Efficacy of gefitinib in patients with advanced non-small cell carcinoma of the lung harboring common, uncommon and complex EGFR mutations

Background: As the commonest EGFR-TKI being used in Hong Kong, gefitinib has shown to be efficacious and safe as first line treatment for L858R mutation and exon 19 deletion with less gastrointestinal and cutaneous adverse events than erlotinib and afatinib. However, the evidence for therapeutic efficacy for uncommon and complex EGFR mutations is lacking. Whether gefitinib is efficacious for uncommon and complex EGFR mutations worth studying. Objectives: To assess the therapeutic efficacy of gefitinib, as measured by progression-free survival and overall survival, among advanced stage lung cancer patients with common, uncommon and complex EGFR mutations. Methods: This is a retrospective cohort study that included 241 Chinese patients with advanced non-small cell carcinoma of lung harboring EGFR mutations and received gefitinib 250 mg daily as first-line treatment. The progression-free survival [PFS] and overall survival [OS] for patients with different EGFR mutations, namely exon 19 deletion, L858R mutation in exon 21, uncommon EGFR mutations and complex EGFR mutations were analyzed. Results: Among the 241 patients, 118 [49%] had exon 19 deletion, 104 [43%] had L858R mutation in exon 21, 6 [2.5%] had uncommon EGFR mutations, 13 [5.4%] had complex EGFR mutations. The mean age was 69. 72% of the patients were female and with 81% being non-smoker. For patients with complex EGFR mutations, regardless of the presence of exon 19 deletion and L858R mutation as the component, have better PFS and OS than patients with single common EGFR mutations [Exon 19 deletion or L858R mutation]. Patients with uncommon EGFR mutations have inferior PFS and OS than those with common EGFR mutations. Conclusion: Gefitinib is a possible option for patients with complex EGFR mutations while it may not be the preferred treatment option in patients with single uncommon EGFR mutations.