HGF/MET-directed therapeutics in gastroesophageal cancer: a review of clinical and biomarker development

Transformable DNA Nanorobots Reversibly Regulating Cell Membrane Receptors for Modulation of Cellular Migrations

Oligomerization of cellular membrane receptors plays crucial roles in activating intracellular downstream signaling cascades for controlling cellular behaviors in physiological and pathological processes. However, the reversible and controllable regulation of receptors in a user-defined manner remains challenging. Herein, we developed a versatile DNA nanorobot (nR) with installed aptamers and hairpin structures to reversibly and controllably regulate cell migration. This was achieved by dimerization and de-dimerization of mesenchymal-epithelial transition (Met) receptors through DNA strand displacement reactions. The functionalized DNA nR not only plays similar roles as hepatocyte growth factor (HGF) in inducing cell migration but also allows a downgrade to the original state of cell migration. The advanced DNA nanomachines can be flexibly designed to target other receptors for manipulating cellular behaviors and thus represent a powerful tool for the future of biological and medical engineering.

c-Met+ Cytotoxic T Lymphocytes Exhibit Enhanced Cytotoxicity in Mice and Humans In Vitro Tumor Models

CD8+ cytotoxic T lymphocytes (CTLs) play a crucial role in anti-tumor immunity. In a previous study, we identified a subset of murine effector CTLs expressing the hepatocyte growth factor (HGF) receptor, c-Met (c-Met+ CTLs), that are endowed with enhanced cytolytic capacity. HGF directly inhibited the cytolytic function of c-Met+ CTLs, both in 2D in vitro assays and in vivo, leading to reduced T cell responses against metastatic melanoma. To further investigate the role of c-Met+ CTLs in a three-dimensional (3D) setting, we studied their function within B16 melanoma spheroids and examined the impact of cell-cell contact on the modulation of inhibitory checkpoint molecules' expression, such as KLRG1, PD-1, and CTLA-4. Additionally, we evaluated the cytolytic capacity of human CTL clones expressing c-Met (c-Met+) and compared it to c-Met- CTL clones. Our results indicated that, similar to their murine counterparts, c-Met+ human CTL clones exhibited increased cytolytic activity compared to c-Met- CTL clones, and this enhanced function was negatively regulated by the presence of HGF. Taken together, our findings highlight the potential of targeting the HGF/c-Met pathway to modulate CTL-mediated anti-tumor immunity. This research holds promise for developing strategies to enhance the effectiveness of CTL-based immunotherapies against cancer.

HGF/c-Met signaling promotes the migration and proliferation of deer antler MSCs

The complete regeneration of deer antlers is based on the proliferation and differentiation of stem cells. Mesenchymal stem cells (MSCs) of antlers have an important role in antler regeneration and rapid growth and development. HGF is mainly synthesized and secreted by mesenchymal cells. After binding to its receptor c-Met, which transduces signals into cells to stimulate cell proliferation and migration in various organs to promote tissue morphogenesis and angiogenesis. However, the role and mechanism of the HGF/c-Met signaling pathway on antler MSCs are still unclear. In this study, we established antler MSCs with overexpression and interference of HGF gene by lentivirus and small interference RNA, observed the effect of HGF/c-Met signal pathway on the proliferation and migration of antler MSCs, and detected the expression of downstream related signal pathway genes, to explore the mechanism of HGF/c-MET signal pathway on the proliferation and migration of antler MSCs. The results showed that the HGF/c-Met signal affects the expression of RAS, ERK and MEK genes, regulates the proliferation of pilose antler MSCs through Ras/Raf, MEK/ERK pathway, affects the expression of Gab1, Grb2, AKT and PI3K genes, and regulates the migration of MSCs of pilose antler through Gab1/Grb2 and PI3K/AKT pathway.

Gumarontinib in patients with non-small-cell lung cancer harbouring MET exon 14 skipping mutations: a multicentre, single-arm, open-label, phase 1b/2 trial

Background

Approximately 3-4% of patients with non-small-cell lung cancer (NSCLC) have MET exon 14 (METex14) skipping mutations. We report primary results from the phase 2 stage of a phase 1b/2 study of gumarontinib, a selective, potent, oral MET inhibitor, in patients with METex14 skipping mutation-positive (METex14-positive) NSCLC.

Methods

The single-arm, multicentre, open-label, phase 2 stage of the GLORY study was conducted at 42 centres across China and Japan. Adults with locally advanced or metastatic METex14-positive NSCLC received oral gumarontinib 300 mg once daily in continuous 21-day cycles until disease progression, intolerable toxicity, or withdrawal of consent. Eligible patients had failed one or two prior lines of therapy (not including a MET inhibitor), were ineligible for/refused chemotherapy, and had no genetic alterations targetable with standard therapies. The primary endpoint was objective response rate in patients with a valid baseline tumour assessment, by blinded independent review. The study was registered at ClinicalTrials.gov (NCT04270591).

Findings

Between Aug 2, 2019 and Apr 28, 2021, 84 patients were enrolled and received gumarontinib (median follow-up 13.5 months [IQR 8.7-17.1]), at data cut-off (Apr 28, 2022) five patients whose METex14 status could not be confirmed by a central laboratory were excluded from the efficacy analysis. The objective response rate was 66% (95% CI 54-76) overall (n = 79), 71% (95% CI 55-83) in treatment-naïve patients (n = 44), and 60% (95% CI 42-76) in previously-treated patients (n = 35). The most common treatment-related adverse events (any grade) were oedema (67/84 patients, 80%) and hypoalbuminuria (32/84, 38%). Grade ≥3 treatment-emergent adverse events occurred in 45 (54%) patients. Treatment-related adverse events leading to permanent discontinuation occurred in 8% (7/84) of patients.

