Phase 1b Trial of Ficlatuzumab, a Humanized Hepatocyte Growth Factor Inhibitory Monoclonal Antibody, in Combination With Gefitinib in Asian Patients With NSCLC

[Research Progresses in the Treatment of NSCLC with MET Gene Variants: A Riview]

Mesenchymal-epithelial transition factor (MET) has long been considered as the most crucial and promising driver gene in the occurrence and development of non-small cell lung cancer (NSCLC), except for epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK), and c-ROS oncogene 1 receptor tyrosine kinase (ROS1). In recent years, therapeutic drugs targeting MET have been continuously developed and applied in clinical practice. First, the curative effect of NSCLC patients with MET exon 14 skipping mutations has been further improved. In addition, when MET amplification occurs after resistance to EGFR tyrosine kinase inhibitors (EGFR-TKIs) in patients with advanced EGFR-mutant NSCLC, the combination of MET-TKIs and EGFR-TKIs has brought significant survival benefits and many other advances. This article reviews the treatment progress of NSCLC patients with different types of MET variants under different circumstances, which provides reference for the selection of clinical treatment strategies.
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KRAS and MET in non-small-cell lung cancer: two of the new kids on the 'drivers' block

Non-small-cell lung cancer (NSCLC) is a heterogeneous disease, and therapeutic management has advanced to identify various critical oncogenic mutations that promote lung cancer tumorigenesis. Subsequent studies have developed targeted therapies against these oncogenes in the hope of personalized treatment based on the tumor's molecular genomics. This review presents a comprehensive review of the biology, new therapeutic interventions, and resistance patterns of two well-defined subgroups, tumors with KRAS and MET alterations. We also discuss the status of molecular testing practices for these two key oncogenic drivers, considering the progressive introduction of next-generation sequencing (NGS) and RNA sequencing in regular clinical practice.

MET Gene Dysregulation as a Promising Therapeutic Target in Lung Cancer-A Review

Several molecular abnormalities in the MET gene have been identified, including overexpression, amplification, point mutations, and "skipping mutation" in exon 14. Even though deregulated MET signaling occurs rarely in non-small cell lung cancer (NSCLC), it possesses tumorigenic activity. Since the discovery of the significant role played by MET dysregulations in resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKI), many clinical trials have been focused on mechanisms underlying this acquired resistance. Therefore, new therapeutic strategies are being considered in the personalized therapy of NSCLC patients carrying MET abnormalities. First, MET kinase inhibitors (tepotinib and capmatinib) have been shown to be effective in the first and subsequent lines of treatment in NSCLC patients with "skipping mutations" in exon 14 of MET gene. In this article, the authors show the role of MET signaling pathway alterations and describe the results of clinical trials with MET inhibitors in NSCLC patients.

When the MET receptor kicks in to resist targeted therapies

Although targeted therapies have increased the life expectancy of patients with druggable molecular alterations directly involved in tumor development, the efficacy of these therapies is limited by acquired resistances leading to treatment failure. Most targeted therapies, including ones exploiting therapeutic antibodies and kinase inhibitors, are directed against receptor tyrosine kinases (RTKs) or major signaling hubs. Resistances to these therapies arise when inhibition of these targets is bypassed through activation of alternative signaling pathways. In recent years, activation of the receptor tyrosine kinase MET has been shown to promote resistance to various targeted therapies. This casts MET as important actor in resistance. In this review, we describe how the MET receptor triggers resistance to targeted therapies against RTKs such as EGFR, VEGFR, and HER2 and against signaling hubs such as BRAF. We also describe how MET can be its own resistance factor, as illustrated by on-target resistance of lung tumors harboring activating mutations causing MET exon 14 skipping. Interestingly, investigation of all these situations reveals functional physiological relationships between MET and the target of the therapy to which the cancer becomes resistant, suggesting that resistance stems from preexisting mechanisms. Identification of MET as a resistance factor opens the way to co-treatment strategies that are being tested in current clinical trials.

