Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2014

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Assumptions Used in Black-Scholes Option Pricing Model

The fair values of stock options granted during the three and six months ended June 30, 2014 were estimated as of the dates of grant using the Black-Scholes option pricing model with the following assumptions:

	Three Months Ended June 30, 2014	Six Months Ended June 30, 2014
Risk-free interest rate	1.80% - 1.99%	1.80% - 2.72%
Expected volatility	65%	65% - 71%
Expected dividend yield	0%	0%
Expected life of employee options (in years)	6.25	6.25
Expected life of nonemployee options (in years)	10	10

Summary of Compensation Expense Relating to Stock Options

During the three and six months ended June 30, 2014 and 2013, the Company recognized compensation expense relating to stock options, as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2014		2013		2014		2013
Research and development	$	159	$	23	$	231	$	31
General and administrative		297		17		578		20
Total stock option expense	$	456	$	40	$	809	$	51

Summary of Stock Option Award Activity under Stock Incentive Plans

A summary of stock option award activity under the Company’s Stock Incentive Plans as of and for the six months ended June 30, 2014 is presented below:

	Number of Shares			Weighted Average Exercise Price
Outstanding, December 31, 2013		490,160		$	1.34
Granted		614,000			12.11
Exercised		(46,000	)		0.64
Outstanding, June 30, 2014		1,058,160			7.62
Options exercisable, June 30, 2014		476,451		$	2.43