Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net loss	$ (10,050,005)	$ (10,247,450)
Depreciation and amortization	341,058	243,750
Change in fair value of earn-out milestone liability	575,979	(106,028)
Deferred revenue	(250,000)	(250,000)
Stock-based compensation costs	804,592	898,520
Shares issued out of treasury		41,113
Amortization of deferred finance charges and debt discount associated with notes payable	35,370	145,586
Change in deferred rent liability	24,488	(16,716)
Loss realized on sale of investment securities		3,858
Accrued interest on short term investments	4,008	26,708
Advances, deposits and other current assets	94,461	(311,222)
Accounts payable	665,605	118,925
Accrued liabilities	428,135	458,775
Net cash (used in) operating activities:	(7,326,309)	(8,994,181)
Cash flows from investing activities:
Proceeds from sale and maturity of investment securities	1,680,000	10,799,890
Purchases of investment securities		(2,160,000)
Refund of security for letter of credit	100,000
Purchases of property and equipment	(21,126)	(42,758)
Net cash provided by investing activities	1,758,874	8,597,132
Cash flows from financing activities:
Proceeds from sale of common stock equity, net of issuance costs	4,252,948	5,430,364
Proceeds from exercise of common stock warrants, net of issuance costs	4,915,286
Principal payment and end of term charges on note payable	(2,595,923)	(1,990,670)
Net cash provided by financing activities	6,572,311	3,439,694
Increase in cash and cash equivalents	1,004,876	3,042,645
Cash and cash equivalents at beginning of period	2,624,162	9,265,144
Cash and cash equivalents at end of period	3,629,038	12,307,789
Supplemental disclosures of cash flow information:
Interest paid	$ 56,386	$ 301,996