Interpretation

Gumarontinib monotherapy had durable antitumour activity with manageable toxicity in patients with locally advanced or metastatic METex14-positive NSCLC when used in first line or later.

Funding

Haihe Biopharma Co., Ltd. Supported in part by grants from the National Science and Technology Major Project of China for "Clinical Research of Gumarontinib, a highly selective MET inhibitor" (2018ZX09711002-011-003); the National Natural Science Foundation of China (82030045 to S.L. and 82172633 to YF.Y); Shanghai Municipal Science & Technology Commission Research Project (19411950500 to S.L.); Shanghai Shenkang Action Plan (16CR3005A to S.L.) and Shanghai Chest Hospital Project of Collaborative Innovation (YJXT20190105 to S.L.).

The Role of cMET in Gastric Cancer—A Review of the Literature

Gastric cancer (GC) is an important cause of cancer worldwide with over one million new cases yearly. The vast majority of cases present in stage IV disease, and it still bears a poor prognosis. However, since 2010, progress has been made with the introduction of targeted therapies against HER2 and with checkpoint inhibitors (PDL1). More agents interfering with other targets (FGFR2B, CLDN18.2) are being investigated. cMET is a less frequent molecular target that has been studied for gastric cancer. It is a proto-oncogene that leads to activation of the MAPK pathway and the PI3K pathway, which is responsible for activating the MTOR pathway. The prevalence of cMET is strongly debated as different techniques are being used to detect MET-driven tumors. Because of the difference in diagnostic assays, selecting patients who benefit from cMET inhibitors is difficult. In this review, we discuss the pathway of cMET, its clinical significance and the different diagnostic assays that are currently used, such as immunohistochemy (IHC), fluorescence in situ hybridization (FISH), the H-score and next-generation sequencing (NGS). Next, we discuss all the current data on cMET inhibitors in gastric cancer. Since the data on cMET inhibitors are very heterogenous, it is difficult to provide a general consensus on the outcome, as inclusion criteria differ between trials. Diagnosing cMET-driven gastric tumors is difficult, and potentially the only accurate determination of cMET overexpression/amplification may be next-generation sequencing (NGS).

Management of Peripheral Edema in Patients with MET Exon 14-Mutated Non-small Cell Lung Cancer Treated with Small Molecule MET Inhibitors

Small molecule mesenchymal-epithelial transition (MET) inhibitors, such as crizotinib, capmatinib, and tepotinib, are treatment options for metastatic non-small cell lung cancer (NSCLC) in adult patients whose tumors have a mutation that leads to MET exon 14 skipping. In clinical trials, these MET inhibitors were associated with a high incidence of peripheral edema, although this was generally mild-to-moderate in severity. There is limited information about the mechanism involved in MET inhibitor-induced peripheral edema. Perturbation of hepatocyte growth factor (HGF)/MET signaling may disrupt the permeability balance in the vascular endothelium and thus promote edema development. Another potential mechanism is through effects on renal function, although this is unlikely to be the primary mechanism. Because edema is common in cancer patients and may not necessarily be caused by the cancer treatment, or other conditions that have similar symptoms to peripheral edema, a thorough assessment is required to ascertain the underlying cause. Before starting MET-inhibitor therapy, patients should be educated about the possibility of developing peripheral edema. Patient limb volume should be measured before initiating treatment, to aid assessment if symptoms develop. Since the exact mechanism of MET inhibitor-induced edema is unknown, management is empiric, with common approaches including compression stockings, specific exercises, massage, limb elevation, and/or diuretic treatment. Although not usually required, discontinuation of MET inhibitor treatment generally resolves peripheral edema. Early diagnosis and management, as well as patient information and education, are vital to decrease the clinical burden associated with edema, and to reinforce capmatinib treatment adherence.

MET Gene High Copy Number (Amplification/Polysomy) Identified in Melanoma for Potential Targeted Therapy

OBJECTIVES

Aberrant expression of the mesenchymal epithelial transition factor (MET) gene has been observed in several malignancies, and drugs targeting the MET gene have been implicated in clinical trials with promising results. Hence, MET is a potentially targetable oncogenic driver. We explored the frequency of MET gene high copy number in melanomas and carcinomas.

METHODS

The study group included 135 patients. Tissue microarrays were constructed with 19 melanomas and 116 carcinomas diagnosed from 2010 to 2012. We screened MET gene copy number by fluorescence in situ hybridization analysis using probes for MET gene and CEP7 as control.

RESULTS

We found MET gene amplification in 2 (11%) of 19 melanoma cases, whereas 5 (26%) of 19 melanoma cases showed polysomy. For carcinomas, there was no MET gene amplification identified. However, 8 (7%) of 116 cases showed polysomy.

CONCLUSIONS

In our study, MET gene amplification was identified in 11% of melanomas and is relatively concordant with few reported studies. However, about 26% of the additional melanoma cases showed MET gene polysomy, which has not been reported as per our knowledge. If these results are validated with further orthogonal studies, more of the melanoma cases could potentially benefit from targeted therapy with MET tyrosine kinase inhibitors.

