SHARE-BASED COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Schedule of Share-Based Compensation Expense

The following table sets forth the amount of share-based compensation expense recognized by the Company by line item on its consolidated statements of operations for the years ended December 31, 2020, 2019 and 2018 (in thousands):

	Year ended December 31,
	2020		2019		2018
Research and development	$	350	$	188	$	505
General and administrative	1,407		1,049		778
Total Share-based Compensation	$	1,757	$	1,237	$	1,283

Schedule of Stock Option Activity

The following table sets forth a summary of the Company’s total stock option activity, including awards granted under the 2014 Plan and 2009 Plan and inducement grants made outside of stockholder approved plans, for the years ended December 31, 2020, 2019 and 2018:

	Number of Shares under Option (in thousands)	Weighted-Average Exercise Price	Weighted-Average Remaining Contractual  Life (in years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2017	2,696	$3.16	8.55	$	146
Granted	3,546	$1.71
Exercised	(439)	$0.62
Canceled or forfeited	(1,861)	$3.21
Outstanding at December 31, 2018	3,942	$2.12	9.14	$	57
Granted	3,986	$1.02
Exercised	(90)	$1.10
Canceled or forfeited	(1,602)	$1.78
Outstanding at December 31, 2019	6,236	$1.52	8.83	$	358
Granted	4,044	$0.87
Exercised	(12)	$1.13
Canceled or forfeited	(121)	$1.04
Outstanding at December 31, 2020	10,147	$1.26	8.50	$	3,160
Exercisable at December 31, 2020	4,228	$1.63	7.85	$	931

Schedule of Weighted-Average Inputs and Assumptions in Black-Scholes Option

For the years ended December 31, 2020, 2019 and 2018, the grant-date fair value of stock options was determined using the following weighted-average inputs and assumptions in the Black-Scholes option pricing model:

	Year ended December 31,
	2020	2019	2018
Fair value of common stock	$0.56	$1.02	$1.71
Exercise price of the option	$0.87	$1.02	$1.71
Expected term (in years)	6.1	6.0	6.0
Risk-free interest rate	1.3%	2.1%	2.8%
Expected volatility	71.5%	78.1%	74.2%
Dividend yield	—%	—%	—%