In September 2024, the Board of Directors (the Board) adopted the Company's 2024 Inducement Equity Incentive Plan (the Inducement Plan), and subject to the adjustment provisions of the Inducement Plan, reserved 1,200,000 shares of the Company’s common stock for issuance pursuant to equity awards granted under the Inducement Plan. The Inducement Plan allows the Company to make equity awards to prospective employees of the Company as an inducement to such individual's commencement of employment with the Company.

Total shares reserved and available for grant under the Inducement Plan as of March 31, 2025, are 1,188,000.

Under the Company's 2021 Equity Incentive Plan (the 2021 Plan), 4,000,000 shares of the Company’s common stock were initially reserved for issuance of equity awards to employees, directors, and consultants, under terms and provisions established by the Board. The number of shares of common stock available for issuance under the 2021 Plan automatically increases on the first day of January for a period of ten years, commencing on January 1, 2022, in an amount equal to the lesser of: 4,000,000 shares; 4% of the outstanding shares of the Company’s common stock as of the last day of the immediately preceding year; or such other amount as the board of directors may determine.

The total number of shares reserved and available for grant under the 2021 Plan as of March 31, 2025 is 2,149,004.

On January 22, 2025, the Compensation Committee of the Company's Board approved a repricing of certain outstanding vested and unvested stock option awards under the 2016 Plan and 2021 Plan for eligible employees and certain other service providers (the Repricing Participants). The per share exercise price of eligible stock option awards was reduced to $1.21, the closing price of the Company's common stock on January 24, 2025 (the Repricing Effective Date). To receive the benefit of the repricing, Repricing Participants must remain a Service Provider (as such term is defined in the 2016 Plan or 2021 Plan) through the period (the Retention Period) that begins on the Repricing Effective Date through the earlier of July 24, 2025 or a change in control (the earlier of such dates, the Retention Date) and not exercise any of their repriced stock options prior to the Retention Date. Option holders who exercise their repriced stock options prior to the Retention Date must pay the original exercise price per share of such repriced options. No other changes were made to the terms and conditions of the eligible stock option awards. The stock option repricing impacted 4.1 million stock option awards and affected 89 employees and service providers.

On February 6, 2025, the Company's Board approved an option repricing applicable to Faraz Ali, the Company's Chief Executive Officer, with terms mirroring the aforementioned repricing approved on January 22, 2025, except that for Mr. Ali, the options eligible for repricing were limited to options with exercise prices higher than $5.25 per share. The total number of shares underlying Mr. Ali’s repriced options was 915,875 shares.

The repricing resulted in a total incremental stock-based compensation expense of $1.3 million, which was calculated using the Black-Scholes option pricing model, of which $1.0 million is associated with vested repriced options as of the Retention Date and will be recognized on a straight-line basis over the Retention Period. The remaining $0.3 million of the incremental stock-based compensation expense is associated with unvested repriced options beyond the Retention Period and will be recognized on a straight-line basis over the remaining original vesting periods. For the three months ended March 31, 2025, the Company recognized $0.4 million of incremental stock-based compensation expense.

The following table summarizes stock option activity:


	Shares			Weighted Average Exercise Price
				(in dollars)
Outstanding as of December 31, 2024		9,253,976		$	6.51
Granted		2,280,125		$	1.15
Exercised		—		$	—
Cancelled		(388,568	)	$	4.69
Outstanding as of March 31, 2025		11,145,533		$	5.48

Since the reporting period covered by the table above is before the aforementioned Retention Date and any employees who exercised their repriced stock options during the reporting period would have to pay the original exercise price, the weighted average exercise price in the table above does not include the effect of repricing.

Stock option awards granted to employees generally vest over a four-year period. The contractual term of stock option awards is generally 10 years from the grant date.

The fair value of the Company’s stock option awards is estimated on the date of grant using the Black-Scholes option pricing model using the following assumptions:


	Three Months Ended March 31,
	2025	2024
Expected term (in years)	6.0	6.0-6.1
Expected volatility	91%	93%
Risk-free interest rate	4.3%-4.5%	3.9% – 4.3%
Expected dividend yield	—%	—%

Restricted stock units (RSUs) are awards that entitle the holder to receive freely tradable shares of the Company’s common stock upon the completion of a specific period of continued service. RSUs generally vest over a two to four year period and are subject to forfeiture if employment terminates prior to the release of vesting restrictions. RSUs are valued at the market price of the underlying common stock on the date of grant. The Company recognizes noncash compensation expense for the fair value of RSUs on a straight-line basis over the requisite service period of the awards. The following table summarizes activity of RSUs granted to employees with service-based vesting under the 2021 Plan.


	Shares			Weighted Average Grant Date Fair Value per Share
				(in dollars)
Unvested as of December 31, 2024		1,354,178		$	4.14
Granted		1,466,353		$	1.18
Vested		(295,191	)	$	3.79
Forfeited		(253,827	)	$	2.78
Unvested as of March 31, 2025		2,271,513		$	2.43

Under the Company's 2021 Employee Stock Purchase Plan (the ESPP), the Company initially reserved 800,000 shares for future issuance. The number of shares of common stock available for issuance under the ESPP

automatically increases on the first day of each fiscal year for a period of ten years beginning with 2022 in an amount equal to the lesser of: 800,000 shares; 1% of the outstanding shares of the Company’s common stock as of the last day of the immediately preceding year; or such other amount as the Board may determine. As of March 31, 2025, 2,465,077 shares were reserved for future issuance under the ESPP. Under the Company’s ESPP, employees are generally eligible to participate and can purchase shares on each purchase date established semi-annually through payroll deductions at the lower of 85% of the fair market value of the Company’s stock at the commencement of the offering period or each purchase date of the offering period. Each offering period spans 6 months. The ESPP permits eligible employees to purchase common stock through payroll deductions for up to 15% of qualified compensation, up to an annual limit of $25,000 per the Internal Revenue Service. For the three months ended March 31, 2025 and 2024, the stock-based compensation expense for ESPP was not material.

The following table summarizes stock-based compensation recognized in the Company’s condensed statements of operations and comprehensive loss:


	Three Months Ended March 31,
	2025		2024
Research and development	$	2,047	$	1,989
General and administrative		1,684		2,235
Total stock-based compensation	$	3,731	$	4,224