MET alterations in advanced non-small cell lung cancer.

Precision medicine has helped identify several tumor molecular aberrations to be treated with targeted therapies. These therapies showed substantial improvement in efficacy without excessive toxicity in patients with specific oncogenic drivers with advanced cancers. In metastatic lung cancers, the implementation of broad platforms for molecular tumor sequencing has helped oncology providers identify oncogenic drivers linked with better outcomes when treated upfront with targeted therapies. Mesenchymal-epithelial transition factor (MET) alterations are present in up to 60% of non-small cell lung cancer and are associated with a poor prognosis. Capmatinib and tepotinib are currently the only two approved targeted therapies by the U.S. Food and Drug Administration (FDA) for patients with MET exon 14 skipping mutation. Several agents are being developed to tackle an unmet need in patients with MET alterations. Some of these agents are being used in combination with EGFR targeted therapy to mitigate resistance to EGFR inhibitor. These agents are poised to provide new hope for these patients.

MEK inhibitor sensitivity in BRAF fusion-driven prostate cancer.

PURPOSE: The identification of subpopulations harboring druggable targets has become a major step forward in the subclassification of solid tumors into small groups suitable for specific therapies. BRAF fusions represent a paradigm of uncommon and targetable oncogenic events and have been widely correlated to the development of specific malignancies. However, they are only present in a limited frequency across most common tumor types. At this regard, we performed a genomic screening aimed to identifying rare variants associated to advanced prostate cancer development. METHODS: Tumoral tissue genomic screening of 41 patients developing advanced prostate cancer was performed at our center as part of the GETHI XX study. The project, sponsored by the Spanish Collaborative Group in Rare Cancers (GETHI), aims to analyze the molecular background of rare tumors and to discover unfrequent molecular variants in common tumors. RESULTS: Here we present the clinical outcome and an in-deep molecular analysis performed in a case harboring a SND1-BRAF fusion gene. The identification of such rearrangement in a patient refractory to standard therapies led to the administration of trametinib (MEK inhibitor). Despite unsensitive to standard therapies, the patient achieved a dramatic response to trametinib. A comprehensive study of the tumor demonstrated this event to be a trunk alteration with higher expression of MEK in areas of tumor invasion. CONCLUSIONS: Our study describes the patient-driven discovery of the first BRAF fusion-driven prostate cancer effectively treated with trametinib. Consequently, MAPK pathway activation could define a new subtype of prostate cancer susceptible to a tailored management.

Genetic screening and molecular characterization of MET alterations in non-small cell lung cancer.

PURPOSE: Aberrant activation of MET as a result of exon 14-skipping (METex14) mutations or gene amplification is an oncogenic mechanism in non-small cell lung carcinoma (NSCLC) and a potential therapeutic target. The purpose of this study was to characterize MET alterations in a cohort of NSCLC patients treated with surgery. METHODS AND PATIENTS: 157 NSCLCs of various histopathologies, including pulmonary sarcomatoid carcinomas (PSC), were tested for MET alterations. METex14 mutations, MET copy number alterations and the levels of MET protein were determined by Sanger sequencing, fluorescence in situ hybridization and immunohistochemistry, respectively. Concurrent alterations of other important cancer genes and immunostaining of the downstream effector, phopho-S6, were also determined. RESULTS: METex14 mutations and MET amplification were detected in seven tumors. MET genetic alterations were found predominantly in the lung adenocarcinoma (ADC) and PSC histopathologies. High levels of MET protein were found in most MET-amplified tumors, but not in all METex14-mutated tumors. Strong phopho-S6 staining was observed in about half of the MET-activated tumors. One tumor with METex14 exhibited concurrent ERBB2 amplification. CONCLUSIONS: MET activation, by either METex14 mutations or amplification, is characteristic of a subset of early stage NSCLCs and may coexist with ERBB2 amplification. This may have potential therapeutic implications. The presence of METex14 mutations was associated with low levels of MET protein, which may limit the use of total MET immunostaining as a marker for preselecting patients for MET-targeted therapies.