MET gene copy number predicts worse overall survival in patients with non-small cell lung cancer (NSCLC); a systematic review and meta-analysis

Phase II study investigating the efficacy and safety of glesatinib (MGCD265) in patients with advanced NSCLC containing MET activating alterations

OBJECTIVES

Dysregulated signaling by mesenchymal epithelial transition factor (MET) and heightened AXL activation are implicated in the pathogenesis of non-small cell lung cancer (NSCLC). Glesatinib (MGCD265) is an investigational, oral inhibitor of MET and AXL.

MATERIALS AND METHODS

This open-label, Phase II study investigated glesatinib (free-base suspension [FBS] capsule 1050 mg BID or spray-dried dispersion [SDD] tablet 750 mg BID) in patients with advanced, previously treated NSCLC across four cohorts grouped according to presence of MET activating mutations or amplification in tumor or ctDNA. The primary endpoint was objective response rate (ORR).

RESULTS

Sixty-eight patients were enrolled: n = 28 and n = 8 with MET exon 14 skipping mutations in tumor tissue and ctDNA, respectively, and n = 20 and n = 12 with MET gene amplification in tumor tissue and ctDNA, respectively. Overall, ORR was 11.8 %, median progression-free survival was 4.0 months, and median overall survival was 7.0 months. Among patients with MET activating mutations, ORR was 10.7 % with tumor testing and 25.0 % with ctDNA testing. For MET amplification, responses were observed only in patients enrolled by tumor testing (ORR 15.0 %). Diarrhea (82.4 %), nausea (50.0 %), increased alanine aminotransferase (41.2 %), fatigue (38.2 %), and increased aspartate aminotransferase (36.8 %) were the most frequent adverse events assessed as related to study medication. Glesatinib exposure was similar with the SDD tablet and FBS capsule formulations. The study was terminated early by the sponsor due to modest clinical activity.

CONCLUSIONS

Glesatinib had an acceptable safety profile in patients with advanced, pre-treated NSCLC with MET activating alterations. Modest clinical activity was observed, which likely reflects suboptimal drug bioavailability suggested by previously reported Phase I data, and pharmacodynamic findings of lower than anticipated increases in circulating soluble shed MET ectodomain (s-MET).

Improved Survival Outcomes in Patients With MET-Dysregulated Advanced NSCLC Treated With MET Inhibitors: Results of a Multinational Retrospective Chart Review

BACKGROUND

We evaluated the disease and patient characteristics, treatment, and MET testing patterns, predictive biomarkers and survival outcomes in patients with MET-dysregulated metastatic non-small-cell lung cancer (NSCLC) in a real-world setting.

PATIENTS AND METHODS

This was a multinational, retrospective, noninterventional chart review study. Data from medical records of patients with advanced/metastatic EGFR wild-type, MET-dysregulated NSCLC (December 2017-September 2018) were abstracted into electronic data collection forms.

RESULTS

Overall, 211 patient charts were included in this analysis; 157 patients had MET exon 14 skipping mutations (METex14; with or without concomitant MET amplification) and 54 had MET amplification only. All patients were tested for METex14, whereas MET amplification was evaluated in 168 patients. No overlap was reported between MET dysregulation and ALK, ROS1 or RET rearrangements, or HER2 exon 20 insertions. Overall, 56 of 211 patients (26.5%) received MET inhibitor (METi) therapy in any treatment-line setting (31.2% in the METex14 cohort; 13% in the MET-amplified only cohort). In the METex14 cohort, median OS in patients receiving METi was 25.4 months versus 10.7 months in patients who did not (HR [95% CI]: 0.532 [0.340-0.832]; P = .0055). In the MET-amplified only cohort, median OS was 20.6 months in patients treated with METi compared with 7.6 months in those without METi (HR [95% CI]: 0.388 [0.152-0.991]; P = .0479).

CONCLUSIONS

MET alterations in NSCLC typically occur in the absence of other oncogenic driver mutations and are associated with poor survival outcomes. Notably, METi therapies are associated with improved survival outcomes in patients with MET-dysregulated NSCLC.

Real-World Treatment Outcomes of MET Exon14 Skipping in Non-small Cell Lung Cancer: GFPC 03-18 Study

BACKGROUND

MET-targeted tyrosine kinase inhibitors (TKIs) demonstrated efficacy in advanced non-small cell lung cancer (aNSCLC) with MET exon14 skipping mutations (METexon14); yet, data on the management of these patients in clinical practice is sparse.

OBJECTIVE

The aim of this study was to describe the management of METexon14 aNSCLC patients.

PATIENTS AND METHODS

This real-life, retrospective study analyzed the management of METexon14 aNSCLC. The primary endpoint was the median overall survival (mOS). Secondary endpoints were to assess investigator-progression-free survival (PFS) and mOS in different subgroups: patients treated with (a) crizotinib, regardless of treatment line; (b) anti-MET TKIs (crizotinib, tepotinib, capmatinib); and (c) immunotherapy.

RESULTS

A total of 118 patients were included between December 2015 and January 1, 2020 in 13 centers. Median age was 73 years, 62.7% were female, 83.9% had adenocarcinoma, 92.4% at stage IV, and 27% had more than three metastatic sites. The majority of the patients (106, 89.8%) received at least one systemic treatment; 73% received at least one anti-MET TKI: crizotinib (68.6%), tepotinib (16%), capmatinib (10%). Only 10% received two anti-MET TKIs in their treatment sequences. With a median follow-up of 16 months (95% CI 13.6-29.7), mOS was 27.1 months (95% CI 18-31.4). There was no significant difference between mOS of patients treated and never treated with crizotinib, 19.7 (95% CI 13.6-29.7) and 28 (95% CI 16.4-NR) months, respectively (p = 0.16); mOS of the TKI cohort and of the TKI-naïve patient cohort were 27.1 (95% CI 18-29.7) and 35.6 (95% CI 8.6-NR) months respectively, with no significant difference (p = 0.7).

CONCLUSIONS

In this real-life study, there was no evidence of benefit in mOS with anti-MET TKIs.

Phase I Study Evaluating Glesatinib (MGCD265), An Inhibitor of MET and AXL, in Patients with Non-small Cell Lung Cancer and Other Advanced Solid Tumors

BACKGROUND

Heightened signaling by mesenchymal epithelial transition factor (MET) is implicated in tumorigenesis. Glesatinib is an investigational, oral inhibitor of MET and AXL.

OBJECTIVE

This phase I study determined the maximum tolerated dose (MTD), recommended phase II dose (RP2D), and safety profile of glesatinib in patients with advanced or unresectable solid tumors. Antitumor activity and pharmacokinetics (PK) were secondary objectives.

PATIENTS AND METHODS

Four formulations of glesatinib glycolate salt (capsule, unmicronized, micronized, and micronized version 2 [V2] tablets) and two free-base formulations (free-base suspension [FBS] capsule and spray-dried dispersion [SDD] tablet), developed to enhance drug exposure and optimize manufacturing processes, were evaluated in patients with genetically unselected advanced/unresectable solid tumors. MTD, based on dose-limiting toxicities (DLTs) observed during the first 21-day treatment cycle, was further evaluated in dose-expansion cohorts comprising patients with overexpression of MET and/or AXL, MET/AXL amplification, MET-activating mutations, or MET/AXL rearrangements for confirmation as the RP2D.

RESULTS

Glesatinib was evaluated across 27 dose-escalation cohorts (n = 108). Due to suboptimal exposure with glesatinib glycolate salt formulations in the initial cohorts, investigations subsequently focused on the FBS capsule and SDD tablet; for these formulations, MTD was identified as 1050 mg twice daily and 750 mg twice daily, respectively. An additional 71 patients received glesatinib in the FBS and SDD dose-expansion cohorts. At MTDs, the most frequent treatment-related adverse events were diarrhea (FBS, 83.3%; SDD, 75.0%), nausea (57.1%, 30.6%), vomiting (45.2%, 25.0%), increased alanine aminotransferase (45.2%, 30.6%), and increased aspartate aminotransferase (47.6%, 27.8%). Exploratory pharmacodynamic analyses indicated target engagement and inhibition of MET by glesatinib. Antitumor activity was observed with glesatinib FBS 1050 mg twice daily and SDD 750 mg twice daily in tumors harboring MET/AXL alteration or aberrant protein expression, particularly in patients with non--small cell lung cancer (NSCLC). In patients with NSCLC, the objective response rate was 25.9% in those with MET/AXL mutation or amplification and 30.0% in a subset with MET-activating mutations. All six partial responses occurred in patients with tumors carrying MET exon 14 deletion mutations.

