Equity (Tables)

3 Months Ended

Mar. 31, 2016

Equity [Abstract]

Summary of Stock Option Activity

A summary of the stock option activity under the Company’s plans for the three months ended March 31, 2016 is as follows:

	Number of		Weighted average
	shares		exercise price
Options outstanding at December 31, 2015		5,326,505	$	3.07
Options granted		762,500		6.77
Less:
Options exercised		1,218,292		0.92
Options canceled or expired		139,542		4.68
Options outstanding at March 31, 2016		4,731,171		3.42
Exercisable at March 31, 2016		1,753,494	$	2.32

Summary of Stock-Based Compensation Expense Recognized for Stock Options and Restricted Stock Included in Consolidated Statements of Operations

Stock based compensation expense recognized for stock options and restricted stock and included in the consolidated statements of operations was allocated as follows (in thousands): 

	Three Months Ended March 31,
	2016			2015
Research and development expense	$	(9	)	$	55
General and administrative expense		796			287
Total stock based compensation expense	$	787		$	342

Summary of Warrant Activity

A summary of the warrant activity for the three months ended March 31, 2016 is as follows:

	Number of		Weighted average
	shares		exercise price
Warrants outstanding at December 31, 2015		650,000	$	1.48
Warrants granted		—		—
Less:
Warrants exercised		—		—
Warrants canceled or expired		—		—
Warrants outstanding at March 31, 2016		650,000		1.48
Exercisable at March 31, 2016		530,000	$	1.49