Safety of Tepotinib in Patients with MET Exon 14 Skipping NSCLC and Recommendations for Management

INTRODUCTION

The MET inhibitor tepotinib demonstrated durable clinical activity in patients with advanced MET exon 14 (METex14) skipping NSCLC. We report detailed analyses of adverse events of clinical interest (AECIs) in VISION, including edema, a class effect of MET inhibitors.

PATIENTS AND METHODS

Incidence, management, and time to first onset/resolution were analyzed for all-cause AECIs, according to composite categories (edema, hypoalbuminemia, creatinine increase, and ALT/AST increase) or individual preferred terms (pleural effusion, nausea, diarrhea, and vomiting), for patients with METex14 skipping NSCLC in the phase II VISION trial.

RESULTS

Of 255 patients analyzed (median age: 72 years), edema, the most common AECI, was reported in 69.8% (grade 3, 9.4%; grade 4, 0%). Median time to first edema onset was 7.9 weeks (range: 0.1-58.3). Edema was manageable with supportive measures, dose reduction (18.8%), and/or treatment interruption (23.1%), and rarely prompted discontinuation (4.3%). Other AECIs were also manageable and predominantly mild/moderate: hypoalbuminemia, 23.9% (grade 3, 5.5%); pleural effusion, 13.3% (grade ≥ 3, 5.1%); creatinine increase, 25.9% (grade 3, 0.4%); nausea, 26.7% (grade 3, 0.8%), diarrhea, 26.3% (grade 3, 0.4%), vomiting 12.9% (grade 3, 1.2%), and ALT/AST increase, 12.2% (grade ≥ 3, 3.1%). GI AEs typically occurred early and resolved in the first weeks.

CONCLUSION

Tepotinib was well tolerated in the largest trial of a MET inhibitor in METex14 skipping NSCLC. The most frequent AEs were largely mild/moderate and manageable with supportive measures and/or dose reduction/interruption, and caused few withdrawals in this elderly population.

Cytokine Interaction With Cancer-Associated Fibroblasts in Esophageal Cancer

Esophageal cancer (EC) is a highly aggressive cancer with poor outcomes under current treatment regimens. More recent findings suggest stroma elements, specifically cancer-associated fibroblasts (CAFs), play a role in disease occurrence and progression. Cancer-associated fibroblasts are largely the product of converted fibroblasts, but a variety of other local cell types including epithelial cells, endothelial cells, and mesenchymal cells have also been shown to transform to CAFs under the correct conditions. Cancer-associated fibroblasts primarily function in the communication between the tumor microenvironment and cancer cells via cytokine and chemokine secretions that accentuate immunosuppression and cancer growth. Cancer-associated fibroblasts also pose issues for EC treatment by contributing to resistance of current chemotherapeutics like cisplatin. Targeting this cell type directly proves difficult given the heterogeneity between CAFs subpopulations, but emerging research provides hope that treatment is on the horizon. This review aims to unravel some of the complexities surrounding CAFs’ impact on EC growth and therapy.

Capmatinib successfully overcomes tepotinib-induced intolerable peripheral edema

In May 2020 and February 2021, capmatinib and tepotinib, respectively were approved by the Food and Drug Administration (FDA) for the treatment of metastatic non‐small cell lung carcinoma harboring mesenchymal‐epithelial transition (MET) exon 14 skipping alterations. Herein, we present a case of intolerable peripheral edema caused by tepotinib, in which MET inhibitor could be continued by switching to capmatinib. Peripheral edema has been identified as one of the most common adverse events in capmatinib and tepotinib; however, there is no unified management for this adverse event. This is the first report that two MET inhibitors have different effects on the development of peripheral edema, and that the MET inhibitors can be continued by switching these drugs.

The Significance of MET Expression and Strategies of Targeting MET Treatment in Advanced Gastric Cancer

Background

Accurate assessment of predictive biomarker expression is critical in patient selection in clinical trials or clinical practice. However, changes in biomarker expression may occur after treatment. The aim of the present study was to evaluate the effects of chemotherapy on MET expression in gastric cancer (GC).

Methods

MET expression was examined immunohistochemically before and after treatment in 122 patients with unresectable or recurrent GC, and was evaluated according to H-score or the scoring criteria used in the MetMAb trial. MET gene amplification was assessed by chromogenic in situ hybridization (CISH). The antitumor effect of MET targeted therapy was investigated in human gastric cancer cells in vitro and in vivo, and the underlying molecular mechanisms were analyzed by western blot.

Results

MET expression was associated with Lauren classification as well as tumor differentiation by either scoring system. MET amplification was not associated with clinical characteristics. Of the 71 patients who had paired pre- and post-treatment tumor tissues, 28 patients (39%) were initially positive for MET expression, and 43 (61%) were negative. Twenty-five patients (35%) showed significant changes in MET expression after treatment (P=0.007). Additionally, there was a concomitant overexpression of MET and HER2 in a subset of GC patients. MET inhibitor volitinib could significantly inhibit cell proliferation and xenograft growth in vitro and in vivo in MKN45 cells with MET and phosphorylated MET (pMET) high expressions via suppressing downstream PI3K/Akt and MAPK signaling pathways. Furthermore, combination therapy targeting both MET and HER2 demonstrated a synergistic antitumor activity.

Conclusions

MET expression is altered post chemotherapy and MET status should be evaluated in real-time. Both MET and pMET expressions might need to be considered for patients suitable for volitinib treatment.

