STOCK BASED COMPENSATION (Tables)

6 Months Ended

Jun. 30, 2020

STOCK BASED COMPENSATION

Summary of option activity for employee and non employee awards

				Weighted
		Weighted		Average
		Average		Remaining	Aggregate
	Number of	Exercise		Contractual	Intrinsic
	Shares	Price		Term	Value
				(Years)	(in thousands)
Outstanding at January 1, 2020	7,453,076	$	7.46	7.7	$	1,313
Granted	1,477,422		3.88
Exercised	(311,028)		3.02
Forfeited	(45,897)		6.26
Outstanding at June 30, 2020	8,573,573	$	7.01	7.7	$	40,475
Vested or expected to vest at June 30, 2020	8,573,573	$	7.01	7.7	$	40,475
Options exercisable at June 30, 2020	4,656,466	$	7.39	6.8	$	21,417

Schedule of assumptions used in determining fair value of the stock options granted

	Six Months Ended June 30,
	2020			2019
Expected volatility	80%	–	81%	61%	–	82%
Risk-free interest rate	0.42%	–	1.73%	1.87%	–	2.58%
Expected dividend yield		0%			0%
Expected term (in years)	5.91	–	6.08	0.5	–	6.63

Schedule of stock based compensation expense

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2020		2019		2020		2019
Cost of product revenues	$	9	$	39	$	28	$	41
Research and development		551		795		1,274		1,402
Selling, general and administrative		1,933		1,787		3,686		3,651
Total	$	2,493	$	2,621	$	4,988	$	5,094

Summary of the outstanding RSUs

			Weighted Average
			Grant Date
	Shares		Fair Value
Non-vested and outstanding balance at December 31, 2019	-	$	-
Changes during the period:
RSUs granted	263,560		11.70
PSUs granted	693,537		11.70
Non-vested and outstanding balance at June 30, 2020	957,097	$	11.70

Schedule of reserved common stock shares upon exercise of rights under equity compensation plans

	June 30,	December 31,
	2020	2019
Warrant rights to acquire Common Stock	334,680	384,163
ESPP	523,860	438,307
Outstanding inducement stock option awards	717,500	705,500
2009 Plan	2,262,070	2,530,586
2017 Plan	7,836,141	4,429,849
Total	11,674,251	8,488,405