Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2018

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 March 31,
	2018		2017
Research and development	$	1,591	$	590
General and administrative		2,040		815
Total	$	3,631	$	1,405

Summary of Stock Option and Other Equity Award Activity Under Plans

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

	Shares Subject to			Weighted Average
	Outstanding Options and Awards			Exercise Price per Share
Balance at December 31, 2017		2,964,549		$	11.54
Options and awards granted		991,932			52.05
Options exercised		(110,961	)		7.26
Options and awards canceled		(52,156	)		19.13
Balance at March 31, 2018		3,793,364			22.15