Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2016

Summary of Stock Option Activity

Stock option activity is summarized as follows:

	Number of Outstanding Options			Weighted Average Price
Balance as of December 31, 2015		2,625,280		$	8.83
Granted		1,691,619		$	6.39
Exercised		(15,045	)	$	1.27
Canceled		(479,148	)	$	11.07
Balance as of June 30, 2016		3,822,706		$	7.50

Schedule of Restricted Stock Units Activity

During the six months ended June 30, 2016, we granted restricted stock units to employees. Restricted stock unit activity is summarized as follows:

	Number of Outstanding Restricted Stock Units			Weighted Average Grant Date Fair Value
Balance as of December 31, 2015		—		$	—
Granted		128,593		$	5.00
Released		(2,080	)	$	5.48
Canceled		—		$	—
Balance as of June 30, 2016		126,513		$	4.99

Schedule of Allocation of Stock-Based Compensation for All Options Including Performance Options with Market Condition and Restricted Stock Units

The allocation of stock-based compensation for all options, including performance options with a market condition, and restricted stock units is as follows (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2016		2015		2016		2015
Research and development	$	527	$	441	$	1,074	$	796
General and administrative		846		375		1,579		623
	$	1,373	$	816	$	2,653	$	1,419

Summary of Common Stock Reserved for Future Issuance

Common stock reserved for future issuance is as follows:

	June 30, 2016		December 31, 2015
Common stock warrants		25,970		25,970
Common stock options and awards outstanding		3,949,219		2,625,280
Shares available under the 2014 Plan		984,357		984,357
Shares available under the 2015 Plan		509,089		903,350
Shares available under the 2015 ESPP Plan		433,845		227,623
		5,902,480		4,766,580

Employee Stock Option [Member]

Summary of Assumptions Used to Determine Fair Value of Employee Stock Option Grants and Performance Options with Market Condition

The assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee stock option grants were as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2016		2015		2016		2015
Expected term (in years)	5.50 – 6.08		5.77-6.08		5.50 – 6.08		5.77 – 6.08
Risk-free interest rate	1.37% – 1.55	%	1.47%-1.78	%	1.37% – 1.90	%	1.47% – 1.78	%
Expected volatility	81.49% – 82.53	%	81.60% – 88.10	%	81.15% – 82.53	%	81.60% – 100.90	%
Expected dividend yield	0.00	%	0.00	%	0.00	%	0.00	%

Performance Options with Market Condition [Member]

Summary of Assumptions Used to Determine Fair Value of Employee Stock Option Grants and Performance Options with Market Condition

The assumptions used at grant date to determine the fair value of the performance options with a market condition were as follows:

Expected term (in years)	5.06
Risk-free interest rate	2.24		%
Expected volatility	83.26		%
Expected dividend yield		0.00	%