CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Current assets:
Cash and cash equivalents	$ 30,582	$ 24,846	$ 24,007
Short-term investments	0	1,999
Accounts receivable	248	108
Prepaid expenses and other current assets	1,691	2,786
Total current assets	32,521	29,739
Property and equipment, net	379	523
Operating lease right-of-use asset, net	584	0
Other assets	1	0
Total assets	33,485	30,262
Current liabilities:
Accounts payable	286	1,096
Accrued liabilities	3,020	5,108
Current portion of notes payable	3,417	3,976
Total current liabilities	6,723	10,180
Notes payable, net of current portion	5,380	4,328
Other liabilities	211		0
Total liabilities	12,314	14,508
Commitments and contingencies
Stockholders’ equity:
Common stock, $0.01 par value; 100,000,000 shares authorized; 53,077,348 and 34,861,876 shares issued and outstanding at June 30, 2020 and December 31, 2019, respectively	531	349
Additional paid-in capital	203,291	183,574
Accumulated deficit	(182,651)	(168,169)
Total stockholders’ equity	21,171	15,754	$ 33,437
Total liabilities and stockholders’ equity	$ 33,485	$ 30,262