of this Current Report, including Exhibit 99.1, is intended to be furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly provided by specific reference in such a filing.

Chief Financial Officer and Treasurer — Andrew Gengos: The Company appointed Andrew Gengos as the Chief Financial Officer and Treasurer, succeeding Mallory Morales.

Other Events. On June 1, 2026, Immuneering Corporation (the "Company") announced updated data from its ongoing Phase 2a clinical trial evaluating atebimetinib (formerly known as IMM-1-104), a once-daily oral mitogen-activated protein kinase kinase (or "MEK") inhibitor, in combination with modified Gemcitabine/nab-Paclitaxel (“mGnP”) in first-line pancreatic cancer patients. The Company announced that, as of a cutoff date of April 24, 2026 (the “Cutoff Date”), 17.3 month median overall surviva…

of this Current Report, including Exhibit 99.1, is intended to be furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly provided by specific reference in such a filing.

of this Current Report, including Exhibit 99.1, is intended to be furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly provided by specific reference in such a filing.

Other Events. On January 7, 2026, Immuneering Corporation (the "Company") announced updated interim data from its ongoing Phase 2a clinical trial evaluating atebimetinib (formerly known as IMM-1-104), a once-daily oral mitogen-activated protein kinase kinase (or MEK) inhibitor, in combination with modified Gemcitabine/nab-Paclitaxel (“mGnP”) in first-line pancreatic cancer patients. The Company announced that, as of a cutoff date of December 15, 2025 (the “Cutoff Date”), 64% overall survival…

of this Current Report, including Exhibit 99.1, is intended to be furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly provided by specific reference in such a filing.

Other Events. On August 13, 2025, the Company entered into an equity distribution agreement with Piper Sandler & Co. relating to the sale of shares of the Company's Class A common stock having a maximum aggregate offering price of up to $100,000,000 from time to time pursuant to at-the-market transactions (the "ATM Program"). As of the date of this report, the Company has not sold any shares under the ATM Program. In connection with the Offering, the Company (i) reduced the maximum aggregate…

Entry into a Material Definitive Agreement. On September 24, 2025, Immuneering Corporation (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Leerink Partners LLC and Oppenheimer & Co. Inc., as underwriters (the “Underwriters”), in connection with the public offering, issuance and sale by the Company of 18,959,914 shares of the Company’s Class A common stock, at a public offering price of $9.23 per share, pursuant to an effective shelf registration stat…

On September 24, 2025, the Company issued a press release announcing the entry into the Purchase Agreement, a copy of which is attached hereto as Exhibit 99.1.

Other Events. On September 24, 2025, the Company announced updated interim data from its ongoing Phase 2a clinical trial arm evaluating atebimetinib (formerly known as IMM-1-104), a once-daily oral mitogen-activated protein kinase kinase (or MEK) inhibitor, in combination with modified Gemcitabine/nab-Paclitaxel (“mGnP”) in first-line pancreatic cancer patients, which is part of Company’s ongoing Phase 1/2a clinical trial of atebimetinib in patients with advanced RAS- and/or RAF-mutant solid…

Entry Into a Material Definitive Agreement. On September 24, 2025, Immuneering Corporation (the “Company”) entered into a securities purchase agreement (the “Purchase Agreement”) with Aventis Inc. (the “Investor”), a wholly owned subsidiary of Sanofi, a French société anonyme, pursuant to which the Company, in a private placement transaction (the “Private Placement”), agreed to issue and sell to the Investor $25.0 million of shares (the “Class A Shares”) of the Company’s Class A common stock,…

Entry into a Material Definitive Agreement. On August 21, 2025, Immuneering Corporation (the “Company”) entered into a Securities Purchase Agreement (the “Purchase Agreement”) with the purchasers party thereto (the “Investors”), pursuant to which the Company agreed to sell securities to the Investors in a private placement (the “Private Placement”). The Purchase Agreement provided for the sale and issuance by the Company of: (i) an aggregate of 6,329,113 shares (the “Shares”) of the Company’s…

Unregistered Sales of Equity Securities. The information contained in

Other Events. On August 21, 2025, the Company issued a press release announcing the pricing of the Private Placement described above in

of this Current Report, including Exhibit 99.1, is intended to be furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly provided by specific reference in such a filing.

Other Events. On June 17, 2025, Immuneering Corporation (the "Company", "we", "us" and "our") announced interim data from its ongoing Phase 2a clinical trial arm evaluating atebimetinib (formerly known as IMM-1-104), a once-daily oral mitogen-activated protein kinase kinase ("MEK") inhibitor, in combination with modified Gemcitabine/nab-Paclitaxel ("mGnP") in first-line pancreatic cancer patients (the "mGnP Arm"), which is part of Company's ongoing Phase 1/2a clinical trial of atebimetinib in…

of this Current Report, including Exhibit 99.1, is intended to be furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly provided by specific reference in such a filing.

of this Current Report, including Exhibit 99.1, is intended to be furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly provided by specific reference in such a filing.

Other Events. Recent Developments On January 7, 2025, Immuneering Corporation (the "Company", "we", "us" and "our") announced updated and initial interim response and safety data from three Phase 2a arms of the Company's ongoing Phase 1/2a clinical trial of IMM-1-104 in patients with advanced RAS-mutant solid tumors, and also announced initial interim pharmacokinetic (“PK”), pharmacodynamic (“PD”) and safety data from the Phase 1 portion of the Company's ongoing Phase 1/2a clinical trial of I…

of this Current Report, including Exhibit 99.1, is intended to be furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly provided by specific reference in such a filing.

Director — Thomas J. Schall, Ph.D.: Dr. Thomas J. Schall was elected to the Board and appointed to the Compensation Committee.

Other Events. Recent Developments On September 12, 2024, Immuneering Corporation (the "Company", "we", "us" and "our") announced initial response data for the first five patients treated with IMM-1-104 in combination with modified gemcitabine/nab-paclitaxel in first-line pancreatic cancer, part of the Phase 2a portion of the Company's Phase 1/2a clinical trial of IMM-1-104 in advanced RAS-mutant solid tumors. The Company announced that as of September 12, 2024, of the five initial patients ev…

of this Current Report, including Exhibit 99.1, is intended to be furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly provided by specific reference in such a filing.

The filing describes a repricing of underwater stock options for certain employees and service providers.