Genetic Aberations In Pten And Pik3ca And Prognosis In Wild-Type Egfr Gene Mutation Patients That Received Erlotinib

e22043 Background: Loss of PTEN and gain of PIK3CA have been postulated as downstream mechanisms of resistance to anti-EGFR therapy in NSCLC. Clinical data suggests use of EGFR tyroisine kinase inhibitors (EGFR TKIs) is inferior to second line chemotherapy in patients without EGFR sensitizing gene mutations. The purpose of this study was to identify wild type NSCLC patients(pts) with improved outcomes on erlotinib based on PTEN loss and gains in PIK3CA and chromosome 3 (CEP3), on which is located PIK3CA. Methods: Pts treated with erlotinib were included for analysis. Five micron sections of formalin-fixed tumor tissue were assessed by fluorescent in situ hybridization (FISH) using probes for PTEN, PIK3CA and the centromere of CEP3. FISH signals were enumerated by 2 readers, counting 50 cells each. FISH enumeration results were used to determine parameters influencing the overall survival(OS) post therapy. OS time between FISH (+) and FISH (-) pts was compared by COX Proportional Hazard Model and Log-rank ...