Stock-based compensation (Tables)

6 Months Ended

Jun. 30, 2016

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 six months ended June 30, 2016:

	Shares		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Outstanding at December 31, 2015	1,824,973		$	8.34
Granted	699,820		9.94
Exercised	(6,401	)	1.26
Cancelled or forfeited	(93,375	)	12.94
Outstanding at June 30, 2016	2,425,017		$	8.64	8.87	$	6,528,784
Exercisable at June 30, 2016	605,959		$	7.09	8.24	$	2,864,265
Vested or expected to vest at June 30, 2016	2,115,540		$	8.55	8.37	$	6,034,998

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 June 30, 2016		Three Months Ended June 30, 2015		Six Months Ended June 30, 2016		Six Months Ended June 30, 2015
Research and development	$	684,695	$	855,083	$	1,280,161	$	1,812,293
Selling, general and administrative	1,303,626		785,476		2,226,321		1,574,026
Total	$	1,988,321	$	1,640,559	$	3,506,482	$	3,386,319