Stockholders’ Equity (Tables)

6 Months Ended

Jun. 30, 2016

Stockholders' Equity

Schedule of stock-based compensation expense recognized by award type

	Three Months Ended				Six months ended
	June 30,				June 30,
	2015		2016		2015		2016
Options awards	$	1,233,950	$	618,896	$	2,561,157	$	1,659,704
Restricted stock awards		59,063		(55,781)		352,687		(167,344)
Total stock-based compensation expense	$	1,293,013	$	563,115	$	2,913,844	$	1,492,360

Schedule of total compensation cost recognized for all stock-based compensation awards in the statements of operations

	Three Months Ended				Six months ended
	June 30,				June 30,
	2015		2016		2015		2016
Research and development	$	347,281	$	27,588	$	816,959	$	64,639
General and administrative		945,732		535,527		2,096,885		1,427,721
Total stock-based compensation expense	$	1,293,013	$	563,115	$	2,913,844	$	1,492,360

Summary of activity for all options

		Weighted Average		Weighted Average	Aggregate
		Exercise Price		Contractual	Intrinsic
	Shares	Per Share		Life (In Years)	Value
Outstanding—December 31, 2015	4,020,783	$	5.48	7.8	$	—
Granted	—		—
Exercised	—		—
Forfeited	(986,145)		5.45
Outstanding—June 30, 2016	3,034,638	$	5.49	7.2	$	—
Vested and expected to vest—June 30, 2016	3,027,715	$	5.49	7.2	$	—
Exercisable at June 30, 2016	2,628,632	$	5.48	7.0	$	—

Schedule of warrants outstanding to purchase shares of the entity's common stock

		Number of
		Shares	Exercise
Warrant Series	Underlying Equity Security	Issuable	Price		Expiration Date
2007 Warrant	common stock	1,961	$	7.65	May 2017
2009/2010 Warrants	common stock	52,815	$	0.85	November 2019-March 2020