Stock-based compensation (Tables)

9 Months Ended

Sep. 30, 2017

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

Summary of stock option activity

The following table summarizes stock option activity for employees and non-employees for the nine months ended September 30, 2017:

	Shares		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Outstanding at December 31, 2016	2,156,250		$	8.66	7.94	$	1,605,684
Granted	1,018,500		4.23
Exercised	(1,226	)	1.67
Cancelled or forfeited	(471,602	)	9.37
Outstanding at September 30, 2017	2,701,922		$	6.87	7.60	$	731,233
Exercisable at September 30, 2017	1,359,109		$	7.49	6.40	$	610,027
Vested or expected to vest at September 30, 2017	2,701,922		$	6.87	7.60	$	731,233

Summary of stock-based compensation expense

Total stock-based compensation expense recognized for employee and non-employee restricted common stock, and stock options granted to employees and non-employees is included in the Company's condensed consolidated statement of operations as follows:

	Three Months Ended September 30, 2017		Three Months Ended September 30, 2016		Nine Months Ended September 30, 2017		Nine Months Ended September 30, 2016
Research and development	$	386,636	$	783,603	$	1,172,655	$	2,063,764
Selling, general and administrative	618,145		1,076,985		2,094,224		3,303,306
Total	$	1,004,781	$	1,860,588	$	3,266,879	$	5,367,070