Immuneering Corporation: Immuneering Presents Compelling 17.3-Month Median Overall Survival and Favorable Tolerability with Atebimetinib + Chemotherapy in First-Line Pancreatic Cancer Patients at ASCO

- 17.3 months median overall survival in 55 first-line pancreatic cancer patients; vs. 8.5 months for standard of care chemotherapy in the pivotal MPACT study -

- Only two categories of Grade 3+ treatment-related adverse events occurring in =10% of patients, both chemotherapy related -

- 84% of participants maintained or gained weight at three months -

- Global Phase 3 MAPKeeper 301 trial (NCT07562152) in first-line metastatic pancreatic cancer actively recruiting, with first patient dosing expected in mid-2026 -

- Company to hold investor conference call today, at 8:00 a.m. EDT -

NEW YORK, June 01, 2026 (GLOBE NEWSWIRE) -- Immuneering Corporation (Nasdaq: IMRX), a late-stage clinical oncology company focused on keeping cancer patients alive and helping them thrive, today announced updated clinical data from its ongoing Phase 2a trial evaluating atebimetinib in combination with modified gemcitabine/nab-paclitaxel (mGnP) in first-line metastatic pancreatic ductal adenocarcinoma (mPDAC).

The data are being presented in an oral session at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting (see Abstract #4013 and accompanying presentation) by Peter Vu, M.D., M.H.A., Associate Professor of Medicine and Medical Director, Cancer Quality, GI Medical Oncology, Experimental Therapeutics & Cellular and Regenerative Medicine at UC San Diego Moores Cancer Center. The presentation showcases data from an expanded cohort totaling 55 first-line pancreatic cancer patients.

"As pancreatic cancer clinicians, we are urgently seeking therapies capable of meaningfully extending survival while preserving patients' quality of life," said Daniel Ahn, D.O., Mayo Clinic Arizona, an investigator on the Phase 2a trial of atebimetinib. "The median overall survival of 17.3 months observed in this study is incredibly encouraging relative to historical outcomes in first-line metastatic pancreatic cancer. Equally important, atebimetinib demonstrated a notably favorable tolerability profile, with limited severe treatment-related toxicities and encouraging indicators of preserved functional status, including weight stability - key characteristics for treatments balancing durable clinical benefit and patient experience. Data from this expanded cohort reinforce atebimetinib's strong potential in first-line pancreatic cancer."

This open-label, single-arm Phase 2a trial evaluated atebimetinib at 320 mg once daily in combination with mGnP in participants with first-line metastatic pancreatic cancer, irrespective of mutational status. The Company reported the following as of the April 24, 2026 data cutoff date:

• In the expanded 55-patient cohort, median overall survival was 17.3 months (95% CI: 11.2, not reached), compared to 8.5 months median overall survival in the pivotal Phase 3 MPACT study of standard of care gemcitabine/nab-paclitaxel (Von Hoff et al, NEJM, 2013). The median follow-up was 11.6 months.
• Median progression-free survival was 8.3 months (95% CI: 5.9, 9.6), disease control rate (DCR) was 82%, and the confirmed overall response rate (ORR) was 36%.
• In the original 34-patient cohort with longer follow-up (median 17.0 months), median overall survival was also observed to be 17.3 months (95% CI: 11.6, not reached) - supporting the consistency of the survival signal across cohorts with different durations of follow-up.
  

"The data presented at ASCO further strengthen our conviction that atebimetinib has the potential to redefine what it means to live with metastatic pancreatic cancer," said Ben Zeskind, Ph.D., Co-founder and Chief Executive Officer of Immuneering. "The combination of compelling survival data and a highly favorable safety profile supports the evaluation of this regimen in our Phase 3 study for first-line pancreatic cancer patients, which is now recruiting. We believe the ability of our deep cyclic MEK inhibitors to improve overall survival, while maintaining tolerability, may represent an important advancement for patients and physicians alike."

Only two categories of Grade 3 or higher treatment-related adverse events occurred in at least 10% of participants, both related to chemotherapy. No Grade 4 adverse events related to atebimetinib and no Grade 5 treatment-related adverse events were reported. Only one participant discontinued atebimetinib while continuing mGnP. The safety profile observed in the trial compared favorably to historical experiences with intensive chemotherapy treatments and combination regimens under development in pancreatic cancer.

Additionally, 84% of participants with available data maintained or gained weight at three months, a potentially important indicator of preserved performance status and tolerability in this patient population where cachexia is common and correlated with poorer outcomes.

