Phase II study of oral S-1 with irinotecan and bevacizumab (SIRB) as first-line therapy for patients with metastatic colorectal cancer

Fluorouracil (5-FU) plus irinotecan combined with bevacizumab has significant activity in metastatic colorectal cancer (mCRC), but S-1 has become a substitute for continuous infusion of 5-FU and has a very low incidence of hand-foot syndrome. With the S-1 plus irinotecan regimen (SIR), the response rate was 62.5%, and the progression-free survival was 8.0 months. We report here on an update of efficacy and safety of the SIR plus bevacizumab (SIRB) regimen as first line treatment for mCRC patients. Fifty-one eligible patients with histologically confirmed advanced or recurrent colorectal cancer received this treatment. S-1 was administered orally on days 1-14 of a 21-day cycle. Patients were assigned on the basis of body surface area (BSA) to receive one of the following oral doses twice daily: 40 mg, 50 mg, or 60 mg. Irinotecan (150 mg/m(2)) plus bevacizumab (7.5 mg/kg) were administered by intravenous infusion on day 1. Safety analysis identified a grade 3/4 neutropenia rate of 26%. Other grade 3/4 toxicities were diarrhea (8%), nausea (6%), vomiting (2%), and hypertension (8%). The response rate was 67% and the median progression-free survival time was 373 days. The SIRB regimen appears to be highly active and well tolerated as first-line treatment for mCRC.