Epidermal Growth Factor Receptor Intron-1 Polymorphism Predicts Gefitinib Outcome in Advanced Non-small Cell Lung Cancer

Introduction: Epidermal growth factor receptor (EGFR) gene intron I contains a polymorphic single sequence dinucleotide repeat (CA), whose length has been found to inversely correlate with transcriptional activity. This study was designed to assess the role of (CA)(n) polymorphism in predicting the outcome of gefitinib treatment in advanced non-small cell lung cancer (NSCLC). Methods: Blood and tumor tissue from 58 patients with advanced NSCLC submitted to gefitinib were collected. EGFR intron I gene polymorphism, along with EGFR gene mutation, gene copy number and immunohistochemistry expression were determined. Moreover, a panel of lung cancer cell lines characterized for EGFR intron I polymorphism was also studied. Results: EGFR intron I polymorphism showed a statistically significant correlation with the gefitinib response (response rate 25 versus 0%, for patients with a (CA)(16) and with a (CA)(else) genotype, respectively; p = 0.044). Patients with a (CA)(16) genotype had a longer survival compared with those with a (CA)(else) genotype (11.4 versus 4.8 months, respectively; p = 0.037). In addition, cell lines lacking the (CA)(16) allele showed a statistically significant higher IC50 compared with cell lines bearing at least one (CA)(16) allele (p = 0.003). Conclusions: This study supports a potential role of EGFR intron I polymorphism in predicting the outcome of gefitinib treatment in advanced NSCLC.