Unaudited Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 11,771	$ 13,047
Marketable securities	2,000	7,291
Accounts receivable	406	251
Prepaid expenses and other current assets	737	365
Inventory	507	477
Total current assets	15,421	21,431
Deposits and other assets	105	105
Property and equipment, net	701	735
Total assets	16,227	22,271
Current liabilities:
Accounts payable	3,161	3,070
Accrued expenses and other current liabilities	5,322	4,666
Note payable, current portion	2,500	3,889
Total current liabilities	10,983	11,625
Notes payable, net of discount	21,577	15,177
Accrued interest	450	273
Other liabilities	59	73
Total liabilities	33,069	27,148
Commitments and contingencies (Note 6)
Stockholders' equity (deficit):
Common stock, $0.001 par value per share; 250,000,000 shares authorized, 94,098,515 and 93,569,642 shares issued and outstanding as of March 31, 2017 and December 31, 2016	94	94
Additional paid-in capital	200,859	199,751
Accumulated deficit	(217,795)	(204,722)
Total stockholders' deficit	(16,842)	(4,877)
Total liabilities and stockholders' equity (deficit)	$ 16,227	$ 22,271