Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flows from operating activities
Net loss	$ (36,069)	$ (19,968)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	974	826
Net amortization (accretion) of premiums (discounts) on marketable securities	518	899
Stock-based compensation	5,649	3,976
Amortization of right-of-use assets	694	642
Changes in assets and liabilities
Accounts receivable	815	552
Prepaid expenses and other assets	(51)	(1,719)
Accounts payable	1,916	796
Accrued and other liabilities	3,099	1,724
Contract liabilities	(16,358)	(13,633)
Lease liabilities	(826)	(749)
Net cash used in operating activities	(39,639)	(26,654)
Cash flows from investing activities
Purchases of property and equipment, net	(2,342)	(1,581)
Purchases of marketable securities	(102,222)	(133,046)
Maturities of marketable securities	100,119	117,663
Sales of marketable securities	0	4,018
Net cash used in investing activities	(4,445)	(12,946)
Cash flows from financing activities
Proceeds from issuance of common stock related to at-the-market offering program, net of issuance costs	(75)	57,308
Proceeds from ESPP purchase	784	327
Proceeds from exercise of common stock options, net of repurchases	435	355
Net cash provided by financing activities	1,144	57,990
Net increase (decrease) in cash, cash equivalents and restricted cash	(42,940)	18,390
Cash, cash equivalents and restricted cash, at beginning of period	92,152	72,143
Cash, cash equivalents and restricted cash, at end of period	49,212	90,533
Reconciliation of cash, cash equivalents and restricted cash
Cash and cash equivalents	49,106	90,427
Restricted cash	106	106
Cash, cash equivalents and restricted cash	49,212	90,533
Supplemental disclosure of cash flow information:
Cash paid for income taxes	0	4
Cash paid for interest	32	37
Supplemental non-cash investing and financing activities:
Purchases of property and equipment in accounts payable and accrued liabilities	1,021	378
Unpaid offering costs	0	171
Vesting of early exercised options and restricted stock	$ 0	$ 21