The 2013 Equity Incentive Plan (2013 Plan) provides the Board of Directors the discretion to grant stock options and other equity-based awards to employees, directors, and consultants of the Company. The Board of Directors administers the 2013 Plan and has discretion to delegate some or all of the administration of the 2013 Plan to a committee or committees or an officer. To date, the Company has only granted Incentive Stock Options (ISOs) and Non-statutory Stock Options (NSOs) to employees, consultants, and directors. Following the completion of the Company’s IPO no additional shares have been granted under the 2013 Plan. However, the 2013 Plan will continue to govern outstanding equity awards granted thereunder. To the extent outstanding options granted under the 2013 Plan are cancelled, forfeited or otherwise terminated without being exercised and would otherwise have been returned to the share reserve under the 2013 Plan, the number of shares underlying such awards will be available for future grant under the 2021 Equity Incentive Plan.

In February 2021, the Board of Directors adopted the 2021 Equity Incentive Plan (2021 Plan), and our stockholders approved the 2021 Plan. The 2021 Plan is a successor to and continuation of the 2013 Plan. To date, the Company has only granted ISOs, NSOs and Restricted Stock Units (RSUs) to employees and directors. Therefore, the below discussion is limited to the terms applicable to ISOs and NSOs (collectively, stock options or options), and RSUs.

In February 2021, the Company’s Board of Directors adopted the ESPP, and our stockholders approved the ESPP. The price at which stock is purchased under the ESPP is equal to 85% of the fair market value of the Company's common stock on the first or the last day of the offering period, whichever is lower. Generally, each offering under the ESPP will be for a period of six months as determined by the Company's Board of Directors. Employees may invest up to 15% of their qualifying gross compensation through payroll deductions. In no event may an employee purchase more than 4,750 shares of common stock during any six-month offering period.

As of March 31, 2022, there were 212,147 shares issued under the ESPP. The ESPP is a compensatory plan as defined by the authoritative guidance for stock compensation. Stock-based compensation expense of $0.1 million related to the ESPP has been recorded for the three months ended March 31, 2022 and 2021.

In November 2021, the Company's Board of Directors adopted the 2021 Inducement Plan (Inducement Plan). The Inducement Plan was adopted without stockholder approval pursuant to Nasdaq Listing Rule 5635(c)(4). Under the Inducement Plan, the Company may grant nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance awards and other awards to individuals not previously employees or non-employee directors of the Company, as an inducement toward entering into employment with the Company. The maximum number of shares of common stock that may be issued under the Inducement Plan is 3,000,000 shares.

A summary of stock option activity during the three months ended March 31, 2022 is as follows:


	Number of Units Outstanding			Weighted Average Strike Price per Unit		Weighted Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2021		8,590,411		$	5.48		8.8	$	6,196
Granted		256,800		$	1.89
Exercised		(65,862	)	$	1.50
Forfeited		(697,607	)	$	6.67
Expired		(161,468	)	$	3.43
Outstanding at March 31, 2022		7,922,274		$	5.33		8.6	$	—
Exercisable at March 31, 2022		2,753,490		$	5.28		8.4	$	—
Nonvested at March 31, 2022		5,168,784		$	5.36		8.8	$	—

As of March 31, 2022, the total unrecognized stock-based compensation related to stock options, excluding the stock option granted to Brian Coe, a former Chief Executive Officer of the Company with the performance condition (discussed further below), was $16.6 million, which is expected be recognized over a weighted-average period of approximately 3 years.

During 2020, Mr. Coe received stock options for the purchase of 241,958 shares of common stock that vest upon the first sale by the Company of a regulatory authorized product. As of March 31, 2022, there was $1.8 million of unrecognized compensation expense related to these stock options as the achievement of the performance condition was not deemed probable.

A summary of RSU activity during the three months ended March 31, 2022 is as follows:


	Number of Units Outstanding			Weighted Average Grant Date Fair Value (per RSU)
Outstanding at December 31, 2021		407,720		$	5.72
Granted		41,300		$	2.53
Vested		—		$	—
Forfeited		(80,905	)	$	5.86
Outstanding at March 31, 2022		368,115		$	5.35

As of March 31, 2022, the total unrecognized stock-based compensation related to RSUs was $1.7 million, which is expected to be recognized over a weighted average period of approximately 4 years.

The following table summarizes the components of stock-based compensation expense recorded in the Company’s statement of operations and comprehensive loss (in thousands):


	Three Months Ended March 31,
	2022		2021
Research and development	$	575	$	623
Selling, general and administrative		970		1,149
Total stock-based compensation	$	1,545	$	1,772