Targeted Therapy Approaches for MET Abnormalities in Non-Small Cell Lung Cancer

The tyrosine kinase receptor mesenchymal epithelial transition (MET) is a proto-oncogene that, through the activation of the MET-hepatocyte growth factor (HGF) pathway, encodes a variety of biological processes, including cell development, proliferation, invasion, and migration. Abnormal activation of the MET pathway, occurring through MET protein overexpression, and gene amplification or mutation, can contribute to oncogenesis and has been implicated in non-small cell lung cancer (NSCLC). Though it is associated with poor clinical outcome in NSCLCs, MET overexpression and its role as a therapeutic target remains somewhat elusive due to discrepancies in its occurrence. Unlike MET overexpression, MET amplification has demonstrated a stronger potential as a biomarker for therapeutic treatment, with clinical data indicating a compelling connection between a high MET gene copy number and a high response rate to targeted therapies. However, MET exon 14 skipping mutations, occurring in 3%-4 % of lung adenocarcinomas, are of particular interest, as tumors harboring these mutations have shown a significant response to MET inhibitors. Following the discovery of MET as a potential therapeutic target, extensive clinical studies have proposed three approaches to targeting MET: (1) MET tyrosine kinase inhibitors (TKIs), including crizotinib, capmatinib, tepotinib, savolinitib, and cabozantinib; (2) MET or HGF monoclonal antibodies, including emibetuzumab and ficlatuzumab; and (3) MET or HGF antibody drug conjugates, including telisotuzumab. Herein, we discuss the relevant clinical trials, particularly focusing on the efficacy as well as the safety and tolerability of the treatment options, in the promising field of targeting MET in NSCLC.

A Fusion Transcription Factor-Driven Cancer Progresses to a Fusion-Independent Relapse via Constitutive Activation of a Downstream Transcriptional Target

Targeted monotherapies usually fail due to development of resistance by a subgroup of cells that evolve into recurrent tumors. Alveolar rhabdomyosarcoma is an aggressive myogenic soft-tissue cancer that is associated with a characteristic PAX3-FOXO1 gene fusion encoding a novel fusion transcription factor. In our myoblast model of PAX3-FOXO1-induced rhabdomyosarcoma, deinduction of PAX3-FOXO1 simulates a targeted therapy that antagonizes the fusion oncoprotein. This simulated therapy results initially in regression of the primary tumors, but PAX3-FOXO1-independent recurrent tumors eventually form after a delay. We report here that upregulation of FGF8, a direct transcriptional target of PAX3-FOXO1, is a mechanism responsible for PAX3-FOXO1-independent tumor recurrence. As a transcriptional target of PAX3-FOXO1, FGF8 promoted oncogenic activity in PAX3-FOXO1-expressing primary tumors that developed in the myoblast system. In the recurrent tumors forming after PAX3-FOXO1 deinduction, FGF8 expression was necessary and sufficient to induce PAX3-FOXO1-independent tumor growth through an autocrine mechanism. FGF8 was also expressed in human PAX3-FOXO1-expressing rhabdomyosarcoma cell lines and contributed to proliferation and transformation. In a human rhabdomyosarcoma cell line with reduced PAX3-FOXO1 expression, FGF8 upregulation rescued oncogenicity and simulated recurrence after PAX3-FOXO1-targeted therapy. We propose that deregulated expression of a PAX3-FOXO1 transcriptional target can generate resistance to therapy directed against this oncogenic transcription factor and postulate that this resistance mechanism may ultimately be countered by therapeutic approaches that antagonize the corresponding downstream pathways. SIGNIFICANCE: In a model of cancer initiated by a fusion transcription factor, constitutive activation of a downstream transcriptional target leads to fusion oncoprotein-independent recurrences, thereby highlighting a novel progression mechanism and therapeutic target.

