Predictors of the Efficacy of FOLFIRI plus Bevacizumab as Second-Line Treatment in Metastatic Colorectal Cancer Patients

Purpose. Fluoropyrimidine-based chemotherapy plus bevacizumab (BV) is the standard treatment for metastatic colorectal cancer (mCRC). The aim of this study was to investigate the efficacy of BV plus FOLFIRI (5-fluorouracil, leucovorin, irinotecan) as second-line treatment in mCRC patients refractory to first-line oxaliplatin-based chemotherapy, and determine potential predictive factors affecting survival. Methods. Thirty-four consecutive patients were included in this retrospective study. All patients received FOLFIRI plus 5 mg/kg BV until progression or unmanageable toxicity occurred. Clinical factors and KRAS status were evaluated as potential biomarkers of efficacy. Results. The overall response was 23.5%. The median progression-free survival (PFS) and time-to-treatment failure (TTF) were 248 and 221 days, respectively. The median overall survival (OS) was 651 days. A univariate analysis revealed that normal thrombin antithrombin complex, alkaline phosphatase, lactate dehydrogenase, and carbohydrate antigen 125 (CA125) levels at baseline were associated with better PFS, TTF, and OS. A multivariate analysis showed that only the CA125 level at baseline was an independent negative predictor of both PFS and OS. KRAS status was not identified as a predictor. Conclusions. The results of this study suggest that FOLFIRI plus BV is a viable option in second-line treatment for mCRC refractory to first-line FOLFOX (5-fluorouracil, leucovorin, oxaliplatin) alone, and indicate that CA125 might be a predictive biomarker for the outcome.