Recent Advances on the Role of EGFR Tyrosine Kinase Inhibitors in the Management of NSCLC With Uncommon, Non Exon 20 Insertions, EGFR Mutations

The first-line treatment of choice for patients with EGFR mutation-positive NSCLC is an EGFR tyrosine kinase inhibitor (TKI), of which five as follows are predominantly available in practice: gefitinib, erlotinib, afatinib, dacomitinib, and osimertinib. Most prospective clinical trial data with these agents are limited to patients with the common activating and sensitizing EGFR mutations as follows: exon 19 deletions and exon 21 L858R point mutations. However, 10% to 20% of patients with NSCLC harbor uncommon EGFR mutations that have variable sensitivity to different EGFR TKIs. Owing to their molecular structures, afatinib, dacomitinib, and osimertinib have broader inhibitory profiles than the first-generation agents, gefitinib and erlotinib. Nevertheless, the paucity of prospective clinical data, the wide heterogeneity of uncommon mutations, and the existence of compound mutations in up to 25% of the cases complicate treatment decisions in this patient subgroup. Here, we collate the latest preclinical and clinical data regarding the activity of different TKIs against major uncommon EGFR mutations including compound mutations, but excluding exon 20 insertions which are generally insensitive to TKIs. On the basis of these data, we offer suggestions regarding treatment strategies for uncommon EGFR mutations. Moving forward, it will be important to include uncommon EGFR mutations in the first-line molecular analysis of all patients with adenocarcinoma of the lung, as this will help optimize patient outcomes according to their precise genotype.