Molecular changes in epidermal growth factor receptor (EGFR) in non-small cell lung cancer (NSCLC) biopsies at time of progression compared to initial biopsy

e22066 Background: EGFR mutations predict sensitivity and clinical outcome to tyrosine kinase inhibitors (TKI) in NSCLC. The two most commonly described mutations are Exon 19 deletion and Exon 21 L858R missense mutations. Genetic alterations over time have been described in other tumour types, but studies assessing EGFR genotypic changes with lung cancer progression are lacking. We sought to compare EGFR mutational status from lung tumors at time of recurrence or progression with the primary tumor. Methods: Using the Jewish General Hospital lung cancer database, of all patients diagnosed with NSCLC since 1999, those with biopsies at two different points in time were identified. All tumour samples were genotyped for EGFR exons 19 and 21 mutations using denaturing high performance liquid chromatography (dHPLC). Results: 29 patients were identified. Data for 12 patients, whose time of recurrence or progression varied between 4 months and 6 years, are available at this time. Of 12 patients, one had EGFR exon ...