IMRX Immuneering Corp - 8-K

Item 8.01 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 survival (“mOS”) was observed in the intent-to-treat population of 55 patients dosed at the 320 mg once-daily dose level of atebimetinib in combination with mGnP (the “320 mg ITT Population”), with median follow-up time of 11.6 months. The standard of care (described below) reported a 8.5 month mOS. As of the Cutoff Date, the median progression free survival ("mPFS") of the 320 mg ITT Population was 8.3 months. As of the Cutoff Date, in response evaluable patients from the 320 mg ITT Population, a 36% (18/50 patients) overall response rate ("ORR") and 82% (41/50 patients) disease control rate ("DCR") was observed. Additionally, as of the Cutoff Date, among the subset of patients from the 320 mg ITT Population for which sufficient weight stability data was available, 84% of such patients either gained weight or else were within 5% of original recorded baseline weight.

The data reported by the Company included patients from same patient cohort (N=34) as the Company previously reported in January 2026, as well as an additional 21 patients, together comprising the full 320 mg ITT Population.

The estimates of (and other references to) standard of care set forth above with respect to mOS data were reported out directly from the publicly available third-party MPACT pivotal trial data for gemcitabine/nab-paclitaxel. The Company’s Phase 1/2a clinical trial of atebimetinib does not include a head-to-head comparison against any other agents, and caution should be exercised when comparing data across trials.

The Company also announced that, as of the Cutoff Date, atebimetinib in combination with mGnP continued to be generally well tolerated. As of the Cutoff Date, Grade ≥ 3 treatment-emergent adverse events (“TEAEs”) observed in 10% or greater of patients in the 320 mg ITT Population consisted of Anemia (nine patients or 16%) and Neutropenia (ten patients or 18%). Grade ≥ 3 TEAEs observed in less than 10% of patients in the 320 mg ITT Population included Rash (5%), Fatigue (2%), Vomiting (2%), and Oedema Peripheral (2%). No Grade 5 TEAEs were observed in this patient population and no new safety signals were identified.

The Company also announced that it expects the following anticipated milestones:

• In mid-2026, dosing the first patient in a pivotal Phase 3 clinical trial of atebimetinib in combination with mGnP in first-line pancreatic cancer patients (known as MAPKeeper 301), with a topline data readout expected in mid-2028.

• In the second half of 2026, dosing the first patient in a clinical trial of atebimetinib in combination with Libtayo® in non-small cell lung cancer patients, with a preliminary data readout expected in late-2027.

• In the fourth quarter of 2026, additional pre-clinical data of atebimetinib in combination with anti-PD-1 in non-small cell lung cancer.

• In mid-2027, beginning IND-enabling studies for the Company's next Deep Cyclic Inhibition® product candidate program.

Forward-Looking Statements

This Current Report on Form 8-K (this "Current Report") contains forward-looking statements, including within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this Current Report that do not relate to matters of historical fact should be considered forward-looking statements, including, without limitation, statements regarding: the Company’s plans to develop, manufacture and commercialize its product candidates; the treatment potential of atebimetinib, alone or in combination with other agents, including with mGnP in first-line pancreatic cancer and with Libtayo in non-small cell lung cancer; the timing of the Company's planned preclinical studies and clinical trials (including a pivotal trial evaluating atebimetinib) and related patient dosing and data readouts; and the timing and content of the Company's future data releases and presentations.

These forward-looking statements are based only on the Company’s current expectations and are subject to inherent uncertainties, risks and assumptions that are difficult to predict. Factors that could cause actual results to differ include, but are not limited to, the important factors discussed under the caption “Risk Factors” in the Company’s Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2026, filed with the U.S. Securities and Exchange Commission (the “SEC”) on May 15, 2026, as such factors may be updated from time to time in the Company’s filings with the SEC, which could cause actual results to differ materially from those indicated by the forward-looking statements made in this Current Report. Any such forward-looking statements represent management’s estimates as of the date of this Current Report. While the Company may elect to update such forward-looking statements at some point in the future, except as required by law, it disclaims any obligation to do so, even if subsequent events cause the Company’s views to change. These forward-looking statements should not be relied upon as representing the Company’s views as of any date subsequent to the date of this Current Report.