Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock Option Activity

The following table summarizes stock option activity for the three months ended March 31, 2019 (share amounts in thousands):

	Options			Weighted- Average Exercise Price
Outstanding as of December 31, 2018		5,020		$	5.62
Granted		2,343		$	2.02
Exercised		—			—
Forfeited		(16	)	$	3.70
Outstanding as of March 31, 2019		7,347		$	4.48

Summary of Non-cash Stock Based Compensation Expense

Total non-cash stock-based compensation expense recognized in the accompanying condensed statements of operations is as follows (in thousands):

	Three Months Ended March 31,
	2019		2018
Cost of product sales	$	3	$	4
Research and development		659		637
Selling, general and administrative		834		2,072
Total stock-based compensation	$	1,496	$	2,713