CONCLUSIONS

The safety profile of single-agent glesatinib was acceptable. SDD 750 mg twice daily was selected as the preferred glesatinib formulation and dose based on clinical activity, safety, and PK data. Observations from this study led to initiation of a phase II study of glesatinib in patients with NSCLC stratified by type of MET alteration (NCT02544633).

CLINICAL TRIALS REGISTRATION

ClinicalTrials.gov NCT00697632; June 2008.

Met inhibitors in the treatment of lung cancer: the evidence to date

INTRODUCTION

: The hepatocyte growth factor (HGF) receptor MET is an oncogenic driver in a subpopulation of Non-small Lung Cancer Cells (NSCLC) at the primary tumor stage or in acquired resistance to treatment with tumor-targeting tyrosine kinase inhibitors (TKIs).

AREAS COVERED

This article summarizes the mechanisms leading to overexpression and activation of MET by amplification and mutations including exon 14 aberrations. Furthermore, the methods to detect and categorize MET as a tumor driver and the selective TKIs for patient treatment are discussed.

EXPERT OPINION

: Activating mutations and rearrangements of kinases in NSCLC are the target of successful therapeutic intervention. However, MET activation involves a number of complex alterations including gene amplification, prevention of degradation by METex14 exon skipping and a host of gene mutations. A high-level of MET expression is the precondition for tumor responses to TKIs and the confirmation of MET-dependent tumor progression is difficult in primary lesions and in tumors exhibiting resistance to mutated EGFR-directed therapy in absence of standardized and concordant assays of MET amplification.

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.

Novel Pyridine Bioisostere of Cabozantinib as a Potent c-Met Kinase Inhibitor: Synthesis and Anti-Tumor Activity against Hepatocellular Carcinoma

Two novel bioisosteres of cabozantinib, 3 and 4, were designed and synthesized. The benzene ring in the center of the cabozantinib structure was replaced by trimethylpyridine (3) and pyridine (4), respectively. Surprisingly, the two compounds showed extremely contrasting mesenchymal-epithelial transition factor (c-Met) inhibitory activities at 1 μM concentration (4% inhibition of 3 vs. 94% inhibition of 4). The IC₅₀ value of compound 4 was 4.9 nM, similar to that of cabozantinib (5.4 nM). A ligand-based docking study suggested that 4 includes the preferred conformation for the binding to c-Met in the conformational ensemble, but 3 does not. The anti-proliferative activity of compound 4 against hepatocellular carcinoma (Hep3B and Huh7) and non-small-cell lung cancer (A549 and H1299) cell lines was better than that of cabozantinib, whereas 3 did not show a significant anti-proliferative activity. Moreover, the tumor selectivity of compound 4 toward hepatocellular carcinoma cell lines was higher than that of cabozantinib. In the xenograft chick tumor model, compound 4 inhibited Hep3B tumor growth to a much greater extent than cabozantinib. The present study suggests that compound 4 may be a good therapeutic candidate against hepatocellular carcinoma.

Correlation between PD-L1 expression and MET gene amplification in patients with advanced non-small cell lung cancer and no other actionable oncogenic driver

Non-small cell lung cancers (NSCLC) are the most common type of lung cancer and can be classified according to the presence of mutually exclusive oncogenic drivers. The majority of NSCLC patients present a non-actionable oncogenic driver, and treatment resistance through the amplification of the METproto-oncogene (MET) or the expression of programmed cell death protein 1 ligand (PD-L1) is common. Herein, we investigated the relation between MET gene amplification and PD-L1 expression in patients with advanced NSCLC and no other actionable oncogenic driver (i.e., EGFR, ALK, ROS1). Our retrospective observational study analyzed data from 48 patients (78% men, median age 66 years) admitted to the Germans Trias i Pujol Hospital, Spain, between July 2015 and February 2019. Patients presenting MET amplification showed a higher proportion of PD-L1 expression (93% vs. 39%; p < 0.001) and overexpression (64% vs. 27%; p = 0.020) than those with non-amplified MET. PD-L1 expression was not significantly different when analyzed by sex (p = 0.624), smoking history (p = 0.429), and Eastern Cooperative Oncology Group Performance Status (p = 0.597) Overall survival rates were not significantly affected by MET amplification (high and intermediate amplification vs low amplification and non-amplificated) (p = 0.252) nor PD-L1 expression (> vs =< 50%) (p = 0.893). In conclusion, a positive correlation was found between MET gene amplification and PD-L1 expression and highly expressed (above 50%) in patients with NSCLC and no other actionable oncogenic driver. It could be translated as new guided-treatment oportunities for these patients.

Real-world insights into patients with advanced NSCLC and MET alterations

Objectives:

To describe characteristics, treatment and outcomes of non-small cell lung cancer (NSCLC) patients with MET alterations (MET exon 14 [METex14] skipping or MET amplification [METamp]) in real-world clinical care.

Methods:

This non-interventional cohort study used real-world data extracted from electronic medical records from academic oncology sites in Israel, The Netherlands, Taiwan, and the USA. Patients had confirmed diagnosis of advanced (Stage IIIB–IV) NSCLC harboring MET alterations (date of diagnosis = index date) between 1 Jan 2010 and 30 Sept 2018. Medical history was assessed prior to and at the index date (baseline period), and outcomes from first date of treatment to death, loss to follow-up, or end of study period.

Results:

A total of 117 patients were included (METex14 n = 70; METamp n = 47); testing methods were heterogeneous. Concomitant oncogenic mutations were more common in the METamp cohort than METex14. Patients in the METex14 cohort were older than those in METamp, and a larger proportion were never smokers. Anticancer first-line therapies received by patients (METex14; METamp) included chemotherapy only (44%; 41%), MET inhibitors (33%; 29%), immune checkpoint inhibitor (ICI) mono-(12%; 15%) and combination-therapy (8%; 3%). Second-line therapies included chemotherapy (35%; 30%) and MET inhibitors (30%; 39%). In the METex14 cohort, objective response rate (ORR) was generally low (first-line 28%; second-line 30%); no patients who received ICIs had a response. In the METamp cohort, ORR was 36% in first-line and 22% in second-line. Median (95% confidence interval) overall survival from start of first-line therapy was 12.0 months (6.8, 19.2) in the METex14 cohort and 22.0 months (9.8, 31.2) in METamp.

Conclusions:

Heterogeneous treatments reflect the changing landscape and availability of new treatments, as well as the high unmet medical need in older, METex14 patients who had more advanced disease at diagnosis. MET-targeted therapies could be beneficial in patients with these rare MET alterations.

Has programmed cell death ligand-1 MET an accomplice in non-small cell lung cancer?-a narrative review

Recently approved and highly specific small-molecule inhibitors of c-MET exon 14 skipping mutations (e.g., capmatinib, tepotinib) are a new and important therapeutic option for the treatment of non-small cell lung cancer (NSCLC) patients harbouring c-MET alterations. Several experimental studies have provided compelling evidence that c-MET is involved in the regulation of the immune response by up-regulating inhibitory molecules (e.g., PD-L1) and down-regulating of immune stimulators (e.g., CD137, CD252, CD70, etc.). In addition, c-MET was found to be implicated in the regulation of the inflamed tumour microenvironment (TME) and thereby contributing to an increased immune escape of tumour cells from T cell killing. Moreover, it is a major resistance mechanism following treatment of epidermal growth factor receptor mutations (EGFRmut) with tyrosine kinase receptor inhibitors (TKIs). In line with these findings c-MET alterations have also been shown to be associated with a worse clinical outcome and a poorer prognosis in NSCLC patients. However, the underlying mechanisms for these experimental observations are neither fully evaluated nor conclusive, but clearly multifactorial and most likely tumour-specific. In this regard the clinical efficacy of checkpoint inhibitors (CPIs) and TKIs against EGFRmut in NSCLC patients harbouring c-MET alterations is also not yet established, and further research will certainly provide some guidance as to optimally utilise CPIs and c-MET inhibitors in the future.

Exploring the resistance mechanisms of second-line osimertinib and their prognostic implications using next-generation sequencing in patients with non-small-cell lung cancer

INTRODUCTION

Although osimertinib overcomes the T790M mutation acquired after traditional epidermal growth factor receptor (EGFR) gene tyrosine kinase inhibitor (TKI) treatment, resistance to osimertinib eventually occurs. We explored resistance mechanisms of second-line osimertinib and their clinical implications by comparing next-generation sequencing (NGS) results before and after resistance acquisition.

