Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2017

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Company's Stock Option Activity and Related Information

A summary of the Company’s stock option activity and related information is as follows:

				Options Outstanding
	Shares Available for Grant			Number of Stock Options Outstanding			Weighted- Average Exercise Price		Weighted- Average Remaining ContractualLife (Years)		Aggregate Intrinsic Value
											(In thousands)
Balance at December 31, 2016		2,168,391			6,127,291		$	2.60		7.3	$	7,800
Additional options authorized		1,743,247			-
Options granted		(2,352,187	)		2,352,187			5.18
Options exercised		-			(294,801	)		0.84
Options canceled		79,025			(79,025	)		3.65
Balance at September 30, 2017		1,638,476			8,105,652		$	3.40		7.5	$	19,381
Vested and exercisable at September 30, 2017					4,543,819		$	2.29		6.4	$	15,878
Vested and expected to vest at September 30, 2017					7,810,868		$	3.35		7.5	$	19,077

Schedule of Weighted-Average Assumptions Used in Black-Scholes Option-Pricing Model to Estimate Fair Value of Employee Stock Option at Grant Date

The fair value of employee stock option was estimated at the date of grant using a Black-Scholes option-pricing model with the following weighted-average assumptions:  

	Nine Months Ended September 30,
	2017		2016
Expected term (in years)		6.0		6.0
Expected volatility%		66.9%		59.9%
Risk-free interest rate%		2.1%		1.3%
Expected dividend yield%		0.0%		0.0%

Summary of Stock-Based Compensation Expense

Total stock-based compensation expense recognized in the Company’s condensed consolidated statements of operations is classified as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Research and development	$	221	$	111	$	602	$	467
Selling and marketing		70		40		193		78
General and administrative		693		803		1,971		1,654
Total stock-based compensation expense	$	984	$	954	$	2,766	$	2,199