Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 39,768	$ 42,268
Restricted cash	297	299
Prepaid expenses and other current assets	2,082	913
Total current assets	42,147	43,480
Property and equipment, net	206	216
Operating lease right-of-use asset	1,265	1,443
Total assets	43,618	45,139
Current liabilities:
Accounts payable	2,903	1,379
Accrued expenses	4,631	4,196
Advances from collaboration partners	10,723	3,723
Derivative liabilities	270
Current portion of operating lease liability	647	657
Total current liabilities	19,174	9,955
Long-term debt	12,120	11,996
Operating lease liability	638	804
Total liabilities	31,932	22,755
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.01 par value per share, 5,000,000 shares authorized, no shares issued or outstanding as of March 31, 2022 and December 31, 2021
Common stock, $0.01 par value per share, 500,000,000 shares authorized, 87,074,455 and 87,071,324 shares issued and 86,653,089 and 86,649,958 shares outstanding as of March 31, 2022 and December 31, 2021, respectively	871	871
Common stock in treasury, at cost, 421,366 shares as of March 31, 2022 and December 31, 2021	(2,190)	(2,190)
Additional paid-in capital	262,948	262,026
Accumulated deficit	(249,943)	(238,323)
Total stockholders’ equity	11,686	22,384
Total liabilities and stockholders’ equity	$ 43,618	$ 45,139