Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2015

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation Expense

Our stock-based compensation expense for the three and six months ended June 30 was as follows:

	Three months ended						Six months ended
	June 30,						June 30,
	2015			2014			2015			2014
Research and development expense	$	698,039		$	39,596		$	1,281,708		$	225,889
General and administrative expense		653,535			474,064			1,378,760			808,877
Total stock-based compensation	$	1,351,574		$	513,660		$	2,660,468		$	1,034,766
Effect on basic and diluted net loss per share	$	(0.01	)	$	(0.01	)	$	(0.03	)	$	(0.02	)

Stock Option Activity

A summary of our stock option activity for the three months ended June 30, 2015 is as follows:

	Number of options			Weighted-average exercise price ($) per share
Outstanding options at March 31, 2015		276,229			18.66
Granted (1)		2,490,000			0.70
Exercised		—			—
Cancelled		(1,000	)		32.40
Outstanding options at June 30, 2015		2,765,229			2.49

Summary of Changes in Unvested Options

A summary of changes in unvested options for the three months ended June 30, 2015 is as follows:

	Number of options		Weighted-average exercise price ($) per share		Weighted-average grant date fair value ($) per option
Unvested options at March 31, 2015		—		—		—
Granted		2,490,000		0.70		0.46
Vested		—		—		—
Cancelled		—		—		—
Unvested options at June 30, 2015		2,490,000		0.70		0.46

Summary of Changes in Restricted Stock Unit Activity

A summary of changes in our restricted stock units for the three months ended June 30, 2015 is as follows:

	Number of RSUs			Weighted Average Grant Date Fair Value ($)
Outstanding at March 31, 2015		9,984,518			1.25
Granted (1)		150,000			0.71
Vested and exercised		(597,500	)		1.70
Cancelled		(178,500	)		1.27
Outstanding at June 30, 2015		9,358,518			1.22

(1) These stock awards are performance based and vest on achievement of predefined milestones.