The Company currently grants equity-based awards under its 2020 Incentive Award Plan (“2020 Plan”) and its 2022 Employment Inducement Award Plan (“Inducement Award Plan”). The Company previously granted equity-based awards under its 2005 Equity Incentive Plan (“2005 Plan”) and 2016 Equity Incentive Plan (“2016 Plan” and together with the 2020 Plan, the Inducement Award Plan and the 2005 Plan, the “Plans”). The Company also maintains the 2020 Employee Stock Purchase Plan (the “ESPP”).

A summary of the restricted stock unit activity under the Plans for the three months ended March 31, 2025 was as follows:


	Shares			Weighted- Average Grant Date Fair Value
Restricted stock units outstanding as of December 31, 2024		2,143,802		$	2.65
Granted		2,973,000		$	0.20
Vested		(365,121	)	$	5.44
Forfeited		(14,251	)	$	1.55
Restricted stock units outstanding as of March 31, 2025		4,737,430		$	0.90

A summary of the stock option activity under the Plans for the three months ended March 31, 2025 was as follows:


	Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2024		6,314,561		$	5.66		7.5	$	—
Granted		—			—
Exercised		—			—
Cancelled		(1,800,575	)		9.21
Outstanding at March 31, 2025		4,513,986		$	4.25		7.4	$	—

The fair value of each stock option granted to employees, directors and non-employees was estimated on the date of grant using the Black-Scholes option-pricing model, or a Monte Carlo simulation in the case of certain options granted to executive officers, with the following weighted-average assumptions for the three months ended March 31, 2024 :


	Three months ended March 31, 2024
Risk-free interest rate		4.1	%
Expected dividend yield		—	%
Expected term (in years)		6.0
Expected volatility		77.1	%

No stock options were granted during the three months ended March 31, 2025. The weighted-average fair value of options granted to employees, directors and non-employees during the three months ended March 31, 2024 was $3.64.

Stock-based compensation expense included in the Company’s consolidated statements of operations and comprehensive loss was as follows (in thousands):


	Three Months Ended March 31,
	2025		2024
Research and development	$	273	$	703
General and administrative		552		1,459
Total	$	825	$	2,162

For the three months ended March 31, 2025 no stock-based compensation expense was recorded to liabilities. For the three months ended March 31, 2024, $281,000 of the stock-based compensation expense was recorded to liabilities.

Unrecognized stock-based compensation related to stock-based options amounted to $3.0 million at March 31, 2025 and is expected to be recognized over a weighted average period of approximately 2.3 years. Unrecognized stock-based compensation related to restricted stock units amounted to $2.2 million at March 31, 2025 and is expected to be recognized over a weighted average period of approximately 2.1 years.

On February 14, 2025, options to purchase 1,694,590 shares of common stock at an average per share price of $9.28, previously granted under the 2020 Stock Option Plan were voluntarily forfeited by certain executives and returned to the pool of options available for grant under the 2020 Stock Option Plan for future issuance. No replacement options were granted to those executives. Included in the forfeited options were options to purchase 550,000 shares of common stock granted in March 2024 with performance-based vesting conditions.

As of March 31, 2025, there were 2,159,351 shares available for grant under the 2020 Plan and 863,000 shares available for grant under the Inducement Award Plan.

As of March 31, 2025, the Company issued 1,000 shares under the 2020 ESPP. In June 2024 the Company indefinitely suspended the offering of its 2020 ESPP. As of March 31, 2025, there are a total of 986,500 shares available for issuance under the 2020 ESPP.