Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Operating activities
Net loss	$ (59,998)	$ (36,647)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	1,212	1,275
Stock-based compensation expense	6,726	4,619
Net amortization of premiums on marketable securities	641	195
Changes in operating assets and liabilities:
Accounts receivable	2,143	2,000
Unbilled accounts receivable	394	(126)
Prepaid expenses and other current assets	25	1,773
Operating lease assets and liabilities	42	221
Other assets	(1,563)	47
Accounts payable	471	622
Accrued expenses and other liabilities	3,448	397
Deferred revenue	(2,929)	(7,981)
Net cash used in operating activities	(49,472)	(34,047)
Investing activities
Purchases of marketable securities	(15,166)	(51,785)
Maturities of marketable securities	67,784	38,673
Purchases of property and equipment	(1,564)	(827)
Net cash provided by (used in) investing activities	51,054	(13,939)
Financing activities
Proceeds from issuance of common stock in connection with follow-on offering, net of issuance costs	0	47,407
Principal payments on capital lease obligations	0	(18)
Proceeds from issuance of common stock under benefit plans, net	3,159	324
Net cash provided by financing activities	3,159	47,713
Net increase (decrease) in cash, cash equivalents and restricted cash	4,741	(273)
Cash, cash equivalents, and restricted cash, beginning of period	36,504	58,144
Cash, cash equivalents, and restricted cash, end of period	41,245	57,871
Supplemental cash flow information
Cash paid for operating lease liabilities	1,400	0
Non-cash investing and financing activities:
Property and equipment purchases unpaid at end of period	151	59
Cash and cash equivalents	40,153	56,779
Restricted cash	$ 1,092	$ 1,092