Share-Based Compensation - (Tables)

3 Months Ended

Mar. 31, 2020

Share-based Payment Arrangement [Abstract]

Schedule of Allocation of Share-based Compensation Costs by Award Type

Share-based compensation expense, net of estimated forfeitures, includes expenses related to stock options and RSUs granted to employees, non-employee directors and consultants, as well as options granted to employees to purchase shares under the ESPP. Stock-based compensation by award type was as follows:

	Three Months Ended March 31,
	2020		2019
Stock options	$	1,374	$	1,622
Restricted stock units	936		821
Employee stock purchase plan	14		27
Total	$	2,324	$	2,470

Schedule of Allocation of Share-based Compensation Costs by Financial Statement Line

The Company allocated stock-based compensation expense in the Company’s Consolidated Statements of Operations and Comprehensive Loss as follows:

	Three Months Ended March 31,
	2020		2019
Research and development	$	1,153	$	1,170
General and administrative	1,171		1,300
Total	$	2,324	$	2,470

Summary of the stock option activity including weighted average exercise prices, options outstanding and exercisable

A summary of the stock option activity, weighted average exercise prices, options outstanding, exercisable and expected to vest as of March 31, 2020 is as follows (in thousands except weighted average exercise price):

	Number of Shares Underlying Options		Weighted Average Exercise Price
Outstanding, December 31, 2019	6,780		$	10.89
Granted	105		$	6.58
Exercised	(49	)	$	2.78
Forfeited	(201	)	$	17.36
Outstanding, March 31, 2020	6,635		$	10.69
Vested and exercisable, March 31, 2020	3,482		$	17.07
Vested and expected to vest, March 31, 2020	6,383		$	10.97

Summary of the Company's outstanding shares of RSU awards

The following table presents a summary of the Company's outstanding RSU awards granted as of March 31, 2020 (in thousands except weighted average grant-date fair value):

	Restricted Stock Units		Weighted Average Grant-Date Fair Value
Outstanding, December 31, 2019	1,481		$	7.79
Awarded	19		$	6.35
Vested	(12	)	$	72.92
Forfeited	(87	)	$	4.79
Outstanding, March 31, 2020	1,401		$	7.40
Outstanding, Expected to vest	1,228		$	4.89