The prognostic value of chromosome 7 polysomy in non-small cell lung cancer patients treated with gefitinib.

Introduction: Specific subpopulations of non-small cell lung cancer (NSCLC) patients defined by clinical features and molecular profiles seem to derive greater benefit from epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors, but no general consensus on molecular testing to optimize treatment has emerged. The objective of this study was to evaluate chromosome 7 polysomy and other potential indicators of gefitinib efficacy in advanced NSCLC patients.

Methods: Paraffin-embedded tumors from 82 patients treated with gefitinib were analyzed by immunohistochemistry for expression of EGFR and other markers, and by fluorescence in situ hybridization for EGFR gene or chromosome copy number. Mutational status was assessed by single-strand conformational polymorphism, sequence-specific polymerase chain reaction, and direct sequencing. Molecular and clinical characteristics were evaluated in relation to objective response (OR), progression-free survival (PFS), and overall survival (OS).

Results: EGFR mutational status (p = 0.002), never smoking (p = 0.052), and chromosome 7 polysomy (p = 0.029) were significant indicators of OR. EGFR mutation, pAKT or PTEN expression, and chromosome 7 polysomy were associated with longer OS. There was a significant difference in OS between the chromosome 7 polysomy groups (p = 0.015) and the groups with both chromosome 7 polysomy and pAkt (p = 0.002) and both chromosome7 polysomy and PTEN (p = 0.04). In a stepwise proportional hazards analysis, chromosome 7 polysomy and PTEN expression were both significantly associated with longer OS (p = 0.004 and 0.017 respectively).

Conclusion: These results suggest that further study of chromosome 7 polysomy and of pAKT and PTEN expression in patients treated with EGFR tyrosine kinase inhibitors is warranted in developing a clinical test for selecting patients for gefitinib therapy.