METHODS

We enrolled 34 patients with advanced EGFR-mutant adenocarcinoma whose biopsied tumour tissues were subjected to targeted NGS at the time of progression on osimertinib. For comparison, NGS was also performed on archived tumour tissues from each patient excised before osimertinib initiation.

RESULTS

The tumours of three patients' were observed to have transformed to small-cell carcinoma and those of two patients to squamous cell carcinoma. Among the remaining 29 patients, T790M mutations were maintained in seven patients (24.1%), including four patients (13.8%) acquiring C797S mutations and one with MET amplification. Among the 22 patients (75.9%) with T790M loss, a variety of novel mutations were identified, including KRAS mutations, PIK3CA mutations, and RET fusion, but MET amplifications (n = 4, 18.2%) were most frequently identified variations. Progression-free survival (PFS) on osimertinib was shorter among patients with T790M loss than among those who maintained T790M (5.36 versus 13.81 months, p = 0.009), and MET-amplified patients were found to have much worse PFS among patients with T790M loss (2.10 versus 6.35 months, p = 0.01).

CONCLUSIONS

Loss of the T790M mutation was associated with early resistance to osimertinib, and this was exacerbated by MET amplification. Further work is needed to fully understand the implications of each resistance mechanism.

Phase I/II Study of Capmatinib Plus Erlotinib in Patients With MET-Positive Non-Small-Cell Lung Cancer

PURPOSE

MET dysregulation is an oncogenic driver in non-small-cell lung cancer (NSCLC), as well as a mechanism of TKI (tyrosine kinase inhibitor) resistance in patients with epidermal growth factor receptor (EGFR)-mutated disease. This study was conducted to determine safety and preliminary efficacy of the combination EGFR and MET inhibitors as a strategy to overcome and/or delay EGFR-TKI resistance.

METHODS

A standard 3 + 3 dose-escalation trial of capmatinib in combination with erlotinib in patients with MET-positive NSCLC was used. Eighteen patients in the dose-escalation cohort received 100-600 mg twice daily of capmatinib with 100-150 mg daily of erlotinib. There were two dose-expansion cohorts. Cohort A included 12 patients with EGFR-mutant tumors resistant to TKIs. Cohort B included five patients with EGFR wild-type tumors. The primary outcome was to assess safety and determine the recommended phase II dose (RP2D) of the combination.

RESULTS

The most common adverse events of any grade were rash (62.9%), fatigue (51%), and nausea (45.7%). Capmatinib exhibited nonlinear pharmacokinetics combined with erlotinib, while showing no significant drug interactions. The RP2D was 400 mg twice daily capmatinib tablets with 150 mg daily erlotinib. The overall response rate (ORR) and DCR in dose-expansion cohort A was 50% and 50%, respectively. In cohort B, the ORR and disease control rate were 75% and 75%.

CONCLUSION

Capmatinib in combination with erlotinib demonstrated safety profiles consistent with prior studies. We observed efficacy in specific patient populations. Continued evaluation of capmatinib plus EGFR-TKIs is warranted in patients with EGFR activating mutations.

Acquired MET amplification in non-small cell lung cancer is highly associated with the exposure of EGFR inhibitors and may not affect patients' outcome

MET amplification has been associated with shorter survival in cancer patients and thought to represent one of two major mechanisms for developing resistance to therapy with EGFR inhibitors. We retrospectively studied 99 patients who had non-small cell lung cancer (NSCLC) and had at least two FISH analyses for MET/CEP7 at different time points during the course of disease. Four (4%) patients showed MET amplification in the initial diagnostic biopsy, and 16 (16%) patients acquired MET amplification in the follow-up biopsy specimens. Acquired MET amplification was highly associated with EGFR inhibitor treatment. Except for EGFR and TP53 mutations, other gene mutations were rare in the patients with MET amplification. Patients with acquired MET amplification showed no significant survival difference comparing to the patients who did not show MET amplification.

Targeting the MET-Signaling Pathway in Non-Small-Cell Lung Cancer: Evidence to Date

The c-MET proto-oncogene (MET) plays an important role in lung oncogenesis, affecting cancer-cell survival, growth and invasiveness. The MET receptor in non-small-cell lung cancer (NSCLC) is a potential therapeutic target. The development of high-output next-generation sequencing techniques has enabled better identification of anomalies in the MET pathway, like the MET exon-14 (METex14) mutation. Moreover, analyses of epidermal growth factor-receptor (EGFR) and mechanisms of resistance to tyrosine-kinase inhibitors (TKIs) demonstrated the importance of MET amplification as an escape mechanism in patients with TKI-treated EGFR-mutated NSCLCs. This review summarizes the laboratory findings on MET and its anomalies, trial results on METex14 alterations and MET amplification in non-EGFR mutated NSCLCs, and acquired resistance to TKI in EGFR-mutated NSCLCs. The outcomes of the first trials with anti-MET agents on non-selected NSCLC patients or those selected for MET overexpression were disappointing. Two situations seem the most promising today for the use of anti-MET agents to treat these patients: tumors harboring METex14 and those EGFR-sensitive mutation mutated under TKI-EGFR with a MET-amplification mechanism of resistance or EGFR-resistance mutation.

MET receptor in oncology: From biomarker to therapeutic target

First discovered in the 1984, the MET receptor tyrosine kinase (RTK) and its ligand hepatocyte growth factor or HGF (also known as scatter factor or SF) are implicated as key players in tumor cell migration, proliferation, and invasion in a variety of cancers. This pathway also plays a key role during embryogenesis in the development of muscular and nervous structures. High expression of the MET receptor has been shown to correlate with poor prognosis and resistance to therapy. MET exon 14 splicing variants, initially identified by us in lung cancer, is actionable through various tyrosine kinase inhibitors (TKIs). For this reason, this pathway is of interest as a therapeutic target. In this chapter we will be discussing the history of MET, the genetics of this RTK, and give some background on the receptor biology. Furthermore, we will discuss directed therapeutics, mechanisms of resistance, and the future of MET as a therapeutic target.

The clinical efficacy of combinatorial therapy of EGFR-TKI and crizotinib in overcoming MET amplification-mediated resistance from prior EGFR-TKI therapy

BACKGROUND

MET amplification is one of the EGFR-independent mechanisms of EGFR tyrosine kinase inhibitor (TKI) resistance. Combinatorial therapy of EGFR-TKI and crizotinib has been explored as a strategy to overcome resistance by simultaneously targeting both EGFR and MET pathways; however, no consensus still exists on the optimal combination regimen with the most benefit.

METHODS

Retrospective analysis was performed on the clinical and sequencing data obtained from eleven patients with lung adenocarcinoma who acquired MET amplification at progression from prior EGFR-TKI therapy and received a combination of EGFR-TKI and crizotinib.

RESULTS

Acquired MET amplification was detected in four and seven patients who progressed from first-line gefitinib and second-line osimertinib, respectively. Six and five patients received a combination of either first-generation (gefitinib, erlotinib, or icotinib) or third-generation (osimertinib) EGFR-TKI and crizotinib, respectively. Nine patients achieved partial response, resulting in an overall response rate of 81.8 %. The median progression-free survival of the cohort was 5.8 months. Moreover, analysis of acquired resistance mechanisms from nine patients identified EGFR T790 M from three patients who progressed from first-generation EGFR-TKI and crizotinib, while EGFR T790 M/trans-C797S and L718Q, EGFR G724S, and CCDC6-RET fusion were detected from one patient each who progressed from osimertinib and crizotinib regimen. Loss of MET amplification was also observed in a majority of the patients at progression from the combination therapy.

CONCLUSIONS

Our study provides clinical evidence of the efficacy of combinatorial regimen with either first- or third-generation EGFR-TKI and crizotinib after the emergence of MET amplification-mediated EGFR-TKI resistance in patients with EGFR-mutant NSCLC.

High-level gain of mesenchymal-epithelial transition factor (MET) copy number using next-generation sequencing as a predictive biomarker for MET inhibitor efficacy

Background

In clinical oncology, targeted next-generation sequencing (NGS) has become an integral part of the routine molecular diagnostics repertoire. However, a consensus is yet to be agreed on the optimal mesenchymal-epithelial transition factor (MET) copy number (CN) cut-off value based on NGS data that could predict the MET-amplified non-small cell lung cancer (NSCLC) patients who could benefit from MET tyrosine kinase inhibitor (TKI) therapy. In this study, we aimed to identify the criteria to define MET amplification derived from NGS data.

