A phase I/II study of biweekly capecitabine and irinotecan plus bevacizumab as second-line chemotherapy in patients with metastatic colorectal cancer

BACKGROUND Triweekly capecitabine plus irinotecan (XELIRI) is not completely regarded as a valid substitute for fluorouracil, leucovorin, and irinotecan (FOLFIRI) in metastatic colorectal cancer (mCRC) because of the potential for greater toxicity. We conducted a phase I/II study to assess the efficacy and safety of biweekly XELIRI plus bevacizumab (BV) as second-line chemotherapy for mCRC. METHODS Patients with mCRC who had received prior chemotherapy including oxaliplatin and BV and had a UGT1A1 genotype of wild-type or heterozygous for UGT1A1*6 or *28 were eligible for this study. Treatment comprised capecitabine 1,000 mg/m(2) twice daily from the evening of day 1 to the morning of day 8, intravenous irinotecan on day 1, and BV 5 mg/kg on day 1 every 2 weeks. The phase I study consisted of two steps (irinotecan 150 and 180 mg/m(2)), and dose-limiting toxicity was assessed during the first treatment cycle. The primary endpoint of the phase II study was progression-free survival (PFS). RESULTS The recommended dose of irinotecan was determined to be 180 mg/m(2) in the phase I study. Between November 2010 and August 2013, 44 patients were enrolled in phase II. The patients' characteristics were as follows (N=44): median age, 60 years (range 32-80); male/female, 21/23; and UGT1A1 wild-type/heterozygous, 29/15. The median PFS was 6.8 months (95% confidence interval, 5.3-8.2 months), and the primary endpoint was met. Median overall survival was 18.3 months. The response rate was 22.7%. There was no significant difference in PFS or overall survival according to UGT1A1 status. Grade 3 or higher adverse events were mainly neutropenia in six patients and diarrhea in five patients. There were no other severe adverse events or treatment-related deaths. CONCLUSION In mCRC patients with wild-type or heterozygous UGT1A1*6 or *28 genotype, biweekly XELIRI + BV is effective and feasible as second-line chemotherapy. Biweekly XELIRI + BV is considered a valid substitute for FOLFIRI + BV in mCRC.