First Biologic Drug in the Treatment of RAS Wild-Type Metastatic Colorectal Cancer: Anti-EGFR or Bevacizumab? Results From a Meta-Analysis

Alessandro Ottaiano, Alfonso De Stefano, Monica Capozzi, Anna Nappi, Chiara De Divitiis, Carmela Romano, Lucrezia Silvestro, Antonino Cassata, Rossana Casaretti, Salvatore Tafuto, Michele Caraglia, Massimiliano Berretta, Guglielmo Nasti, Antonio Avallone

Introduction: We performed a meta-analysis in order to analyze and quantify the effect on survival of starting therapy in RAS wild-type (wt) metastatic colorectal cancer (mCRC) patients with anti-EGFR agents or bevacizumab. Patients and Methods: Randomized, phase II or III, clinical trials reporting overall survival (OS) in RAS wt mCRC patients treated with first-line chemotherapy (CT) associated with bevacizumab or anti-EGFR agents were selected. The primary end-point of this meta-analysis was OS; findings were depicted in classical Forest plots. Results: Seven studies met the criteria for meta-analysis including 3,805 patients. The pooled second-line cross-over rate to bevacizumab was 36.6%, to anti-EGFR 33.2%. Only one study was selected reporting comparison between CT vs. CT plus bevacizumab in RAS wt patients with a HR of 1.13 in favor of CT (CI: 0.89-1.43, p = 0.317). The pooled HRs were 0.89 (95% CI: 0.79-1.00) for CT plus anti-EGFR vs. CT and 0.81 (95% CI: 0.71-0.92) in favor of CT plus anti-EGFR vs. CT plus bevacizumab. Subgroup analysis showed a positive prognostic impact of starting CT plus anti-EGFR in left colon cancer (pooled HR: 0.70; CI: 0.54-0.85) while a positive trend of starting CT plus bevacizumab was observed in right colon cancer (pooled HR: 1.29; CI: 0.81-1.77). Conclusions: This meta-analysis shows that starting therapy in RAS wt mCRC patients with an anti-EGFR agent improves OS when the primary tumor location is in the left colon but a strong limitation of previous studies is the very low rate of biologic drug therapy cross-over.