Case Report: Dramatic Response to Crizotinib in a Patient With Non-Small Cell Lung Cancer Positive for a Novel ARL1-MET Fusion

A novel HLA-DQB2::MET gene fusion variant in lung adenocarcinoma with prolonged response to tepotinib: a case report

Background

MET rearrangements are infrequently observed in non-small cell lung cancer (NSCLC). Advanced genomic detection techniques have unveiled such infrequent genomic variations, particularly MET fusions in approximately 0.5% of NSCLC patients. Tyrosine kinase inhibitors (TKIs) have revolutionized the standard of care in lung cancer and more recently a second generation MET TKI tepotinib received Food and Drug Administration (FDA) approval for MET exon 14 alterations in metastatic NSCLC. Despite this, the therapeutic landscape for MET-rearranged NSCLC patients remains significantly unexplored. The aim of our report is to detail a unique case of a patient with metastatic lung adenocarcinoma with a novel HLA-DQB2::MET fusion detected by next-generation sequencing (NGS) following previous treatment resistance.

Case Description

A 73-year-old female was initially started on carboplatin, pemetrexed and pembrolizumab with maintenance, but eventually had progression in the left upper lobe (LUL). Upon progression she was enrolled in a clinical trial of a monoclonal antibody with or without a PD-1 inhibitor, but brain metastasis progression was eventually detected by magnetic resonance imaging (MRI) requiring stereotactic radiosurgery (SRS) and a craniotomy. The trial drug was eventually discontinued due to progression and toxicity and NGS on bronchoscopy tissue revealed HLA-DQB2::MET fusion. The patient was initiated on tepotinib and continues with clinical and radiological stable disease for over 12 months. The patient's response to a MET inhibitor, tepotinib, underscores the potential efficacy of selective MET inhibitors for individuals with previously unexplored MET fusions.

Conclusions

The positive response to tepotinib of a patient with NSCLC harboring a novel MET-Fusion underscores the importance of the use of comprehensive next-generational sequencing-based panels and highlights the necessity for additional research and clinical exploration of selective MET inhibitors for managing NSCLC with MET rearrangements.

Response to Savolitinib in a Patient with Advanced Poorly Differentiated Lung Carcinoma Positive for a Novel EML4-MET Gene Fusion

Background

Cellular-mesenchymal to epithelial transition factor (c-MET) alterations have significant therapeutic implications in non-small cell lung cancer (NSCLC). Although MET fusion is a rare genomic event, advances in detection technologies have enabled the identification of various MET fusion partner genes. However, standard therapeutic options for MET fusion in NSCLC cases remain undefined. This report presents a novel fusion variant, EML4-MET, encompassing exons 1 to 13 of EML4 and exons 15 to 21 of MET, including the entire MET kinase domain, and discusses the response of this case to savolitinib treatment.

Case Presentation

A 65-year-old woman was diagnosed with advanced poorly differentiated lung carcinoma. Molecular profiling of circulating tumor DNA (ctDNA), carried out by next-generation sequencing (NGS), identified a novel EML4-MET fusion. The patient was administered the MET receptor tyrosine kinase inhibitor savolitinib at 400 mg daily. One month later, computed tomography (CT) revealed some lesions with volume reduction. However, COVID-19 diminished the efficacy of savolitinib. Regrettably, the patient succumbed to respiratory and circulatory failure due to disease progression in March 2023.

Conclusion

This case uncovers a new type of MET fusion and expands the range of potential MET fusion targets in NSCLC. The patient responded to savolitinib, suggesting a reference basis for the treatment of similar cases with EML4-MET fusion in the future. Additional research is warranted to assess the biological significance of the EML4-MET fusion in NSCLC.

MET fusions are targetable genomic variants in the treatment of advanced malignancies

Targeted therapy for malignancies has developed rapidly in recent years, benefiting patients harboring genetic mutations sensitive to relevant tyrosine kinase inhibitors (TKIs). With the development of targeted sequencing techniques, an increasing number of detectable genomic alterations in malignancies, including MET fusions, have been revealed. MET fusions, although rare among malignancies, might be functional driver genes that participate in activating downstream signaling pathways and promoting cell proliferation. Therefore, it is believed that MET fusions could be targetable genomic variants of MET, and inhibition of MET is considered an optionable therapeutic choice for patients harboring MET fusions. According to the summary presented in this review, we recommend MET-TKIs as suitable treatment agents for patients harboring primary MET fusions. For patients harboring acquired MET fusions after the development of resistance to TKIs targeting primary genomic alterations, such as sensitive EGFR mutations, treatment with a MET-TKI alone or in combination with TKIs targeting primary genomic alterations, such as EGFR-TKIs, is hypothesized to be a reasonable option for salvage treatment. In summary, MET fusions, despite their low incidence, should be taken into consideration when developing treatment strategies for cancer patients.

Identification of MET fusions as novel therapeutic targets sensitive to MET inhibitors in lung cancer

INTRODUCTION

Alterations in the MET gene, including amplifications and exon 14 skipping mutations, have been identified as actionable oncogenic alterations. However, MET fusions are rarely detected in lung cancer, and their sensitivity to therapeutics has not been systematically analyzed.

METHODS

The data from 30876 lung cancer patients from the LAVA database and 7966 patients from cBioPortal database were screened. Basic demographic and clinical information for the patients harboring MET fusions were collected. A lung squamous cell cancer patient harboring a novel EML4-MET fusion was treated with crizotinib. Additionally, a literature review was performed to summarize the cases of patients harboring MET fusions and their treatment information.

RESULTS

MET fusions were found in only 0.2% to 0.3% of lung cancer patients and appeared in almost all exons of the MET gene. Intragenic MET fusions were found in 52.6% (41/78) of the included patients. Crizotinib was effective for MET fusions, including a novel identified EML4-MET fusion, even after the failure of multiple lines of treatment. This result suggested that acquired MET fusions become more regionally selective, as they usually occurred in exons encoding the extracellular region. Interestingly, the MET-fused genes in primary MET fusions or acquired MET fusions were very different, which indicated the different functions and influences of the disease.

CONCLUSION

MET fusions are rare, and half of the fusion types were intragenic fusions. Lung cancer patients harboring primary or acquired MET fusions could benefit from crizotinib. In addition, EML4-MET was first reported in this study as a novel MET fusion type.