STOCK-BASED COMPENSATION (Tables)

6 Months Ended

Jun. 30, 2018

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

Schedule of fair values of stock options granted, estimated using Black-Scholes option valuation model assumptions

We estimated the fair value of stock options awarded during the six months ended June 30, 2017 and 2018 using the Black-Scholes option valuation model. The fair values of stock options granted for the periods were estimated using the following assumptions: 

	Stock Option Grants Awarded During the Six Months Ended June 30, 2017	Stock Option Grants Awarded During the Six Months Ended June 30, 2018
Stock Price	$4.36 to $4.68	$4.12 to $5.96
Dividend Yield	0.00%	0.00%
Expected Volatility	60%	70%
Risk-free interest rate	1.98% - 2.14%	2.50% - 2.89%
Expected Life	7 years	7 years

Summary of stock option activity

The following is a summary of our stock option activity during the six months ended June 30, 2018: 

	Number of Options		Weighted Average Exercise Price		Weighted Average Grant Date Fair Value		Weighted Average Remaining Life In Years
Outstanding, January 1, 2018	1,082,490		$	4.87	$	3.00	8.38
Granted	117,500		4.93		3.34		9.00
Exercised	(4,692	)	2.91		1.75		—
Canceled / Forfeited	(65,645	)	4.72		2.89		—
Outstanding, June 30, 2018	1,129,653		$	4.89	$	3.05	8.02

	Number of Options		Weighted Average Exercise Price		Weighted Average Grant Date Fair Value		Weighted Average Remaining Life In Years
Exercisable, January 1, 2018	704,303		$	5.08	$	3.17	8.15
Vested	74,002		4.76		2.89		7.69
Exercised	(4,692	)	2.91		1.75		—
Canceled / Forfeited	(16,432	)	4.69		2.80		—
Exercisable, June 30, 2018	757,181		$	5.07	$	3.16	7.66

Schedule of information related to stock options outstanding and exercisable

The following table presents information related to stock options outstanding and exercisable at June 30, 2018: 

Options Outstanding		Options Exercisable
Exercise Price	Outstanding Number of Options	Weighted Average Remaining Life In Years	Exercisable Number of Options
$1.93 – $2.00	146,183	7.60	81,009
$3.83 – $4.75	556,045	8.90	355,058
$5.01 – $6.00	267,125	6.21	202,358
$6.18 – $7.20	70,000	6.34	49,697
$7.54 – $7.80	67,800	6.54	50,299
$8.06 – $12.98	22,500	6.55	18,760
	1,129,653	7.66	757,181

Schedule of restricted stock unit activity

A summary of restricted stock unit activity for the six months ended June 30, 2018 is as follows: 

	Number of Restricted Share Units		Weighted- Average Grant-Date Fair Value Per Share
Outstanding at January 1, 2018	1,476,858		$	4.96
Granted	1,171,304		4.76
Vested	(478,816	)	5.01
Forfeited	(6,799	)	4.98
Outstanding at June 30, 2018	2,162,547		$	4.84

Schedule of stock-based compensation

Total equity-based compensation costs recorded in the condensed consolidated statements of operations is allocated as follows: 

	Three Months Ended June 30, 2017		Three Months Ended June 30, 2018		Six Months Ended June 30, 2017		Six Months Ended June 30, 2018
Research and development
Employees	$	309,000	$	767,000	$	535,000	$	1,303,000
Non-employees	15,000		49,000		41,000		44,000
Total research and development	324,000		816,000		576,000		1,347,000
General and administrative
Employees and directors	317,000		727,000		684,000		1,134,000
Non-employees	24,000		84,000		98,000		109,000
Total general and administrative	341,000		811,000		782,000		1,243,000
Total equity-based compensation	$	665,000	$	1,627,000	$	1,358,000	$	2,590,000