Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2022

Share-Based Payment Arrangement [Abstract]

Stock Option Activity

The following table summarizes stock option activity for the six months ended June 30, 2022 (share amounts in thousands):

	Options			Weighted- Average Exercise Price
Outstanding as of December 31, 2021		11,708		$	4.15
Granted		1,327		$	2.02
Exercised		(23	)	$	1.76
Forfeited		(471	)	$	4.27
Outstanding as of June 30, 2022		12,541		$	3.92

Summary of Restricted Stock Unit, Activity

The following table summarizes restricted stock unit activity for the six months ended June 30, 2022 (share amounts in thousands):

	Restricted Stock Units			Weighted-Average Grant-Date Fair Value
Unvested as of December 31, 2021		1,650		$	2.16
Granted		390		$	2.03
Vested		(189	)	$	2.21
Forfeited		(64	)	$	2.16
Unvested as of June 30, 2022		1,787		$	2.12

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 June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Cost of product sales	$	—	$	—	$	—	$	3
Research and development		854		817		1,778		1,617
Selling, general and administrative		940		994		1,910		2,154
Total stock-based compensation	$	1,794	$	1,811	$	3,688	$	3,774