Current and future treatment options for MET exon 14 skipping alterations in non-small cell lung cancer

It has been over three decades since the hepatocyte growth factor (HGF) ligand and its receptor MET proto-oncogene (MET) pathway was established as promoting cancer growth and metastasis. MET exon 14 skipping (METex14) alterations occur in 3-4% of all non-small cell lung cancer (NSCLC) patients, typically in elderly patients (older than 70 years), and result in constitutive activation of the MET receptor by altering a region required for receptor degradation. Multi-kinase inhibitor of MET, such as crizotinib, and more recently selective MET inhibitors, such as capmatinib and tepotinib, have demonstrated clinical efficacy and safety in METex14 NSCLC patients in clinical trials. These results have led to the approval of MET inhibitors by regulatory agencies across the globe. The success also fueled the excitement of further development of therapeutic strategies to target METex14 in lung cancers. This article provides an overview of the clinical development program targeting METex14 in NSCLC, including small molecular tyrosine kinase inhibitors and anti-MET antibodies. Furthermore, combination therapy immune checkpoint inhibitors or other targeted therapies are also under development in various patient populations, with acquired resistance immune or targeted therapy. Clinical trials in different development stages are ongoing and more drugs targeted to c-MET will be available for NSCLC patients with METex14 skipping mutations in the future.

Phase I Study of Ficlatuzumab and Cetuximab in Cetuximab-Resistant, Recurrent/Metastatic Head and Neck Cancer

Cetuximab, an anti-EGFR monoclonal antibody (mAb), is approved for advanced head and neck squamous cell carcinoma (HNSCC) but benefits a minority. An established tumor-intrinsic resistance mechanism is cross-talk between the EGFR and hepatocyte growth factor (HGF)/cMet pathways. Dual pathway inhibition may overcome cetuximab resistance. This Phase I study evaluated the combination of cetuximab and ficlatuzumab, an anti-HGF mAb, in patients with recurrent/metastatic HNSCC. The primary objective was to establish the recommended Phase II dose (RP2D). Secondary objectives included overall response rate (ORR), progression-free survival (PFS), and overall survival (OS). Mechanistic tumor-intrinsic and immune biomarkers were explored. Thirteen patients enrolled with no dose-limiting toxicities observed at any dose tier. Three evaluable patients were treated at Tier 1 and nine at Tier 2, which was determined to be the RP2D (cetuximab 500 mg/m² and ficlatuzumab 20 mg/kg every 2 weeks). Median PFS and OS were 5.4 (90% CI = 1.9–11.4) and 8.9 (90% CI = 2.7–15.2) months, respectively, with a confirmed ORR of 2 of 12 (17%; 90% CI = 6–40%). High circulating soluble cMet levels correlated with poor survival. An increase in peripheral T cells, particularly the CD8⁺ subset, was associated with treatment response whereas progression was associated with expansion of a distinct myeloid population. This well-tolerated combination demonstrated promising activity in cetuximab-resistant, advanced HNSCC.

The c-MET oncoprotein: Function, mechanisms of degradation and its targeting by novel anti-cancer agents

BACKGROUND

The c-MET oncoprotein drives cancer progression in a variety of tumors through its signaling transduction pathways. This oncoprotein is also degraded by multiple mechanisms involving the lysosome, proteasome and cleavage by proteases. Targeting c-MET degradation pathways may result in effective therapeutic strategies.

SCOPE OF REVIEW

Since the discovery of oncogenic functions of c-MET, there has been a great deal of effort to develop anti-cancer drugs targeting this oncoprotein. Unexpectedly, novel di-2-pyridylketone thiosemicarbazones that demonstrate marked anti-tumor activity, down-regulate c-MET through their ability to bind intracellular iron and via mechanisms including, down-regulation of MET mRNA, enhanced lysosomal processing and increased metalloprotease-mediated cleavage.

MAJOR CONCLUSIONS

The c-MET oncoprotein regulation and degradation pathways are complex. However, with increasing understanding of its degradation mechanisms, there is also greater opportunities to therapeutically target these pathways.

GENERAL SIGNIFICANCE

Understanding the mechanisms of degradation of c-MET protein and its regulation could lead to novel therapeutics.

First-in-human phase I trial of anti-hepatocyte growth factor antibody (YYB101) in refractory solid tumor patients

Background

YYB101, a humanized monoclonal antibody against hepatocyte growth factor (HGF), has shown safety and efficacy in vitro and in vivo. This is a first-in-human trial of this antibody.

