STOCK-BASED COMPENSATION (Tables)

6 Months Ended

Jun. 30, 2016

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

The following table summarizes the Company’s stock awards granted for each of the periods indicated:

	For the Three Months Ended June 30,								For the Six Months Ended June 30,
	2016				2015				2016					2015
	Grants		Weighted Average Grant Date Fair Value		Grants		Weighted Average Grant Date Fair Value		Grants			Weighted Average Grant Date Fair Value		Grants		Weighted Average Grant Date Fair Value
Stock options		7,600	$	15.61		367,167	$	15.69		1,213,376	⁽¹⁾	$	11.94		1,974,711	$	11.34
Restricted stock awards		—	$	—		110,783	$	13.54		25,775	⁽²⁾	$	13.71		116,783	$	13.56

(1)

Included in 2016 stock option grants are 287,500 options with performance conditions that are not probable of being achieved as of June 30, 2016. When and if deemed probable that certain performance milestones will be achieved within the required time frame, the Company will recognize up to $3.4 million of stock-based compensation related to these grants. The remaining stock options granted during the periods presented in the table have only service-based criteria and vest over four years.

(2)	Included in 2016 restricted stock awards (“RSA”) are 18,755 shares granted to certain employees in lieu of a portion of their 2015 annual bonus payments. These RSA grants have six-month vesting schedules. The remaining RSAs will be fully vested by June 2017.

Summary of Stock-Based Compensation Expense by Function Included within Condensed Consolidated Statement of Operations and Comprehensive Loss

The following table summarizes stock-based compensation expense by function included within the unaudited condensed consolidated statements of operations and comprehensive loss:

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
	2016		2015		2016		2015
	(in thousands)
Research and development	$	2,404	$	2,562	$	4,853	$	5,008
General and administrative		4,426		3,368		8,667		15,078
Total stock-based compensation expense	$	6,830	$	5,930	$	13,520	$	20,086

Summary of Stock-Based Compensation Expense by Grant Type Included within Condensed Consolidated Statement of Operations and Comprehensive Loss

The following table summarizes stock-based compensation expense by grant type included within the unaudited condensed consolidated statements of operations and comprehensive loss:

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
	2016		2015		2016		2015
	(in thousands)
Stock options	$	5,772	$	5,099	$	11,470	$	18,650
Restricted stock awards		273		132		457		174
Stock appreciation rights		115		115		230		262
Employee stock purchase plan		670		584		1,363		1,000
Total stock-based compensation expense	$	6,830	$	5,930	$	13,520	$	20,086