CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net loss	$ (21,142)	$ (22,810)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,423	1,933
Stock-based compensation	5,567	1,319
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(690)	(3,660)
Accounts payable	(1,675)	93
Accrued liabilities	(1,117)	335
Deferred rent	336
Deferred revenue	(22,378)	(2,842)
Net cash used in operating activities	(38,676)	(25,632)
Cash flows from investing activities:
Maturities of marketable securities	129,169
Purchase of marketable securities	(95,992)	(174,205)
Purchase of property and equipment	(6,152)	(2,557)
Net cash provided by (used in) investing activities	27,025	(176,762)
Cash flows from financing activities:
Proceeds from initial public offering, net of issuance costs		77,264
Proceeds from issuances of common stock	94	65
Proceeds from the term loan		4,540
Deferred financing costs		(134)
Payments of the term loan	(1,111)
Net cash (used in) provided by financing activities	(1,017)	81,735
Net (decrease) increase in cash, cash equivalents and restricted cash	(12,668)	(120,659)
Cash, cash equivalents and restricted cash—beginning of period	39,130	135,633
Cash, cash equivalents and restricted cash—end of period	26,462	14,974
Supplemental disclosures of cash flow information:
Cash paid for interest	130	137
Supplemental disclosures of noncash investing and financing activities:
Purchase of property and equipment included in accrued liabilities	$ 134	73
Deferred financing costs included in accrued liabilities		134
Conversion of convertible preferred stock into common stock		$ 162,223