Methods

Sequencing data from matched plasma and tissue samples from 40 MET-amplified NSCLC patients were used to derive a normalization method, referred to as adjusted copy number (adCN). Clinical outcomes from an additional 18 MET TKI-treated NSCLC patients with solely MET-amplified cancers were analyzed to validate the adCN cut-offs.

Results

AdCN, calculated as the absolute CN generated from NGS relative to the maximum mutant allele fraction (maxMAF) per sample, was demonstrated to have a high correlation with MET CN in tissue and plasma samples (R²=0.73). Using a cut-off value of 5.5 and 13, tertile stratification of adCN was able to distinguish patients with high-level MET amplification. The MET TKI-treated patients with adCN >13, categorized as high-level amplification, had significantly longer progression-free survival (PFS) than those with adCN <13 (P=0.009), suggesting that adCN positively correlated with the response to MET TKI.

Conclusions

We derived a normalization method that could reflect the relative CN and distinguish MET-amplified NSCLC patients with high-level gene amplification who were sensitive to crizotinib, suggesting adCN could potentially serve as a predictive biomarker for MET TKI response.

Top-level MET gene copy number gain defines a subtype of poorly differentiated pulmonary adenocarcinomas with poor prognosis

Background

MET amplifications occur in human tumors, including non-small cell lung cancer (NSCLC). MET inhibitors have demonstrated some clinical activity in MET amplified NSCLC, presumably with a gene dose effect. However, the definition of MET positivity or MET amplification as a potential oncogenic driver is still under debate. In this study, we aimed to establish the molecular subgroup of NSCLC with the highest unequivocal MET amplification level and to describe the prevalence, and histologic and clinical phenotype of this subgroup.

Methods

A total of 373 unselected patients with NSCLC were consecutively tested for MET gene copy number (GCN) by FISH. Mean GCN, MET/CEN7 ratio and other FISH parameters were identified and correlated with morphological and molecular pathological characteristics of the tumors as well as with clinical data.

Results

Based on the variability of obtained data a top-level category of MET amplification was newly defined (>90th percentile of average GCN; ≥10 MET gene copies per tumor cell). This criterion was fulfilled in 2% of analyzed tumors. These tumors were exclusively poorly differentiated adenocarcinomas with a predominant solid subtype and pleomorphic features. Rarely, co-alterations were detected (KRAS mutation or MET exon 14 skipping mutation). In this top-level group, there were no EGFR mutations or ALK or ROS1 alterations. The most important clinical feature was a significantly shortened overall survival (HR 3.61; median OS 8.2 vs. 23.6 months). Worse prognosis did not depend on initial stage or treatment.

Conclusions

The newly defined top-level category of MET amplification in NSCLC defines a specific subgroup of pulmonary adenocarcinoma with adverse prognosis and characteristic morphological features. Lower levels of MET gene copy number seem to have probably no specific value as a prognostic or predictive biomarker.

Progress on treatment of MET signaling pathway in non-small cell lung cancer

MET activation includes gene mutation, amplification, and protein overexpression. Clinical evidence suggests that MET activation is both a primary oncogenic driver in lung cancer, and a secondary driver after acquired resistance to EGFR tyrosine kinase inhibitors (TKIs). Several small molecule TKIs have already shown to be effective in the MET pathway. However, the activation form and the diagnostic criteria of MET oncogene are still controversial, especially in patients resistant to EGFR TKIs or ALK TKIs. With the development of new MET inhibitors, a quantity of emerging trials has focused on the mechanism of acquired resistance to MET TKIs and therapeutic strategies after resistance.

MET Oncogene in Non-Small Cell Lung Cancer: Mechanism of MET Dysregulation and Agents Targeting the HGF/c-Met Axis

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death worldwide and has a poor prognosis. Current treatments for advanced NSCLC included traditional chemotherapy, radiotherapy, targeted therapy, and immunotherapy. The efficacy of targeted therapy relies on oncogene addiction. Mesenchymal-epithelial transition factor (MET) gene can encode unconventional receptor tyrosine kinases with pleiotropic functions, when signals are abnormally activated, it can initiate and maintain tumor transformation, promote cell proliferation, survival, tumor invasion and angiogenesis. Thus, it is a promising therapeutic target. Previous studies have shown that elevated levels of HGF and/or overexpression of c-Met are associated with poor prognosis in lung cancer. In preclinical and clinical trials, c-MET inhibitors have shown some antitumor activity in NSCLC. Although the efficacy results of MET inhibitors in Phase III clinical trials are disappointing, given the molecular heterogeneity of NSCLC, only subgroups of patients with MET gene alterations may benefit from c-MET inhibitors. The challenge for the future is to screen out the potential beneficiaries. To solve this problem, there is need for large data analysis for the detection methods and treatment effects, to establish standards that meet the MET activation status, and determine reliable thresholds to achieve effective patient stratification and clinical decision making. This article summarized the structure of the hepatocyte growth factor (HGF)/c-Met axis, the different mechanisms of MET addiction, as well as MET amplification as acquired resistance mechanism to epidermal growth factor receptor-tyrosine kinase inhibitors, the latest advances of MET inhibitors, and immuotherapy in the treatment of NSCLC with MET alterations.

The Prognostic Role of MET Protein Expression Among Surgically Resected Non-small Cell Lung Cancer Patients: A Meta-Analysis

Objectives: MET protein expression has been reported to be in relevance with the survival of NSCLC patients in various studies, yet the results were inconsistent. The purpose of our study set out to determine the prognostic role of both c-MET and p-MET expression among NSCLC that underwent surgical resection.

Methods: Data were obtained from retrospective cohort studies by searching on PubMed, Cochrane Library, EMBASE and Web of Science, and a meta-analysis was performed to assess the prognostic role of MET expression among NSCLC.

Results: Totally 18 literatures including 5,572 surgically resected NSCLC cases staged I-IV were included for data synthesis. The positive rate of c-MET and p-MET was 1,753/4,315 and 135/1,257. The pooled hazard ratios (HRs) regarding c-MET and p-MET expression for overall survival (OS) was 1.623 (95% CI: 1.176–2.240, p = 0.003) and 1.710 (95% CI: 0.823–3.533, p = 0.15), respectively. Subgroup analysis results on Asian (HR = 2.115, p < 0.001), adenocarcinoma (HR = 2.220, p < 0.001) and rabbit polyclonal antibodies (HR = 2.107, p < 0.001) etc. were also indicative.

Conclusion: C-MET over-expression among NSCLC patients that underwent surgical resection is a prognostic factor that indicated adverse survival on OS. Whereas, p-met didn't appear to have an impact on the prognosis of NSCLC. The studies are need and the topic could be re-valued by then.

Antibody-drug conjugates for lung cancer in the era of personalized oncology

With 9.6 million deaths in 2018, cancer represents one of the most common causes of death, both in men and women. Despite recent advances in the understanding of molecular mechanisms involved in cancer development and progression, treatment options are still limited. Limitations of traditional chemotherapy include the lack of selectivity and the unfavorable safety profile. The efficacy of targeted therapies (e.g., tyrosine kinase inhibitors) is also limited by their cytostatic action, which inhibits tumor cell proliferation without inducing tumor cell death, and by the risk of acquired resistance. Antibody-drug conjugates (ADCs), a newly developed class of engineered anticancer drugs, consist of recombinant monoclonal antibodies against tumor-specific antigens that are covalently bound to cytotoxic agents. They have been designed to overcome the limitations of traditional chemotherapy and targeted therapies by combining the target selectivity of monoclonal antibodies with the high potency of cytotoxic drugs. Currently, ADCs that have received regulatory approval include brentuximab vedotin for CD30-positive Hodgkin lymphoma and trastuzumab emtansine for human epidermal growth factor receptor 2-positive breast cancer. However, over 80 novel ADCs are actively being investigated in preclinical studies and early-phase clinical trials. In this review, we will provide a comprehensive overview of the biological rational, efficacy and safety of ADCs as therapeutic agents against non-small cell lung cancer and small cell lung cancer.

