In September 2023, the Company adopted the 2023 Equity Incentive Plan (the 2023 Plan) that became effective in connection with the Company’s IPO. The 2023 Plan provides for the grant of stock options, restricted stock awards, restricted stock unit awards, and other stock-based awards to employees, directors, and non-employee service providers of the Company.

Awards granted under the 2023 Plan expire no later than ten years from the date of grant. The price of stock options shall not be less than 100% of the estimated fair value on the date of grant and typically vest over a four-year period although may be granted with different vesting terms. The 2023 Plan initially reserved 16,373,061 shares of common stock for the issuance of future awards and provides for an automatic annual increase in the number of shares of common stock reserved for future issuance under the 2023 Plan.

In September 2023, the Company adopted the 2023 Employee Share Purchase Plan (the 2023 ESPP) that became effective in connection with the Company’s IPO. The 2023 ESPP initially reserved 1,526,984 shares of common stock for the issuance of future awards and provides for an automatic annual increase in the number of shares of common stock reserved for future issuance under the 2023 ESPP. As of September 30, 2024, no shares have been issued under the ESPP.

In January 2020, the Company adopted the 2020 Equity Incentive Plan (the 2020 Plan) that provides for the grant of stock options, restricted stock awards, restricted stock unit awards, and other stock-based awards to employees, directors, and non-employee service providers of the Company. The 2020 Plan was suspended in connection with the Company’s IPO and no further grants will be made under the 2020 Plan. The 2020 Plan continues to govern the terms and conditions of outstanding awards granted under the 2020 Plan.

Upon the closing of the BlackThorn acquisition in September 2020, the Company assumed BlackThorn’s 2015 Equity Incentive Plan (the 2015 Plan, and collectively with the 2020 Plan and 2023 Plan, the Plans), pursuant to which outstanding stock options previously granted under the 2015 Plan converted into stock options to purchase common stock of the Company, which remain subject to the terms and conditions of the 2015 Plan. The 2015 Plan was suspended in connection with the closing of the acquisition of BlackThorn in September 2020.

Stock Option Activity


	Outstanding Stock Options			Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Term (years)		Aggregate Intrinsic Value
	(in thousands, except per share amounts and years)
Outstanding as of December 31, 2023		13,783		$	6.39		8.7	$	146,966
Granted		3,557			16.23
Exercised		(1,664	)		3.76
Canceled and forfeited		(1,368	)		7.52
Expired		(137	)		3.62
Outstanding as of September 30, 2024		14,171		$	9.08		8.5	$	72,957
Vested as of September 30, 2024		4,688		$	5.64		7.7	$	36,184
Exercisable as of September 30, 2024		4,732		$	5.63		7.7	$	36,565

The stock option activity table above excludes options granted to purchase 446,068 shares of common stock that were originally granted with market conditions to one of the Company’s executives.

The Company’s Plans allow for the grant of restricted common stock and restricted stock units to certain employees, executives, non-employee scientific advisors, and third-party service providers. The restrictions lapse over time primarily according to service-based vesting conditions of each award. In the event of a voluntary or involuntary termination of the holder’s continuous provision of services to the Company, any unvested portion of the restricted stock award is automatically forfeited.

The following table summarizes the Company’s restricted stock activity:


	Shares of Restricted Common Stock			Weighted- Average Grant Date Fair Value Per Share		Shares of Restricted Stock Units			Weighted- Average Grant Date Fair Value Per Share
	(in thousands, except per share amounts)
Outstanding and unvested as of December 31, 2023		840		$	6.11		353		$	17.00
Granted		414			14.22		1,265			17.43
Vested		(583	)		8.44		(88	)		17.00
Forfeited and expired		—			—		—			—
Cancelled		(263	)		6.41		(72	)		18.07
Outstanding and unvested as of September 30, 2024		408		$	10.82		1,458		$	17.32

In 2020, the Company approved grants of 700,965 stock options and 892,136 shares of restricted common stock to certain of the Company’s scientific advisors, which vest based on the achievement of performance conditions to be determined and continued service to the Company.

As of September 30, 2024, the Company’s board of directors established performance conditions for 401,462 stock options, such that the criteria for establishing a grant date, and accordingly a measurement date, were met for these performance stock options and the remaining 299,503 stock options with performance conditions to be established were cancelled in July 2023 because certain of the Company’s scientific advisors were terminated.

As of September 30, 2024 the performance conditions for 637,240 shares of restricted common stock were established or amended, and the remaining 254,896 shares of restricted common stock with performance conditions to be established were cancelled in July 2023 because the consulting agreements with certain of the Company’s scientific advisors were terminated.

In April 2024, the Company amended the terms of two restricted stock purchase agreements of 127,448 shares each, with performance conditions that had never been set, such that they lapsed in their entirety and become fully vested and unrestricted effective April 1, 2024. The modifications were determined to be improbable-to-probable modifications which resulted in $3.6 million in total expense that was fully recognized during the three months ended June 30, 2024.

Additionally, in April 2024, the Company revised the vesting schedule for two other restricted stock purchase agreements each consisting of 79,656 shares. These agreements originally had performance condition tranches that had been set but were not probable of being met and were amended to instead vest monthly over three years, subject to continued service. The modification of the performance-based tranches were deemed to be improbable-to-probable modifications. Total compensation cost of $2.3 million, equal to the modification date fair value, will be recognized over the remaining service period.

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


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
	(in thousands)				(in thousands)
Research and development	$	3,893	$	2,184	$	13,857	$	5,142
General and administrative		6,053		4,267		16,230		6,047
Total stock-based compensation	$	9,946	$	6,451	$	30,087	$	11,189

As of September 30, 2024, there was $77.6 million and $26.2 million of unrecognized stock-based compensation related to stock options and restricted stock outstanding, respectively, including stock options and restricted common stock for which achievement of milestones was not probable, which were expected to be recognized over a weighted-average remaining service period of 2.3 years and 3.0 years, respectively.