Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 3,096	$ 10,155
Prepaid expenses and other current assets	1,930	950
Total current assets	5,026	11,105
Other assets	90	90
Total assets	5,116	11,195
Current liabilities:
Accounts payable	38,392	40,520
Accrued expenses	14,021	14,791
Deferred revenue	883	883
Total current liabilities	53,296	56,194
Non-current liabilities:
Deferred revenue	1,545	1,766
Total liabilities	54,841	57,960
Stockholders’ deficit:
Common stock, $0.001 par value: 225,000,000 shares authorized at March 31, 2023 and December 31, 2022; 119,080,135 shares issued and outstanding at March 31, 2023 and December 31, 2022	119	119
Additional paid-in capital	636,147	634,925
Accumulated deficit	(685,991)	(681,809)
Total stockholders’ deficit	(49,725)	(46,765)
Total liabilities and stockholders’ deficit	$ 5,116	$ 11,195