Immuneering Announces Extraordinary 86% Overall Survival at 9 Months in First-Line Pancreatic Cancer Patients Treated With Atebimetinib + mGnP

Immuneering Corporation recently announced positive updated survival and safety data from its ongoing Phase 2a trial of atebimetinib (IMM-1-104) in combination with modified gemcitabine/nab-paclitaxel (mGnP) in first-line pancreatic cancer patients (N=34), with 9 months median follow up. The data, to be presented at the Pancreatic Cancer Action Network (PanCAN) Scientific Summit 2025, marks a milestone for the Company in the treatment of one of the deadliest and most treatment-resistant solid tumors. The Company also announced it will not be hosting its previously scheduled conference call.

“Overall survival is the gold standard in oncology and has been Immuneering’s goal from the very beginning. In cancer nothing matters more than keeping patients alive and helping them thrive. We are beyond thrilled to report that not only was our extraordinary 94% overall survival at 6 months sustained with additional follow up time, but that our observed 9-month overall survival of 86% shows an even larger gap with standard of care benchmarks,” said Ben Zeskind, Ph.D., CEO of Immuneering. “To combine such meaningful overall survival with such favorable tolerability has the potential to be truly game-changing for first-line pancreatic cancer patients.”

Extraordinary and Growing Survival Advantage Observed

Atebimetinib (320mg dosed once-daily) + mGnP demonstrated remarkable overall survival (OS) and progression-free survival (PFS) at 9 months median follow up in first-line pancreatic cancer patients (N=34). The MPACT pivotal trial for the standard of care, gemcitabine/nab-paclitaxel, reported significantly lower OS and PFS at 9 months.

• OS observed at 9 months was 86% in patients receiving atebimetinib + mGnP. The median OS was not yet reached as of the data cutoff date. The standard of care reported a ~47% OS at 9 months.
  -As previously reported, OS observed at 6 months was 94% in patients receiving atebimetinib + mGnP. The standard of care reported a 67% OS at 6 months.
• PFS observed at 9 months was 53% in patients receiving atebimetinib + mGnP. The standard of care reported a ~29% PFS at 9 months.
  -PFS observed at 6 months was 70% in patients receiving atebimetinib + mGnP. The standard of care reported a ~44% PFS at 6 months.
• Unless otherwise specified, all data are reported using a data cutoff date of August 26, 2025, from the same patient cohort (N=34) as previously reported in June 2025. The estimates of (and other references to) standard of care with respect to the nine-month follow-up data were extrapolated and reconstructed by the Company based on the publicly available third-party MPACT pivotal trial data for gemcitabine/nab-paclitaxel. The estimates of (and other references to) standard of care set forth above with respect to the six-month follow-up 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 believes these compelling updated survival data reflect the potential for a durable, compounding benefit with atebimetinib + mGnP.

Favorable Tolerability Profile Observed:

• As of the data cutoff date, Atebimetinib (320mg dosed once-daily) + mGnP continued to demonstrate a favorable tolerability profile in first-line pancreatic cancer patients (N=34), with only two categories of adverse events observed at the Grade 3 level in more than 10% of patients (neutropenia and anemia, both of which are categories commonly observed with standard of care chemotherapy).   No new safety signals were identified.

How Did Atebimetinib Achieve Such Extraordinary Survival?

Atebimetinib is a Deep Cyclic Inhibitor: A New Paradigm in Targeted Therapy

• Immuneering’s proprietary Deep Cyclic Inhibitors (DCIs) challenge the conventional model of sustained or continuous inhibition in oncology.
• Most therapies are designed for sustained inhibition, driving cancer to adapt and develop resistance so tumors shrink quickly but temporarily.
• Deep Cyclic Inhibitors are designed to pulse faster than tumors can adapt, so tumors shrink slowly but durably.
• Sustained inhibition also causes suppressed transient signaling in healthy cells, leading to many adverse events.
• Deep Cyclic Inhibitors aim to restore full transient signaling to healthy cells, with the goal of leading to fewer adverse events.

Atebimetinib Targets MEK: A Broader, Potentially More Durable Approach

• MEK is a key control point in the MAPK pathway (RAS-RAF-MEK-ERK), which is pathologically activated in a majority of cancers, including approximately 97% of pancreatic cancers.
• Targeting MEK blocks a broader range of MAPK pathway alterations because it is further downstream, creating the potential for more durable benefit.

“Deep Cyclic Inhibitors like atebimetinib represent a fundamental shift in targeted therapy, away from continuous inhibition and toward pulsatile modulation of key oncogenic pathways,” said Brett Hall, Ph.D., Chief Scientific Officer at Immuneering. “This approach has the potential to deliver both durability and tolerability, two patient-centered essentials oncology has long struggled to balance.”

“Pancreatic cancer remains one of the most challenging cancers we face in the clinic with far too few treatment options available to patients and survival rates that have remained unacceptably low for decades,” said Vincent Chung, MD, FACP, Professor, Department of Medical Oncology and Therapeutics Research at City of Hope, principal investigator of the Phase 2a clinical trial and a paid member of the company’s scientific advisory board. “I have seen firsthand in my own patients the benefits of atebimetinib’s durability and tolerability. The remarkable overall survival, progression-free survival, and tolerability data we are seeing with atebimetinib + mGnP in first-line pancreatic cancer patients, now out to 9 months of median follow up, represent an important step towards creating urgently needed new options for these patients. We are also planning a confirmatory study.”

Near-Term Milestone Expectations

Immuneering is planning for several near-term anticipated milestones related to atebimetinib, including:

• Regulatory feedback on pivotal trial plans in Q4 2025
• Announcing further updated OS and PFS data from first-line pancreatic cancer patients (N=34) treated with atebimetinib + mGnP, including at a scientific conference in 2026
• Pending regulatory feedback, initiating a pivotal Phase 3 trial of atebimetinib in combination with mGnP in first-line pancreatic cancer by the end of 2025, and dosing the first patient by mid-2026
• Initiating additional atebimetinib clinical trial combination arms in 2026, including in non-small cell lung cancer

Immuneering is a clinical-stage oncology company focused on keeping cancer patients alive. The Company is developing an entirely new category of cancer medicines, Deep Cyclic Inhibitors. Immuneering’s lead product candidate, atebimetinib, is an oral, once-daily Deep Cyclic Inhibitor of MEK designed to improve durability and tolerability, and expand indications to include MAPK pathway-driven tumors such as most pancreatic cancers. Atebimetinib is currently in a Phase 2a trial in patients with advanced solid tumors including pancreatic cancer. The Company’s development pipeline also includes early-stage programs. For more information, please visit www.immuneering.com.