Stock Incentive Plans (Tables)

6 Months Ended

Jun. 30, 2016

Summary of Option Activity and Related Information

The following table summarizes option activity and related information:

	Shares Underlying Stock Options Outstanding			Weighted- average Exercise Price
Balance—December 31, 2015		1,577,317		$	6.87
Granted		474,045			5.01
Exercised		(2,770	)		3.14
Forfeited		(205,049	)		6.94
Expired		(1,433	)		11.59
Balance—June 30, 2016		1,842,110			6.38

Summary of Options Outstanding and Exercisable Vested or Expected to Vest

Options outstanding that have vested or are expected to vest as of June 30, 2016 are as follows:

	Number of SharesIssued		WeightedAverage Exercise Price		WeightedAverage Contractual Life (Years)		Aggregate IntrinsicValue (InThousands)
Vested		926,702	$	6.17		6.70	$	977
Expected to vest		781,850		6.59		8.99		35
Total		1,708,552		6.37		7.75	$	1,012

Summary of Unvested RSU Activity

Unvested RSU activity for the six months ended June 30, 2016 is summarized below:

	Number of Shares			Weighted- Average Grant Date Fair Value
Unvested balance—December 31, 2015		106,200		$	6.49
Granted		111,900			5.12
Vested		(26,550	)		6.49
Forfeited		(47,105	)		5.88
Unvested balance—June 30, 2016		144,445			5.63

Summary of Shares Available for Grant

The following table summarizes shares available for grant under the 2014 Plan:

	Shares Available for Grant
Balance—December 31, 2015		404,692
Additional shares authorized for options and RSUs		357,075
Options granted		(474,045	)
Options forfeited		205,049
Options expired		1,433
RSUs granted		(111,900	)
RSUs forfeited		47,105
Balance—June 30, 2016		429,409

Weighted-Average Assumptions Used to Estimated Fair Value of Share-Based Awards

The estimated fair values of employee stock options and ESPP shares were estimated using the Black-Scholes option-pricing model based on the following weighted-average assumptions:

	Three Months Ended June 30,						Six Months Ended June 30,
	2016			2015			2016			2015
Employee stock options
Expected term (in years)	5.3‒ 6.0				5.8		5.3‒ 6.0				6.0
Expected volatility	45.94 – 46.44%				40.04	%	39.60 – 46.44%				40.85	%
Risk-free interest rate	1.13 – 1.52%				1.69	%	1.13 – 1.65%				1.87	%
Expected dividend yield		—	%		—	%		—	%		—	%
Employee stock purchase plan
Expected term (in years)		0.5			0.5			0.5			0.5
Expected volatility		64.21	%		34.08	%		64.21	%		34.08	%
Risk-free interest rate		0.49	%		0.11	%		0.49	%		0.11	%
Expected dividend yield		—	%		—	%		—	%		—	%

Summary of Expense Relating to Employee and Nonemployee Stock-Based Payment Awards from Stock Options and RSUs

Stock-based Compensation Expense

The following table summarizes stock-based compensation expense relating to employee and nonemployee stock options, RSUs, and ESPP shares for the three and six months ended June 30, 2016 and 2015, included in the statements of operations as follows (in thousands): 

	Three Months Ended June 30,				Six Months Ended June 30,
	2016		2015		2016		2015
Cost of testing	$	38	$	54	$	66	$	69
Research and development		100		89		213		136
Sales and marketing		43		36		71		56
General and administrative		186		232		462		431
Total	$	367	$	411	$	812	$	692

2016 Inducement Plan [Member]

Summary of Unvested RSU Activity

Unvested RSU activity for the six months ended June 30, 2016 is summarized below:

	Number of Shares		Weighted- Average Grant Date Fair Value
Unvested balance—December 31, 2015		—	$	—
Granted		141,000		5.93
Vested		—		—
Forfeited		—		—
Unvested balance—June 30, 2016		141,000		5.93

Summary of Shares Available for Grant

The following table summarizes shares available for grant under the Inducement Plan:

	Shares Available for Grant
Balance—December 31, 2015		—
Additional shares authorized for options and RSUs		155,500
RSUs granted		(141,000	)
RSUs forfeited		—
Balance—June 30, 2016		14,500