Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 36,931	$ 37,495
Accounts receivable, net of allowance for doubtful accounts of $12 and $17, respectively	0	4
Inventory	566	571
Prepaid expenses and other current assets	467	1,279
Total current assets	37,964	39,349
Property and equipment, net of accumulated depreciation of $1,191 and $1,051, respectively	1,697	1,598
Intangible assets, net of accumulated amortization of $2,067 and $1,653, respectively	4,273	4,687
Total assets	43,934	45,634
Current liabilities:
Accounts payable	2,624	1,124
Accrued expenses	1,731	1,675
Deferred revenue	473	416
Warrant liability, current	505	278
Total current liabilities	5,333	3,493
Warrant liability, long term	6,459	11,008
Deferred rent	776	724
Total liabilities	12,568	15,225
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	160,842	143,086
Accumulated deficit	(129,520)	(112,718)
Total stockholders’ equity	31,366	30,409
Total liabilities and stockholders’ equity	$ 43,934	$ 45,634