PTEN Gene Expression and Mutations in the PIK3CA Gene as Predictors of Clinical Benefit to Anti-Epidermal Growth Factor Receptor Antibody Therapy in Patients With KRAS Wild-Type Metastatic Colorectal Cancer

Abstract

PURPOSE: To identify novel genetic markers predictive of clinical benefit from epidermal growth factor receptor-directed antibody therapy in patients with metastatic colorectal cancer. PATIENTS AND METHODS: Seventy-six consecutive patients who received cetuximab or panitumumab, either alone or in combination with chemotherapy and with available tumor tissue were included. Tumor tissue was tested by pyrosequencing for mutations at known hot spots in the KRAS, BRAF, PIK3CA, PIK3R1, AKT1, and PTEN genes. PTEN promoter methylation status was analyzed by methylation-specific polymerase chain reaction, and expression was determined by immunohistochemistry (IHC). Forty-four patients had 4 weeks of ..