Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2020

Share-based Payment Arrangement [Abstract]

Summary of Stock-based Compensation Expense

Stock-based compensation expense included in the Company’s condensed consolidated statements of operations and comprehensive loss is as follows (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
General and administrative	$	1,010	$	1,162	$	1,899	$	2,224
Research and development	1,083		973		2,149		1,864
Total stock-based compensation expense	$	2,093	$	2,135	$	4,048	$	4,088

Summary of Stock Option Activity

A summary of the Company’s stock option activity and related information is as follows: 

	Shares	Weighted- Average Exercise Price
Options outstanding at December 31, 2019	5,691,474	$	6.99
Granted	1,616,718	6.51
Exercised	(141,157)	1.67
Canceled	(781,463)	9.85
Options outstanding at June 30, 2020	6,385,572	$	6.63
Exercisable as of June 30, 2020	3,035,054	$	5.12