The therapeutic features of EGFR L858R exon 21 mutation in non-small cell lung cancer

Introduction. Monotherapy with EGFR tyrosine kinase inhibitors (TKIs) results in a worse prognosis for patients with the exon 21 L858R mutation than for patients with exon 19 Del. Thus, the search for alternative drug strategies that improve treatment outcomes for patients with NSCLC with the L858R mutation is an urgent problem. This article presents preliminary results of a pilot study of the effectiveness of chemotherapy integrated into targeted anti-EGFR therapy for patients with non-small cell lung cancer (NSCLC) with a mutation in exon 21 of the EGFR gene. Aim. To improve progression-free survival results on first-line therapy in patients with NSCLC with the L858R mutation. Materials and methods . From 2015 to 2021 23 patients were included in the study with advanced L858R 21 exon mutation NSCLC for the first line of treatment. Patients received TKI therapy for the first 2 months, followed by discontinuation of targeted therapy and receiving 3 courses of paclitaxel and carboplatin. Target therapy was then resumed until disease progression. The follow up period was 36 months. Results. The objective response rate (ORR) was 59.1%. Median progression-free survival 23 months 95% CI: 16–36. Four (18.1%) patients developed grade 3-4 toxicity during chemotherapy, and therefore the 3rd course of chemotherapy was canceled in one patient. Due to toxicity during targeted therapy, gefitinib dose was reduced in one patient and the drug was changed from gefitinib to afatinib in the other one patient. Conclusion. Preliminary results of our study showed that integrating chemotherapy into targeted treatment for this category of patients may become a new worthy option to increase median PFS.