Stockholders' Equity (Tables)

Share-based compensation expense included in the statements of operations for the three and nine months ended September 30, 2015 and 2014 was as follows:

	Three Months Ended September 30,
	2015		2014

Research and development expenses	$	385,153	$	245,000
General and administrative expenses		420,079		411,947
Total	$	805,232	$	656,947

	Nine Months Ended September 30,
	2015		2014

Research and development costs	$	957,907	$	723,558
General and administrative expenses		1,163,142		2,915,414
Total	$	2,121,049	$	3,638,972

A summary of stock option activity during the nine months ended September 30, 2015 and related information is included in the table below:

	Number of Options		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (in years)		Aggregate Intrinsic Value

Outstanding at January 1, 2015		18,986,395	$	1.89		5.1	$	20,306,807
Granted		765,549	$	3.09
Exercised		(1,031,774)	$	0.54			$	68,400
Forfeited		(1,233,890)	$	0.83
Outstanding at September 30, 2015		17,486,280	$	2.10		5.1	$	1,897,315

Exercisable at September 30, 2015		14,240,432	$	2.21		4.6	$	1,277,927

Vested and expected to vest		17,481,198	$	2.10		4.8	$	1,897,315

Range of Exercise Prices	Number of Options Outstanding		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (in years)		Aggregate Intrinsic Value
$0.50 - $1.00		5,000,000	$	0.92		6.8	$	1,500,000
$1.01 - $2.00		4,325,984	$	1.23		6.1		397,315
$2.01 - $3.00		2,122,669	$	2.50		4.0
$3.01 - $5.00		6,037,627	$	3.57		3.4
		17,486,280	$	2.10		5.1	$	1,897,315

The Company uses the Black-Scholes option pricing model for “plain vanilla” options and other pricing models as appropriate to calculate the fair value of options. Significant assumptions used in these models include:

	Nine Months Ended September 30,
	2015	2014

Annual dividend	-	-
Expected life (in years)	4.0-6.0	4.0 - 8.5
Risk free interest rate	1.39%-1.78%	1.12% - 2.50%
Expected volatility	68.6% - 71.8%	68.8% - 100.0%

A summary of warrant activity for the nine months ended September 30, 2015 follows:

	Number of Warrants		Weighted- Average Exercised Price		Weighted- Average Remaining Contractual Life (in years)		Aggregate Intrinsic Value

Outstanding at January 1, 2015		21,422,346	$	2.30		3.8	$	15,984,739
Granted		150,000	$	1.87		4.8
Exercised		(1,724,606)	$	1.94
Forfeited		(24,794)	$	2.13
Outstanding at September 30, 2015		19,822,946	$	2.33		3.3	$	1,271,994

Exercisable at September 30, 2015		19,710,446	$	2.33		3.3	$	1,271,994

A summary of our restricted stock unit activity for the nine months ended September 30, 2015 is as follows:

	Number of RSU's		Weighted- Average Grant Date Fair Value

Outstanding at January 1, 2015		447,275	$	2.18
Granted		-
Vested and converted to common shares		-
Forfeited		-
Outstanding at September 30, 2015		447,275	$	2.18

Exercisable at September 30, 2015		447,275	$	2.18

A summary of our restricted stock activity for the nine months ended September 30, 2015 is as follows:

	Number of RS		Weighted- Average Grant Date Fair Value

Granted		427,808
Converted to common shares		(106,952)
Forfeited		-
Outstanding at September 30, 2015		320,856	$	1.87