Stock-based Compensation (Tables)

3 Months Ended

Mar. 31, 2019

Stock-based Compensation

Summary of stock option activity

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

		Weighted
		average
		exercise
	Shares	price
Outstanding at January 1, 2019	1,132,618	$	48.52
Options granted	242,500		126.45
Options exercised	(8,041)		10.36
Options cancelled	—		—
Outstanding at March 31, 2019	1,367,077	$	62.57
Exercisable at March 31, 2019	673,303	$	20.31

Schedule of stock-based compensation expense

Stock-based compensation expense during the three months ended March 31, 2019 and 2018 was as follows (in thousands):

	Three Months Ended March 31,
	2019		2018
Stock-based compensation expense by type of award:
Stock options	$	5,901	$	1,046
Restricted stock		121		121
Total stock-based compensation expense	$	6,022	$	1,167
Effect of stock-based compensation expense by line item:
Research and development	$	1,877	$	376
General and administrative		4,145		791
Total stock-based compensation expense included in net loss	$	6,022	$	1,167

Schedule of unrecognized stock-based compensation expense

Unrecognized stock-based compensation expense as of March 31, 2019 was as follows (in thousands):

			Weighted
	Unrecognized		average
	stock		remaining
	compensation		period
	expense		(in years)
Stock options	$	40,286	3.16
Restricted stock		151	0.31
Total	$	40,437	3.14