Identification and prevalence of potentially therapeutic targetable variants of major cancer driver genes in ampullary cancer patients in India through deep sequencing

Ampulla is a complex region located at the confluence of pancreatic and common bile duct and intestinal epithelium. Tumors arising in this region are anatomically and morphologically heterogenous, however they show unique as well as overlapping molecular features. Cancers of both these anatomic sites share morphological as well as genetic profile despite having few unique differences. Targeted therapies are currently emerging as one of the demanding approaches for treatment in most cancer types especially for malignant epithelial tumors and therefore genetic profiling of cancers is the key for identification of potentially therapeutic targetable mutations to know their prevalence and prognostic impact. We studied 97 resected cases of formalin fixed paraffin-embedded AC by deep targeted sequencing using Ampliseq cancer hotspot panel comprising of 50 oncogenes and tumor suppressor genes. Potentially therapeutic targetable mutations were observed in 58/83 (70%) cases. Fourteen patients did not show any pathogenic mutation. TP53 (48.1%), KRAS (37.3%), APC (25.3%), SMAD4 (22.8%), MET (16.8%), CTNNB1 (15.6%) and PIK3CA (10.8%) were the major mutated potential therapeutic targets. KRAS mutation (43.2 Vs. 32.6%) was more prevalent in pancreatobiliary subtype, while TP53 (58.6 Vs 35.1), APC (36.9 Vs 10.8), SMAD4 (28.2 Vs 16.2), MET (21.7 Vs 10.8) and CTNNB1 (19.5 Vs 10.8) were more prevalent in intestinal subtype. WNT signaling pathway was the major altered pathway in intestinal subtype. These mutated genes and pathways may be targeted with currently available drugs and may be explored for future development of targetable agents to improve the disease course in patients of AC.

Drug-induced peripheral oedema: An aetiology-based review

Many drugs are responsible, through different mechanisms, for peripheral oedema. Severity is highly variable, ranging from slight oedema of the lower limbs to anasarca pictures as in the capillary leak syndrome. Although most often noninflammatory and bilateral, some drugs are associated with peripheral oedema that is readily erythematous (eg, pemetrexed) or unilateral (eg, sirolimus). Thus, drug-induced peripheral oedema is underrecognized and misdiagnosed, frequently leading to a prescribing cascade. Four main mechanisms are involved, namely precapillary arteriolar vasodilation (vasodilatory oedema), sodium/water retention (renal oedema), lymphatic insufficiency (lymphedema) and increased capillary permeability (permeability oedema). The underlying mechanism has significant impact on treatment efficacy. The purpose of this review is to provide a comprehensive analysis of the main causative drugs by illustrating each pathophysiological mechanism and their management through an example of a drug.

Combination of HGF/MET-targeting agents and other therapeutic strategies in cancer

MET receptor has emerged as a druggable target across several human cancers. Agents targeting MET and its ligand hepatocyte growth factor (HGF) including small molecules such as crizotinib, tivantinib and cabozantinib or antibodies including rilotumumab and onartuzumab have proven their values in different tumors. Recently, capmatinib was approved for treatment of metastatic lung cancer with MET exon 14 skipping. In this review, we critically examine the current evidence on how HGF/MET combination therapies may take advantage of synergistic effects, overcome primary or acquired drug resistance, target tumor microenvironment, modulate drug metabolism or tackle pharmacokinetic issues. Preclinical and clinical studies on the combination of HGF/MET-targeted agents with conventional chemotherapeutics or molecularly targeted treatments (including EGFR, VEGFR, HER2, RAF/MEK, and PI3K/Akt targeting agents) and also the value of biomarkers are examined. Our deeper understanding of molecular mechanisms underlying successful pharmacological combinations is crucial to find the best personalized treatment regimens for cancer patients.

Tepotinib Inhibits the Epithelial-Mesenchymal Transition and Tumor Growth of Gastric Cancers by Increasing GSK3β, E-Cadherin, and Mucin 5AC and 6 Levels

Aberrant expression of mucins (MUCs) can promote the epithelial–mesenchymal transition (EMT), which leads to enhanced tumorigenesis. Carcinogenesis-related pathways involving c-MET and β-catenin are associated with MUCs. In this study, we characterized the expression of EMT-relevant proteins including MET, β-catenin, and E-cadherin in human gastric cancer (GC) cell lines, and further characterized the differential susceptibility of these cell lines compared with the c-MET inhibitor tepotinib. We assessed the antitumor activity of tepotinib in GC cell lines. The effects of tepotinib on cell viability, apoptotic cell death, EMT, and c-MET and β-catenin signaling were evaluated by 3-(4,5 dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl-2-(4-sulfophenyl)-2H-tetrazolium (MTS), flow cytometry, Western blotting, and qRT-PCR. The antitumor efficacy was assessed in MKN45 xenograft mice. Tepotinib treatment induced apoptosis in c-MET-amplified SNU620, MKN45, and KATO III cells, but had no effect on c-MET-reduced MKN28 or AGS cells. Tepotinib treatment also significantly reduced the protein levels of phosphorylated and total c-MET, phosphorylated and total ERK, β-catenin, and c-MYC in SNU620 and MKN45 cells. In contrast, this drug was only slightly active against KATO III cells. Notably, tepotinib significantly reduced the expression of EMT-promoting genes such as MMP7, COX-2, WNT1, MUC5B, and c-MYC in c-MET-amplified GC cells and increased the expression of EMT-suppressing genes such as MUC5AC, MUC6, GSK3β, and E-cadherin. In a mouse model, tepotinib exhibited good antitumor growth activity along with increased E-cadherin and decreased phosphorylated c-MET (phospho-c-MET) protein levels. Collectively, these results suggest that tepotinib suppresses tumor growth and migration by negatively regulating c-MET-induced EMT. These findings provide new insights into the mechanism by which MUC5AC and MUC6 contribute to GC progression.

