Durable Response of Dabrafenib, Trametinib, and Capmatinib in an NSCLC Patient With Co-Existing BRAF-KIAA1549 Fusion and MET Amplification: A Case Report

The Efficacy and Safety of Treating Acquired MET Resistance Through Combinations of Parent and MET Tyrosine Kinase Inhibitors in Patients With Metastatic Oncogene-Driven NSCLC

Introduction

Acquired MET gene amplification, MET exon 14 skip mutations, or MET fusions can emerge as resistance mechanisms to tyrosine kinase inhibitors (TKIs) in patients with lung cancer. The efficacy and safety of combining MET TKIs (such as crizotinib, capmatinib, or tepotinib) with parent TKIs to target acquired MET resistance are not well characterized.

Methods

Multi-institutional retrospective chart review identified 83 patients with metastatic oncogene-driven NSCLC that were separated into the following two pairwise matched cohorts: (1) MET cohort (n = 41)-patients with acquired MET resistance continuing their parent TKI with a MET TKI added or (2) Chemotherapy cohort (n = 42)-patients without any actionable resistance continuing their parent TKI with a platinum-pemetrexed added. Clinicopathologic features, radiographic response (by means of Response Evaluation Criteria in Solid Tumors version 1.1), survival outcomes, adverse events (AEs) (by means of Common Terminology Criteria for Adverse Events version 5.0), and genomic data were collected. Survival outcomes were assessed using Kaplan-Meier methods. Multivariate modeling adjusted for lines of therapy, brain metastases, TP53 mutations, and oligometastatic disease.

Results

Within the MET cohort, median age was 56 years (range: 36-83 y). Most patients were never smokers (28 of 41, 68.3%). Baseline brain metastases were common (21 of 41, 51%). The most common oncogenes in the MET cohort were EGFR (30 of 41, 73.2%), ALK (seven of 41, 17.1%), and ROS1 (two of 41, 4.9%). Co-occurring TP53 mutations (32 of 41, 78%) were frequent. Acquired MET alterations included MET gene amplification (37 of 41, 90%), MET exon 14 mutations (two of 41, 5%), and MET gene fusions (two of 41, 5%). After multivariate adjustment, the objective response rate (ORR) was higher in the MET cohort versus the chemotherapy cohort (ORR: 69.2% versus 20%, p < 0.001). Within the MET cohort, MET gene copy number (≥10 versus 6-10) did not affect radiographic response (54.5% versus 68.4%, p = 0.698). There was no difference in ORR on the basis of MET TKI used (F [2, 36] = 0.021, p = 0.978). There was no difference in progression-free survival (5 versus 6 mo; hazard ratio = 0.64; 95% confidence interval: 0.34-1.23, p = 0.18) or overall survival (13 versus 11 mo; hazard ratio = 0.75; 95% confidence interval: 0.42-1.35, p = 0.34) between the MET and chemotherapy cohorts. In the MET cohort, dose reductions for MET TKI-related toxicities were common (17 of 41, 41.4%) but less frequent for parent TKIs (two of 41, 5%). Grade 3 AEs were not significant between crizotinib, capmatinib, and tepotinib (p = 0.3). The discontinuation rate of MET TKIs was 17% with no significant differences between MET TKIs (p = 0.315). Among pre- and post-treatment biopsies (n = 17) in the MET cohort, the most common next-generation sequencing findings were loss of MET gene amplification (15 of 17, 88.2%), MET on-target mutations (seven of 17, 41.2%), new Ras-Raf-MAPK alterations (three of 17, 17.6%), and EGFR gene amplification (two of 17, 11.7%).

Conclusions

The efficacy and safety of combining MET TKIs (crizotinib, capmatinib, or tepotinib) with parent TKIs for acquired MET resistance are efficacious. Radiographic response and AEs did not differ significantly on the basis of the underlying MET TKI used. Loss of MET gene amplification, development of MET on-target mutations, Ras-Raf-MAPK alterations, and EGFR gene amplification were molecular patterns found on progression with dual parent and MET TKI combinations.

[Chinese Expert Consensus on the Clinical Practice of Non-small Cell Lung Cancer Fusion Gene Detection Based on RNA-based NGS]

RNA-based next-generation sequencing (NGS) has been recommended as a method for detecting fusion genes in non-small cell lung cancer (NSCLC) according to clinical practice guidelines and expert consensus. The primary targetable alterations in NSCLC consist of gene mutations and fusions, making the detection of gene mutations and fusions indispensable for assessing the feasibility of targeted therapies. Currently, the integration of DNA-based NGS and RNA-based NGS allows for simultaneous detection of gene mutations and fusions and has been partially implemented in clinical practice. However, standardized guidelines and criteria for the significance, application scenarios, and quality control of RNA-based NGS in fusion gene detection are still lacking in China. This consensus aims to provide further clarity on the practical significance, application scenarios, and quality control measures of RNA-based NGS in fusion gene detection. Additionally, it offers guiding recommendations to facilitate the clinical implementation of RNA-based NGS in the diagnosis and treatment of NSCLC, ultimately maximizing the benefits for patients from fusion gene detection.
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[Research Progress of BRAF Fusion in Non-small Cell Lung Cancer]

In advanced non-small cell lung cancer (NSCLC), V-Raf murine sarcoma viral oncogene homolog B1 (BRAF) mutation is highly malignant and has poor prognosis, and currently Dabrafenib in combination with Trametinib is approved for first-line treatment of patients with BRAF V600 mutation. In addition to mutations, BRAF fusion can also occur. With the development of gene detection, the detection of BRAF fusion is gradually increasing, but there is a lack of effective therapeutic strategies for BRAF fusion. In this paper, we review the clinical characteristics, mechanism of action, and clinical treatment of BRAF fusion to provide a basis for the treatment of BRAF fusion in NSCLC patients.
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