Phase i study of bevacizumab combined with irinotecan and S-1 as second-line chemotherapy in patients with advanced colorectal cancer

Purpose: The combination of an oral fluoropyrimidine derivative, S-1, and irinotecan has been reported to be a promising regimen for advanced colorectal cancer. However, the safety and efficacy of bevacizumab (BV) to combine with irinotecan and S-1 has not been determined. The aim of the study was to determine the maximum tolerated dose (MTD) and recommended dose (RD) of BV combined with irinotecan plus S-1, and to observe the safety and efficacy of this regimen as second-line chemotherapy in patients with advanced colorectal cancer. Methods: This study initially had been planned as a phase I/II study. Eighty mg/m² of irinotecan on days 1 and 8, 80 mg/m² of S-1 for 14 consecutive days, and two doses of BV (Level 1; 10 mg/kg, Level -1; 7.5 mg/kg) were administered on day 1 every 3 weeks. Results: Fourteen patients were enrolled in phase I of the study between January 2008 and September 2010. Dose-limiting toxicities were diarrhea, abdominal pain, and infection. The MTD and RD of BV were determined to be 10 mg/kg and 7.5 mg/kg, respectively. The main adverse events were leukopenia, anorexia, and diarrhea. There were no treatment-related deaths. An independent review committee was scheduled to evaluate safety in phase I, but this trial closed early due to toxicity. Conclusions: This study identified the risk of gastrointestinal toxicity with the combination of irinotecan, S-1 and BV as second-line chemotherapy in patients with advanced colorectal cancer.