Note 12. Stock-Based Compensation

The Company operates three stock-based compensation plans as of June 30, 2026:

2019 Equity Incentive Plan (Quince)

On December 4, 2014, the Company’s stockholders approved the 2014 Stock Plan (“2014 Plan”), and on April 25, 2019 amended, restated and re-named the 2014 Plan as the 2019 Equity Incentive Plan (the “Quince 2019 Plan”), which became effective as of May 7, 2019, the day prior to the effectiveness of the registration statement filed in connection with the IPO. The remaining shares available for issuance under the 2014 Plan were added to the shares reserved for issuance under the Quince 2019 Plan.

The Quince 2019 Plan provides for the grant of stock options (including incentive stock options and non-qualified stock options), stock appreciation rights, restricted stock, RSUs, performance units, and performance shares to the Company’s employees, directors, and consultants. As of June 30, 2026, the maximum aggregate number of shares that may be issued under the Quince 2019 Plan is 78,309 shares of the Company’s common stock. In addition, the number of shares available for issuance under the Quince 2019 Plan will be annually increased on the first day of each fiscal years beginning with fiscal 2020, by an amount equal to the least of (i) 10,732 shares of common stock; (ii) 4% of the outstanding shares of its common stock as of the last day of its immediately preceding fiscal year; and (iii) such other amount as the Board of Directors may determine.

The Quince 2019 Plan may be amended, suspended or terminated by the Board of Directors at any time, provided such action does not impair the existing rights of any participant, subject to stockholder approval of any amendment to the Quince 2019 Plan as required by applicable law or listing requirements. Unless sooner terminated by the Company's Board of Directors, the Quince 2019 Plan will automatically terminate on April 23, 2029.

As of June 30, 2026, the Company had 10,510 shares available for future issuance under the Quince 2019 Plan.

Stock Options

Stock options under the Quince 2019 Plan may be granted for periods of up to 10 years and at prices no less than 100% of the fair market value of the shares on the date of grant. If, at the time of grant, the optionee directly owns stocks representing more than 10% of the voting power of all our outstanding capital stock, the exercise price for these options must be at least 110% of the fair value of the underlying common stock. Stock options granted to employees and non-employees generally have a maximum term of ten years and vest over four years from the vesting commencement date, of which 25% vest on the one-year anniversary of the vesting commencement date, and 75% vest in equal monthly installments over the remaining three years or monthly vesting over 3 to 4 years. We may grant options with different vesting terms from time to time. Unless an employee's or non-employee's termination is due to cause, disability or death, upon termination of service, any unexercised vested options will be forfeited at the end of the three months from the termination date or expiration of the option, whichever is earlier.

For the three and six months ended June 30, 2026, the Company recognized stock-based compensation expense of $0.7 million and $1.6 million, respectively, related to options granted to employees and non-employees. For the three and six months ended June 30, 2025, the Company recognized stock-based compensation expense of $0.8 million and $1.7 million, respectively, related to options granted to employees and non-employees. The compensation expense is allocated on a departmental basis, based on the classification of the option holder. No income tax benefits have been recognized in the condensed consolidated statements of operations and comprehensive loss for stock-based compensation arrangements. As of June 30, 2026, total unamortized employee stock-based compensation was $7.2 million, which is expected to be recognized over the remaining estimated vesting period of 1.2 years.

The weighted average grant date fair value per share of stock options granted during the six months ended June 30, 2026 and 2025 was $507.87 and $419.35, respectively.

For the six months ended June 30, 2026, in connection with the separation of employees as part of our restructuring activities, the Company extended the post-termination exercise window from 90 days to five years for separated employees and for those with consulting agreements allowed awards to continue vesting through term of the agreements. The Company recorded stock-based compensation expense related to the modification of these awards of $0.1 million.

