Stock-based Compensation

12 Months Ended

Dec. 31, 2025

Share-Based Payment Arrangement [Abstract]

Equity Incentive and Employee Stock Purchase Plans

In June 2021, the Company adopted the 2021 Equity Incentive Plan (“2021 Plan”) and the 2021 Employee Stock Purchase Plan (“2021 ESPP”), both of which became effective on the date of the underwriting agreement related to the Company’s IPO. Under the 2021 Plan, the Company may grant incentive stock options, non-statutory stock options, restricted stock awards (“RSAs”), RSUs, PSUs, stock appreciation rights, performance awards and other stock-based awards. The term of any stock option granted under the 2021 Plan cannot exceed ten years. Generally, stock options (other than performance-based stock options, discussed below) and RSU awards granted by the Company vest over four years,

but may be granted with different vesting terms. PSUs and PBOs generally have a three-year performance period, with vesting subject to the achievement of the associated performance condition. On January 1, 2025, the Company reserved an additional 737,188 shares of common stock for issuance under the 2021 Plan representing 5% of the total common shares outstanding as of December 31, 2024. The Company’s board of directors elected to reserve no additional shares under the 2021 ESPP for the year beginning January 1, 2025.

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 earnings, subject to plan limitations. Unless otherwise determined by the Company’s board of directors, employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first date of an offering or on the purchase date. Under the 2021 ESPP, 51,799, 47,738 and 49,320 shares were issued for the years ended December 31, 2025, 2024 and 2023, respectively.

As of December 31, 2025, 2,105,974 and 200,833 shares were available for future issuance pursuant to the 2021 Plan and the 2021 ESPP, respectively.

Stock-based Compensation Expense

Stock-based compensation expense by classification included within the consolidated statements of operations and comprehensive loss was as follows (in thousands):


	Year Ended December 31,
	2025		2024		2023
Research and development	$	28,743	$	14,577	$	18,207
General and administrative	13,086		18,567		28,877
Total stock-based compensation expense	$	41,829	$	33,144	$	47,084

Research and development stock-based compensation expense for the year ended December 31, 2025 reflects the expense associated with an ICT equity milestone deemed probable of achievement of $19.7 million. See Note 3, Acquisitions, for additional information regarding ICT equity milestones. At December 31, 2025, total stock-based compensation cost related to unvested awards not yet recognized was $26.6 million, which is expected to be recognized over a remaining weighted-average period of 2.4 years.

Stock Options Repricing

In November 2023, the Board of Directors of the Company approved, effective November 16, 2023, a one-time repricing of certain stock option awards that had been granted to date under the 2021 Plan and 2018 Plan. The repricing impacted stock options with exercise prices greater than $47.40 held by employees who remained employed as-of November 16, 2023 and were not impacted by the Company’s November 16, 2023 reduction in workforce. The original exercise prices of the repriced stock options ranged from $52.20 to $359.00 per share for 200 total grantees with 1,170,843 shares repriced. Each stock option was repriced to have a per share exercise price of $37.40, which was the closing price of the Company’s common stock on November 16, 2023. To receive the new exercise price, option holders were required to be employed with the Company through November 15, 2024. Additionally, the vesting schedule for the unvested shares underlying repriced stock options held by executives at the level of senior vice president and above was extended for an additional year. There were no changes to the vesting schedules for employees below the level of senior vice president. No changes were made to the expiration dates of or number of shares underlying the repriced stock options. Incremental stock-based compensation expense resulting from the repricing was $8.9 million in the aggregate. Expense for vested awards was recognized through November 15, 2024 and expense for unvested awards will be recognized over the remaining service life of the option.

Performance-Based Stock Options

During the year ended December 31, 2025, the Company granted performance-based stock options to certain key employees. Performance-based stock options (“PBOs”) awarded to employees have a three-year performance period and vest based upon the Company’s performance against a two and three-year relative total shareholder return (“rTSR”) metric or upon the achievement of certain clinical development milestones. Certain of the clinical development milestones were probable of achievement as of December 31, 2025, representing 7,062 shares. For the portion of PBOs subject to certain clinical development milestones, 50% vest upon the achievement of the applicable milestone and the remaining 50% vest upon the earlier of (a) one year of service from the date of such achievement and (b) the end of the three-year performance period. The vesting of all PBOs granted is also subject to the respective employee’s continued employment. The Company

valued the portion of the PBOs subject to the rTSR metric using a Monte Carlo simulation. The number of PBOs granted subject to the rTSR metrics represents the target number of options that are eligible to be earned based on the achievement of the metrics established at the beginning of the performance period, which ends on December 31st of the three-year performance period. For the portion of PBOs subject to the rTSR metrics, employees may ultimately earn between zero and 200% of the target number of PBOs granted based on the degree of achievement of the applicable rTSR metric. Accordingly, additional PBOs may be issued or currently outstanding PBOs may be cancelled upon final determination of the degree of achievement of the applicable rTSR metric. PBOs have contractual terms of ten years from grant date.