(-)-Oleocanthal as a Dual c-MET-COX2 Inhibitor for the Control of Lung Cancer

Lung cancer (LC) represents the topmost mortality-causing cancer in the U.S. LC patients have overall poor survival rate with limited available treatment options. Dysregulation of the mesenchymal epithelial transition factor (c-MET) and cyclooxygenase 2 (COX2) initiates aggressive LC profile in a subset of patients. The Mediterranean extra-virgin olive oil (EVOO)-rich diet already documented to reduce multiple malignancies incidence. (-)-Oleocanthal (OC) is a naturally occurring phenolic secoiridoid exclusively occurring in EVOO and showed documented anti-breast and other cancer activities via targeting c-MET. This study shows the novel ability of OC to suppress LC progression and metastasis through dual targeting of c-MET and COX-2. Western blot analysis and COX enzymatic assay showed significant reduction in the total and activated c-MET levels and inhibition of COX1/2 activity in the lung adenocarcinoma cells A549 and NCI-H322M, in vitro. In addition, OC treatment caused a dose-dependent inhibition of the HGF-induced LC cells migration. Daily oral treatment with 10 mg/kg OC for 8 weeks significantly suppressed the LC A549-Luc progression and prevented metastasis to brain and other organs in a nude mouse tail vein injection model. Further, microarray data of OC-treated lung tumors showed a distinct gene signature that confirmed the dual targeting of c-MET and COX2. Thus, the EVOO-based OC is an effective lead with translational potential for use as a prospective nutraceutical to control LC progression and metastasis.

Nongenetic engineering strategies for regulating receptor oligomerization in living cells

Nongenetic strategies for regulating receptor oligomerization in living cells based on DNA, protein, small molecules and physical stimuli.

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.

Bispecific Aptamer Induced Artificial Protein-Pairing: A Strategy for Selective Inhibition of Receptor Function

Cell surface receptors play a critical role in modulating intracellular signal transduction, making them important drug targets. However, it remains challenging to develop a selective and efficient strategy for regulating receptor function. Herein, we develop a strategy, called bispecific aptamer induced artificial protein-pairing, to selectively regulate receptor function. In this strategy, bispecific aptamer probes act as molecular mediators to bind to both a target receptor protein and a paired protein, which brings the two proteins into close proximity on the living cell membrane. Importantly, the paired proteins work not only as a cancer biomarker for enhancing cell selectivity but also as a blocking assistant to inhibit target receptor function via strong steric hindrance effect. Compared with single-aptamer-mediated regulation, the proposed bispecific aptamer probes afford substantial improvement in selective and efficient regulation of receptor function and downstream signaling pathways. This work offers a versatile methodology to design molecular mediators that can modulate receptor function, thereby providing a new way for developing novel therapeutic drugs.

Evaluation of Intratumoral and Intertumoral Heterogeneity of MET Protein Expression in Gastric Cancer

Tumor heterogeneity of a target molecule could contribute to failure of the targeted therapy. We investigated the heterogeneity of MET expression within same primary gastric cancer (GC) and between primary and corresponding secondary GC lesions using immunohistochemistry (IHC). Intratumoral heterogeneity was defined as discordant MET status among 3 tissue microarray cores (3 different areas of same tumor). IHC 3+ was considered positive for MET overexpression. MET overexpression was observed in 2.7% (50/1869) of all examined cores and 5.3% (33/623) of primary GCs. When we compared MET IHC results between 3 cores from each tumor, intratumoral heterogeneity was identified (65.0% in total 623 cases; 84.4% in 480 cases with any staining intensity; 84.9% in 251 cases with moderate to strong intensity; 90.9% in 33 cases with strong intensity). Of 33 MET-overexpressed GCs, the average proportion of strongly stained area was 19.6% in the whole sections. Of 269 cases with primary GC and regional lymph node metastasis, 17 (6.3%) showed MET positivity in which 9 (52.9%) were discordant (negative conversion). In 123 cases with primary and corresponding local recurrent/distant metastatic GC, 3 (2.4%) showed MET positivity in which 2 (66.7%) were discordant (positive conversion). In the survival analysis, MET IHC 3+ in lymph node metastases was an independent negative prognostic factor for overall survival. We found that MET overexpression is uncommon and highly heterogeneous in GC. This severe heterogeneity of MET status should be considered in tissue sampling and development of biomarkers for anti-MET therapy.

The repression and reciprocal interaction of DNA methyltransferase 1 and specificity protein 1 contributes to the inhibition of MET expression by the combination of Chinese herbal medicine FZKA decoction and erlotinib

ETHNOPHARMACOLOGICAL RELEVANCE

The Chinese herbal medicine Fuzheng Kang-Ai (FZKA) decoction obtained from Guangdong Kangmei Pharmaceutical Company, which contains 12 components with different types of constituents, has been used as part of the adjuvant treatment of lung cancer for decades. We previously showed that FZKA decoction enhances the growth inhibition of epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI)-resistant non-small cell lung cancer (NSCLC) cells by suppressing glycoprotein mucin 1 (MUC1) expression. However, the molecular mechanism underlying the therapeutic potential, particularly in sensitizing or/and enhancing the anti-lung cancer effect of EGFR-TKIs, remains unclear.

