Equity Incentive Plans (Tables)

3 Months Ended

Mar. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity

The following table summarizes stock option activity during the three months ended March 31, 2019:

	Shares Subject to Options Outstanding					Weighted- Average
				Weighted-		Remaining
				Average Exercise		Contractual Life		Aggregate
	Shares			Price		(Years)		Intrinsic Value
								(in thousands)
Outstanding as of December 31, 2018		5,107,329		$	7.51		9.7	$	16,343
Options granted		2,390,144		$	21.74
Option exercised		(27,500	)	$	2.61
Options forfeited/cancelled		—
Outstanding as of March 31, 2019		7,469,973		$	12.08		9.6	$	72,708
Options vested and exercisable as of March 31, 2019		160,682		$	3.20		8.9	$	2,968

Summary of Restricted Stock Activity

The summary of the Company’s restricted stock activity is as follows:

	Number of			Weighted-
	Restricted			Average
	Stock Units			Grant Date
	Outstanding			Fair Value
Nonvested at December 31, 2018		7,482,032		$	4.01
Granted		—			—
Vested		(1,619,592	)	$	4.31
Forfeited		—			—
Nonvested at March 31, 2019		5,862,440		$	3.92

Stock-Based Compensation Expense Reported in Condensed Consolidated Statements of Operations

Stock-based compensation expense has been reported in the Company’s condensed consolidated statements of operations as follows (in thousands):

	Three months ended
	March 31,
	2019		2018
Research and development	$	1,293	$	4
General and administrative		1,796		601
Total stock-based compensation	$	3,089	$	605