A summary of the Company’s PBO activity was as follows:


	Number of PBOs	Weighted-Average Exercise Price Per Share		Weighted- Average Remaining Contractual Life (in years)	Aggregate Intrinsic Value (in thousands)
PBOs outstanding as of December 31, 2024	—	$	—	—	$	—
Granted(1)	138,250	$	11.07
Exercised	—	$	—
Canceled or forfeited	(39,382)	$	11.07
PBOs outstanding as of December 31, 2025	98,868	$	11.07	9.11	$	1,949
PBOs exercisable as of December 31, 2025	—	$	—	—	$	—

(1) PBO grants reflect the target number of shares eligible to be earned at the time of grant.

Performance-Based Restricted Stock Units

During the year ended December 31, 2024, the Company granted PSU awards to certain key employees. PSUs awarded to employees have a three-year performance period and vest based upon the Company’s performance against a two and three-year rTSR metric, or upon the achievement of certain clinical development milestones. Certain of the clinical development milestones were determined to be probable of achievement as of December 31, 2025, representing 58,238 shares. For the portion of PSUs subject to certain clinical development milestones (other than the bonus clinical development milestone), 50% vest upon the achievement of the applicable milestone, and the remaining 50% vest upon the earlier of (a) one year of service from the date of such achievement and (b) the end of the three-year performance period. The vesting of all PSU awards granted is also subject to the respective employee’s continued employment. The Company valued the portion of PSUs subject to the rTSR metric using a Monte Carlo simulation. The number of PSUs granted subject to the rTSR metrics represents the target number of units that are eligible to be earned based on the achievement of the metrics established at the beginning of the performance period, which ends on December 31st of the three-year performance period. For the portion of PSUs subject to the rTSR metrics, employees may ultimately earn between zero and 200% of the target number of PSUs granted based on the degree of achievement of the applicable rTSR metric. Accordingly, additional PSUs may be issued or currently outstanding PSUs may be cancelled upon final determination of the degree of the achievement of the applicable rTSR metric. Stock-based compensation expense recognized for the PSU awards was $1.7 million and $1.9 million for the years ended December 31, 2025 and 2024, respectively and zero for the year ended December 31, 2023.

A summary of the Company’s PSU activity was as follows:


	Performance-Based Restricted Stock Units Outstanding	Weighted-Average Value at Grant Date Per Share
Unvested PSUs as of December 31, 2024	135,170	$	37.63
PSUs granted(1)	—	$	—
PSUs vested	(33,623)	$	36.00
PSUs forfeited or canceled	(36,029)	$	39.36
Unvested PSUs as of December 31, 2025	65,518	$	37.51

(1) PSU grants reflect the target number of shares eligible to be earned at the time of grant.

The fair value of PSUs vested during the year ended December 31, 2025 was $0.4 million and was zero during both the years ended December 31, 2024 and 2023. As of December 31, 2025, certain of the PSU metrics have been met, resulting in 33,623 shares vesting.

Restricted Stock Units

A summary of the Company’s RSU activity was as follows:


	Restricted Stock Units Outstanding	Weighted-Average Value at Grant Date Per Share
Unvested RSUs as of December 31, 2024	281,190	$	34.40
RSUs granted	287,735	$	11.82
RSUs vested	(139,928)	$	25.66
RSUs forfeited or canceled	(122,582)	$	24.88
Unvested RSUs as of December 31, 2025	306,415	$	19.77

The fair value of RSUs vested during the years ended December 31, 2025, 2024 and 2023 was $1.7 million, $2.0 million and $1.4 million, respectively.

Stock Options

A summary of the Company’s stock option activity was as follows:


	Number of Stock Options	Weighted-Average Exercise Price Per Share		Weighted- Average Remaining Contractual Life (in years)	Aggregate Intrinsic Value (in thousands)
Options outstanding as of December 31, 2024	2,239,354	$	49.80	6.62	$	1,479
Granted	864,491	$	14.25
Exercised	(3,750)	$	11.07
Canceled or forfeited	(403,651)	$	36.96
Options outstanding as of December 31, 2025	2,696,444	$	40.32	6.14	$	17,090
Options exercisable as of December 31, 2025	1,660,556	$	52.51	4.40	$	4,704

The fair value of stock options and performance-based stock options granted to employees, directors and consultants valued using the Black-Scholes option pricing model was estimated on the date of grant using the following weighted-average assumptions:


	Year Ended December 31,
	2025		2024		2023
Risk-free interest rate	4.05	%	4.17	%	4.13	%
Expected volatility	85.7	%	75.9	%	88.0	%
Expected term (in years)	6.04		5.89		6.06
Expected dividend yield	0	%	0	%	0	%

The weighted-average grant date fair value of options granted for the years ended December 31, 2025, 2024 and 2023 was $10.31 per share, $26.00 per share and $33.80 per share, respectively. The intrinsic value of options exercised during the years ended December 31, 2025, 2024 and 2023 was $0.1 million, $2.9 million and $6.5 million, respectively.