Afatinib, an effective treatment for patient with lung squamous cell carcinoma harboring uncommon EGFR G719A and R776C co-mutations

Clinical outcome of Brazilian patients with non-small cell lung cancer in early stage harboring rare mutations in epidermal growth factor receptor

The common epidermal growth factor receptor (EGFR) mutations, such as the L858R point mutation in exon 21 and the in-frame deletional mutation in exon 19, have been definitively associated with response to EGFR-tyrosine kinase inhibitors (EGFR-TKI). However, the clinical outcome and response to treatment for many other rarer mutations are still unclear. In this study, we report the results of Brazilian patients in stage IB-IIIA non-small cell lung cancer (NSCLC) following complete resection with minimal residual disease and EGFR mutations treated with adjuvant chemotherapy and/or EGFR-TKIs. The frequency of EGFR mutations was investigated in 70 cases of early stage NSCLC. Mutations in exons 18 and 20, uncommon mutations in exons 19 and 21, as well as in exons 3, 7, 14, 16, 22, 27, and 28, and/or the presence of different mutations in a single tumor (complex mutations) are considered rare. EGFR mutations were detected in 23 tumors (32.9%). Fourteen cases carried rare mutations and were treated with platinum-based chemotherapy and two cases were treated with erlotinib. The clinical outcome is described case by case with references to the literature. Notably, we found two rare EGFR mutations and one of them with an unknown response to chemotherapy and/or EGFR-TKIs. We have provided complementary information concerning the clinical outcome and treatment of patients with early stage NSCLC for several rare EGFR mutations not previously or only rarely reported. Description of cases harboring rare mutations can support the decision-making process in this subset of patients.

Case Report: Heterogeneity of Resistance Mechanisms in Different Lesions Co-Mediate Acquired Resistance to First-Line Icotinib in EGFR Mutant Non-Small Cell Lung Cancer

Epidermal growth factor receptor (EGFR)-activating mutations are major oncogenic mechanisms in non-small cell lung cancer (NSCLC). Most patients with NSCLC with EGFR mutations benefit from targeted therapy with EGFR- tyrosine kinase inhibitors (TKIs). One of the main limitations of targeted therapy is that the tumor response is not durable, with the inevitable development of drug resistance. Previous studies demonstrated that the potential resistance mechanisms are diverse, including the presence of EGFR T790M, MET amplification, mesenchymal transformation, and anaplastic lymphoma kinase (ALK) rearrangement. The patient in our report was diagnosed with stage IA lung adenocarcinoma harboring the EGFR L858R mutation and underwent radical surgery. The patient received icotinib for 12 months after recurrence. Subsequent molecular analysis of the left pleural effusion indicated that LCLAT1-ALK fusion might be an underlying mechanism contributing to the acquired resistance to icotinib. Ensartinib was prescribed, but the lesion in the right lung continued to progress. Hence, a re-biopsy and molecular analysis of lesions in the right lung was performed to solve this problem. In contrast to the left pleural effusion, EGFR exon 20 T790M might have mediated the acquired resistance in lesions in the right lung of this patient. The combination of osimertinib and ensartinib has achieved a rapid partial response until now. The complexity and heterogeneity in our case may provide new insights into the resistance mechanisms of targeted therapy.