Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2017

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Stock-Based Compensation Expense Related to Options Granted to Employees and Consultants

The following table sets forth stock-based compensation expense related to options granted to employees and consultants for all periods presented (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2017		2016		2017		2016
Research and development	$	610	$	247	$	1,200	$	421
General and administrative		731		357		1,546		597
Total	$	1,341	$	604	$	2,746	$	1,018

Summary of Stock Option Activity Under Plans

The following summarizes option activity under the 2012 Equity Incentive Plan and 2015 Stock Option and Incentive Plan:

	Shares Subject to			Weighted Average
	Outstanding Options			Exercise Price Per Share
Balance at December 31, 2016		2,141,868		$	6.42
Options granted		1,340,475		$	12.49
Options exercised		(15,281	)	$	1.66
Options canceled		(134,920	)	$	10.01
Balance at June 30, 2017		3,332,142		$	8.74