Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2019

Stock-Based Compensation

Schedule of stock-based compensation expense attributable to share-based payments made to employees and directors and included in operating expenses

	Three Months Ended				Six Months Ended
	June 30,				June 30,
(in thousands)	2019		2018		2019		2018
Stock-based compensation:
Research and development
Employee Stock Purchase Plan	$	12	$	29	$	18	$	51
Equity Incentive Plan		320		520		650		1,076
	$	332	$	549	$	668	$	1,127
General and administrative
Employee Stock Purchase Plan	$	8	$	18	$	14	$	32
Equity Incentive Plan		549		971		1,223		1,968
	$	557	$	989	$	1,237	$	2,000
Total stock-based compensation expense	$	889	$	1,538	$	1,905	$	3,127

Schedule of weighted average assumptions applied to options

	Six Months Ended
	June 30,
	2019		2018
Average risk-free interest rate		2.3%		2.2%
Expected dividend yield		—		—
Expected lives (years)		4.0		3.9
Expected volatility		82.8%		75.6%
Weighted average exercise price (per share)	$	3.02	$	17.42

Schedule of information related to outstanding and exercisable options

($ in thousands, except per share data)	Stock Options	Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Life (in years)	Aggregate Intrinsic Value
Outstanding at December 31, 2018	3,304,531	$	18.42	6.6	$	—
Granted	610,002		3.02
Exercised	—		—
Forfeited	(60,595)		13.36
Expired	(9,561)		40.42
Outstanding at June 30, 2019 (1)	3,844,377	$	15.99	6.6	$	9
Exercisable at June 30, 2019	2,217,289	$	21.36	4.9	$	—

(1) Includes both vested stock options as well as unvested stock options for which the requisite service period has not been rendered but that are expected to vest based on achievement of a service condition.

Schedule of summary of restricted stock activity

($ in thousands, except per share data)	Number of Shares	Weighted-Average Grant Date Fair Value
Nonvested shares at December 31, 2018	—	$	—
Granted	194,550		3.14
Cancelled	(925)		3.14
Vested	—		—
Nonvested shares at June 30, 2019	193,625	$	3.14