Immuneering (IMRX) Study result summary

Clinical trial results and survival outcomes

• Median overall survival was 17.3 months in both the original 34-patient and expanded 55-patient cohorts for first-line metastatic pancreatic cancer, nearly doubling the 8.5 months seen with standard chemotherapy in the MPACT study, with consistent survival curves.

• Median progression-free survival was 8.3 months, with an overall response rate of 36% and a disease control rate of 82%, all well separated from standard of care benchmarks.

• 84% of patients were weight stable or gained weight at three months, indicating preserved performance status and contributing to improved survival and higher rates of second-line therapy.

• Only two categories of Grade 3 or higher treatment-related adverse events occurred in more than 10% of patients, both chemotherapy-related, with no Grade 4 or 5 adverse events related to atebimetinib.

• No genetic testing was required for enrollment, broadening patient access and reflecting a mutation-agnostic response pattern.

Study design, comparators, and future plans

• The study was open-label and non-randomized, contextualized against benchmarks such as MPACT, PRODIGE, and NAPOLI-3.

• The global Phase III MAPKeeper 301 trial is actively recruiting, randomizing atebimetinib plus modified gemcitabine nab-paclitaxel against standard of care, with first patient dosing expected mid-2026 and topline results in 2028.

• A Phase II trial of atebimetinib plus anti-PD-1 in non-small cell lung cancer will begin dosing in the second half of 2026.

• Preclinical and clinical exploration of atebimetinib in combination with other agents is ongoing.

Technology and mechanism of action

• Atebimetinib is a novel, once-daily oral MEK inhibitor developed using Deep Cyclic Inhibitor technology for pulsatile inhibition, aiming to improve tolerability and durability.

• The approach allows potent pathway suppression with recovery periods to reduce toxicity and delay resistance.

• The mutation-agnostic mechanism enables broad applicability without genetic testing.

• Patent protection for atebimetinib extends into late 2045.