2019 Equity Incentive Plan (Novosteo)

On May 19, 2022, in accordance with the terms of Agreement and Plan of Merger and Reorganization between the Company, Novosteo, Inc., and the other parties thereto, the Company assumed the 2019 Novosteo, Inc. Equity Incentive Plan (the "2019 Novosteo Plan"). The 2019 Novosteo Plan provides for the grant of stock options (including incentive stock options and non-qualified stock options), stock appreciation rights, restricted stock, RSUs, performance units, and performance shares to the Novosteo legacy employees. On the closing date, each outstanding Novosteo stock option granted under Novosteo’s equity compensation plans was converted into a corresponding stock option with the number of shares underlying such option and the applicable exercise price adjusted based on the exchange ratio of 0.0911. Each such converted stock option continues to be subject to substantially the same terms and conditions as applied to the corresponding Novosteo stock option prior to the acquisition. The maximum aggregate number of shares that may be issued under the 2019 Novosteo Plan is 2,725 shares of the Company’s common stock.

The 2019 Novosteo Plan may be amended, suspended or terminated by the Board of Directors at any time, provided such action does not impair the existing rights of any participant, subject to stockholder approval of any amendment to the 2019 Novosteo Plan as required by applicable law or listing requirements. Unless sooner terminated by the Board of Directors, the 2019 Novosteo Plan will automatically terminate on May 20, 2029.

Stock options under the 2019 Novosteo Plan may be granted for periods of up to 10 years and at prices no less than 100% of the fair market value of the shares on the date of grant. If, at the time of grant, the optionee directly owns stocks representing more than 10% of the voting power of all our outstanding capital stock, the exercise price for these options must be at least 110% of the fair value of

the underlying common stock. Stock options granted to employees and non-employees generally have a maximum term of ten years and vest over four years from the vesting commencement date, of which 25% vest on the one-year anniversary of the vesting commencement date, and 75% vest in equal monthly installments over the remaining three years or monthly vesting over 3 to 4 years. We may grant options with different vesting terms from time to time. Unless an employee's or non-employee's termination is due to cause, disability or death, upon termination of service, any unexercised vested options will be forfeited at the end of the three months from the termination date or expiration of the option, whichever is earlier.

As of June 30, 2026, the Company had 960 shares available for future issuance under the 2019 Novosteo Plan.

For the three and six months ended June 30, 2026, the Company recognized stock-based compensation expense of $0 and $44 thousand, respectively, related to options granted to employees and non-employees for the 2019 Novosteo Plan. For the three and six months ended June 30, 2025, the Company recognized stock-based compensation expense of $48 thousand and $97 thousand, respectively, related to options granted to employees and non-employees for the 2019 Novosteo Plan. The compensation expense is allocated on a departmental basis, based on the classification of the option holder. No income tax benefits have been recognized in the condensed consolidated statements of operations and comprehensive loss for stock-based compensation arrangements. As of June 30, 2026, there was no total unamortized employee stock-based compensation.

Restricted Stock Awards

There was no restricted stock awards activity during the six months ended June 30, 2026.

For the three and six months ended June 30, 2026, the Company recognized no stock-based compensation expense related to restricted stock awards. For the three and six months ended June 30, 2025, the Company recognized stock-based compensation expense of $0.1 million and $0.2 million related to restricted stock awards. The compensation expense is allocated on a departmental basis, based on the classification of the award holder. No income tax benefits have been recognized in the condensed consolidated statement of operations and comprehensive loss for stock-based compensation arrangements. The fair value of vested restricted stock awards was $0.1 million and $0.2 million for the three and six months ended June 30, 2025, respectively.

