Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2016

Summary of Estimated Fair Value of Stock Option Award

The estimated fair value of each stock option award granted was determined on the date of grant using the Black Scholes option-pricing valuation model with the following weighted-average assumptions for option grants during the three and nine months ended September 30, 2016 and 2015:

	Three and Nine Months Ended September 30,
	2016		2015
Common Stock Options
Risk free interest rate	1.25% - 1.58%		l.50% - 1.87%
Expected option term	5.3 - 6.0 years		5.5 - 6.0 years
Expected volatility of common stock	74.44 - 75.91%		71.99% - 76.74%
Expected dividend yield		0.0%		0.0%

Summary of Estimated Fair Value of Employee Stock Purchase Plan Award

The estimated fair value of each ESPP award was determined on the date of grant using the Black Scholes option-pricing valuation model with the following weighted-average assumptions for option grants during the three and nine months ended September 30, 2016 and 2015:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2015		2016		2015
Employee Stock Purchase Plan
Risk free interest rate		0.47%		0.26%	0.47% - 0.50%		0.08% - 0.26%
Expected term	6 months		6 months		6 months		6 months
Expected volatility of common stock		212.80%		69.64%	83.83% - 212.80%		62.91% - 69.64%
Expected dividend yield		0.0%		0.0%		0.0%		0.0%

Summary of Recognized Non-Cash Stock-Based Compensation Expense

The Company recognized non-cash stock-based compensation expense to employees and directors in its research and development and its general and administrative functions as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2015		2016		2015
Research and development	$	177,767	$	144,719	$	487,704	$	433,252
General and administrative		274,469		226,956		810,575		694,561
Total stock-based compensation expense	$	452,236	$	371,675	$	1,298,279	$	1,127,813