Consolidated Statements of Operations - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenue	$ 260,000	$ 475,000
Operating expenses
Research and development	5,678,000	3,992,000
General and administrative	8,413,000	6,710,000
Impairment charges	9,547,000
Total operating expenses	23,638,000	10,702,000
Loss from operations	(23,378,000)	(10,227,000)
Other income (expense)
Change in fair value of derivative liabilities	4,538,000	9,940,000
Other expenses	(554,000)	(302,000)
Total other income, net	3,984,000	9,638,000
Loss before taxes	(19,394,000)	(589,000)
Income tax benefit	556,000	73,000
Net loss	(18,838,000)	(516,000)
Excess of fair value of consideration transferred on conversion of Series B redeemable convertible preferred stock	(3,580,000)
Accretion of Series B redeemable convertible preferred stock	(1,858,000)	(10,278,000)
Net loss attributable to common stockholders	$ (24,276,000)	$ (10,794,000)
Per share information:
Net loss per share of common stock - basic & diluted	$ (2.47)	$ (1.99)
Weighted average number of shares of common stock outstanding - basic & diluted	9,838,455	5,411,204