Stock Based Compensation (Tables)

9 Months Ended

Sep. 30, 2016

Schedule of total stock-based compensation expense from stock options and warrants

The following table sets forth the total stock-based compensation expense resulting from stock options and warrants included in our Condensed Statements of Operations:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2016			2015			2016		2015
Research and development — employee	$	455,341		$	402,292		$	1,443,347	$	1,131,072
General and administrative — employee		586,315			482,954			3,742,733		3,182,798
Total employee stock-based compensation	$	1,041,656		$	885,246		$	5,186,080	$	4,313,870

Research and development — non-employee	$	—		$	—		$	—	$	—
General and administrative — non-employee		(5,938	)		(27,647	)		214,524		206,437
Total non-employee stock-based compensation	$	(5,938	)	$	(27,647	)	$	214,524	$	206,437

Schedule of share-based payment award, fair value of the stock options granted , assumptions

The fair value of the stock options was estimated using the Black-Scholes option-pricing model, based on the following assumptions:

	Nine Months Ended September 30, 2016			Nine Months Ended September 30, 2015
Risk-free interest rate		1.72	%		2.21	%
Expected volatility		74.9	%		78.2% - 84.4	%
Expected lives (years)		6			6 - 10
Expected dividend yield		0.00	%		0.00	%

Schedule of share-based compensation, stock options, activity

Presented below is our stock option activity:

	Nine Months Ended September 30, 2016
	Number of Options (Employees)			Number of Options (Non-Employees)			Total Number of Options			Weighted-Average Exercise Price
Outstanding at January 1, 2016		13,583,862			635,714			14,219,576		$	3.10
Granted		475,000			—			475,000		$	2.05
Exercised, Forfeited or Expired		(1,221,040	)		(35,714	)		(1,256,754	)	$	3.30
Outstanding at September 30, 2016		12,837,822			600,000			13,437,822		$	3.04
Options exercisable at September 30, 2016		9,242,803			600,000			9,842,803		$	3.27

Schedule of share-based compensation, summarizes significant ranges of outstanding stock options

The following table summarizes significant ranges of outstanding stock options under our plans at September 30, 2016:

Range of Exercise Prices		Total Number of Options		Weighted-Average Remaining Contractual Life (years)		Weighted-Average Exercise Price		Total Number of Options Exercisable		Weighted-Average Remaining Contractual Life (years)		Weighted-Average Exercise Price
$	0.60 – $2.00		1,274,498		6.34	$	1.78		1,224,498		6.19	$	1.83
$	2.01 – $2.50		7,899,179		8.41	$	2.33		4,522,874		8.06	$	2.30
$	2.51 – $4.00		968,291		7.37	$	2.88		937,458		7.34	$	2.87
$	4.01 – $32.55		3,295,854		6.46	$	5.30		3,157,973		6.42	$	5.32
			13,437,822		7.66	$	3.04		9,842,803		7.23	$	3.27