Phase 1 study of capmatinib in MET-positive solid tumor patients: Dose escalation and expansion of selected cohorts

Capmatinib is an oral, ATP‐competitive, and highly potent, type 1b MET inhibitor. Herein, we report phase 1 dose‐escalation results for capmatinib in advanced MET‐positive solid tumor patients and dose expansion in advanced non‐lung tumors. Capmatinib was well tolerated with a manageable safety profile across all explored doses. Dose‐limiting toxicities (DLT) occurred at 200 mg twice daily (bid), 250 mg bid, and 450 mg bid capsules; however, no DLT were reported at 600 mg bid (capsules). Capmatinib tablets at 400 mg bid had comparable tolerability and exposure to that of 600 mg bid capsules. Maximum tolerated dose was not reached; recommended phase 2 dose was 400 mg bid tablets/600 mg bid capsules; at this dose, C_trough >EC₉₀ (90% inhibition of c‐MET phosphorylation in animal models) is expected to be achieved and maintained. Among the dose‐expansion patients (N = 38), best overall response across all cohorts was stable disease (gastric cancer 22%, hepatocellular carcinoma 46%, other indications 28%); two other indication patients with gene copy number (GCN) ≥6 achieved substantial tumor reduction. Near‐complete immunohistochemically determined phospho‐MET inhibition (H‐score = 2) was shown following capmatinib 450 mg bid capsule in paired biopsies obtained from one advanced colorectal cancer patient. Incidence of high‐level MET GCN (GCN ≥6) and MET‐overexpressing (immunohistochemistry 3+) tumors in the expansion cohorts was 8% and 13%, respectively; no MET mutations were observed. Thus, the recommended phase 2 dose (RP2D) of capmatinib was 600 mg bid capsule/400 mg bid tablet. Capmatinib was well tolerated and showed antitumor activity and acceptable safety profile at the RP2D.

(ClinicalTrials.gov Identifier: NCT01324479).

HGF/MET pathway aberrations as diagnostic, prognostic, and predictive biomarkers in human cancers

Cancer is a major cause of death worldwide. MET tyrosine kinase receptor [MET, c-MET, hepatocyte growth factor (HGF) receptor] pathway activation is associated with the appearance of several hallmarks of cancer. The HGF/MET pathway has emerged as an important actionable target across many solid tumors; therefore, biomarker discovery becomes essential in order to guide clinical intervention and patient stratification with the aim of moving towards personalized medicine. The focus of this review is on how the aberrant activation of the HGF/MET pathway in tumor tissue or the circulation can provide diagnostic and prognostic biomarkers and predictive biomarkers of drug response. Many meta-analyses have shown that aberrant activation of the MET pathway in tumor tissue, including MET gene overexpression, gene amplification, exon 14 skipping and other activating mutations, is almost invariably associated with shorter survival and poor prognosis. Most meta-analyses have been performed in non-small cell lung cancer (NSCLC), breast, head and neck cancers as well as colorectal, gastric, pancreatic and other gastrointestinal cancers. Furthermore, several studies have shown the predictive value of MET biomarkers in the identification of patients who gain the most benefit from HGF/MET targeted therapies administered as single or combination therapies. The highest predictive values have been observed for response to foretinib and savolitinib in renal cancer, as well as tivantinib in NSCLC and colorectal cancer. However, some studies, especially those based on MET expression, have failed to show much value in these stratifications. This may be rooted in lack of standardization of methodologies, in particular in scoring systems applied in immunohistochemistry determinations or absence of oncogenic addiction of cancer cells to the MET pathway, despite detection of overexpression. Measurements of amplification and mutation aberrations are less likely to suffer from these pitfalls. Increased levels of MET soluble ectodomain (sMET) in circulation have also been associated with poor prognosis; however, the evidence is not as strong as it is with tissue-based biomarkers. As a diagnostic biomarker, sMET has shown its value in distinguishing cancer patients from healthy individuals in prostate and bladder cancers and in melanoma. On the other hand, increased circulating HGF has also been presented as a valuable prognostic and diagnostic biomarker in many cancers; however, there is controversy on the predictive value of HGF as a biomarker. Other biomarkers such as circulating tumor DNA (ctDNA) and tumor HGF levels have also been briefly covered. In conclusion, HGF/MET aberrations can provide valuable diagnostic, prognostic and predictive biomarkers and represent vital assets for personalized cancer therapy.

Capmatinib for the treatment of non-small cell lung cancer

Introduction: Activation of the MET pathway through MET amplifications or mutations is present in 3-4% of stage IV non-squamous non-small cell lung cancers (NSCLC). High MET amplifications and exon 14 skipping mutations are associated with poor prognosis: new treatments are needed for these patients. Capmatinib is a highly selective, potent small-molecule MET inhibitor with antitumor activity in NSCLC in vitro and in vivo. Areas covered: This article provides an overview of the capmatinib clinical development program in NSCLC, both as monotherapy in NSCLC with a dysregulated MET pathway, and in combination with epidermal growth factor receptor (EGFR) inhibitor therapy in EGFR-mutant NSCLC with MET-based acquired resistance to previous EGFR inhibition. Expert opinion: In the GEOMETRY Mono-1 study, treatment with capmatinib resulted in high response rates in stage IV NSCLC with MET exon 14 skipping mutations, particularly in first line, supporting testing for this biomarker at the time of diagnosis. Durable responses have been reported and results in MET-amplified NSCLC are eagerly anticipated. In EGFR-mutant NSCLC, notable responses have been observed in combination with an EGFR-tyrosine kinase inhibitor (TKI) in case of acquired resistance to EGFR-TKIs based on high MET amplification.

Mesenchymal–epithelial transition gene amplification and protein overexpression in stage IV pulmonary adenocarcinoma

Background

In non-small cell lung cancer (NSCLC), MET gene copy number gain, including gene amplification and chromosome 7 polysomy, is reportedly associated with patient prognosis. Although relationship between MET copy number gain and poor prognosis has been suggested in surgically resected non-small cell lung cancer, the clinical significance of MET copy number gain and protein overexpression in patients with advanced unresectable tumor is unclear.

Methods

We assessed MET copy number gain and protein expression using fluorescence in situ hybridization and immunohistochemistry in 88 patients with clinical stage IV pulmonary adenocarcinoma receiving chemotherapy, immunotherapy or palliative care.

Results

We found MET amplification, polysomy 7 and high MET protein expression in 10.2, 18.2 and 62.5% of 88 cases, respectively. Gene amplification and high protein expression were not significantly associated. A univariate analysis showed that MET amplification-positive patients had increased overall survival (HR 0.335, 95% CI: 0.119–0.945; P = 0.0388). Although it was not statistically significant in the multivariate analysis of the whole cohort, with the removal of patients who did not receive any treatment other than palliative care, MET amplification independently improved the overall survival (HR 0.178, 95% CI: 0.041–0.770; P = 0.0209). Chromosome 7 polysomy and high MET protein expression did not affect the overall survival.

Conclusions

Although MET amplification-positive tumor is considered aggressive, our results suggest that it has a more favorable prognosis than amplification-negative cases in stage IV pulmonary adenocarcinoma with medical treatment.

Mesenchyme to epithelial transition protein expression, gene copy number and clinical outcome in a large non-small cell lung cancer surgical cohort

Background

In non-small cell lung cancer (NSCLC), mesenchyme to epithelial transition (MET) protein abundance increases with disease stage and is implicated in resistance to tyrosine kinase inhibitors. To better clarify the impact of MET overexpression on tumor behavior, we investigated a large cohort of patients who underwent curative surgical resection to determine whether MET gene amplification or protein abundance was prognostic.

Methods

Tissue microarrays (TMAs) were constructed using triplicate 1 mm cores of FFPE primary NSCLC specimens. TMAs underwent immunohistochemical (IHC) staining with the SP44 clone (Ventana) and cores were considered positive if >50% of tumor exhibited 2+ staining. The highest of triplicate values was used. MET gene amplification was detected using either SISH using Ventana's MET DNP probe or FISH using the D7S486/CEP 7 Abbott Probe. DNA was subjected to mutational profiling using Sequenom's LungCarta panel.

Results

Data from two institutions comprising 763 patients (516; 68%) male were generated, including 360 stage I, 226 stage II, 160 stage III and 18 resected stage IV. High MET protein expression was detected in 25% (193/763), and was significantly more common in adenocarcinomas than squamous cell carcinoma (P<0.01). MET gene copy number (GCN) correlated with high MET protein expression by IHC (P=0.01). Increased MET protein expression was associated with EGFR and KRAS mutations (P<0.01 for both). Once polysomy was excluded, true MET gene amplification was detected in only 8/763 (1%) of samples. In multivariate analysis, neither MET protein abundance nor GCN were correlated to overall patient survival.

Conclusions

MET expression by IHC and GCN amplification was not prognostic in this large Caucasian surgical series. MET's primary role remains as a therapeutic target.

