Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option and PRSU Activity

The following table shows the stock option and PRSU activity, as follows:

	Shares Issuable Under Options and PRSUs			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
						(In years)		(In thousands)
Outstanding as of January 1, 2018		782,340		$	14.28		8.8	$	8.5
Granted		267,950			5.02
Exercised		(15,120	)		4.74
Forfeited / Canceled		(60,353	)		7.31
Outstanding as of December 31, 2018		974,817			12.31		8.2		—
Granted		815,400			1.75
PRSUs vested		(78,450	)		4.83
Forfeited / Canceled		(11,500	)		4.41
Outstanding as of December 31, 2019		1,700,267		$	7.64		8.2	$	—
Stock awards vested and expected to vest as of December 31, 2019		1,645,267		$	7.64		8.2	$	—
Options exercisable as of December 31, 2019		882,576		$	12.49		7.3	$	—

Schedule of Stock-Based Compensation Expense Related to Stock-Based Awards

Total compensation expense related to all of the Company’s stock-based awards for the years ended December 31, 2019 and 2018 was comprised of the following (in thousands):

	Year Ended December 31,
	2019		2018
Stock-based compensation classified as:
Research and development expense	$	343	$	249
General and administrative expense		965		1,294
Total stock-based compensation expense	$	1,308	$	1,543

Schedule of Assumptions Used in Black-Scholes Option Pricing Model to Determine the Fair Value of Stock Options Granted

The following table presents the assumptions used in the Black-Scholes option pricing model to determine the fair value of stock options granted in the periods presented, as follows:

	Year Ended December 31,
	2019	2018
Expected stock price volatility	74% - 87%	63% - 86%
Risk-free interest rate	1% - 3%	2% - 3%
Expected life of option (in years)	6	5 - 7
Estimated dividend yield	0%	0%