Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2019

Equity [Abstract]

Summary of Stock Based Compensation Expense

Stock compensation expense was allocated between departments in continuing operations as follows (in thousands).

	Three Months Ended March 31,
	2019		2018
Research and development	$	53	$	105
General and administrative		149		235
Total	$	202	$	340

Schedule of Fair Value of Award Granted Using Black-Scholes Option Pricing Model

The fair value of each award granted was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions

	Three Months Ended March 31,
	2019	2018
Expected life (years)	6.0-6.1	6.0
Risk-free interest rate	2.6%	2.7%
Volatility	71%	70%
Dividend rate	—  %	—  %

Summary of Stock Option Transactions

The following table summarizes stock option transactions for the three months ended March 31, 2019 as issued under the Plans:

	Shares Available			Number of Options			Weighted- Average Exercise Price per		Weighted Average Remaining Contractual Term
	for Grant			Outstanding			Share		(in years)
Balance at December 31, 2018		1,150,961			1,667,153		$	6.03		8.27
Additional shares authorized		223,742
Options granted		(464,000	)		464,000		$	1.67
Options exercised		—			—			—		—
Options canceled/forfeited		15,046			(15,046	)	$	8.83		—
Balance at March 31, 2019		925,749			2,116,107		$	5.05		8.43
Options vested at March 31, 2019					901,140		$	9.14		7.52
Options vested and expected to vest at March 31, 2019					2,116,107		$	5.05		8.43