Materials and Methods

YYB101 was administered intravenously to refractory cancer patients once every 4 weeks for 1 month, and then once every 2 weeks until disease progression or intolerable toxicity, at doses of 0.3, 1, 3, 5, 10, 20, 30 mg/kg, according to a 3+3 dose escalation design. Maximum tolerated dose, safety, pharmacokinetics, and pharmacodynamics were studied. HGF, MET, PD-L1, and ERK expression was evaluated for 9 of 17 patients of the expansion cohort (20 mg/kg).

Results

In 39 patients enrolled, no dose-limiting toxicity was observed at 0.3 mg/kg, and the most commonly detected toxicity was generalized edema (n = 7, 18.9%) followed by pruritis and nausea (n = 5, 13.5%, each), fatigue, anemia, and decreased appetite (n = 4, 10.8%, each). No patient discontinued treatment because of adverse events. YYB101 showed dose-proportional pharmacokinetics up to 30 mg/kg. Partial response in 1 (2.5%) and stable disease in 17 (43.5%) were observed. HGF, MET, PD-L1, and ERK proteins were not significant predictors for treatment response. However, serum HGF level was significantly lowered in responders upon drug administration. RNA sequencing revealed a mesenchymal signature in two long-term responders.

Conclusion

YYB101 showed favorable safety and efficacy in patients with refractory solid tumors. Based on this phase I trial, a phase II study on the YYB101 + irinotecan combination in refractory metastatic colorectal cancer patients is planned.

Conclusion

ClinicalTrials.gov Identifier: NCT02499224.

Impact of MET alterations on targeted therapy with EGFR-tyrosine kinase inhibitors for EGFR-mutant lung cancer

EGFR-tyrosine kinase inhibitors (EGFR-TKIs) have achieved remarkable outcomes in the treatment of patients with EGFR-mutant non-small-cell lung cancer, but acquired resistance is still the main factor restricting their long-term use. In addition to the T790 M mutation of EGFR, amplification of the MET (or c-MET) gene has long been recognized as an important resistance mechanism for first- or second-generation EGFR-TKIs. Recent studies suggest that a key mechanism of acquired resistance to third-generation EGFR-TKIs (such as osimertinib) may be MET amplification and/or protein overactivation, especially when they are used as a first-line treatment. Therefore, in patients resistant to first-generation EGFR-TKIs caused by MET amplification and/or protein overactivation, the combination of osimertinib with MET or MEK inhibitors may be considered.

Epigenetic activation of hepatocyte growth factor is associated with epithelial-mesenchymal transition and clinical outcome in non-small cell lung cancer

Hepatocyte growth factor (HGF) expression is repressed in normal differentiated lung epithelial cells, but its expression is aberrantly upregulated in non-small cell lung cancer (NSCLC) and acts as a poor prognostic factor. The underlying molecular mechanisms of aberrant HGF expression are unclear. In this study, a novel differential methylation region located in the HGF promoter was identified, which was associated with aberrant HGF expression in NSCLC. The correlations of HGF promoter methylation detected by methylation specific PCR and HGF expression detected by immunohistochemistry with clinical outcomes were assessed in NSCLC patients. DNA methylation of the HGF promoter was correlated with the activation of HGF expression, which induced epithelial-mesenchymal transition, cell migration and invasion. According to the clinical correlation analysis in 63 NSCLC patients, those with high methylation were more likely to have stages III and IV (51.6% vs. 25.0%, P<0.05) and metastasis (57.5% vs. 16.7%, P<0.05) than patients with low methylation. In addition, compared with the protein marker of HGF expression, the DNA methylation marker of the HGF promoter had higher specificity for prognostic analysis of metastases in NSCLC. Our study indicated the regulatory mechanisms related to DNA methylation of the HGF promoter for HGF expression in NSCLC epithelial cells, and suggested that the DNA methylation signature of the HGF promoter could potentially be employed as a biomarker to improve the prognostic accuracy of NSCLC.

c-Met Signaling Protects from Nonalcoholic Steatohepatitis- (NASH-) Induced Fibrosis in Different Liver Cell Types

