CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating activities
Net loss	$ (16,514)	$ (13,139)
Adjustments to reconcile net loss to net cash used in operating activities:
Amortization of premium (accretion of discount) on marketable securities	218	(4)
Depreciation and amortization	280	199
Stock-based compensation expense	2,687	2,088
Gain on foreign currency translation	38	204
Changes in operating assets and liabilities:
Accounts receivable	0	(5,010)
Prepaid expenses and other current assets	(112)	(562)
Accounts payable, accrued expenses, and other current liabilities	362	2,421
Deferred revenue	(841)	5,065
Deferred rent	(28)	(7)
Net cash used in operating activities	(13,910)	(8,745)
Investing activities
Purchase of marketable securities	(15,734)	(46,883)
Proceeds from maturities of marketable securities	28,372	0
Purchase of property and equipment	(227)	(98)
Net cash provided by (used in) investing activities	12,411	(46,981)
Financing activities
Proceeds from issuance of common stock, net of issuance costs	1,180	69,842
Proceeds from exercise of stock options, net of repurchases	121	30
Net cash provided by financing activities	1,301	69,872
Net increase (decrease) in cash and cash equivalents	(198)	14,146
Cash and cash equivalents at beginning of period	24,918	77,383
Cash and cash equivalents at end of period	$ 24,720	$ 91,529