MATERIALS AND METHODS

Cell viability was measured using 3-(4, 5-diMEThylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and 5-ethynyl -2'-deoxyuridine (EdU) assays. Western blot analysis was performed to examine the protein expressions of DNA methyltransferase 1 (DNMT1), specificity protein 1 (SP1), and MET, an oncogene encoding for a trans-membrane tyrosine kinase receptor activated by the hepatocyte growth factor (HGF). The expression of MET mRNA was measured by quantitative real-time PCR (qRT-PCR). Exogenous expression of DNMT1 and SP1, and MET were carried out by transient transfection assays. The promoter activity of MET was tested using Dual-luciferase reporter assays. A nude mouse xenografted tumor model further evaluated the effect of the combination of FZKA decoction and erlotinib in vivo.

RESULTS

The combination of FZKA and erlotinib produced an even greater inhibition of NSCLC cell growth. FZKA decreased the expressions of DNMT1, SP1, and MET (c-MET) proteins, and the combination of FZKA and erlotinib demonstrated enhanced responses. Interestingly, there was a mutual regulation of DNMT1 and SP1. In addition, exogenously expressed DNMT1 and SP1 blocked the FZKA-inhibited c-MET expression. Moreover, excessive expressed MET neutralized FZKA-inhibited growth of NSCLC cells. FZKA decreased the mRNA and promoter activity of c-MET, which was not observed in cells with ectopic expressed DNMT1 gene. Similar findings were observed in vivo.

CONCLUSION

FZKA decreases MET gene expression through the repression and mutual regulation of DNMT1 and SP1 in vitro and in vivo. This leads to inhibit the growth of human lung cancer cells. The combination of FZKA and EGFR-TKI erlotinib exhibits synergy in this process. The regulatory loops among the DNMT1, SP1 and MET converge in the overall effects of FZKA and EGFR-TKI erlotinib. This in vitro and in vivo study clarifies an additional novel molecular mechanism underlying the anti-lung cancer effects in response to the combination of FZKA and erlotinib in gefitinib-resistant NSCLC cells.

Identification of key genes and associated pathways in KIT/PDGFRA wild‑type gastrointestinal stromal tumors through bioinformatics analysis

Gastrointestinal stromal tumors (GISTs) are the most common type of mesenchymal tumor in the gastrointestinal tract. The present study aimed to identify the potential candidate biomarkers that may be involved in the pathogenesis and progression of v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog (KIT)/platelet-derived growth factor receptor α (PDGFRA) wild-type GISTs. A joint bioinformatics analysis was performed to identify the differentially expressed genes (DEGs) in wild-type GIST samples compared with KIT/PDGFRA mutant GIST samples. Gene Ontology function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of DEGs was conducted using Database for Annotation, Visualization and Integrated Discovery and KEGG Orthology-Based Annotation System (KOBAS) online tools, respectively. Protein-protein interaction (PPI) networks of the DEGs were constructed using Search Tool for the Retrieval of Interacting Genes online tool and Cytoscape, and divided into sub-networks using the Molecular Complex Detection (MCODE) plug-in. Furthermore, enrichment analysis of DEGs in the modules was analyzed with KOBAS. In total, 546 DEGs were identified, including 238 upregulated genes primarily enriched in ‘cell adhesion’, ‘biological adhesion’, ‘cell-cell signaling’, ‘PI3K-Akt signaling pathway’ and ‘ECM-receptor interaction’, while the 308 downregulated genes were predominantly involved in ‘inflammatory response’, ‘sterol metabolic process’ and ‘fatty acid metabolic process’, ‘small GTPase mediated signal transduction’, ‘cAMP signaling pathway’ and ‘proteoglycans in cancer’. A total of 25 hub genes were obtained and four modules were mined from the PPI network, and sub-networks also revealed these genes were primarily involved in significant pathways, including ‘PI3K-Akt signaling pathway’, ‘proteoglycans in cancer’, ‘pathways in cancer’, ‘Rap1 signaling pathway’, ‘ECM-receptor interaction’, ‘phospholipase D signaling pathway’, ‘ras signaling pathway’ and ‘cGMP-PKG signaling pathway’. These results suggested that several key hub DEGs may serve as potential candidate biomarkers for wild-type GISTs, including phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit γ, insulin like growth factor 1 receptor, hepatocyte growth factor, thrombospondin 1, Erb-B2 receptor tyrosine kinase 2 and matrix metallopeptidase 2. However, further experiments are required to confirm these results.

Novel Targeted Therapies for Esophagogastric Cancer

Gastroesophageal cancer (GEC) remains a major cause of cancer-related mortality worldwide. Although the incidence of distal gastric adenocarcinoma (GC) is declining in the United States, proximal esophagogastric junction adenocarcinoma (EGJ) is increasing in incidence. GEC, including GC and EGJ, is treated uniformly in the metastatic setting. Overall survival in the metastatic setting remains poor. Molecular characterization of GEC has identified mutations and copy number variations, along with other oncogenes, biomarkers, and immuno-oncologic checkpoints that may serve as actionable therapeutic targets. This article reviews these key aberrations, their impact on protein expression, therapeutic implications, and clinical directions within each pathway.

