Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net loss	$ (15,721,334)	$ (16,657,137)
Non-cash items included in net loss:
Depreciation and amortization	511,587	365,625
Change in fair value of earn-out milestone liability	(670,172)	556,382
Impairment of in-process research and development	2,520,000
Deferred revenue	(375,000)	(375,000)
Stock-based compensation costs	951,488	1,331,094
Shares issued out of treasury		79,238
Amortization of deferred finance charges and debt discount associated with notes payable	35,370	198,806
Change in deferred rent liability	61,328	(25,981)
Loss realized on sale of investment securities		3,858
Net changes in:
Accrued interest on short term investments	4,008	22,205
Advances, deposits and other current assets	115,106	(136,871)
Accounts payable	(72,777)	195,716
Accrued liabilities	207,217	725,660
Net cash (used in) operating activities:	(12,433,179)	(13,716,405)
Cash flows from investing activities:
Proceeds from sale and maturity of investment securities	1,680,000	10,800,000
Purchases of investment securities		(4,515,125)
Refund of security for letter of credit	100,000
Purchases of property and equipment	(21,126)	(48,928)
Net cash provided by investing activities	1,758,874	6,235,947
Cash flows from financing activities:
Proceeds from sale of common stock equity, net of issuance costs	8,405,190	5,428,965
Proceeds from exercise of common stock warrants, net of issuance costs	4,925,886
Principal payment and end of term charges on note payable	(2,595,923)	(3,029,429)
Net cash provided by financing activities	10,735,153	2,399,536
Increase (decrease) in cash and cash equivalents	60,848	(5,080,922)
Cash and cash equivalents at beginning of period	2,624,162	9,265,144
Cash and cash equivalents at end of period	2,685,010	4,184,222
Supplemental disclosures of cash flow information:
Interest paid	$ 56,386	$ 409,996