Does the Addition of Biologic Agents to Chemotherapy in Patients with Unresectable Colorectal Cancer Metastases Result in a Higher Proportion of Patients Undergoing Resection? A Systematic Review and…

Jessica Bogach, Oren Levine, Sameer Parpia, Marlie Valencia, Leyo Ruo, Pablo Serrano

Surgical resection provides the best opportunity for cure for metastatic colorectal cancer. Whether addition of a biologic agent to chemotherapy improves the rate of conversion from unresectable to resectable disease remains uncertain. We carried out a systematic review of the literature and meta-analysis to define the impact of biologic agents on resection. We searched Medline, Embase, CENTRAL, and PubMed for randomized controlled trials published up until April 2017 comparing chemotherapy and biologics (intervention) vs. chemotherapy alone (control) in treatment-naïve patients with unresectable metastatic colorectal cancer. Study selection, data abstraction, risk of bias, and quality of evidence assessment were performed in duplicate. Random-effects meta-analysis was used to estimate the pooled odds ratio (OR) for resection rate and corresponding confidence interval (CI). Nine studies, including a total of 4345 patients, were analyzed. Seven studies assessed epithelial growth factor receptor (EGFR)-directed monoclonal antibodies, and two used antiangiogenic agents. The addition of a biologic agent to chemotherapy was associated with higher resection rate (OR 1.47, 95% CI 1.07-2.02; resection rate 8.4 vs. 6.1%). Subgroup analysis based on mechanism of action of drugs showed benefit for resection rate only with EGFR-directed agents (OR 1.70, 95% CI 1.10-2.64). Heterogeneity among studies was low (I 2  = 34%). The addition of biologic agents to systemic chemotherapy in patients with initially unresectable metastatic colorectal cancer improved resection rate. The optimal biologic agent for this outcome cannot yet be determined.