During 2015, the Company established the Long Term Incentive Plan (“Incentive Plan”), under which incentive stock options, nonqualified stock options, restricted stock or other awards may be awarded to employees, directors or consultants of the Company. The options typically vest over a four-year period. Upon the effectiveness of the Company’s 2021 Incentive Award Plan (the “2021 Plan”), the Company ceased granting awards under the Incentive Plan. However, the Incentive Plan continues to govern awards outstanding thereunder.

On July 23, 2021, the Company’s Board of Directors adopted, and on July 23, 2021 its stockholders approved, the 2021 Plan, which became effective on July 29, 2021. The 2021 Plan provides for the grant of incentive stock options, stock appreciation rights, restricted stock awards, restricted stock units, and other stock-based awards. The number of shares reserved for issuance under the 2021 Plan was initially equal to 2,590,000 plus an annual increase on the first day of each calendar year, beginning on January 1, 2022 and ending on and including January 1, 2031, equal to the lesser of (i) 4% of the aggregate number of shares of Class A common stock outstanding on the final day of the immediately preceding calendar year and (ii) such smaller number of shares of Class A common stock as determined by the Board of Directors. No more than 15,350,000 shares of Class A common stock may be issued under the 2021 Plan upon the exercise of

incentive stock options. Shares issued under the 2021 Plan may be authorized but unissued shares, shares purchased on the open market or treasury shares. If an award under the 2021 Plan expires, lapses or is terminated, exchanged for or settled in cash, surrendered, repurchased, cancelled without having been fully exercised/settled or forfeited, any unused shares subject to the award will, as applicable, become or again be available for new grants under the 2021 Plan. In addition, shares subject to stock options issued under the Incentive Plan may become available for issuance under the 2021 Plan to the extent such stock options are canceled, forfeited, exchanged, settled in cash or otherwise terminated. As of September 30, 2025, there were 969,941 shares available for future issuance under the 2021 Plan.

On July 23, 2021, the Company’s Board of Directors adopted, and on July 23, 2021 its stockholders approved, the 2021 Employee Stock Purchase Plan (the “2021 ESPP”), which became effective on July 29, 2021. A total of 250,000 shares of Class A common stock were initially reserved for issuance under this plan. The number of shares of Class A common stock that may be issued under the 2021 ESPP will automatically increase on the first day of each calendar year, beginning on January 1, 2022 and ending on and including January 1, 2031, equal to the lesser of (i) 1% of the shares of Class A common stock outstanding on the final day of the immediately preceding calendar year and (ii) such smaller number of shares of Class A common stock as determined by the Board of Directors, provided that not more than 3,340,000 shares of Class A common stock may be issued under the 2021 ESPP. As of September 30, 2025, there were 849,697 shares of common stock reserved for future issuance under the 2021 ESPP and 530,911 shares had been granted or purchased under the 2021 ESPP.

On May 21, 2024 (the “Effective Date”), based upon the recommendation of the Compensation Committee of the Company's Board of Directors, the Board of Directors approved an option repricing, in accordance with the 2021 Plan, which repricing was effected on the Effective Date. The repricing applied to options to purchase shares of the Company’s Class A common stock with an exercise price per share greater than $3.01 that were held by then current employees and certain non-employee service providers under the 2021 Plan (the “Eligible Options”), including E.B. Brakewood, the Company’s Chief Business Officer, and Michael Bookman, the Company's Chief Legal Officer.

Options held by Benjamin Zeskind, Ph.D., the Company’s President and Chief Executive Officer, Brett Hall, Ph.D., the Company's Chief Scientific Officer, and the non-employee members of the Board were not eligible for the repricing.

As a result of the option repricing, as of the Effective Date, the exercise price of all Eligible Options was reduced to $3.01 per share, which represented approximately two times the closing trading price of the Company’s Class A common stock on the Nasdaq Global Market on the Effective Date; however, the exercise price for repriced options would revert to the original exercise price for any exercise occurring prior to June 30, 2025 (the "Retention Period"), unless there was a change of control of the Company or the option holder’s employment has been terminated (i) by the Company without cause or (ii) by reason of death or disability. The repriced options otherwise remain subject to their existing terms and conditions as set forth in the 2021 Plan and applicable award agreements. As of the Effective Date, outstanding options to purchase 2,986,354 shares were deemed Eligible Options and were repriced such that the exercise price per share for such outstanding options was reduced to $3.01 per share. There were no changes to the number of shares, the vesting schedule or the expiration date of the Eligible Options.