RNA Interference-Mediated Gene Silencing in Esophageal Adenocarcinoma

RNA interference (RNAi) is a normal physiological mechanism in which a short effector antisense RNA molecule regulates target gene expression. It is a powerful tool to silence a particular gene of interest in a sequence-specific manner and can be used to target against various molecular pathways in esophageal adenocarcinoma by designing RNAi targeting key pathogenic genes. RNAi-based therapeutics against esophageal adenocarcinoma can be developed using different strategies including inhibition of overexpressed oncogenes, blocking cell division by interfering cyclins and related genes or enhancing apoptosis by suppressing anti-apoptotic genes. In addition, RNAi against multidrug resistance genes or chemo-resistance targets may provide promising cancer therapeutic options. Here, we describe RNAi technology using MET, a proto-oncogene in esophageal adenocarcinoma cells, as a model target. Lentiviral particles expressing MET shRNA was used to silence MET genes. Then, Western blot analysis was performed to confirm MET knockdown.

HER2 Confers Resistance to Foretinib Inhibition of MET-Amplified Esophageal Adenocarcinoma Cells

BACKGROUND

Recent genomic studies indicated that esophageal adenocarcinoma (EAC) is driven by amplification of c-MET or HER2 or both in a subset of patients. We studied the effect of MET targeting by the small molecule inhibitor foretinib in EAC cells and the interplay between MET and HER2 signaling.

METHODS

We measured the expression levels and phosphorylation status of MET and HER2 proteins in EAC cell lines using Western blot analysis. The expression levels of MET and HER2 were manipulated by transfecting cells with specific siRNA or a plasmid expressing HER2. The small molecule inhibitors of c-MET and ERBB1/2 (foretinib and lapatinib, respectively) were tested for effect on growth, apoptosis, and downstream signaling pathways of EAC cells as single agents or in combination. The response to inhibitors was correlated to the levels of MET, HER2 expression, and amplification status.

RESULTS

Foretinib inhibits phosphorylation of MET, which correlated with reduced EAC cell growth and inhibition of AKT and ERK phosphorylation. Cell growth inhibition by foretinib is most profound in the ESO51 cell line, which has MET gene amplification and overexpression. Inhibition of MET signaling by foretinib or siRNA-specific knock down of MET expression induces apoptosis in ESO51 cells. Ectopic expression of HER2 reduces foretinib-mediated growth inhibition and downstream ERK phosphorylation in ESO51-HER2 cells. The EAC OE33 cell line, with amplification and overexpression of both MET and HER2, demonstrated reduced sensitivity to foretinib or lapatinib and had a transient effect on downstream inhibition of phosphorylated AKT and ERK (p-AKT, p-ERK). The coadministration of foretinib and lapatinib effectively blocked both MET and HER2 signaling through the p-AKT and p-ERK pathways, dramatically inhibited growth, and induced apoptosis to overcome single-agent resistance in OE33 cells.

CONCLUSIONS

The mechanism for foretinib growth inhibition in MET-amplified EAC tumor cells is demonstrated. The interplay of dual MET/HER2 overexpression in the AKT and ERK pathways for esophageal cancer is described. Therefore, combination therapy could be a novel strategy for EAC with amplification of both MET and HER2.

Expression of c-Met and hepatocyte growth factor in various gastric pathologies and its association with Helicobacter pylori infection

Activation of the hepatocyte growth factor (HGF)/c-Met signaling pathway was identified to be associated with malignant tumors. The present study aimed at determining the expression of HGF and c-Met in gastric carcinogenesis and its association with Helicobacter pylori infection. Gastric biopsies were obtained from 160 H. pylori-negative and -positive patients, including those with chronic gastritis, intestinal metaplasia, dysplasia and gastric cancer (GC). Proteins were extracted from GES-1, gastric epithelial, and AGS, gastric adenocarcinoma, cells following co-culture with H. pylori in vitro. The expression of HGF and c-Met in gastric tissues or cells was determined using immunohistochemistry and western blot analysis. The expression of c-Met increased in GC tissues (72.5%) compared with that in pre-cancerous lesions (17.5, 17.5 and 30%). Additional analysis identified that the expression of HGF and c-Met was significantly increased in the presence of H. pylori infection in dysplasia and gastric cancer samples. Furthermore, H. pylori may activate the HGF/c-Met signaling pathway in vitro, which may contribute to gastric carcinogenesis.

Targeting MET in cancer therapy

MET encodes a receptor tyrosine kinase c-MET for hepatocyte growth factor (HGF). The specific combination of c-MET and HGF activates downstream signaling pathways to trigger cell migration, proliferation, and angiogenesis. MET exon 14 alterations and MET gene amplification play a critical role in the origin of cancer. Several monoclonal antibodies and small-molecule inhibitors of c-MET have been evaluated in clinical trials. In patients with advanced non-small cell lung cancer, cabozantinib and crizotinib showed clear efficacy with a generally tolerable adverse events profile. In gastrointestinal cancers, most phase III trials of MET inhibitors showed negative results. In hepatocellular carcinoma, based on the encouraging results of some phase II studies, a series of phase III trials are currently recruiting patients to access the efficacy and safety of MET inhibitors.

