Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 117,811	$ 110,537
Short-term investments	145,715	143,222
Unbilled grant receivable	2,234	2,336
Prepaid expenses and other current assets	3,394	4,704
Total current assets	269,154	260,799
Restricted cash	210
Property and equipment, net	4,354	3,757
Operating lease right-of-use asset	1,415	1,460
Long-term investments	37,644	65,936
Other long-term assets	225	56
Total assets	313,002	332,008
Current liabilities:
Accounts payable	1,431	567
Accrued liabilities	7,743	8,437
Current operating lease liability	297	288
Total current liabilities	9,471	9,292
Operating lease liability, less current portion	1,554	1,632
Total liabilities	11,025	10,924
Stockholders' equity:
Common stock, $0.0001 par value; 900,000,000 shares authorized at March 31, 2022 and December 31, 2021, respectively; 37,624,058 and 37,379,077 shares issued and outstanding at March 31, 2022 and December 31, 2021, respectively	4	4
Additional paid-in capital	420,304	417,363
Accumulated other comprehensive loss	(1,456)	(388)
Accumulated deficit	(116,875)	(95,895)
Total stockholders' equity	301,977	321,084
Total liabilities and stockholders' equity	$ 313,002	$ 332,008