Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 26,453	$ 30,007
Prepaid expenses and other current assets	1,923	3,028
Total current assets	28,376	33,035
Property and equipment, net	318	401
Operating lease assets	291	549
Other assets	123	123
Total assets	29,108	34,108
Current liabilities:
Accounts payable	570	3,048
Loan payable, net of discount	3,992	3,992
Accrued expenses and other current liabilities	1,885	3,370
Operating lease liabilities, net of discount	296	498
Total current liabilities	6,743	10,908
Loan payable, net of current portion and discount	3,992	5,988
Operating lease liabilities, net of current portion		14
Total liabilities	10,735	16,910
Commitments and contingencies (Note 7)
Stockholders’ equity:
Undesignated preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares issued or outstanding
Common stock, $0.001 par value; 125,000,000 shares authorized; 32,224,734 and 24,735,009 shares issued and outstanding at June 30, 2020 and December 31, 2019, respectively	32	25
Additional paid-in capital	197,846	182,117
Accumulated deficit	(179,505)	(164,944)
Total stockholders’ equity	18,373	17,198
Total liabilities and stockholders’ equity	$ 29,108	$ 34,108