Stock-based Compensation

3 Months Ended

Mar. 31, 2026

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”), restricted stock units (“RSUs”), performance-based restricted stock units (“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 vest over a three-year performance period, with vesting subject to the achievement of the associated performance condition. On January 1, 2026, the Company reserved an additional 1,062,567 shares of common stock for issuance under the 2021 Plan representing 5% of the total common shares outstanding as of December 31, 2025. On January 1, 2026 the Company also reserved 212,513 additional shares under the 2021 ESPP representing 1% of the total common shares outstanding as of December 31, 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, no shares were issued for both the three months ended March 31, 2026 and 2025.

As of March 31, 2026, 2,390,019 and 413,346 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 condensed consolidated statements of operations and comprehensive loss was as follows (in thousands):


	Three Months Ended March 31,
	2026		2025
Research and development	$	2,201	$	2,388
General and administrative	2,094		3,636
Total stock-based compensation expense	$	4,295	$	6,024

At March 31, 2026, total stock-based compensation cost related to unvested awards not yet recognized was $40.0 million, which is expected to be recognized over a remaining weighted-average period of 2.9 years.

Performance-Based Stock Options

During the three months ended March 31, 2025, the Company granted performance-based stock options (“PBOs”) to certain key employees. 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 March 31, 2026, 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, 2025(1)	98,868	$	11.07	9.11	$	1,949
Granted	—	$	—
Exercised	—	$	—
Canceled or forfeited	—	$	—
PBOs outstanding as of March 31, 2026	98,868	$	11.07	8.86	$	889
PBOs exercisable as of March 31, 2026	—	$	—	—	$	—

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

Performance-Based Restricted Stock Units

PSUs 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 March 31, 2026, representing 29,118 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 approximately $0.2 million and $0.5 million for the three months ended March 31, 2026 and 2025, respectively.

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, 2025(1)	65,518	$	37.51
PSUs granted	—	$	—
PSUs vested	(29,120)	$	36.00
PSUs forfeited or canceled	—	$	—
Unvested PSUs as of March 31, 2026	36,398	$	38.72

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

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, 2025	306,415	$	19.77
RSUs granted	265,716	$	23.90
RSUs vested	(28,130)	$	25.64
RSUs forfeited or canceled	(12,459)	$	19.31
Unvested RSUs as of March 31, 2026	531,542	$	21.54

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, 2025	2,696,444	$	40.32	6.14	$	17,090
Granted	620,000	$	24.11
Exercised	(2,348)	$	11.07
Canceled or forfeited	(94,722)	$	43.39
Options outstanding as of March 31, 2026	3,219,374	$	37.13	6.83	$	6,959
Options exercisable as of March 31, 2026	1,630,342	$	52.13	4.52	$	2,972

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:


	Three Months Ended March 31,
	2026		2025
Risk-free interest rate	3.81	%	4.39	%
Expected volatility	91.9	%	83.5	%
Expected term (in years)	6.04		6.08
Expected dividend yield	0	%	0	%

The weighted-average grant date fair value of options granted for the three months ended March 31, 2026 and 2025 were $18.55 per share and $8.19 per share, respectively.