In October 2012, the Company adopted the 2012 Equity Incentive Plan, or the 2012 Plan, under which 238,095 shares of the Company’s common stock were initially reserved for issuance to employees, directors and consultants.

In July 2021, the Company adopted the 2021 Incentive Award Plan, or 2021 Plan, which became effective in connection with the IPO. The 2012 Plan was terminated in connection with the IPO when the 2021 Plan became effective; however, awards granted under the 2012 Plan that remain outstanding continue to be governed by the 2012 Plan. Shares reserved for issuance under the 2012 Plan but not subject to awards as of the date of the IPO were added to the available shares in the 2021 Plan. Shares subject to awards granted under the 2012 Plan that were or are forfeited to the Company, terminated without exercise or repurchased for the original purchase price after the IPO have been and will be added to the shares reserved for issuance under the 2021 Plan.

Under the terms of the 2021 Plan, the Company may grant stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance bonus awards, performance stock unit awards, dividend equivalents awards or other stock or cash-based awards to individuals who are then employees, consultants, or directors of the Company. Under the terms of the 2021 Plan, options may be granted at an exercise price not less than fair market value. For employees holding more than 10% of the voting rights of all classes of stock, the exercise prices for incentive and non-statutory stock options may not be less than 110% of fair market value, as determined by the board of directors. The terms of options granted under the 2021 Plan may not exceed ten years. The vesting schedule of newly issued option grants is generally four years.

The Company initially reserved 3,450,000 shares of common stock for issuance under the 2021 Plan. The number of shares initially reserved will be increased by (i) any shares available for issuance under the 2012 Plan as of the day before the IPO, (ii) any shares that are subject to the 2012 Plan that become available for issuance under the 2012 Plan and (iii) the annual increase on January 1 of each year, beginning January 1, 2022, and continuing through and including January 1, 2031, by 5% of the shares of common stock outstanding on the last day of the immediately preceding fiscal year, or a lesser number of shares determined by the Company's board of directors. As of June 30, 2022, there were 3,780,239 shares available for grant under the 2021 Plan.

In July 2021, the Company adopted the Employee Stock Purchase Plan, or the ESPP, which became effective in connection with the IPO. The purpose of the ESPP is to assist employees of the Company in acquiring a stock ownership interest in the Company, to help such employees provide for their future security and to encourage them to remain in the employment of the Company. The ESPP is intended to qualify as an “employee stock purchase plan” within the meaning of Section 423 of the Code. The compensation committee of the board of directors administers the Company’s ESPP.

The maximum aggregate number of shares of common stock that may be issued pursuant to the exercise of purchase rights under the Company’s ESPP that are granted to employees is 4,703,469 shares. Additionally, the number of shares of common stock reserved for issuance under the Company’s ESPP increases automatically each year, beginning on January 1, 2022, and continuing through and including January 1, 2031, by 1% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year, or a lesser number as determined by the board of directors. Shares subject to purchase rights granted under the Company’s ESPP that terminate without having been exercised in full will not reduce the number of shares available for issuance under the Company’s ESPP. As of June 30, 2022, the Company has reserved 685,317 shares of common stock under the ESPP. There are two ESPP offering periods each year and the first offering period started on June 1, 2022. Each offering period has one purchase period which occurs every six months. There were no shares issued under the ESPP during the three and six months ended June 30, 2022.

Stock option activity under the 2012 Plan and the 2021 Plan was as follows:


	Options Available for Grant			Number of Options Outstanding			Weighted-Average Exercise Price Per Share		Weighted-Average Remaining Contractual Life (years)		Aggregate Intrinsic Value
											(in thousands)
Outstanding as of January 1, 2022		2,673,582			4,028,461		$	8.81		8.40	$	60,089
Authorized		1,676,587			—			—
Granted		(631,520	)		631,520			17.67
Exercised		—			(206,130	)		2.29
Cancelled		61,590			(61,590	)		19.65
Outstanding as of June 30, 2022		3,780,239			4,392,261		$	10.24		8.25	$	26,189
Exercisable as of June 30, 2022					1,527,275		$	3.58		6.71	$	15,328

The aggregate intrinsic values of options outstanding and exercisable were calculated as the difference between the exercise price of the options and the closing price of the Company’s common stock of $13.39 as of June 30, 2022.

The total intrinsic value of options exercised during the three and six months ended June 30, 2022 was $0.1 million and $3.9 million, respectively. The total intrinsic value of options exercised during the three and six months ended June 30, 2021 was $0.3 million. Such intrinsic value of options exercised is the difference between the fair value of Company’s common stock at the time of exercise and the exercise price of the stock option.

The weighted-average grant-date fair value per share for stock options granted during the three months ended June 30, 2022 and 2021 was $9.88 and $4.21, respectively. The weighted-average grant-date fair value per share for stock options granted during the six months ended June 30, 2022 and 2021 was $12.10 and $2.82, respectively.

The estimated grant-date fair value of the Company’s stock options was calculated using the Black-Scholes option pricing model, based on the following assumptions:


	Three Months Ended June 30,		Six Months Ended June 30,
	2022	2021	2022	2021
Expected term (in years)	5.5 - 6.1	6.1	5.5 - 6.1	5.9 - 6.1
Expected volatility	77.1%	67.7%	77.1% - 78.1%	67.7% - 69.9%
Risk-free interest rate	2.8% - 3.3%	1.0%	1.7% - 3.3%	0.6% - 1.1%
Expected dividend yield	—%	—%	—%	—%

Expected Term—The expected term represents the period that the Company’s stock-based awards are expected to be outstanding and is determined using the simplified method, which is based on the mid-point between the contractual term and vesting period.

Volatility—The Company determines volatility based on the historical volatilities of comparable publicly traded life science companies over a period equal to the expected term because it does not have sufficient trading history for its common stock price. The comparable companies were chosen based on the similar size, stage in the life cycle, or area of specialty. The Company will continue to apply this process until sufficient historical information regarding volatility on its own stock becomes available.

Risk-Free Interest Rate—The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award.

Dividend Yield—The Company has never paid and has no plans to pay any dividends on its common stock. Therefore, the Company has used an expected dividend yield of zero.

Total stock-based compensation recognized for the periods presented is as follows:


	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021

Research and development	$	710	$	131	$	1,363	$	188
General and administrative		1,032		303		1,730		565
Total stock-based compensation expense	$	1,742	$	434	$	3,093	$	753

As of June 30, 2022, total unrecognized stock-based compensation expense is approximately $22.5 million, related to unvested stock options to be recognized over the remaining weighted-average vesting period of 2.9 years.