Equity Incentive Plans (Tables)

6 Months Ended

Jun. 30, 2022

Share-Based Payment Arrangement [Abstract]

Summary of Stock-Based Compensation Expense Recognized

Stock-based compensation expense recognized for stock options, restricted stock units ("RSUs"), performance-based restricted stock units ("PRSUs") and our employee stock purchase program (the "ESPP") are recorded as operating expenses in our condensed statements of operations and comprehensive loss, as follows (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Selling, general and administrative	$	2,220	$	2,132	$	4,728	$	4,127
Research and development	973		1,087		2,096		2,179
Total	$	3,193	$	3,219	$	6,824	$	6,306

Summary of Total Unrecognized Stock-Based Compensation Expense, Net of Estimated Forfeitures

As of June 30, 2022, our total unrecognized stock-based compensation expense, net of estimated forfeitures, and average remaining vesting period, included the following (dollars in thousands):

	Unrecognized Compensation Expense		Average Remaining Vesting Period (Years)
Stock option grants	$	13,096	2.7
RSU grants	$	3,524	2.9
ESPP	$	21	0.2

Schedule of Stock Option Activity

A summary of our stock option activity and related information for the six months ended June 30, 2022 is as follows (in thousands, except dollar amounts):

	Number of Shares	Weighted-Average Exercise Price per Share
Balance at December 31, 2021	10,417	$	7.00
Options granted	4,773	$	0.88
Options exercised	—	$	—
Options forfeited or canceled	(1,190)	$	7.04
Balance at June 30, 2022	14,000	$	4.91
Exercisable at June 30, 2022	7,085	$	6.91

Schedule of Restricted Stock Units Activity

A summary of our RSUs activity and related information for the six months ended June 30, 2022 is as follows (in thousands, except dollar amounts):

	Number of RSUs	Weighted-Average Grant Date Fair Value Per Share
Non-vested restricted stock units at December 31, 2021	3,529	$	2.04
Granted	1,980	$	0.81
Vested	(3,714)	$	1.26
Forfeited	(121)	$	2.85
Non-vested restricted stock units at June 30, 2022	1,674	$	2.26