The Company grants share-based awards under the 2020 Stock Option Plan, as amended (the “2020 Plan”). The Company may grant under the 2020 Plan incentive stock options, nonqualified stock options, restricted stock awards, restricted stock units and other share-based awards to the Company’s officers, employees, directors and consultants. Options under the 2020 Plan may be granted for periods of up to 10 years and at prices no less than 100.0% of the estimated fair value of the shares on the date of grant as determined by the Board, provided, however, that the exercise price of an incentive stock option granted to a 10.0% stockholder shall not be less than 110.0% of the estimated fair value of the shares on the date of grant and the option is not exercisable after the expiration of five years from the date of grant. Options generally vest monthly over four years with or without one year cliff vesting. Per the 2020 Plan, granted options maybe early exercised prior to vesting and the Company will issue shares of restricted stock upon the early exercise with vesting terms consistent with the original grant. Upon completion of the Company’s IPO, the remaining shares available for issuance under the 2020 Plan were retired.

In June 2021, the Company’s Board of Directors approved the 2021 Stock Option and Incentive Plan (the “2021 Plan”) that became effective immediately prior to the date when the Company’s prospectus was declared effective by the SEC on June 24, 2021. The Company initially reserved 5,636,000 shares of common stock for issuance of awards under the 2021 Plan. The 2021 Plan provides that the number of shares reserved and available for issuance under the plan will automatically increase each January 1, beginning on January 1, 2022, by 5% of the outstanding number of shares of the Company’s common stock on the immediately preceding December 31, or such lesser number of shares as determined by the Company’s compensation committee. On January 1, 2022, the number of shares of common stock available under the 2021 Plan increased by 2,900,541 shares pursuant to this evergreen provision of the 2021 Plan. The option exercise price of each option will be determined by the Company’s compensation committee but generally may not be less than 100% of the fair market value of the Company’s common stock on the date of grant. The term of each option will be fixed by the Company’s compensation committee and may not exceed ten years from the date of grant. The grant date fair value of all awards made under the 2021 Plan and all other cash compensation paid by the Company to any non-employee director for services as a non-employee director in any calendar year may not exceed $1.0 million for the first year of service and $750.0 thousand for each year of service thereafter.

As of December 31, 2022, there were 5,382,907 shares available for future issuance under the 2021 Plan.

During the year ended December 31, 2020, the Company issued 832,983 shares as restricted stock awards under the 2020 Plan. The purchase price of the restricted common stock awards was fair value as determined by the Board at the issuance date. The shares vest monthly over four years with the one-year cliff vesting from the grant date. Upon termination of employment, the Company has the right to repurchase any unvested restricted shares. The repurchase price for unvested shares of common stock will be the lower of (i) the fair market value on the date of repurchase or (ii) their original purchase price. There were no shares issued during the years ended December 31, 2022 and 2021.

The Company accounted for restricted stock awards as early exercised options and recognized a liability in other liabilities when cash was received for the purchase of shares of restricted stock awards. As shares of restricted stock awards vest, the Company reclassified the liability to common stock and additional paid in capital. As of December 31, 2022 and 2021, the Company recorded a minimal liability for restricted stock awards included in accrued expenses and other current liabilities.

There were 5,140 shares of restricted stock award shares canceled and repurchased as of December 31, 2022. No restricted stock award shares were cancelled or repurchased as of December 31, 2021. There were 553,443 and 345,966 shares of restricted stock vested as of December 31, 2022 and 2021, respectively.

In June 2021, the Company’s board of directors and stockholders approved the 2021 Employee Stock Purchase Plan (the “2021 ESPP”) which became effective upon the IPO. The 2021 ESPP is intended to qualify as an employee stock purchase plan under Section 423 of the Internal Revenue Code of 1986, as amended, and is administered by the Company’s board of directors and the Compensation Committee of the board of directors. Under the 2021 ESPP, 564,000 shares of the Company’s common stock have been initially reserved for employee purchases of the Company’s common stock. The 2021 ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their eligible compensation. At the end of each offering period, employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock at the beginning of the offering period or at the end of each applicable purchase period. The first purchase period commenced upon the

completion of the Company’s IPO and ended on November 30, 2021 and the subsequent offering periods commenced on December 1, 2021, June 1, 2022, and December 1, 2022. The Company recorded $0.1 million in accrued liabilities as of December 31, 2022.

