Equity Incentive Plans

3 Months Ended

Mar. 31, 2022

Share-based Payment Arrangement [Abstract]

Equity Incentive Plans

EQUITY INCENTIVE PLANS

Stock-Based Compensation

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 March 31,
	2022		2021
Research and development	$	1,214	$	1,092
Selling, general and administrative	2,508		1,995
Total	$	3,722	$	3,087

As of March 31, 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	$	14,865	3.0
RSU grants	$	4,894	1.3
ESPP	$	53	0.8

Stock Options

A summary of our stock option activity and related information for the three months ended March 31, 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	3,535	$	0.98
Options exercised	—	$	—
Options forfeited or canceled	(1,006)	$	7.18
Balance at March 31, 2022	12,946	$	5.34
Exercisable at March 31, 2022	6,476	$	7.16

Restricted Stock Units

A summary of our RSUs activity and related information for the three months ended March 31, 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	1,120	$	0.98
Vested	(113)	$	3.62
Forfeited	(88)	$	2.02
Non-vested restricted stock units at March 31, 2022	4,448	$	1.73

Employee Stock Purchase Plan

In February 2022, we sold approximately 0.1 million shares of our common stock under the ESPP. The shares were purchased by employees at a purchase price of $0.65 per share resulting in proceeds to us of approximately $0.1 million.

Issuance of Common Stock for Services

Under Our Amended and Restated Non-Employee Director Compensation Program, members of our board of directors may elect to receive shares of our stock in lieu of their cash fees. During the three months ended March 31, 2022, we issued no shares of our common stock to members of the board of directors in accordance with the program.