The effect of the option repricing resulted in a total incremental non-cash stock-based compensation expense of $0.6 million, which was calculated using the Black-Scholes option-pricing model, of which $0.2 million of the incremental non-cash stock-based compensation expense is associated with vested repriced options and will be recognized on a straight-line basis through the 13-month Retention Period. The remaining $0.4 million of the incremental non-cash stock-based compensation expense is associated with unvested repriced options and will be recognized as follows: (a) if the Retention Period is greater than the remaining original vesting period of the repriced option, the incremental cost will be amortized on a straight-line basis through the Retention Period end date or (b) if the Retention Period is less than the remaining original vesting term of the repriced option, the incremental cost will be amortized on a straight-line basis over the remaining original vesting period.

During the three and nine months ended September 30, 2025, the Company recognized incremental stock-based compensation expense of $32 thousand and $193 thousand, respectively, associated with the repricing which is included in general and administrative and research and development expense in the condensed consolidated statement of operations and comprehensive loss. During the three and nine months ended September 30, 2024, the Company recognized incremental stock-based compensation expense totaling $84 thousand and $120 thousand, respectively, associated with the repricing which is included in general and administrative and research and development expense in the condensed consolidated statement of operations and comprehensive loss.

On March 20, 2025, the Company’s Board of Directors adopted the Immuneering Corporation 2025 Employment Inducement Award Plan (the "Inducement Award Plan"), without stockholder approval pursuant to Rule 5635(c)(4) of the Nasdaq Stock Market LLC listing rules. The Inducement Award Plan provides for the grant of non-qualified stock options, stock appreciation rights, restricted stock awards, restricted stock units, and other stock-based awards. The number of shares reserved for issuance under the Inducement Award Plan was initially equal to 500,000 shares. Shares issued under the Inducement Award Plan may be authorized but unissued shares, shares purchased on the open market or treasury shares. If an award under the Inducement Award Plan expires, lapses or is terminated, exchanged for or settled in cash, surrendered, repurchased, cancelled without having been fully exercised/settled or forfeited, any unused shares subject to the award will, as applicable, become or again be available for new grants under the Inducement Award Plan. As of September 30, 2025, there were 382,000 shares available for future issuance under the Inducement Award Plan.

The Company recognized stock-based compensation expense of $1,456,080 and $4,673,290 during the three and nine months ended September 30, 2025, respectively. During the three and nine months ended September 30, 2024, the Company recognized stock-based compensation expense of $1,640,116 and $4,776,623, respectively. As of September 30, 2025, compensation expense remaining to be recognized for outstanding stock options was $7,761,498 and to be recognized over a weighted-average period of 2.42 years.

The fair value of options granted is calculated on the grant date using the Black-Scholes option valuation model. Prior to the Company’s IPO on August 3, 2021, the Company was a private company and thus lacks company-specific historical and implied volatility information. Therefore, it estimates its expected stock volatility based on the historical volatility of a publicly traded set of peer companies and expects to continue to do so until such time as it has adequate historical data regarding the volatility of its own publicly traded stock price. For the nine months ended September 30, 2025, the Company granted 2,362,294 shares of stock options at a weighted-average grant date fair value of $1.99.


	Nine Months Ended September 30,
	2025	2024

Weighted-average risk-free interest rate	3.76% - 4.55%	3.93% - 4.82%
Expected term (in years)	5.51 - 10.00	5.00 - 10.00
Expected dividend yield	0%	0%
Expected volatility	65.86% - 67.33%	66.08% - 69.85%


	Number of Options	Weighted- Average Exercise Price per Share		Weighted Average Remaining Contractual Term (in Years)	Aggregate Intrinsic Value

Outstanding at December 31, 2024	6,382,149	$	4.40
Granted	2,362,294	1.99
Exercised	(48,825)	2.84
Cancelled	(369,425)	2.90
Outstanding at September 30, 2025	8,326,193	$	3.81	7.36	$	29,535,941

Vested and exercisable at September 30, 2025	4,996,711	$	4.49	6.47	$	15,447,408


	Three Months Ended September 30,				Nine Months Ended September 30,
	2025		2024		2025		2024

Research and development	$	602,179	$	714,573	$	1,945,585	$	1,959,834
General and administrative	853,901		925,543		2,727,705		2,816,789
Total	$	1,456,080	$	1,640,116	$	4,673,290	$	4,776,623