Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 29,268	$ 37,495
Accounts receivable, net of allowance for doubtful accounts of $12 and $17, respectively	0	4
Inventory	482	571
Prepaid expenses and other current assets	1,244	1,279
Total current assets	30,994	39,349
Property and equipment, net	1,582	1,598
Intangible assets, net of accumulated amortization of $2,204 and $1,653, respectively	4,136	4,687
Total assets	36,712	45,634
Current liabilities:
Accounts payable	499	602
Related party payable	10,720	1,001
Accrued expenses	1,779	1,196
Deferred revenue	457	416
Warrant liability, current	1,910	278
Total current liabilities	15,365	3,493
Warrant liability, long term	6,365	11,008
Deferred rent	779	724
Total liabilities	$ 22,509	$ 15,225
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares outstanding	$ 0	$ 0
Common stock, $0.001 par value; 100,000,000 shares authorized; 43,898,785 and 40,856,815 shares issued and outstanding, respectively	44	41
Additional paid-in capital	161,330	143,086
Accumulated deficit	(147,171)	(112,718)
Total stockholders’ equity	14,203	30,409
Total liabilities and stockholders’ equity	$ 36,712	$ 45,634