Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2017

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Relevant Data Used to Estimate Fair Value of Stock Option Grants

The relevant data used to determine the value of the stock option grants for the three months ended March 31, 2017 and 2016 are as follows:

	Three months ended March 31,
	2017			2016
Risk-free interest rates	2.23-2.29%			1.39-1.90%
Expected dividend yield		0.00	%		0.00	%
Expected term (in years)		6.0			6.1
Expected volatility	71.0-71.6%			83.8-84.1%

Summary of Stock Option Activity

The following table summarizes stock option activity for the three months ended March 31, 2017:

(In thousands, except per share amounts)	SharesIssuable UnderOptions			WeightedAverage ExercisePrice
Outstanding as of December 31, 2016		3,268		$	14.84
Granted		280			19.74
Exercised		(59	)		9.47
Cancelled		(23	)		17.86
Outstanding as of March 31, 2017		3,466		$	16.20
Options vested and expected to vest at March 31, 2017		3,466		$	16.20
Options exercisable at March 31, 2017		1,337		$	13.28

Stock-Based Compensation Expense Related to Stock Options

The Company recorded stock-based compensation expense related to stock options for the three months ended March 31, 2017 and 2016 as follows:

	Three months ended March 31,
(In thousands)	2017		2016
Research and development	$	879	$	537
General and administrative		1,499		1,104
	$	2,378	$	1,641