Stock Based Compensation (Tables)

6 Months Ended

Jun. 30, 2014

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 the Company’s unaudited interim statements of operations:

	Three Months Ended June 30,				Six Months Ended June 30,
	2014		2013		2014		2013
Research and development — employee	$	234,484	$	53,583	$	409,638	$	103,755
General and administrative — employee		325,379		202,589		637,339		387,229
Total employee stock-based compensation	$	559,863	$	256,172	$	1,046,977	$	490,984

Research and development — non-employee	$	—	$	—	$	—	$	—
General and administrative — non-employee		160,629		152,074		352,620		179,286
Total non-employee stock-based compensation	$	160,629	$	152,074	$	352,620	$	179,286

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

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

	Six Months Ended June 30, 2014			Six Months Ended June 30, 2013
Risk-free interest rate		1.92	%		1.11	%
Expected volatility		87.0% - 89.6	%		85.2% - 85.8	%
Expected lives (years)		6 - 10			6
Expected dividend yield		0.00	%		0.00	%

Schedule of share-based compensation, stock options, activity

Presented below is the Company’s stock option activity:

	Six Months Ended June 30, 2014
	Number of Options (Employees)			Number of Options (Non-Employees)		Total Number of Options			Weighted-Average Exercise Price
Outstanding at January 1, 2014		6,228,593			167,143		6,395,736		$	3.11
Granted		300,000			—		300,000		$	5.31
Forfeited		(4,500	)		—		(4,500	)	$	2.35
Outstanding at June 30, 2014		6,524,093			167,143		6,691,236		$	3.21
Options exercisable at June 30, 2014		3,705,835			167,143		3,872,978		$	3.64

Schedule of unvested stock options activity

A summary of the unvested stock options as of June 30, 2014, and changes during the six-month period then ended, are presented below:

	Number of Options (Employees)			Number of Options (Non-Employees)		Total Number of Options			Weighted-Average Grant Date Fair Value per Share
Non-vested at January 1, 2014		3,102,873			—		3,102,873		$	1.66
Granted		300,000			—		300,000		$	3.92
Forfeited		(4,500	)		—		(4,500	)	$	1.69
Vested		(580,115	)		—		(580,115	)	$	1.74
Non-vested at June 30, 2014		2,818,258			—		2,818,258		$	1.88

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

The following table summarizes significant ranges of outstanding stock options under the Company’s plans at June 30, 2014:

Range of Exercise Prices		Number of Options		Weighted-Average Remaining Contractual Life (years)		Weighted-Average Exercise Price		Number of Options Exercisable		Weighted-Average Remaining Contractual Life (years)		Weighted-Average Exercise Price
$	1.83 - $2.50		5,126,723		8.96	$	2.22		2,649,036		8.96	$	2.16
$	2.51 – $3.50		194,482		6.46	$	2.79		154,720		6.46	$	2.69
$	3.51 – $8.00		991,534		6.54	$	6.27		690,725		6.54	$	6.70
$	8.01 – $32.55		378,497		2.63	$	8.86		378,497		2.63	$	8.86
			6,691,236		8.17	$	3.21		3,872,978		8.17	$	3.64