Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 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			—
Granted		(2,042,487	)		2,042,487			5.04
Exercised		—			(559	)		3.00
Cancelled		7,361			(7,361	)		4.66
Balance at March 31, 2017		1,876,512			8,161,858			3.21		7.8	$	43,281
Vested and exercisable at March 31, 2017					3,906,790		$	1.77		6.3	$	26,345
Vested and expected to vest at March 31, 2017					7,800,566		$	3.15		7.7	$	41,818

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:  

	Three Months Ended March 31,
	2017		2016
Expected term (in years)		6.0		6.0
Expected volatility%		67.1%		69.8%
Risk-free interest rate%		2.1%		1.5%
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 March 31,
	2017		2016
Research and development	$	165	$	121
Selling and marketing		51		24
General and administrative		553		411
Total stock-based compensation expense	$	769	$	556