Consolidated Statements of Cash Flows - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating activities:
Net loss	$ (3,246,000)	$ (3,112,000)
Adjustments required to reconcile net loss to net cash used in operating activities:
Change in fair value of derivative liabilities	(114,000)	(1,406,000)
Stock-based compensation	171,000	816,000
Non-cash interest expense	7,000
Warrants expensed to in-process research and development		204,000
Amortization of patents	8,000	8,000
Depreciation	85,000	73,000
Other non-cash adjustments	3,000
Changes in operating assets and liabilities:
Accounts receivable, net	10,000	111,000
Accounts payable, accrued expenses, deferred revenue and other	(520,000)	507,000
Accrued severance	(11,000)	(241,000)
Prepaid expenses and other current assets	308,000	(45,000)
Net cash used in operating activities	(3,299,000)	(3,085,000)
Investing activities:
Purchases of property and equipment	(5,000)	(112,000)
Net cash used in investing activities	(5,000)	(112,000)
Financing activities:
Principal payment on note payable	(205,000)
Net cash used in financing activities	(205,000)
Net decrease in cash and cash equivalents	(3,509,000)	(3,197,000)
Cash and cash equivalents, beginning of period	5,711,000	9,370,000
Cash and cash equivalents, end of period	$ 2,202,000	6,173,000
Supplemental schedule of non-cash financing activities:
Accretion of Series B redeemable convertible preferred stock		$ 1,725,000