Increasing Diluent Volume Decreases Bendamustine-Induced Venous Irritation without Reducing the Therapeutic Efficacy

The intravenous injection of bendamustine often induces venous irritation, which reduces patients' QOL. We previously reported that the dilution of the final volume of bendamustine from 250 to 500 mL significantly decreased the incidence of venous irritation. However, the influence of this change on the therapeutic efficacy of bendamustine remains unclear. Therefore, the aim of this study was to evaluate the efficacy and safety profiles of bendamustine at different dilutions of the final volume, comparing with the correspondences of previous studies. Thirty-four patients, who received a total of 161 courses of bendamustine and rituximab chemotherapy, were included in this study. The overall response rate of this regimen was 94.1% in this study, which was comparable to that reported in the BRB study (94.2%, a phase II study of bendamustine plus rituximab therapy in Japanese patients). Additionally, the median progression-free survival was not inferior to that reported in the BRB study. Bendamustine-induced venous irritation was observed in 17.6% of the patients during the first treatment cycle administered at a final volume of 500 mL, and was found to be lower than that observed in the control, where bendamustine was administered at a final volume of 250 mL (85.7%). These results suggest that diluting bendamustine to 500 mL, but not to 250 mL, reduces the incidence of venous irritation without a negative impact on its therapeutic efficacy; thus, this simple strategy may be beneficial to ensure efficacy and safety in patients receiving regimens including bendamustine.