Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 131,701	$ 60,625
Short-term investments	153,239	124,057
Unbilled grant receivable	2,589	1,300
Prepaid expenses and other current assets	2,968	6,355
Total current assets	290,497	192,337
Property and equipment, net	2,916	2,649
Operating lease right-of-use asset	1,547	936
Long-term investments	64,939	83,509
Other long-term assets	225	132
Total assets	360,124	279,563
Current liabilities:
Accounts payable	1,166	1,158
Accrued liabilities	6,205	3,123
Current operating lease liability	263	124
Total current liabilities	7,634	4,405
Operating lease liability, less current portion	1,781	876
Total liabilities	9,415	5,281
Stockholders' equity:
Common stock, $0.0001 par value; 900,000,000 shares authorized at June 30, 2021 and December 31, 2020, respectively; 37,251,711 and 32,485,784 shares issued and outstanding at June 30, 2021 and December 31, 2020, respectively	4	3
Additional paid-in capital	414,550	315,288
Accumulated other comprehensive income	37	33
Accumulated deficit	(63,882)	(41,042)
Total stockholders' equity	350,709	274,282
Total liabilities and stockholders' equity	$ 360,124	$ 279,563