Overexpression-mediated activation of MET in the Golgi promotes HER3/ERBB3 phosphorylation

Ligand-dependent oligomerization of receptor tyrosine kinases (RTKs) results in their activation through highly specific conformational changes in the extracellular and intracellular receptor domains. These conformational changes are unique for each RTK subfamily, limiting cross-activation between unrelated RTKs. The proto-oncogene MET receptor tyrosine kinase overcomes these structural constraints and phosphorylates unrelated RTKs in numerous cancer cell lines. The molecular basis for these interactions is unknown. We investigated the mechanism by which MET phosphorylates the human epidermal growth factor receptor-3 (HER3 or ERBB3), a catalytically impaired RTK whose phosphorylation by MET has been described as an essential component of drug resistance to inhibitors targeting EGFR and HER2. We find that in untransformed cells, HER3 is not phosphorylated by MET in response to ligand stimulation, but rather to increasing levels of MET expression, which results in ligand-independent MET activation. Phosphorylation of HER3 by its canonical co-receptors, EGFR and HER2, is achieved by engaging an allosteric site on the HER3 kinase domain, but this site is not required when HER3 is phosphorylated by MET. We also observe that HER3 preferentially interacts with MET during its maturation along the secretory pathway, before MET is post translationally processed by cleavage within its extracellular domain. This results in accumulation of phosphorylated HER3 in the Golgi apparatus. We further show that in addition to HER3, MET phosphorylates other RTKs in the Golgi, suggesting that this mechanism is not limited to HER3 phosphorylation. These data demonstrate a link between MET overexpression and its aberrant activation in the Golgi endomembranes and suggest that non-canonical interactions between MET and other RTKs occur during maturation of receptors. Our study highlights a novel aspect of MET signaling in cancer that would not be accessible to inhibition by therapeutic antibodies.

Cancer Immunotherapy: The Dawn of Antibody Cocktails

Since the approval of the first monoclonal antibody (mAb), rituximab, for hematological malignancies, almost 30 additional mAbs have been approved in oncology. Despite remarkable advances, relatively weak responses and resistance to antibody monotherapy remain major open issue. Overcoming resistance might require combinations of drugs blocking both the major target and the emerging secondary target. We review clinically approved combinations of antibodies and either cytotoxic regimens (chemotherapy and irradiation) or kinase inhibitors. Thereafter, we focus on the most promising and currently very active arena that combines mAbs inhibiting immune checkpoints or growth factor receptors. Clinically approved and experimental oligoclonal mixtures of mAbs targeting different antigens (hetero-combinations) or different epitopes of the same antigen (homo-combinations) are described. Effective oligoclonal mixtures of antibodies that mimic the polyclonal immune response will likely become a mainstay of cancer therapy.

Prognostic value of MET copy number gain in non-small-cell lung cancer: an updated meta-analysis

The alterations of MET have been detected in non-small-cell lung cancer (NSCLC). However, the prognostic impact of MET gene copy number gain (CNG) has not been consistent among studies. We performed this meta-analysis to evaluate the prognostic value of high MET CNG in patients with NSCLC. A systematic computerized search of the electronic databases including PubMed, EMBASE, Google scholar, and Cochrane Library (up to November 2017) was carried out. From twenty-one studies, 7,647 patients were included in the pooled analysis of hazard ratios (HRs) with 95% confidence intervals (CIs) for disease-free survival or overall survival. Compared with patients with NSCLC showing low MET CNG, those with tumors harboring high MET CNG showed significantly worse survival (HR = 1.45, 95% CI: 1.16-1.80, p = 0.001). Subgroup analyses showed that high MET CNG significantly correlated with a poor prognosis especially in patients with adenocarcinoma (HR = 1.41, 95% CI: 1.11-1.79, p = 0.005) and Asian populations (HR = 1.58, 95% CI: 1.32-1.88, p < 0.00001).

In conclusion, this meta-analysis indicates that high MET CNG is an adverse prognostic factor in patients with NSCLC. Subgroup analyses suggest that high MET CNG is associated with a worse prognosis, especially in patients with adenocarcinoma and Asian populations. However, large prospective studies using standardized methods based on the homogeneous populations are warranted to validate the prognostic value of MET amplification in patients with NSCLC.

The multiple paths towards MET receptor addiction in cancer

Targeted therapies against receptor tyrosine kinases (RTKs) are currently used with success on a small proportion of patients displaying clear oncogene activation. Lung cancers with a mutated EGFR provide a good illustration. The efficacy of targeted treatments relies on oncogene addiction, a situation in which the growth or survival of the cancer cells depends on a single deregulated oncogene. MET, a member of the RTK family, is a promising target because it displays many deregulations in a broad panel of cancers. Although clinical trials having evaluated MET inhibitors in large populations have yielded disappointing results, many recent case reports suggest that MET inhibition may be effective in a subset of patients with unambiguous MET activation and thus, most probably, oncogene addiction. Interestingly, preclinical studies have revealed a particularity of MET addiction: it can arise through several mechanisms, and the mechanism involved can differ according to the cancer type. The present review describes the different mechanisms of MET addiction and their consequences for diagnosis and therapeutic strategies. Although in each cancer type MET addiction affects a restricted number of patients, pooling of these patients across all cancer types yields a targetable population liable to benefit from addiction-targeting therapies.

MET Expression in Advanced Non-Small-Cell Lung Cancer: Effect on Clinical Outcomes of Chemotherapy, Targeted Therapy, and Immunotherapy

BACKGROUND

The receptor tyrosine kinase MET is implicated in malignant transformation, tumor progression, metastasis, and acquired treatment resistance. We conducted an analysis of the effect of MET expression and MET genomic aberrations on the outcome of patients with advanced or metastatic pulmonary adenocarcinomas prospectively enrolled in an institutional precision oncology program.

PATIENTS AND METHODS

Standardized immunohistochemistry (IHC) analyses of MET and markers of pathway activation were available in 384 patients, and next-generation sequencing-based MET hotspot mutation analyses were available from 892 patients. Clinical data were retrieved with a median follow-up from initial diagnosis of 37 months.

RESULTS

High MET expression, defined as MET IHC 3+ or MET H-Score in the upper quartile, was observed in 102 of 384 patients (26.6%). MET exon 14 mutations were only detected in 7 of 892 patients (0.78%). High MET expression correlated with activation markers of the mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathways only in cases without Kirsten rat sarcoma viral oncogene homolog (KRAS), epidermal growth factor receptor (EGFR), v-Raf murine sarcoma viral oncogene homolog B (BRAF), anaplastic lymphoma kinase (ALK) and proto-oncogene tyrosine-protein kinase ROS (ROS1) aberrations. There was no association of MET expression with outcome during chemotherapy. High MET expression negatively affected the outcome during EGFR-targeting therapy but was associated with more favorable results with programmed death 1/programmed death ligand 1 (PD-L1)-directed therapy, independent of smoking history, PD-L1 expression or KRAS mutation. Two patients with MET exon 14 mutation and high PD-L1 expression failed to respond to pembrolizumab.

CONCLUSION

MET expression affects the outcomes of targeted therapies in non-small-cell lung cancer, thus supporting the development of biomarker-informed combination strategies. The interaction of MET expression and MET mutation with immune checkpoint inhibitor therapy is novel and merits further investigation.

Outcome of EGFR-mutated NSCLC patients with MET-driven resistance to EGFR tyrosine kinase inhibitors

Background

Several mechanisms of acquired resistance to EGFR tyrosine kinase inhibitors (TKIs) in EGFR-mutated NSCLC have been described including the T790M mutation and MET amplification. Whereas T790M mutation confers prolonged survival and sensitivity to 3rd generation TKIs, data are lacking on clinical features and outcome of MET-driven resistant EGFR-mutated NSCLC patients.

Methods

Patients with metastatic EGFR-mutated NSCLC displaying high MET overexpression or MET amplification, detected on a biopsy performed after progression on EGFR TKI, were identified in 15 centers. Clinical and molecular data were retrospectively collected.

Results

Forty two patients were included. The median overall survival (OS), and the median post EGFR TKI progression overall survival (PPOS) were 36.2 months [95%CI 27.3-66.5] and 18.5 months [95%CI 10.6-27.4] respectively. Nineteen out of 36 tumors tested for MET FISH had MET amplification. A T790M mutation was found in 11/41 (26.8%) patients. T790M-positive patients had a better OS than T790M-negative patients (p=0.0224). Nineteen patients received a MET TKI. Objective response was reported in 1 out of 12 evaluable patients treated with a MET inhibitor as a single agent and in 1 of 2 patients treated with a combination of MET and EGFR TKIs.