Effective January 1, 2022, the number of shares of common stock available under the 2021 ESPP increased by 564,000 shares pursuant to the evergreen provision of the 2021 ESPP.


	Year Ended December 31,
	2022			2021
Expected volatility	73.00% - 75.00%			72.00% - 74.00%
Expected dividend yield		0	%		0	%
Expected term (in years)	0.5			0.44 - 0.5
Risk-free interest rate	0.10% - 4.65%			0.10% - 1.00%

Stock options issued under the 2020 Plan and 2021 Plan, generally, vest over a four-year period and expire ten years from the date of grant. Certain options provide for accelerated vesting if there is a change in control, as defined in the individual award agreements.

The Company used the Black-Scholes option pricing model to estimate stock-based compensation expense for stock option awards granted during the periods presented, with the following assumptions.


	Year Ended December 31,
	2022			2021
Expected volatility	74.00% - 75.00%			72.00% - 77.74%
Expected dividend yield		0	%		0	%
Expected term (in years)	5.97 - 6.01			5.48 - 6.04
Risk-free interest rate	1.91% - 4.23%			0.56% - 1.34%

A summary of option activity under the 2020 Plan and the 2021 Plan during the year ended December 31, 2022 is as follows:


	Number of Options			Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding as of December 31, 2021		5,056,743		$	8.77		9.2	$	18,503
Options granted - 2021 Plan		3,292,702		$	7.91
Options exercised		(67,196	)	$	0.30
Options cancelled		(526,946	)	$	8.99
Outstanding as of December 31, 2022		7,755,303		$	8.47		8.7	$	794
Exercisable		2,330,389		$	8.74		8.3	$	388
Vested and expected to vest as of December 31, 2022		7,755,303		$	8.47		8.7	$	794

Aggregate intrinsic value represents the difference between the fair value of the underlying common stock and the exercise price as of December 31, 2022. The weighted-average grant date fair value of options granted during the year ended December 31, 2022 was $5.21 per share. The intrinsic value of the stock options exercised was $0.2 and $5.0 million for the years ended December 31, 2022 and 2021, respectively.

The terms of the 2020 Plan permit the exercise of options granted prior to vesting, subject to required approvals. The unvested shares are subject to the repurchase right upon termination of employment at the original purchase price. The repurchase right lapses in 180 days after the termination of the employee’s employment. Shares purchased by employees pursuant to the early exercise of stock options are not deemed, for accounting purposes, to be issued until those shares vest according to their respective vesting schedules. Cash received for early exercised stock options is recorded as other liabilities on the balance sheet and is reclassified to common stock and additional paid-in capital as such shares vest. During the years ended December 31, 2022 and 2021, the Company repurchased 189,414 and 138,596 shares that were previously early exercised.

At December 31, 2022 and 2021, 554,695 and 1,195,631 shares, respectively, remained subject to the right of repurchase as a result of the early exercised stock options. The remaining liability related to early exercised shares as of December 31, 2022 and 2021 was $0.1 and $0.3 million, respectively, and was recorded in accrued expenses and other current liabilities, respectively, in the balance sheets.

The following table presents the components of stock-based compensation expense for the Company’s stock-based awards for the periods presented (in thousands):


	Year Ended December 31,
	2022		2021
Restricted stock awards and founders’ common stock awards	$	11	$	9
ESPP		391		215
Stock options		13,132		7,647
Total stock-based compensation expense	$	13,534	$	7,871

The above stock-based compensation expense also includes the expenses of $2.2 and $0.3 million related to stock options issued to non-employees during the years ended December 31, 2022 and 2021, respectively.

The following table presents the classification of stock-based compensation expense for the Company’s stock-based awards for the periods presented (in thousands):


	Year Ended December 31,
	2022		2021
Research and development expenses	$	5,317	$	2,685
General and administrative expenses		8,217		5,186
Total stock-based compensation expense	$	13,534	$	7,871

As of the years ended December 31, 2022 and 2021, there was $31.0 and $30.5 million, respectively, of unrecognized stock-based compensation expense related to the employee and non-employee awards, which is expected to be recognized over a weighted-average period of 2.6 years and 3.3 years, respectively.