First-line therapy in non-small cell lung cancer patients with EGFR activating mutations: a consideration of the clinical position of osimertinib based on the subset of Japanese patients in the FLAURA study

We review the efficacy and safety of first-line EGFR-TKIs focusing on the FLAURA study, and discuss treatment strategies for patients with NSCLC harbouring EGFR mutations. Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have been established as the standard first-line treatment for patients with previously untreated advanced non-small cell lung cancer (NSCLC) with an EGFR activating mutation. In the FLAURA study, osimertinib, third-generation EGFR-TKI, resulted in significantly longer progression-free survival and overall survival (OS) than first-generation EGFR-TKIs (gefitinib or erlotinib) in patients with previously untreated advanced NSCLC with an EGFR activating mutation. Osimertinib is now widely used as first-line therapy for those patients. In Japanese subset analysis of the FLAURA study, the median progression-free survival was prolonged by osimertinib (19.1 months) relative to gefitinib (13.8 months). However, there was no apparent OS benefit, albeit at the level of an exploratory post-hoc analysis. Although the safety profile in the Japanese subset was generally consistent with the overall population, the incidence of liver enzyme increases in the gefitinib group and that of interstitial lung disease/pneumonitis in the osimertinib group was higher among Japanese patients. There is now an increasing number of first-line treatment options for NSCLC with EGFR mutations, including EGFR-TKIs in combination with platinum-doublet chemotherapy or anti-angiogenic drugs. These combinations show progression-free survival benefits similar to osimertinib regardless of the mutation type. Therefore, a first-line combination regimen followed by osimertinib remains an attractive strategy. We review data from the randomized clinical trials of first-line EGFR-TKIs including a subset of Japanese patients and discuss first-line therapies for patients with NSCLC harbouring EGFR mutations.