Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity

A summary of stock option activity under our 2011 Equity Incentive Plan (“2011 Plan”) for the three months ended March 31, 2019 is presented below (in thousands, except per share and contractual life data).

	Number of Shares			Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Life (in Years)
Options outstanding as of December 31, 2018		7,120		$	3.83		6.81
Granted		2,103		$	0.78
Exercised		—		$
Forfeited or expired		(636	)	$	3.99
Options outstanding as of March 31, 2019		8,587		$	3.07		7.77
Options exercisable as of March 31, 2019		3,357		$	5.26		5.76

Summary of Restricted Stock Unit (RSU) Activity

The following table summarizes restricted stock unit (“RSU”) activity for the three months ended March 31, 2019 (in thousands, except per share data):

	Number of Shares			Weighted Average Grant Date Fair Value Per Share
Outstanding as of December 31, 2018		35		$	12.43
Awarded		527			0.75
Vested and released		(49	)		3.66
Forfeited/canceled		—			—
Outstanding as of March 31, 2019		513		$	1.28

Stock-based Compensation Expense

Stock-based compensation expense recognized for stock-based awards in the condensed consolidated statements of operations for the three months ended March 31, 2019 and 2018 was as follows (in thousands):

	Three Months Ended March 31,
	2019		2018
Cost of sales	$	47	$	65
Research and development		187		103
Clinical and regulatory		34		92
Selling and marketing		130		123
General and administrative		500		902
	$	898	$	1,285