CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Current assets
Cash and cash equivalents	$ 70,578	$ 77,563
Marketable securities	0	13,371
Prepaid expenses and other current assets	2,874	7,558
Total current assets	73,452	98,492
Property and equipment, net	11,720	6,053
Other assets	3,804	4,087
Total assets	88,976	108,632
Current liabilities
Accounts payable	3,881	8,062
Accrued expenses and other current liabilities	7,787	9,900
Operating lease obligations	526	498
Current portion of long term debt	1,266	0
Total current liabilities	13,460	18,460
Non-current liabilities
Operating lease obligations, less current portion	3,308	3,587
Long term debt, net of current portion	1,472	2,289
Other non-current liabilities	455	244
Total non-current liabilities	5,235	6,120
Total liabilities	18,695	24,580
Commitments and contingencies (Note 13)
Stockholders' equity
Common stock; $0.01 par value; 295,000,000 shares authorized, 256,608,552 and 221,721,182 shares issued, and 256,487,052 and 221,599,682 shares outstanding at June 30, 2023 and December 31, 2022, respectively	2,566	2,217
Treasury stock, at cost, 121,500 shares at June 30, 2023 and December 31, 2022	(48)	(48)
Additional paid-in capital	320,181	294,874
Accumulated other comprehensive income	22	26
Accumulated deficit	(252,441)	(213,018)
Total stockholders' equity	70,281	84,052
Total liabilities and stockholders' equity	88,976	108,632
Series A Preferred Stock
Stockholders' equity
Preferred stock issued	0	0
Series B Preferred Stock
Stockholders' equity
Preferred stock issued	$ 1	$ 1