SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

9 Months Ended

Sep. 30, 2017

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Summary of allocation of stock-based compensation expense included in operating expenses on condensed statements of operations related to share-based payment awards

The following table summarizes the stock-based compensation expense included in operating expenses on our condensed statements of operations related to stock options, restricted stock awards and employee stock purchases for the three and nine months ended September 30, 2017 and 2016 which was allocated as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
(In thousands)	2017		2016		2017		2016
Research and development	$	235	$	352	$	776	$	1,038
General and administrative		1,859		1,775		5,376		5,225
Stock-based compensation expense included in operating expenses	$	2,094	$	2,127	$	6,152	$	6,263

Schedule of assumptions used to estimate the fair value of stock options granted

The fair value of options granted during the nine months ended September 30, 2017 and 2016 has been estimated at the date of grant using the Black Scholes option-pricing model with the following assumptions:

	Nine Months Ended September 30,
	2017	2016
Dividend yield	0%	0%
Expected volatility range	0.884 to 0.892	0.888 to 0.890
Risk-free interest rate range	1.98% to 1.99%	1.21% to 1.38%
Expected term	5.5 yrs	5.5 yrs

Schedule of assumptions used to estimate the fair value of employee stock purchases under the purchase plan

The fair value of employees’ purchase rights during the nine months ended September 30, 2017 and 2016 has been estimated using the Black Scholes option-pricing model with the following assumptions:

	Nine Months Ended September 30,
	2017	2016
Dividend yield	0%	0%
Expected volatility range	0.577 to 0.641	0.641 to 0.684
Risk-free interest rate range	0.45% to 0.89%	0.28% to 0.45%
Expected term range	6 - 12 mos	6 - 12 mos