2022 Inducement Plan

On May 9, 2022, the Company's Board of Directors approved 20,000 shares of common stock, that may be offered or issued under the Quince Therapeutics, Inc. 2022 Inducement Plan (the "2022 Inducement Plan"). The 2022 Inducement Plan was adopted by the independent members of the Board of Directors without stockholder approval pursuant to Rule 5635(c)(4) of the Nasdaq Listing Rules (“Nasdaq Rule 5635(c)(4)”). In accordance with Nasdaq Rule 5635(c)(4), awards under those plans may only be made to an employee who has not previously been an employee or member of the Board of Directors or of any board of directors of any parent or subsidiary of the Company, or following a bona fide period of non-employment by the Company or a parent or subsidiary, if he or she is granted

such award in connection with his or her commencement of employment with the Company or a subsidiary and such grant is an inducement material to his or her entering into employment with the Company or such subsidiary. The terms and conditions of the 2022 Inducement Plan are substantially similar to those of the Quince 2019 Plan.

Options under the 2022 Inducement Plan may be granted for periods of up to 10 years at prices no less than 100% of the fair market value of the shares on the date of grant. Options granted to employees may have different performance goals or other vesting provisions (including continued employment) in accordance with the applicable award agreement. Unless an employee's termination service is due to disability or death, upon termination of service, any unexercised vested options will be forfeited at the end of the three months from the date of termination or expiration of the option, whichever is earlier.

As of June 30, 2026, the Company had 8,333 shares available for future issuance under the 2022 Inducement Plan.

For the three and six months ended June 30, 2026, the Company recognized stock-based compensation expense of $0.2 million and $0.5 million, respectively, related to options granted to employees for the 2022 Inducement Plan. For the three and six months ended June 30, 2025, the Company recognized stock-based compensation expense of $0.3 million and $0.7 million, respectively, related to options granted to employees for the 2022 Inducement Plan. The compensation expense is allocated on a departmental basis, based on the classification of the option holder. No income tax benefits have been recognized in the condensed consolidated statements of operations and comprehensive loss for stock-based compensation arrangements. As of June 30, 2026, there was no total unamortized employee stock-based compensation.

Orphai Equity Incentive Plans

In connection with the Orphai Acquisition, the Company assumed all outstanding and unexercised stock options previously granted by Orphai under its 2013 Employee, Director, and Consultant Equity Incentive Plan (the "2013 Orphai Plan"), as amended, and its 2026 Stock Incentive Plan (the "2026 Orphai Plan") (collectively, the "Orphai Equity Incentive Plans"), whether or not vested as of the acquisition date.

Under the terms of the Merger Agreement, each Orphai stock option was converted into an option to purchase shares of the Company's common stock, with (i) the number of shares subject to each option determined by multiplying the number of shares subject to the original Orphai option by an exchange ratio of 0.6935, rounded down to the nearest whole share, and (ii) the per-share exercise price determined by dividing the original per-share exercise price by the same exchange ratio. The vesting schedule and remaining contractual term of each replacement award were not modified in connection with the assumption, and no vesting was accelerated.

For the three and six months ended June 30, 2026, the Company recognized stock-based compensation expense of $0.5 million, related to options granted to employees and non-employees. The compensation expense is allocated on a departmental basis, based on the classification of the option holder. No income tax benefits have been recognized in the condensed consolidated statements of operations and comprehensive loss for stock-based compensation arrangements. As of June 30, 2026, total unamortized employee stock-based compensation was $0.1 million, which is expected to be recognized over the remaining estimated vesting period of 0.13 years.

The weighted average grant date fair value per share of stock options assumed during the six months ended June 30, 2026 was $19.59.

For the three and six months ended June 30, 2026, the Company recognized stock-based compensation expense of $10.7 million, related to options granted to employees and non-employees. The compensation expense is allocated on a departmental basis, based on the classification of the option holder. No income tax benefits have been recognized in the condensed consolidated statements of operations and comprehensive loss for stock-based compensation arrangements. As of June 30, 2026, total unamortized employee stock-based compensation was $10.5 million, which is expected to be recognized over the remaining estimated vesting period of 1.38 years.

The weighted average grant date fair value per share of stock options assumed during the six months ended June 30, 2026 was $19.80.

Stock-Based Compensation Expense