Stock-based Compensation (Tables)

6 Months Ended

Jun. 30, 2020

Stock-based Compensation

Summary of stock-based compensation expense

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
	(in thousands)				(in thousands)
Employee awards:
Research and development expense	$	1,042	$	792	$	1,922	$	1,500
General and administrative expense		1,561		1,257		3,062		2,372
Total stock-based compensation expense	$	2,603	$	2,049	$	4,984	$	3,872