest − related party	707	102
Supplemental disclosures of non-cash investing and financing activities:
Aggregate exercise price of warrant net exercised − related party (Note 10)	3,002
Follow-on costs in accounts payable and accrued expenses	$ 451
Capital expenditures in accounts payable and accrued expenses		14
Stock option exercises included in prepaid and other current assets		33
Fair value of warrant issued in connection with debt issuance		2,325
Stock option repurchases included in accrued expenses		$ 86