Consolidated Balance Sheets - USD ($)
$ in Thousands
Dec. 31, 2016
Dec. 31, 2015
Current assets:    
Cash and cash equivalents $ 14,753 $ 23,027
Accounts receivable 598 361
Prepaid expenses and other 929 429
Total current assets 16,280 23,817
Equipment, net 2,605 1,135
Deferred tax assets 175 177
Total assets 19,060 25,129
Current liabilities:    
Accounts payable 4,761 2,702
Accrued compensation and related benefits 1,190 1,024
Accrued clinical trial costs 389 82
Accrued expenses 535 513
Note payable   190
Deferred revenue   245
Total current liabilities 6,875 4,756
Warrant liabilities 1,004 649
Stockholders' equity:    
Preferred stock, at stated value; 10,000,000 shares authorized, and no shares issued and outstanding at December 31, 2016 and December 31, 2015
Common stock, $0.001 par value; 150,000,000 shares authorized, 86,629,302 and 83,720,154 shares issued and outstanding at December 31, 2016 and December 31, 2015, respectively 87 84
Additional paid-in capital 329,373 322,582
Accumulated deficit (318,279) (302,942)
Total stockholders' equity 11,181 19,724
Total liabilities and stockholders' equity $ 19,060 $ 25,129