Phase 3 atebimetinib MEK1/2 inhibitor plus modified GnP vs standard GnP in metastatic PDAC

Immuneering’s MAPKeeper 301 is a randomized, open-label Phase 3 trial testing whether adding atebimetinib—an oral small-molecule MEK1/MEK2 inhibitor targeting the MAPK pathway—to a modified schedule of gemcitabine + nab-paclitaxel can improve outcomes versus standard gemcitabine + nab-paclitaxel (GnP) alone in first-line metastatic pancreatic ductal adenocarcinoma. Patients are randomized in parallel assignment to either atebimetinib + mGnP (biweekly IV gemcitabine and nab-paclitaxel on a modified dosing schedule) or standard GnP (weekly 3 weeks on/1 week off). The primary goal is to determine whether the combination improves overall survival while characterizing safety/tolerability and anti-tumor activity. The key scientific/commercial angle is taking a targeted MAPK-pathway agent into a large registrational frontline PDAC setting rather than a biomarker-narrow niche, pairing pathway suppression with a widely used chemo doublet. Today’s care for treatment-naive metastatic PDAC is cytotoxic combination chemotherapy (often modified FOLFIRINOX or gemcitabine + nab-paclitaxel), with subsequent-line options including nanoliposomal irinotecan-based regimens and select biomarker-driven therapies for small subsets.