Stock-Based Compensation

9 Months Ended

Sep. 30, 2017

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

Stock-Based Compensation

11. Stock-Based Compensation

Stock Options

Our stock option awards generally vest over four years and typically have a contractual life of ten years. At September 30, 2017, there was $2,227,080 of unrecognized compensation cost related to stock options, which is expected to be recognized over a weighted-average period of 2.45 years. During the three and nine months ended September 30, 2017, we issued 200,060 and 200,657 shares, respectively, of common stock as a result of option exercises.

Information related to stock options outstanding at September 30, 2017 is as follows:

	Number of Stock Options		Weighted- average Exercise Price		Weighted- average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding		1,720,004	$	4.73		4.93	$	883,740
Exercisable		971,221	$	4.44		4.41	$	857,749
Expected to vest		748,783	$	5.11		5.61	$	25,991

Restricted Stock

At September 30, 2017, we had unvested restricted stock of 25,559 shares with total unrecognized compensation expense of $33,618, which we expect to recognize over a weighted average period of approximately 1.86 years. During the three and nine months ended September 30, 2017, we released 2,130 and 48,987 shares of common stock, respectively, from restriction as a result of the vesting and accelerated vesting of restricted stock.

Stock-based compensation expense

Stock-based compensation expense is classified in the accompanying condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2017 and 2016 as follows:

	Three Months Ended September 30,				Nine Months Ended  September 30,
	2017		2016		2017		2016
Research and development	$	93,821	$	62,871	$	250,061	$	215,596
General and administrative		359,216		132,185		887,064		369,189
Total	$	453,037	$	195,056	$	1,137,125	$	584,784