Erlotinib as a salvage treatment for patients with advanced non-small cell lung cancer after failure of gefitinib treatment: Is there a rationale for a clinical trial?

e19099 Background: Patients (pts) with advanced NSCLC and sensitizing EGFR mutations who initially respond to gefitinib or erlotinib eventually develop acquired resistance to the TKIs. Our goal was to determine the effects of erlotinib 150 mg/d in EGFR mutated pts resistant to gefitinib 250 mg/d, because the EGFR TKI erlotinib is given at a higher biologically active dose than gefitinib. Methods: Retrospective review of 5 EGFR mutated (exon 19 deletions) patients that were given gefitinib and subsequently erlotinib. Results: All pts responded to gefitinib with median progression-free survival of 13 months (95% confidence interval, 4-16). After gefitinib resistance, 60% (3 of 5) of these pts displayed progressive disease while on erlotinib with progression-free survival of 2 months (95% confidence interval, 2-3). These pts acquired the T790M mutation. 2 gefitinib-resistant pts with the acquired L858R-L747S EGFR, which in vitro is sensitive to achievable serum concentrations of erlotinib 150 mg/d, achieved ...