phase III CanStem303C study of BBI 608 + FOLFIRI fails to meet endpoints in colorectal cancer.- Sumitomo Dainippon

Sumitomo Dainippon Pharma Oncology announced that the phase III CanStem303C study evaluating the efficacy and safety of investigational agent BBI 608 (napabucasin) when given in combination with FOLFIRI with or without bevacizumab in patients with previously treated metastatic colorectal cancer failed to reach the primary endpoints of overall survival (OS). Napabucasin in combination with FOLFIRI failed to show significant OS improvement in the general study population and in patients whose tumor was positive for the phosphorylated signal transducer and activator of transcription 3 (pSTAT3) biomarker. The multicenter, open-label, randomized Phase III CanStem303C study evaluated the efficacy and safety of napabucasin in approximately 1,250 patients with previously treated metastatic colorectal cancer. Patients were randomized 1:1 in the study. The study had two primary endpoints – overall survival in all randomized patients and overall survival in a subpopulation of patients whose tumor was positive for the pSTAT3 biomarker. Napabucasin at a dose of 240 mg was administered orally, twice daily in combination with FOLFIRI with or without bevacizumab versus FOLFIRI with or without bevacizumab. The most common adverse events, occurring in patients in the napabucasin combination arm, were consistent with previously published data and included diarrhea, nausea, vomiting and abdominal pain. Final data and analyses of this study will be published for the oncology community.