Stock-Based Compensation Expense (Tables)

9 Months Ended

Sep. 30, 2015

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

The following table summarizes stock option activity under the Company’s stock-based compensation plan during the nine months ended September 30, 2015:

	Number of Options			Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Life (in Years)		Weighted- Average Grant Date Fair Value
Outstanding at December 31, 2014		1,110,744		$	4.59		8.72
Granted		761,382		$	15.08			$	10.95
Options assumed in the Merger		551,363		$	30.11
Exercised		(32,874	)	$	3.51
Canceled		(16,619	)	$	20.30
Outstanding at September 30, 2015		2,373,996		$	14.00		8.51
Vested and expected to vest at September 30, 2015		2,310,312		$	14.08
Vested and exercisable at September 30, 2015		1,090,000		$	17.77

Summary of Stock-Based Compensation Expense

Stock-based compensation expense related to options granted was recorded as follows (in thousands):

	Three Months Ended September 30,					Nine Months Ended September 30,
	2015		2014			2015		2014
Research and development	$	240	$	31		$	375	$	121
General and administrative		620		(712	)		1,099		407
Total	$	860	$	(681	)	$	1,474	$	528