Conclusion

MET-driven resistance to EGFR TKI defines a specific pattern of resistance characterized by low objective response rate to MET inhibitors given alone and overlapping with T790M mutations. Further studies are warranted to define adequate therapeutic strategies for MET-driven resistance to EGFR TKI.

MET in Lung Cancer: Biomarker Selection Based on Scientific Rationale

MET or hepatocyte growth factor (HGF) receptor pathway signaling mediates wound healing and hepatic regeneration, with pivotal roles in embryonic, neuronal, and muscle development. However, dysregulation of MET signaling mediates proliferation, apoptosis, and migration and is implicated in a number of malignancies. In non-small cell lung cancer (NSCLC), aberrant MET signaling can occur through a number of mechanisms that collectively represent a significant proportion of patients. These include MET or HGF protein overexpression, MET gene amplification, MET gene mutation or fusion/rearrangement, or aberrations in downstream signaling or regulatory components. Responses to MET tyrosine kinase inhibitors have been documented in clinical trials in patients with MET-amplified or MET-overexpressing NSCLC, and case studies or case series have shown that MET mutation/deletion is a biomarker that is also predictive of response to these agents. However, other recent clinical data have highlighted an urgent need to elucidate optimal biomarkers based on genetic and/or protein diagnostics to correctly identify patients most likely to benefit in ongoing clinical trials of an array of MET-targeted therapies of differing class. The latest advances in the development of MET biomarkers in NSCLC have been reviewed, toward establishing appropriate MET biomarker selection based on a scientific rationale. Mol Cancer Ther; 16(4); 555-65. ©2017 AACR.

The impact of MET, IGF-1, IGF1R expression and EGFR mutations on survival of patients with non-small-cell lung cancer

Introduction

To compare the efficacy of silver in situ hybridization (SISH) and immunohistochemistry (IHC) in detecting MET and IGF1R alterations and to investigate their prevalence and prognostic significance. A possible correlation between MET receptor expression, MET gene alterations and the two most frequent occurring EGFR gene mutations was also investigated.

Materials and methods

Stage I to IIIA tumors from 326 patients with NSCLC were immunohistochemically tested for protein expression of MET and IGF-1. Their cytoplasmic expression was compared with the gene copy number of the MET and IGF1Rgenes by SISH in paraffin-embedded, formalin-fixed material. Correlations were made with the immunohistochemical expression of two frequent EGFR mutations and clinicopathological variables. Univariate and multivariate survival analyses was used to evaluate the prognostic efficacy of the tested markers.

Results

In univariate analyses, high cytoplasmic MET expression showed a significant negative prognostic effect in adenocarcinoma patients (p = 0.026). MET gene to chromosome 7 ratio was a significant positive prognostic marker (p = 0.005), probably only due to the highly negative prognostic significance of chromosome 7 polysomy (p = 0.002). High IGF1R gene copy number was a negative prognostic marker for all NSCLC patients (p = 0.037). In the multivariate analysis, polysomy of chromosome 7 in tumor cells correlated significantly and independently with a poor prognosis (p = 0.011). In patients with adenocarcinoma, a high cytoplasmic MET expression was an independent negative prognostic marker (p = 0.013). In males a high IGF1R gene copy number to chromosome 15 count ratio was significantly and independently correlated to a poor prognosis (p = 0.018).

Conclusion

MET protein expression provides superior prognostic information compared with SISH. Polysomy of chromosome 7 is an independent negative prognostic factor in NSCLC patients. This finding has an important implication while examining genes located on chromosome 7 by means of SISH. High IGF1R gene copy number to chromosome 15 count ratio is an independent predictor of inferior survival in male patients with primary NSCLC.

Preferential Localization of MET Expression at the Invasion Front and in Spreading Cells Through Air Spaces in Non-Small Cell Lung Carcinomas

The involvement of the HGF/MET pathway in acquisition of an invasive phenotype in non-small cell lung carcinomas (NSCLCs) suggests that MET inhibitors might prove effective against these cancers, but clinical trials have yielded conflicting results. The aim of our study was to evaluate how intratumoral heterogeneity (ITH) of MET staining affects the determination of MET status for therapeutic purposes. We analyzed 64 NSCLC samples, including 33 adenocarcinomas (ADCs) and 31 squamous cell carcinomas (SCCs). We used immunohistochemistry to detect MET and phospho-MET on whole slides and determined the MET SP44 immunoscore and the H-score. A high METMab score (2+/3+) was observed in 34% of NSCLCs and was more prevalent in ADCs (52%) than in SCCs (16%). We found ITH in 73% of ADCs and 77% of SCCs, with higher levels of MET and phospho-MET at the invasion front (in 52% of ADCs and 22% of SCCs) and in tumor cells spreading through air spaces in ADCs. Within-sample ITH was high in 40% of the ADCs and 29% of the SCCs. When different samples from the same tumor were compared, discordant assessments (high MET vs. low MET) were made for 12% of the ADCs and 10% of the SCCs. C-MET and phospho-MET overexpression occurred preferentially in ADCs and in areas involved in tumor progression, in support of the view that MET activation plays a role in the development of an invasive phenotype in NSCLC. To use MET status adequately as a biomarker, one must take the resulting high level of ITH into account.

Sym015: A Highly Efficacious Antibody Mixture against MET-Amplified Tumors

Purpose: Activation of the receptor tyrosine kinase MET is associated with poor clinical outcome in certain cancers. To target MET more effectively, we developed an antagonistic antibody mixture, Sym015, consisting of two humanized mAbs directed against nonoverlapping epitopes of MET.Experimental Design/Results: We screened a large panel of well-annotated human cancer cell lines and identified a subset with highly elevated MET expression. In particular, cell lines of lung cancer and gastric cancer origin demonstrated high MET expression and activation, and Sym015 triggered degradation of MET and significantly inhibited growth of these cell lines. Next, we tested Sym015 in patient- and cell line-derived xenograft models with high MET expression and/or MET exon 14 skipping alterations, and in models harboring MET amplification as a mechanism of resistance to EGFR-targeting agents. Sym015 effectively inhibited tumor growth in all these models and was superior to an analogue of emibetuzumab, a monoclonal IgG4 antibody against MET currently in clinical development. Sym015 also induced antibody-dependent cellular cytotoxicity (ADCC) in vitro, suggesting that secondary effector functions contribute to the efficacy of Sym015.Retrospectively, all responsive, high MET-expressing models were scored as highly MET-amplified by in situ hybridization, pointing to MET amplification as a predictive biomarker for efficacy. Preclinical toxicology studies in monkeys showed that Sym015 was well tolerated, with a pharmacokinetic profile supporting administration of Sym015 every second or third week in humans.Conclusions: The preclinical efficacy and safety data provide a clear rationale for the ongoing clinical studies of Sym015 in patients with MET-amplified tumors. Clin Cancer Res; 23(19); 5923-35. ©2017 AACR.

Targeting MET in Lung Cancer: Will Expectations Finally Be MET?

The hepatocyte growth factor receptor (MET) is a potential therapeutic target in a number of cancers, including NSCLC. In NSCLC, MET pathway activation is thought to occur through a diverse set of mechanisms that influence properties affecting cancer cell survival, growth, and invasiveness. Preclinical and clinical evidence suggests a role for MET activation as both a primary oncogenic driver in subsets of lung cancer and as a secondary driver of acquired resistance to targeted therapy in other genomic subsets. In this review, we explore the biology and clinical significance behind MET proto-oncogene receptor tyrosine kinase (MET) exon 14 alterations and MET amplification in NSCLC, the role of MET amplification in the setting of acquired resistance to EGFR tyrosine kinase inhibitor therapy in EGFR-mutant NSCLC, and the history of MET pathway inhibitor drug development in NSCLC, highlighting current strategies that enrich for biomarkers likely to be predictive of response. Whereas previous trials that focused on MET pathway-directed targeted therapy in unselected or MET-overexpressing NSCLC yielded largely negative results, more recent investigations focusing on MET exon 14 alterations and MET amplification have been notable for meaningful clinical responses to MET inhibitor therapy in a substantial proportion of patients.

