Association Between Regorafenib Dose and Efficacy Against Metastatic Colorectal Cancer in a Real-World Setting

The association between regorafenib dosage in the treatment of metastatic colorectal cancer (mCRC) and efficacy is currently not well established. It was previously reported that the regorafenib dose as prescribed is associated with efficacy, but doses in actual clinical settings have not been analyzed. We retrospectively analyzed patients with mCRC who had received regorafenib as third-line or later chemotherapy between May 2013 and June 2018. Patients who were not treated in the Pharmaceutical Outpatient Clinic for compliance assessment were excluded. Overall survival was calculated using the Kaplan-Meier method. Prognostic factors, including baseline demographics and adverse events, were evaluated using Cox proportional hazard models. A total of 176 patients were enrolled. By multivariate analysis, total dose until the second cycle < 3180 mg (HR = 1.71, 95% CI, 1.20-2.44, P = .003) was one of independent negative predictors of overall survival. Median survival times of the lower-dose group (< 3180 mg) and higher-dose group (≥ 3180 mg) were 5.8 and 7.6 months, respectively (P = .045). The cumulative dose of regorafenib until the second cycle in patients with mCRC was associated with survival. It is important to individualize regorafenib dose in mCRC patients.