Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Operating activities
Net loss	$ (45,315)	$ (22,840)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	5,826	2,083
Depreciation expense	375	230
Non-cash lease expense	92	68
Amortization of premiums and accretion of discounts on available-for-sale securities, net	149	226
Changes in operating assets and liabilities:
Unbilled grant receivable	2,336	(1,289)
Prepaid expenses and other current assets	1,149	3,217
Accounts payable and accrued liabilities	365	3,318
Operating lease liability	(139)	365
Net cash used in operating activities	(35,162)	(14,622)
Investing activities
Purchases of available-for-sale securities	(51,670)	(173,563)
Maturities of available-for-sale securities	71,951	152,740
Proceeds from sales of available-for-sale securities		9,988
Purchases of property and equipment	(896)	(418)
Net cash provided by (used in) investing activities	19,385	(11,253)
Financing activities
Proceeds from exercise of common stock options	507	189
Proceeds from public offering, net of issuance costs		96,762
Net cash provided by financing activities	507	96,951
Net (decrease) increase in cash, cash equivalents and restricted cash	(15,270)	71,076
Cash, cash equivalents and restricted cash, beginning of period	110,537	60,625
Cash, cash equivalents and restricted cash, end of period	$ 95,267	131,701
Supplemental disclosures of cash flow information:
Right-of-use asset obtained in exchange for new operating lease liability		$ 680