Clinical outcome of panitumumab for metastatic colorectal cancer with wild-type KRAS status: a meta-analysis of randomized clinical trials

Panitumumab is a fully human anti-epidermal growth factor receptor (EGFR) monoclonal antibody that has a favorable effect on patients with metastatic colorectal cancer (mCRC) harboring wild-type (WT) KRAS gene. This meta-analysis was planned to quantify the benefit and assess safety. Selected for the analysis were randomized clinical studies that have used panitumumab-based therapy (PBT) for patients with mCRC and where the outcome of patients with WT KRAS was reported. Four eligible studies were analyzed including 1,010 and 1,105 patients who received PBT and the control intervention, respectively. Used in subsequent-line setting, PBT was associated with 42% improvement in progression-free survival (PFS) (hazard ratio [HR] = 0.58; 95% CI, 0.36-0.93; P = 0.02), a non-significant overall survival (OS) benefit (HR = 0.90; [95% CI, 0.76-1.05]; P = 0.18), and a significant increase in objective response rate (ORR) (odds ratio (OR) = 0.67 [95% CI, 1.15-77.98]; P = 0.04). PBT showed no benefit in the first-line setting. Restricted analysis to two studies (first-and second-line setting), where the treatment effect of PBT was prospectively analyzed according to tumor KRAS status, showed significant PFS (HR = 0.77), OS (HR = 0.84), and ORR (OR = 2.06) advantage. Almost all patients' subgroups attained clinical benefit. PBT-related adverse events were similar across comparisons with the exception of toxicities known to be associated with anti-EGFR therapy. This meta-analysis showed significant clinical benefit for PBT for patients with WT KRAS mCRC predominantly when used following prior chemotherapy exposure. The benefit was demonstrated in most subgroup analyses. Further research to better define potential responders is needed.