Background: More than even before, the efficacy of epidermal growth factors (EGFRs) tyrosine kinase inhibitors in non-small-cell lung cancer patients carrying EGFR wild-type tumors has been under investigation. EGFR wild-type patients represent a large and heterogeneous group of patients. In this setting, the role played by high polysomy of chromosome 7 still remains controversial. Indeed, previous reports did not discriminate between chromosome 7 high polysomy and EGFR amplification and/or did not investigate the concurrent presence of EGFR and KRas mutations.
Methods: We retrospectively collected data from 163 patients analyzed for EGFR status (mutation, amplification, chromosome 7 trysomy, and polysomy), in addition to KRas mutation, between 2000 and 2010 in our institute. Erlotinib was administered to 73 of them. Objective responses and progression-free survivals to erlotinib were evaluated.
Results: High polysomy of chromosome 7 characterized 17% (28 of 163) of EGFR/KRas wild-type tumors, independently of smoking status. In this group, 13 patients received erlotinib at progression. The treatment led one complete and four partial responses, and five stable diseases. Two patients progressed. One patient was lost to follow-up. The mean time to progression was 9 months.
Conclusion: Among the EGFR wild-type population, when analyzed separately, high polysomy of chromosome 7 was the only molecular feature conferring clear signs of sensitivity to erlotinib. Therefore, the evaluation of high polysomy of chromosome 7 could become a helpful tool to predict for the benefit from epidermal growth factors tyrosine kinase inhibitors in selected cases.