Clinical evidence on the increased efficacy of sequential epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) therapy in patients with EGFR-mutated non-small-cell lung cancer (NSCLC) is limited. This study aimed to compare the efficacy of upfront use of first-/second-generation TKI followed by osimertinib with upfront osimertinib therapy for each representative EGFR mutation in Japanese patients with NSCLC. Patients with EGFR-mutated NSCLC were classified into two groups: first-/second-generation TKI followed by osimertinib (sequential TKI group) and upfront osimertinib groups. The total time to treatment failure (TTF) of TKI therapies, progression-free survival (PFS), and overall survival (OS) were retrospectively evaluated. Of the 74 patients included in the analysis, 38 and 34 patients had exon 19 deletion and L858R, respectively, and other two patients had minor mutations. The sequential TKI group had a significantly longer TTF than the upfront osimertinib group in overall patients (33.2 vs. 11.2 months; p = 0.007) and in the subgroup of exon 19 deletion (36.7 vs. 10.0 months; p = 0.004), but not in the subgroup of L858R (22.6 vs. 15.6 months; p = 0.37). The similar tendency was observed in PFS. OS of the sequential TKI group was significantly longer compared with the upfront osimertinib group in overall patients, the subgroup of exon 19 deletion, and the subgroup of L858R. The upfront use of first-/second-generation TKI followed by osimertinib is one of the feasible and effective strategies in Japanese patients with EGFR-mutated NSCLC, especially in patients with exon 19 deletion.
Keywords: T790M; epidermal growth factor receptor–tyrosine kinase inhibitor; exon 19 deletion; non-small cell lung cancer; osimertinib.