Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2019

Stock-Based Compensation

Summary of Stock-Based Compensation Expense Recognized

The following table presents stock-based compensation expense recognized for stock options, restricted stock units, or RSUs, performance-based restricted stock units, or PRSUs, and the Company’s employee stock purchase program, or ESPP, in the Company’s statements of operations (in thousands):

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2019		2018		2019		2018
Research and development	$	1,670	$	880	$	3,197	$	2,770
General and administrative		2,209		1,068		4,527		4,206
Total	$	3,879	$	1,948	$	7,724	$	6,976

Summary of Total Unrecognized Stock-Based Compensation Expense, Net of Estimated Forfeitures

	At September 30, 2019
	Unrecognized Compensation Expense		Average Vesting Period
	($ thousands)		(Years)
Stock options grants	$	9,677	2.6
RSU grants		—	—
PRSU grants		1,391	0.9
ESPP		132	0.4