Stock-based Compensation (Tables)

6 Months Ended

Jun. 30, 2018

Stock-based Compensation

Summary of stock option activity

		Weighted
		average
		exercise
	Shares	price
Outstanding at January 1, 2018	976,777	$	11.97
Options granted	218,900		164.00
Options exercised	(58,170)		24.90
Options canceled	—		—
Outstanding at June 30, 2018	1,137,507	$	40.57
Exercisable at June 30, 2018	478,898	$	11.19

Schedule of stock-based compensation expense

Stock-based compensation expense during the three and six months ended June 2018 and 2017 was as follows (in thousands):

	Three Months				Six Months
	Ended June 30,				Ended June 30,
	2018		2017		2018		2017
Stock-based compensation expense by type of award:
Stock options	$	2,104	$	527	$	3,150	$	981
Restricted stock		123		149		244		297
Total stock-based compensation expense	$	2,227	$	676	$	3,394	$	1,278
Effect of stock-based compensation expense by line item:
Research and development	$	732	$	168	$	1,108	$	305
General and administrative		1,495		508		2,286		973
Total stock-based compensation expense included in net loss	$	2,227	$	676	$	3,394	$	1,278

Schedule of unrecognized stock-based compensation expense

Unrecognized stock-based compensation expense as of June 30, 2018 was as follows (in thousands):

			Weighted
	Unrecognized		average
	stock		remaining
	compensation		period
	expense		(in years)
Stock options	$	26,400	2.38
Restricted stock		520	1.06
Total	$	26,920	2.35