Stockholders’ Equity (Tables)

6 Months Ended

Jun. 30, 2020

Stockholders' Equity Note [Abstract]

Schedule of Stock-based Compensation Expense

Stock-based compensation is classified in the Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) as follows (in thousands): 

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
	(unaudited)
Employee:
Research and development	$	716	$	422	$	1,225	$	762
General and administrative	507		248		972		631
Non-Employee:
Research and development	7		11		18		40
General and administrative	2		1		3		3
Total stock-based compensation expense	$	1,232	$	682	$	2,218	$	1,436