Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 33,458	$ 13,047
Marketable securities	7,972	7,291
Accounts receivable	800	251
Prepaid expenses and other current assets	562	365
Inventory, net	3,383	477
Total current assets	46,175	21,431
Deposits and other assets	141	105
Property and equipment, net	839	735
Total assets	47,155	22,271
Current liabilities:
Accounts payable	2,982	3,070
Accrued expenses and other current liabilities	7,262	4,666
Note payable, current portion	5,000	3,889
Total current liabilities	15,244	11,625
Notes payable, net of discount	19,188	15,177
Accrued interest	631	273
Other liabilities	64	73
Total liabilities	35,127	27,148
Commitments and contingencies (Note 7)
Stockholders' equity (deficit):
Common stock, $0.001 par value per share; 250,000,000 shares authorized, 123,186,466 and 93,569,642 shares issued and outstanding as of June 30, 2017 and December 31, 2016	123	94
Additional paid-in capital	242,074	199,751
Accumulated deficit	(230,169)	(204,722)
Total stockholders' equity (deficit)	12,028	(4,877)
Total liabilities and stockholders' equity (deficit)	$ 47,155	$ 22,271