The Company maintains two equity compensation plans, the 2017 Stock Incentive Plan (as amended, the “2017 Plan”) and the 2019 Inducement Equity Incentive Plan (as amended, the “2019 Inducement Plan”), which provide for the grant of stock-based awards to its directors, officers and employees. The equity plans provide for the grant of non-qualified and incentive stock options, as well as restricted stock units (“RSUs”), restricted stock and other stock-based awards.

The weighted-average grant date fair value of options, estimated as of the grant date using the Black-Scholes option pricing model, was $1.29 and $7.96 per option for those options granted during the three months ended March 31, 2023 and 2022, respectively.

The following table summarizes stock option activity under all equity plans (excluding RSUs) during the three months ended March 31, 2023:


	Number of Shares			Weighted Average Exercise Price		Weighted Average Contractual Term		Aggregate Intrinsic Value
						(in years)		(in thousands)
Outstanding as of December 31, 2022		3,979,099		$	10.99		5.27	$	1
Granted		46,413			1.74
Exercised		—			—
Forfeited or cancelled		(26,521	)		13.73
Outstanding as of March 31, 2023		3,998,991		$	10.87		4.94	$	1


Outstanding as of March 31, 2023 - vested and expected to vest	3,998,991	$	10.87	4.94	$	1
Exercisable at March 31, 2023	2,971,459	$	9.95	4.38	$	—

As of March 31, 2023, a total of 11,595,127 shares have been authorized and reserved for issuance under all equity plans and 2,203,755 shares were available for future issuance under such plans.

The Company granted 3,203,199 RSUs to employees during the three months ended March 31, 2023.

The following table summarizes RSU activity under all equity plans during the three months ended March 31, 2023:


	Number of RSU Shares			Weighted Average Grant Date Fair Value
Outstanding as of December 31, 2022		1,300,397		$	7.51
Granted		3,203,199			1.86
Vested and released		(115,618	)		11.18
Forfeited or cancelled		(13,875	)		14.83
Outstanding as of March 31, 2023		4,374,103		$	3.25

As of March 31, 2023, there was approximately $12.9 million of total unrecognized compensation expense related to RSUs, which is expected to be recognized over a weighted-average period of approximately 3.5 years.

The fair value of the RSUs is determined on the date of grant based on the market price of the Company’s common stock on that date. Each RSU represents the right to receive one share of the Company’s common stock, $0.001 par value per share, upon vesting. The RSUs vest in four equal annual installments, subject to the individual’s continued service to the Company through the applicable vesting date, and are subject to the terms and conditions of the Company’s form of RSU agreement under the 2017 Plan.

In July 2022, as part of the retention awards referenced in Note 10, the Company issued awards containing performance-based vesting criteria ("performance-based awards") to be issued on May 31, 2023, with a value of $1.7 million based on the common stock price at such time, subject to the discretion of the Company's Board or Compensation Committee to pay in cash or a combination of cash and stock. Performance-based awards will be recorded as an accrued liability on the Company's condensed consolidated balance sheets and accrued over time as achievement of performance metrics become probable. The performance-based awards are eligible for vesting based on the achievement of certain performance criteria by May 31, 2023 relating to pipeline execution, business development, and financial stewardship. Performance-based awards for which the performance criteria have not been achieved as specified by May 31, 2023 will lapse and be forfeited. The performance-based awards will be subject to acceleration of vesting in the event of termination of employment without cause by the Company or by the executive for good reason (each as defined in the executive’s employment agreement).

In September 2022, the Company approved an award of 140,000 performance-based stock units as part of an executive inducement grant ("Inducement PSUs"). The Inducement PSUs are eligible for vesting based on the same performance criteria, above. To the extent these performance criteria are met by May 31, 2023, 50% of the Inducement PSUs will vest on September 12, 2023 and 50% will vest on September 12, 2024.

The Company recognized $0.7 million of compensation expense associated with performance-based awards and less than $0.1 million of expense associated with the Inducement PSUs during the three months ended March 31, 2023, as the performance conditions were considered probable of achievement.

The Company recorded share-based compensation expense related to incentive stock options, nonqualified stock options, stock grants, and stock-based awards in the following expense categories of its consolidated statements of operations and comprehensive loss (in thousands):


		Three Months Ended March 31,
		2023			2022



Research and development expenses	$	798	$	1,363
General and administrative expenses		1,372		1,840
Total	$	2,170	$	3,203