MEK inhibitors against MET-amplified non-small cell lung cancer

Several receptor tyrosine kinases (RTKs) including EGFR, ALK, and MET have been identified as therapeutic targets in non-small cell lung cancer (NSCLC). Among the downstream pathways of RTKs, the MAPK pathway is particularly important for cancer cell proliferation, differentiation, and survival. In this study, the effects of MEK inhibitors (trametinib and PD0325901) in several NSCLC cell lines with driver gene alterations, especially RTK genes, were tested in vitro using an MTT assay, and a wide range of sensitivities was found. In particular, all the EGFR-mutated cell lines were resistant to MEK inhibitors, whereas all the MET-amplified cell lines were sensitive. A bioinformatics technique and western blot analyses showed that the PI3K/AKT pathway is more activated in EGFR-mutated NSCLC than in MET-amplified NSCLC, and a PI3K inhibitor enhanced the sensitivity to trametinib in the EGFR-mutated cell lines, suggesting that this pathway is associated with resistance to MEK inhibitors. Although the HCC827 cell line (EGFR mutation) was resistant to MEK inhibitors, the HCC827CNXR cell line, whose driver gene shifts from EGFR to MET, exhibited enhanced sensitivity to MEK inhibitors, indicating the biological importance of the MAPK pathway for MET-amplified NCSLC. Furthermore, a synergistic effect of crizotinib (a MET inhibitor) and trametinib was observed in MET-amplified NCLC cell lines. Our findings indicate that the MAPK pathway is biologically important for MET-amplified NSCLC and strongly encourage the development of combination therapy with a MET inhibitor and a MEK inhibitor against MET-amplified NSCLC.

The Efficacy and Risk Profile of c-Met inhibitors in Non-small Cell Lung Cancer: a Meta-analysis

c-MET inhibitors are considered as a kind of novel drugs in non-small cell lung cancer (NSCLC) treatment. However, the results of different clinical studies involving c-MET inhibitors were not consistent. In this report, we performed Meta-analysis to investigate the beneficial and harmful effects of these drugs from 9 studies including 1611 patients in target drug groups and 1605 patients in control groups. As a result, patients in target drugs group had longer progression free survival (PFS) (HR 0.80, 95% CI 0.66-0.99, p = 0.04) but not overall survival (OS) than those in control group, especially in Asian (HR 0.57, 95% CI 0.42-0.76, p < 0.001), Non-squamous (HR 0.79, 95% CI 0.64-0.97, p = 0.03), Phase III (HR 0.66, 95% CI 0.50-0.86, p = 0.002), previous treated (HR 0.77, 95% CI 0.63-0.95, p = 0.01) and small molecular compounds subgroups (HR 0.62, 95% CI 0.50-0.78, p < 0.001). In addition, target drugs did not affect the objective response rate (ORR) but improved disease control rate (DCR) (RR 1.22, 95% CI 1.02-1.46, p = 0.03) of NSCLC patients. Our study first indicated that targeting c-MET therapies improved PFS and DCR in advanced or metastatic NSCLC patients, especially in previous treated Asian patients with adenocarcinoma.

Clinical Significance of C-MET Overexpression and Epidermal Growth Factor Receptor Mutation in Platinum-Based Adjuvant Chemotherapy Outcome in Surgically Resected Lung Adenocarcinoma

PURPOSE

We retrospectively assessed the role of C-MET expression and epidermal growth factor receptor (EGFR) mutation on survival following platinum-based adjuvant chemotherapy. The impact of C-MET on survival was also investigated in relation to EGFR mutation status.

METHODS

We enrolled 311 patients with resected lung adenocarcinoma (high-risk stage 1B-3A), and performed immunohistochemistry (IHC) using C-MET- and mutant EGFR (EGFRmut)-specific antibodies in tissue microarrays.

RESULTS

Adjuvant chemotherapy was administered to 151 patients, 96 of whom relapsed and 85 died by the end of the study. On IHC, C-MET and EGFRmut were positive in 141 (45.3 %) and 88 (28.3 %) cases, respectively. On univariate analysis, adjuvant chemotherapy prolonged relapse-free survival (RFS) and overall survival (OS) in C-MET(+) patients (RFS p = 0.035; OS p = 0.013) but not in C-MET(-) patients. On multivariate analysis, adjuvant chemotherapy was a positive independent prognostic factor in C-MET(+) (RFS p = 0.013; OS p = 0.006) but not in C-MET(-) patients. In addition, univariate analysis showed no effect of EGFRmut status on RFS and OS after chemotherapy, whereas multivariate analysis revealed that adjuvant chemotherapy increased RFS in both EGFRmut(+) and EGFRmut(-) patients [EGFRmut(+) p = 0.033; EGFRmut(-) p = 0.030]. C-MET was a negative prognostic factor for RFS (p = 0.045) and OS (p = 0.007) in the EGFRmut(-) group but not in the EGFRmut(+) group, on multivariate analysis.

CONCLUSIONS

Our data indicate that patients with C-MET overexpression should be considered for adjuvant chemotherapy, and that C-MET negatively correlates with survival in patients with wild-type, but not mutant, EGFR.

Predictive and prognostic value of de novo MET expression in patients with advanced non-small-cell lung cancer

BACKGROUND

Cellular-mesenchymal-epithelial transition (MET) protein has recently been identified as a novel target that shows promise for the treatment of non-small-cell lung cancer (NSCLC). However, the relationship between de novo MET expression and patient outcomes remains unclear.

METHODS

We reviewed the data of patients who had been diagnosed with NSCLC between December 2013 and October 2014. All the patients were evaluated for MET expression status. MET-positive was defined as having an H-score ≥ 60 by immunohistochemistry analysis. MET expression was analyzed in 158 patients who were negative for the common driver genes, including EGFR, ALK, KRAS and ROS1. A chi-squared test was used to assess the clinicopathological parameters. Multivariate analyses were performed using the Cox proportional hazards model.

RESULTS

MET data were available for analysis in 158 advanced NSCLC patients. Of these, based on the MET H-score criteria, the IHC-positive rate was 48.1% (76/158). There were more patients with adenocarcinoma in the MET-positive group compared with the MET-negative group (P=0.01). Nine patients with lymphoepithelioma-like carcinoma had no MET expression. There was no significant difference in overall survival (OS) between MET-positive and -negative patients. There was also no significant difference in the efficacy (Z=-0.44, P=0.66) or progression free survival (PFS) of first-line chemotherapy between the MET-positive and -negative patients (mPFS 6.8 months [95% CI: 5.4-8.2] vs. 5.9 months [5.5-6.3], P=0.92). In the cell model, the MET-positive cell showed no difference in chemotherapy but with a increase in percentage of growth inhibition upon treatment with MET inhibitor INC280 compared to MET-negative cell.

CONCLUSION

Our data showed that de novo MET expression was not rare. It was not a predictive or prognostic factor for stage IV NSCLC patients, but this should be confirmed in larger population cohort.

Prognostic and predictive value of MET deregulation in non-small cell lung cancer

Recent progress in cancer biology has led to the discovery of increasing number of oncogene alterations that have dramatically changed the paradigm of lung cancer treatment. MET is a tyrosine kinase receptor for the hepatocyte growth factor (HGF) that is deregulated in several malignancies, including non-small cell lung cancer (NSCLC). Abnormal MET-HGF signaling pathway activation can occur via different mechanisms, including HGF and/or MET overexpression, MET gene amplification, mutations or rearrangements. MET protein overexpression and increased MET gene number have been identified as poor prognostic factors in several series of surgically resected NSCLC making this receptor an attractive target for cancer treatment. Several clinical trials have recently evaluated the activity of a variety of anti-MET strategies in NSCLC patients with or without molecular selection with a variable degree of success, underscoring the need of establishing the best predictive biomarker for the identification of responding patients.

Targeting the MET pathway for potential treatment of NSCLC

INTRODUCTION

The mesenchymal-epithelial transition (MET) protein is the only known receptor for hepatocyte growth factor and has recently been identified as a novel promising target in several human cancers, including NSCLC. Activation of the MET signaling pathway can occur via different mechanisms. A number of compounds targeting MET have been evaluated in clinical trials, and recent clinical data have begun to afford some insight into the tumor types and patient populations that might benefit from treatment with MET pathway inhibitors.

AREAS COVERED

We review recent publications and information disclosed at public conferences and summarize the epidemiology of dysregulation of MET signaling, and the associations thereof with other driver genes and therapeutic inhibitors useful to treat NSCLC.

EXPERT OPINION

The MET pathway is emerging as a target for advanced NSCLC that is either resistant to EGFR tyrosine kinase inhibitors or that arises de novo. MET inhibitors currently being evaluated in clinical trials have yielded compelling evidence of clinical activities when used to treat various solid tumors, especially NSCLC. Remaining challenges are the identification of patient populations who might benefit from the use of MET inhibitors, and the most effective diagnostic methods for such patients.