Tumor response to EGFR/BRAF/MEK co-inhibition in a patient with EGFR mutated lung adenocarcinoma developing a BRAFV600 mutation as an acquired resistance mechanism

Mechanisms of resistance to targeted therapy and immunotherapy in non-small cell lung cancer: promising strategies to overcoming challenges

Resistance to targeted therapy and immunotherapy in non-small cell lung cancer (NSCLC) is a significant challenge in the treatment of this disease. The mechanisms of resistance are multifactorial and include molecular target alterations and activation of alternative pathways, tumor heterogeneity and tumor microenvironment change, immune evasion, and immunosuppression. Promising strategies for overcoming resistance include the development of combination therapies, understanding the resistance mechanisms to better use novel drug targets, the identification of biomarkers, the modulation of the tumor microenvironment and so on. Ongoing research into the mechanisms of resistance and the development of new therapeutic approaches hold great promise for improving outcomes for patients with NSCLC. Here, we summarize diverse mechanisms driving resistance to targeted therapy and immunotherapy in NSCLC and the latest potential and promising strategies to overcome the resistance to help patients who suffer from NSCLC.

MAP2K1 K57N Conferred an Acquired Resistance to Furmonertinib, Dabrafenib and Trametinib Combined Therapy in Advanced Lung Adenocarcinoma with EGFR Mutation and BRAF V600E

Previous case reports have demonstrated the effectiveness of combination therapy involving EGFR TKI, BRAF inhibitor dabrafenib, and MEK inhibitor trametinib in metastatic non-small-cell lung cancer (NSCLC) patients with acquired BRAF V600E and EGFR mutations. However, the current literature does not provide any reports on the presence of resistant mutations in response to the administration of three-drug combination therapy. Exploring the resistance mechanism of targeted therapy is helpful to optimize the subsequent treatment strategy of patients. Herein, we report a case of a patient with advanced EGFR positive lung adenocarcinoma harboring an acquired BRAF V600E mutation who responded to the combination of furmonertinib, dabrafenib, and trametinib therapy. Unexpectedly, a MAP2K1 K57N acquired mutation was identified by NGS (Next-generation sequencing) analysis of re-biopsy tumor tissue after the patient was resistant to three-drug therapy. As far as we know, this is the first report demonstrating that the efficacy of using combination of furmonertinib and BRAF/MEK inhibitors and the MAP2K1 K57N mutation serves as a resistant mechanism to the three-drug therapy. This novel finding not only revealed a new resistant mutation but also had important implications for the identification of effective patients to EGFR/BRAF/MEK combination therapy.

Detecting acquired V-Raf murine sarcoma viral oncogene homolog B1 V600E mutation associated with osimertinib resistance in epidermal growth factor receptor-mutant lung adenocarcinoma: A case report

Osimertinib has demonstrated efficacy as the first- and second-line treatment for advanced non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) gene mutations. However, EGFR-mutant NSCLC cells often acquire resistance to osimertinib. V-Raf murine sarcoma viral oncogene homolog B1 (BRAF) mutation (BRAF V600E) was detected in a re-biopsy (LC-SCRUM-TRY testing) of a patient with advanced lung adenocarcinoma who was resistant to osimertinib treatment. Currently, the patient is receiving dabrafenib/trametinib combination therapy and is under observation; a slight shrinking effect of cancer has been observed.

Promising response of dabrafenib, trametinib, and osimertinib combination therapy for concomitant BRAF and EGFR-TKI resistance mutations

Despite the initial promise of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) in effectively combating tumor growth, the majority of patients with advanced non-small cell lung cancers (NSCLCs) inevitably develop resistance to these treatments. An infrequent genetic mutation known as BRAFV600E has been identified as a contributing factor to the emergence of acquired resistance to EGFR-TKIs. Genetic alterations in BRAF, particularly V600E, contribute to resistance to osimertinib. However, a combination therapy involving osimertinib, dabrafenib (a BRAF inhibitor), and trametinib has shown effectiveness in overcoming BRAF V600E-mediated resistance in advanced lung adenocarcinoma. This treatment regimen holds promise for similar cases. In our case report, the combination of osimertinib, dabrafenib, and trametinib effectively overcame osimertinib resistance and resulted in sustained partial remission.