Immuneering is currently recruiting patients in MAPKeeper 301 - NCT07562152), a global randomized Phase 3 pivotal trial evaluating atebimetinib plus mGnP versus standard-of-care gemcitabine/nab-paclitaxel in first-line metastatic pancreatic cancer. The trial's primary endpoint is overall survival.

Upcoming Milestones

• Mid 2026: First patient dosed in Phase 3 MAPKeeper 301 trial.
• 2H 2026: First patient dosed in Phase 2 trial of atebimetinib + anti-PD-1 (cemiplimab) in non-small cell lung cancer.
• Q4 2026: Additional preclinical data supporting atebimetinib + anti-PD-1 in non-small cell lung cancer.
• Mid 2027: Begin IND-enabling studies for next DCI drug program.
• Late 2027: Preliminary Phase 2 data: atebimetinib + anti-PD-1 (cemiplimab) in non-small cell lung cancer.
• Mid 2028: Phase 3 MAPKeeper 301 topline readout expected.

Conference Call

Immuneering will host a conference call and live webcast at 8:00 a.m. EDT / 7:00 a.m. CDT on June 1, 2026, to discuss the data. Individuals interested in listening to the live conference call may do so by dialing [phone] for U.S. callers and [phone] for other locations and reference conference ID 7597768, or from the webcast link in the "investors" section of the company's website at www.immuneering.com. A webcast replay will be available in the investor relations section on the company's website for 90 days following the completion of the call.

About Immuneering

Immuneering is a late-stage clinical oncology company dedicated to keeping cancer patients alive and helping them thrive, with an initial focus on patients with RAS, RAF, and other MAPK-driven cancers. The Company is developing an entirely new category of cancer medicines, Deep Cyclic Inhibitors, designed to improve overall survival by three mechanisms: shrinking tumors durably with less resistance, preserving body mass by countering cachexia, and minimizing side effects to maximize performance status and combinability. Immuneering's lead product candidate, atebimetinib, is an investigational, oral, once-daily Deep Cyclic Inhibitor of MEK, designed to improve survival across many cancer indications. The company is conducting a global randomized pivotal trial, MAPKeeper 301, evaluating atebimetinib in combination with chemotherapy in first-line pancreatic cancer patients. The Company's development pipeline also includes additional combination opportunities and preclinical stage programs. For more information, please visit www.immuneering.com.

Forward-Looking Statements

This press release contains forward-looking statements, including within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including, without limitation, statements regarding: the treatment potential of atebimetinib, alone or in combination with other agents to treat cancer, including modified Gemcitabine/nab-paclitaxel (mGnP) in first-line pancreatic cancer; the timing of dosing of the MAPKeeper 301 study and the timing of topline results from the study; the timing of dosing of the Phase 2 combination study of atebimetinib in non-small cell lung cancer, including the timing of preliminary results from the study; timing of IND-enabling studies from the next DCI drug program; the ability of phase 2 results presented at ASCO to translate to success and support evaluation in the Company's phase 3 study; the ability of the three design mechanisms of atebimetinib to shrink tumors durably, improve overall survival and overcome the limitations of conventional MAPK inhibition and provide a more sustained clinical benefit for patients.

These forward-looking statements are based on management's current expectations. These statements are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements, including, but not limited to, the following: the risks inherent in oncology drug research and development, including target discovery, target validation, lead compound identification, and lead compound optimization; we have incurred significant losses, are not currently profitable and may never become profitable; our projected cash runway; our need for additional funding; our unproven approach to therapeutic intervention; our ability to address regulatory questions and the uncertainties relating to regulatory filings, reviews and approvals; the lengthy, expensive, and uncertain process of clinical drug development, including potential delays in activating trial sites or enrolling trial participants, or failure to obtain regulatory approvals; our reliance on third parties and collaborators to conduct our clinical trials, manufacture our product candidates, and develop and commercialize our product candidates, if approved; failure to compete successfully against other drug companies; protection of our proprietary technology and the confidentiality of our trade secrets; potential lawsuits for, or claims of, infringement of third-party intellectual property or challenges to the ownership of our intellectual property; our patents being found invalid or unenforceable; costs and resources of operating as a public company; and unfavorable or no analyst research or reports.

These and other important factors discussed under the caption "Risk Factors" in our Quarterly Report on Form 10-Q for the period ended March 31, 2026, and our other reports filed with the U.S. Securities and Exchange Commission, could cause actual results to differ materially from those indicated by the forward-looking statements made in this press release. Any such forward-looking statements represent management's estimates as of the date of this press release. While we may elect to update such forward-looking statements at some point in the future, except as required by law, we disclaim any obligation to do so, even if subsequent events cause our views to change. These forward-looking statements should not be relied upon as representing our views as of any date subsequent to the date of this press release.

Investor Contact:
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