Share-Based Payments (Tables)

3 Months Ended

Mar. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Stock-Based Compensation Expense

Stock-based compensation expense by award type was as follows (in thousands):

	Three Months Ended March 31,
	2018		2017
Stock options	$	375	$	187
Restricted stock	23		51
Restricted stock units	—		3
Employee stock purchase plan	3		3
	$	401	$	244

The Company allocated stock-based compensation expense as follows in the condensed consolidated statements of operations and comprehensive loss (in thousands):

	Three Months Ended March 31,
	2018		2017
Research and development expense	$	165	$	40
General and administrative expense	236		204
	$	401	$	244

Summary of Stock Option Activity and Related Information

A summary of the stock option activity is presented below:

	Shares		Weighted-Average Exercise Price
Outstanding at December 31, 2017	2,695,796		$	3.16
Granted	102,500		0.93
Exercised	—		—
Cancelled or forfeited	(150,292	)	2.20
Outstanding at March 31, 2018	2,648,004		$	3.13
Exercisable at March 31, 2018	1,580,060		$	3.79
Vested and expected to vest at March 31, 2018(1)	2,586,804		$	3.16

⁽¹⁾  Represents the number of vested stock options, plus the number of unvested stock options expected to vest. The Company adopted ASU 2016-09 as of January 1, 2017 and records forfeitures as they occur.

Summary of Restricted Stock

A summary of the restricted stock is presented below:

	Restricted Stock		Weighted-Average Grant Date Fair Value
Unvested at December 31, 2017	4,430		$	11.43
Vested	(4,430	)	11.43
Unvested at March 31, 2018	—