In March 2024, the Company adopted the 2024 Incentive Plan (as amended, the Plan), which has a term of ten years. The Plan provides for the grant of incentive stock options, nonqualified stock options, restricted stock, dividend equivalents, restricted stock units, stock appreciation rights, and other stock or cash-based awards to its employees, consultants, and directors. Options granted under the Plan are exercisable at various dates as determined upon grant and will expire no more than 10 years from their date of grant. Stock options generally vest over terms of either 36 or 48 months. The exercise price of awards under the Plan shall not be less than 100% of the estimated fair market value of the Company’s stock on the date of grant. In addition, the Plan includes an “evergreen” provision whereby the number of shares of common stock available for issuance under the Plan will be increased annually on the first day of each calendar year during the term of the Plan, beginning in 2025, by an amount equal to the lesser of (i) 5% of the shares of common stock outstanding on the final day of the immediately preceding calendar year or (ii) such smaller number of shares as determined by the Company’s board of directors or an authorized committee of the board of directors. As of June 30, 2024, a total of 2,832,714 shares of common stock were authorized for issuance under the Plan. On June 30, 2024, 2,279,257 of these shares remain available for grant under the Plan.

Prior to the adoption of the Plan, the Company had awarded common stock options under the 2018 Equity Incentive Plan (as amended, the Predecessor Plan). Under the provisions of the Plan, the shares subject to awards issued under the Predecessor Plan that were outstanding as of March 27, 2024, and that are subsequently cancelled or forfeited, will become available for issuance under, and serve to increase the number of shares that may be issued under, the Plan.

Stock option activity under the Plan and certain other related information is as follows:


	Number			Weighted- Average Exercise Price		Weighted- Average Remaining Term (years)		Aggregate- Intrinsic Value (in 000’s)
Balance as of December 31, 2023		2,813,937		$	4.10		7.8	$	562
Granted		1,393,744		$	11.16
Exercised		(15,211	)	$	3.90
Forfeited and expired		(4,034	)	$	4.05
Balance as of June 30, 2024		4,188,436		$	6.47		8.6	$	166
Vested and expected to vest at June 30, 2024		4,188,436		$	6.47		8.6	$	166
Exercisable as of June 30, 2024		1,394,504		$	4.55		7.6	$	165

Aggregate intrinsic value in the above table is the difference between the estimated fair value of the Company’s common stock as of either June 30, 2024 or December 31, 2023, and the exercise price of stock options that had exercise prices below that value.

The options exercised during the three and six months ended June 30, 2024 had an intrinsic value at exercise of approximately $1,000 and $32,000, respectively. The options exercised during the three and six months ended June 30, 2023 had an intrinsic value at exercise of approximately $4,000 and $11,000, respectively.

Stock-based compensation expense was as follows (in thousands):


	Three Months Ended June 30,				Six Months Ended June 30,
	2024		2023		2024		2023
Research and development expenses	$	888	$	395	$	1,412	$	667
General and administrative expenses		1,247		532		2,051		875
Total stock-based compensation	$	2,135	$	927	$	3,463	$	1,542

As of June 30, 2024, unrecognized compensation cost related to outstanding time-based options was $21.2 million, which is expected to be recognized over a weighted-average period of 2.9 years.

The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of the stock options granted during the following periods were as follows:


	Three Months Ended June 30,						Six Months Ended June 30,
	2024			2023			2024			2023
Expected option life (in years)		6.0			6.0			6.0			6.0
Assumed volatility		91.3	%		91.4	%		94.9	%		91.5	%
Assumed risk-free interest rate		4.3	%		3.9	%		4.2	%		3.9	%
Expected dividend yield		—			—			—			—

The weighted-average grant date per share fair value of options granted during the three months ended June 30, 2024 and 2023 was $4.55 and $5.64, respectively. The weighted-average grant date per share fair value of options granted during the six months ended June 30, 2024 and 2023 was $11.59 and $5.64, respectively.

In March 2024, the Company’s board of directors adopted, and the Company’s stockholders approved, the Company’s 2024 Employee Stock Purchase Plan (the ESPP), which became effective in connection with the IPO. The ESPP permits participants to contribute up to a specified percentage of their eligible compensation during a series of offering periods of 24 months, each comprised of four six-month purchase periods, to purchase the Company’s common stock. The purchase price of the shares will be 85% of the fair market value of the Company’s common stock on the first day of trading of the applicable offering period or on the applicable purchase date, whichever is lower. A total of 231,919 shares of common stock were initially reserved for issuance under the ESPP. In addition, the ESPP includes an “evergreen” provision whereby the number of shares of common stock available for issuance under the ESPP will be increased annually on the first day of each calendar year during the term of the ESPP, beginning in 2025, by an amount equal to the lesser of (i) 1% of the shares of common stock outstanding on the final day of the immediately preceding calendar year or (ii) such smaller number of shares as determined by the Company’s board of directors or an authorized committee of the board of directors. The Company recognized stock-based compensation expense related to the ESPP of $0.3 million for both the three and six month periods ended June 30, 2024, and $0 during the three and six months ended June 30, 2023. As of June 30, 2024, the unrecognized compensation cost related to the ESPP was $0.8 million and is expected to be recognized as expense over approximately 1.29 years. As of June 30, 2024, $0.1 million has been withheld on behalf of employees for future purchases under the ESPP and is included in accrued compensation on the condensed balance sheets. The Company issued and sold no shares under the ESPP during the three and six months ended June 30, 2024 and 2023.