Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2016

Disclosure of Compensation Related Costs, Share-based 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, 2016 and 2015 are as follows:

	Three months ended March 31,
	2016			2015
Risk-free interest rates		1.39-1.90	%		1.51-1.83	%
Expected dividend yield		0.00	%		0.00	%
Expected term (in years)		6.1			6.0
Expected volatility		83.8-84.1	%		78.4-81.4	%

Summary of Stock Option Activity

The following table summarizes stock option activity for the three months ended March 31, 2016:

(In thousands, except per share amounts and years)	Shares Issuable Under Options			Weighted Average Exercise Price
Outstanding as of December 31, 2015		1,657		$	14.28
Granted		533			17.92
Exercised		—			—
Canceled		(14	)		16.46
Outstanding as of March 31, 2016		2,176		$	15.16
Options vested and expected to vest at March 31, 2016		1,837		$	14.53
Options exercisable at March 31, 2016		899		$	10.79

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, 2016 is as follows:

	Three months ended March 31,
(In thousands)	2016		2015
Research and development	$	537	$	322
General and administrative		1,104		686
	$	1,641	$	1,008