Immuneering doses first patient in Phase 3 pancreatic cancer trial

Immuneering Corporation has dosed the first patient in MAPKeeper 301, its global, randomised, open-label pivotal Phase 3 trial evaluating atebimetinib combined with modified gemcitabine/nab-paclitaxel (mGnP) against standard gemcitabine/nab-paclitaxel alone in first-line metastatic pancreatic ductal adenocarcinoma (PDAC). The Nasdaq-listed company said topline data on the trial's primary endpoint of overall survival is anticipated in mid-2028.

Atebimetinib is an oral, once-daily MEK inhibitor that Immuneering describes as a "Deep Cyclic Inhibitor," designed to suppress the MAPK pathway in a pulsatile rather than continuous fashion. The company argues this approach reduces acquired resistance and improves tolerability compared with conventional chronic MEK inhibition. Around 90% of PDAC tumours are driven by MAPK pathway aberrations, according to the company, making the pathway a longstanding and logical target for the indication.

Trial design and rationale

The MAPKeeper 301 study (NCT07562152) is enrolling treatment-naive patients with metastatic PDAC across global sites. Randomisation is to atebimetinib plus mGnP or standard GnP alone. Key secondary endpoints include progression-free survival, overall response rate, disease control rate, safety and tolerability, and quality of life. Immuneering has not disclosed the target enrolment figure or the number of sites currently active.

Eileen M. O'Reilly, Winthrop Rockefeller Endowed Chair in Medical Oncology at Memorial Sloan Kettering Cancer Center and lead principal investigator, said: "There is an urgent need for new first-line treatment options that can improve treatment outcomes by augmenting survival and improving quality of life." The involvement of a Memorial Sloan Kettering investigator in a lead PI role adds academic credibility to the programme, though the trial remains at an early operational stage.

Market context and competitive landscape

Pancreatic cancer is one of the most intractable oncology settings. The National Cancer Institute estimates approximately 68,000 new PDAC cases in the United States in 2026, with a five-year survival rate of roughly 13%. GnP and FOLFIRINOX have remained the backbone of first-line therapy for over a decade, and meaningful survival improvements have been elusive.

The MAPK pathway has attracted significant drug development interest across oncology, yet MEK inhibitors have historically struggled in PDAC owing to toxicity and short-lived responses. Immuneering's pulsatile mechanism seeks to address both liabilities. However, the history of the indication warrants scepticism: a number of combination strategies that showed promise in earlier phases have failed to translate in randomised trials against standard of care. Investors and clinicians will therefore scrutinise the prior encouraging survival and tolerability data Immuneering referenced, though the company has not published peer-reviewed results from that earlier work.

Broader competitive context includes the advancement of KRAS G12C and pan-KRAS inhibitors, with several companies progressing combination approaches that also target the MAPK axis upstream of MEK. If any of those programmes generate Phase 3 data before MAPKeeper 301 reads out, the treatment landscape could shift materially.

Immuneering's chief executive Ben Zeskind described global site interest as "overwhelming" and said the company intends to accelerate enrolment with a view to the mid-2028 topline readout.