Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2015

Loss Per Share of Common Stock

Schedule of computation of diluted net loss per share

	Year Ended December 31,
	2014		2015
Numerator:
Net loss	$	(35,958,979)	$	(49,724,054)
Less: income from change in fair value of warrant liability		(418,198)		(191,150)
Numerator for diluted net loss per common share	$	(36,377,177)	$	(49,915,204)
Denominator:
Basic weighted average common shares outstanding		22,290,069		23,692,327
Dilutive common shares from assumed warrant exercises		61,620		38,048
Diluted weighted average shares of common stock outstanding		22,351,689		23,730,375
Diluted net loss per share of common stock	$	(1.63)	$	(2.10)

Schedule of potentially dilutive securities outstanding that have been excluded from the computation of diluted weighted average shares outstanding, as they would be antidilutive

	December 31,
	2014	2015
Warrants	23,747	23,747
Stock options	3,270,363	3,649,046
Common shares issuable upon conversion of the 8% Notes	7,137,031	8,058,271
	10,431,141	11,731,064