Share-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2014

Summary of Share-Based Compensation Expense

The following table summarizes share-based compensation expense for the periods presented (in thousands):



	Three Months Ended June 30,				Six Months Ended June 30,
	2014		2013		2014		2013
Research and development⁽¹⁾	$	566	$	226	$	1,049	$	305
General and administrative	872		516		1,732		777
Total	$	1,438	$	742	$	2,781	$	1,082

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⁽¹⁾	Includes $26,000 and $63,000 for the three months ended June 30, 2014 and 2013, respectively, and $72,000 and $63,000 for the six months ended June 30, 2014 and 2013, respectively, of share-based compensation expense related to options granted to a consultant.

Amended and Restated 2012 Long Term Incentive Plan

Fair Value of Options Granted

The fair value of the options granted to employees and non-employee directors during the three and six months ended June 30, 2014 and 2013 is estimated as of the grant date using the Black-Scholes option-pricing model assuming the weighted-average assumptions listed in the following table:



	Three Months Ended June 30,		Six Months Ended June 30,
	2014	2013	2014	2013
Expected volatility	86.0%	84.5%	84.3%	84.2%
Risk-free interest rate	1.9%	1.7%	1.8%	1.2%
Expected dividend yield	—%	—%	—%	—%
Expected life (in years)	6.0	6.0	6.0	6.0
Weighted average grant date fair value	$17.66	$5.28	$20.40	$4.56

Summary of Company's Share Option Activity

The following table summarizes the Company’s share option activity during the six months ended June 30, 2014:



	Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2013	1,973,500		$	7.50	9.17	$	37,528
Granted	663,000		28.63
Exercised	(57,176	)	6.87
Canceled	—		—
Outstanding at June 30, 2014	2,579,324		$	12.95	8.93	$	28,937
Vested and expected to vest at June 30, 2014	2,491,212		$	12.74	8.92	$	28,341
Vested at June 30, 2014	747,871		$	6.48	8.63	$	12,015

Summary of stock activity by exercise price

The following table summarizes information about the Company's share options outstanding as of June 30, 2014:



				Options Outstanding				Options Exercisable
Range of Exercise Prices				Number of Options	Weighted - Average Remaining Contractual Life (Years)	Weighted Average Exercise Price		Number of Options	Weighted Average Exercise Price
$	6.03	$	6.03	453,375	8.58	$	6.03	159,843	$	6.03
6.41		6.41		808,949	8.58	6.41		391,208	6.41
6.65		6.65		50,000	8.72	6.65		50,000	6.65
6.73		6.73		366,000	8.75	6.73		126,603	6.73
8.21		20.53		232,000	9.12	14.94		20,217	9.55
22.14		22.14		100,000	9.84	22.14		—	—
24.26		24.26		30,000	9.34	24.26		—	—
29.52		29.52		25,000	9.59	29.52		—	—
29.81		29.81		484,000	9.60	29.81		—	—
37.02		37.02		30,000	9.75	37.02		—	—
$	6.03	$	37.02	2,579,324	8.93	$	12.95	747,871	$	6.48