Stock-based Compensation (Tables)

3 Months Ended

Mar. 31, 2019

Share-based Payment Arrangement [Abstract]

Schedule of fair value of options granted

The weighted-average assumptions used in the Black-Scholes option-pricing model used to calculate the fair value of options granted during the three months ended March 31, 2019, were as follows:

	Employee			Non-Employee
Expected volatility		80.6	%		N/A
Expected dividend yield		—			N/A
Expected term (in years)		3.0			N/A
Risk-free interest rate		2.48	%		N/A

Schedule of stock option activity

The following table summarizes the stock option activity, for both equity plans, for the periods indicated as follows:

	Number of Options			Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Term (years)		Aggregate Intrinsic Value (1)
Outstanding at December 31, 2018		1,721,171		$	1.57		4.0	$	—
Granted		8,218		$	0.854		4.9	$	3
Exercised		(54,000	)	$	0.50		—	$	—
Forfeited		(39,500	)	$	—		—	$	—
Expired		—		$	—		—	$	—
Outstanding at March 31, 2019		1,635,889		$	1.54		3.8	$	—
Exercisable at March 31, 2019		1,416,500		$	1.57		3.0	$	—

(1) The aggregate intrinsic value in the table was calculated based on the difference between the estimated fair market value of the Company’s stock and the exercise price of the underlying options. The estimated stock values used in the calculation was $1.22 and $0.59 per share for the three months ended March 31, 2019 and the year ended December 31, 2018, respectively.

Schedule of summarizes restricted stock unit activity

The following table summarizes restricted stock unit activity for the three months ended March 31, 2019:

	Number of Units			Weighted Average Grant-Date Fair Value Per Unit
Outstanding as of December 31, 2018		136,245		$	0.98
Granted		6,262		$	0.854
Vested		(36,666	)(1)	$	0.50
Forfeited		—		$	—
Outstanding as of March 31, 2019		105,841		$	1.26

(1) These shares vested on March 30, 2019 (Saturday) and were issued on Monday, April 1, 2019.

Schedule of stock-based compensation expense

The stock-based compensation expense was recorded as follows:

	Three Months Ended March 31,
	2019		2018
Research and development	$	9	$	29
Selling, general and administrative		243		669
Total stock-based compensation expense	$	252	$	698