The Evolution of BRAF Activation in Non-Small-Cell Lung Cancer

Non-small-cell lung cancer (NSCLC) is the most common subtype of lung cancer, of which approximate 4% had BRAF activation, with an option for targeted therapy. BRAF activation comprises of V600 and non-V600 mutations, fusion, rearrangement, in-frame deletions, insertions, and co-mutations. In addition, BRAF primary activation and secondary activation presents with different biological phenotypes, medical senses and subsequent treatments. BRAF primary activation plays a critical role in proliferation and metastasis as a driver gene of NSCLC, while secondary activation mediates acquired resistance to other targeted therapy, especially for epidermal growth factor tyrosine kinase inhibitor (EGFR-TKI). Treatment options for different activation of BRAF are diverse. Targeted therapy, especially two-drug combination therapy, is an important option. Besides, immune checkpoint inhibitors (ICIs) would be another option since BRAF activation would be a positive biomarker of tumor response of ICIs therapy. To date, no high level evidences support targeted therapy or immunotherapy as prioritized recommendation. After targeted therapy, the evolution of BRAF includes the activation of the upstream, downstream and bypass pathways of BRAF. In this review, therapeutic modalities and post-therapeutic evolutionary pathways of BRAF are discussed, and future research directions are also provided.

Characteristics of and Treatment Strategies for Advanced EGFR-Mutant NSCLC With Concomitant BRAF Variations

Introduction

Methods

Results

Conclusions

Morphologic-Molecular Transformation of Oncogene Addicted Non-Small Cell Lung Cancer

Patients with non-small cell lung cancer, especially adenocarcinomas, harbour at least one oncogenic driver mutation that can potentially be a target for therapy. Treatments of these oncogene-addicted tumours, such as the use of tyrosine kinase inhibitors (TKIs) of mutated epidermal growth factor receptor, have dramatically improved the outcome of patients. However, some patients may acquire resistance to treatment early on after starting a targeted therapy. Transformations to other histotypes—small cell lung carcinoma, large cell neuroendocrine carcinoma, squamous cell carcinoma, and sarcomatoid carcinoma—have been increasingly recognised as important mechanisms of resistance and are increasingly becoming a topic of interest for all specialists involved in the diagnosis, management, and care of these patients. This article, after examining the most used TKI agents and their main biological activities, discusses histological and molecular transformations with an up-to-date review of all previous cases published in the field. Liquid biopsy and future research directions are also briefly discussed to offer the reader a complete and up-to-date overview of the topic.

Targeting BRAF Activation as Acquired Resistance Mechanism to EGFR Tyrosine Kinase Inhibitors in EGFR-Mutant Non-Small-Cell Lung Cancer

Osimertinib has become a standard of care in the first-line treatment of advanced-stage non-small-cell lung cancer (NSCLC) harboring exon 19 and 21 activating mutations in the EGFR gene. Nevertheless, the 18.9-month median progression-free survival emphasizes the fact that resistance to osimertinib therapy is inevitable. Acquired resistance mechanisms to osimertinib in EGFR-driven NSCLC include MET amplification, EGFR C797S mutation, neuroendocrine differentiation, small-cell lung carcinoma histologic transformation, PD-L1 and KRAS amplifications and ESR1-AKAP12 and MKRN1-BRAF translocations, as well as BRAF V600 mutation. This last one represents 3% of the acquired resistance mechanisms to osimertinib. In this review, we discuss the rationale for EGFR/BRAF/MEK co-inhibition in the light of a clinical case of EGFR-mutant NSCLC developing a BRAF V600 mutation as an acquired resistance mechanism to osimertinib and responding to the association of osimertinib plus dabrafenib and trametinib. Additionally, we discuss the acquired resistance mechanisms to osimertinib plus dabrafenib and trametinib combination in that context.