Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Current assets
Cash and cash equivalents	$ 63,372	$ 88,756
Grants receivable	0	806
Prepaid expenses and other current assets	2,513	1,685
Total current assets	65,885	91,247
Property and equipment, net	388	451
Operating lease right-of-use assets	3,589	3,986
Investments in related parties	865	723
Other assets	86	106
Total assets	70,813	96,513
Current liabilities
Accounts payable	2,656	4,710
Accrued expenses	4,086	3,219
Operating lease liabilities, current	943	894
Financing obligation, current	62	58
Deferred revenue, current	0	2,301
Warrant liability	33	114
Total current liabilities	7,780	11,296
Operating lease liabilities, noncurrent	2,990	3,475
Financing obligation, noncurrent	202	235
Other liabilities, noncurrent	81	0
Total liabilities	11,053	15,006
Commitments and contingencies (Note 9)
Stockholders' equity
Common stock, $0.01 par value per share; 300,000,000 and 300,000,000 shares authorized, 30,052,544 and 29,959,060 shares issued and outstanding as of June 30, 2022 and December 31, 2021, respectively	301	300
Additional paid-in capital	297,875	296,445
Accumulated other comprehensive income (loss)	98	(103)
Accumulated deficit	(238,514)	(215,135)
Total stockholders' equity	59,760	81,507
Total liabilities and stockholders' equity	$ 70,813	$ 96,513