Nonalcoholic steatohepatitis (NASH) is the most common chronic, progressive liver disease in Western countries. The significance of cellular interactions of the HGF/c-Met axis in different liver cell subtypes and its relation to the oxidative stress response remains unclear so far. Hence, the present study is aimed at investigating the role of c-Met and the interaction with the oxidative stress response during NASH development in mice and humans. Conditional c-Met knockout (KO) lines (LysCre for Kupffer cells/macrophages, GFAPCre for α-SMA⁺ and CK19⁺ cells and MxCre for bone marrow-derived immune cells) were fed chow and either methionine-choline-deficient diet (MCD) for 4 weeks or high-fat diet (HFD) for 24 weeks. Mice lacking c-Met either in Kupffer cells, α-SMA⁺ and CK19⁺ cells, or bone marrow-derived immune cells displayed earlier and faster progressing steatohepatitis during dietary treatments. Severe fatty liver degeneration and histomorphological changes were accompanied by an increased infiltration of immune cells and a significant upregulation of inflammatory cytokine expression reflecting an earlier initiation of steatohepatitis development. In addition, animals with a cell-type-specific deletion of c-Met exhibited a strong generation of reactive oxygen species (ROS) by dihydroethidium (hydroethidine) (DHE) staining showing a significant increase in the oxidative stress response especially in LysCre/c-Met^mut and MxCre/c-Met^mut animals. All these changes finally lead to earlier and stronger fibrosis progression with strong accumulation of collagen within liver tissue of mice deficient for c-Met in different liver cell types. The HGF/c-Met signaling pathway prevents from steatosis development and has a protective function in the progression to steatohepatitis and fibrosis. It conveys an antifibrotic role independent on which cell type c-Met is missing (Kupffer cells/macrophages, α-SMA⁺ and CK19⁺ cells, or bone marrow-derived immune cells). These results highlight a global protective capacity of c-Met in NASH development and progression.

Status of Agents Targeting the HGF/c-Met Axis in Lung Cancer

Hepatocyte growth factor (HGF) is the ligand for the tyrosine kinase receptor c-Met (Mesenchymal Epithelial Transition Factor also known as Hepatocyte Growth Factor Receptor, HGFR), a receptor with expression throughout epithelial and endothelial cell types. Activation of c-Met enhances cell proliferation, invasion, survival, angiogenesis, and motility. The c-Met pathway also stimulates tissue repair in normal cells. A body of past research shows that increased levels of HGF and/or overexpression of c-Met are associated with poor prognosis in several solid tumors, including lung cancer, as well as cancers of the head and neck, gastro-intestinal tract, breast, ovary and cervix. The HGF/c-Met signaling network is complex; both ligand-dependent and ligand-independent signaling occur. This article will provide an update on signaling through the HGF/c-Met axis, the mechanism of action of HGF/c-Met inhibitors, the lung cancer patient populations most likely to benefit, and possible mechanisms of resistance to these inhibitors. Although c-Met as a target in non-small cell lung cancer (NSCLC) showed promise based on preclinical data, clinical responses in NSCLC patients have been disappointing in the absence of MET mutation or MET gene amplification. New therapeutics that selectively target c-Met or HGF, or that target c-Met and a wider spectrum of interacting tyrosine kinases, will be discussed.

Role of cMET in the development and progression of colorectal cancer

Mesenchymal-epithelial transition (MET) is a member of a distinct subfamily of heterodimeric receptor tyrosine kinase receptors that specifically binds the hepatocyte growth factor (HGF). Binding to HGF leads to receptor dimerization/multimerization and phosphorylation, resulting in its catalytic activation. MET activation drives the malignant progression of several tumor types, including colorectal cancer (CRC), by promoting signaling cascades that mainly result in alterations of cell motility, survival, and proliferation. MET is aberrantly activated in many human cancers through various mechanisms, including point mutations, gene amplification, transcriptional up-regulation, or ligand autocrine loops. MET promotes cell scattering, invasion, and protection from apoptosis, thereby acting as an adjuvant pro-metastatic gene for many tumor types. In CRC, MET expression confers more aggressiveness and worse clinical prognosis. With all of this rationale, inhibitors that target the HGF/MET axis with different types of response have been developed. HGF and MET are new promising targets to understand the pathogenesis of CRC and for the development of new, targeted therapies.