Update on Gastroesophageal Adenocarcinoma Targeted Therapies

Gastroesophageal cancer (GEC) remains a major cause of cancer-related mortality worldwide. Although the incidence of distal gastric adenocarcinoma (GC) is declining in the United States, proximal esophagogastric junction adenocarcinoma (EGJ) incidence is rising. GC and EGJ, together, are treated uniformly in the metastatic setting as GEC. Overall survival in the metastatic setting remains poor, with few molecular targeted approaches having been successfully incorporated into routine care to date-only first-line anti-HER2 therapy for ERBB2 amplification and second-line anti-VEGFR2 therapy. This article reviews aberrations in epidermal growth factor receptor, MET, and ERBB2, their therapeutic implications, and future directions in targeting these pathways.

Hepatocyte Growth Factor/C-Met Axis in Thyroid Cancer: From Diagnostic Biomarker to Therapeutic Target

The hepatocyte growth factor (HGF)/c-met axis plays a crucial role in cancer development by promoting cellular proliferation, motility, and morphogenesis, as well as angiogenesis. Different cellular distributions of both the ligand and the receptor in benign vs malignant lesions indicate this biological system as a candidate for a diagnostic biomarker of malignancy occurring in endocrine glands, such as the thyroid and pituitary. Furthermore, the HGF/c-met expression may help to identify a subset of patients eligible for potential targeted therapies with HGF/c-met inhibitors or antagonists in thyroid tumour, as well as in other malignancies. This may be relevant for iodine-refractory cancers, the treatment of which is still a major challenge. With this in mind, HGF/c-met expression in thyroid cancer tissue may be useful for prognostic and therapeutic stratification of patients.

The mechanisms of radioresistance in esophageal squamous cell carcinoma and current strategies in radiosensitivity

Esophageal cancer is the eighth most common cancer and the sixth leading cause of cancer-related death worldwide. Surgery is the primary form of treatment, but the survival is poor, especially for patients with locally advanced esophageal cancer. Radiotherapy has been a critical treatment option that may be combined with chemotherapy in patients with unresectable esophageal cancer. However, resistance to chemoradiotherapy might result in treatment failures and cancer relapse. This review will mainly focus on the possible cellular mechanisms and tumor-associated microenvironmental (TAM) factors that result in radioresistance in patients with esophageal cancer. In addition, current strategies to increase radiosensitivity, including targeted therapy and the use of radiosensitive biomarkers in clinical treatment, are discussed in this review.

Randomized, Double-Blind, Placebo-Controlled, Multicenter Phase II Study of Onartuzumab Plus Bevacizumab Versus Placebo Plus Bevacizumab in Patients With Recurrent Glioblastoma: Efficacy, Safety, and Hepatocyte Growth Factor and O6-Methylguanine–DNA Methyltransferase Biomarker Analyses

Purpose

Bevacizumab regimens are approved for the treatment of recurrent glioblastoma in many countries. Aberrant mesenchymal-epithelial transition factor (MET) expression has been reported in glioblastoma and may contribute to bevacizumab resistance. The phase II study GO27819 investigated the monovalent MET inhibitor onartuzumab plus bevacizumab (Ona + Bev) versus placebo plus bevacizumab (Pla + Bev) in recurrent glioblastoma.

Methods

At first recurrence after chemoradiation, bevacizumab-naïve patients with glioblastoma were randomly assigned 1:1 to receive Ona (15 mg/kg, once every 3 weeks) + Bev (15 mg/kg, once every 3 weeks) or Pla + Bev until disease progression. The primary end point was progression-free survival by response assessment in neuro-oncology criteria. Secondary end points were overall survival, objective response rate, duration of response, and safety. Exploratory biomarker analyses correlated efficacy with expression levels of MET ligand hepatocyte growth factor, O6-methylguanine–DNA methyltransferase promoter methylation, and glioblastoma subtype.

Results

Among 129 patients enrolled (Ona + Bev, n = 64; Pla + Bev, n = 65), baseline characteristics were balanced. The median progression-free survival was 3.9 months for Ona + Bev versus 2.9 months for Pla + Bev (hazard ratio, 1.06; 95% CI, 0.72 to 1.56; P = .7444). The median overall survival was 8.8 months for Ona + Bev and 12.6 months for Pla + Bev (hazard ratio, 1.45; 95% CI, 0.88 to 2.37; P = .1389). Grade ≥ 3 adverse events were reported in 38.5% of patients who received Ona + Bev and 35.9% of patients who received Pla + Bev. Exploratory biomarker analyses suggested that patients with high expression of hepatocyte growth factor or unmethylated O6-methylguanine–DNA methyltransferase may benefit from Ona + Bev.

Conclusion

There was no evidence of further clinical benefit with the addition of onartuzumab to bevacizumab compared with bevacizumab plus placebo in unselected patients with recurrent glioblastoma in this phase II study; however, further investigation into biomarker subgroups is warranted.

Targeted therapies for advanced and metastatic adenocarcinoma of the gastroesophageal junction: is there something new?

Despite improvements in systemic chemotherapy (CT), the prognosis of metastatic adenocarcinoma of the gastroesophageal junction remains poor. Over the years, new targeting agents have become available and were tested, with or without CT, in first or subsequent lines of therapy. The epidermal growth factor receptor family was targeted with monoclonal antibodies (MoAbs) (trastuzumab, cetuximab, panitumumab) and tyrosin kinase inhibitors (TKIs) (lapatinib, erlotinib, gefitinib). Only trastuzumab, in combination with cisplatin and fluoropyrimidines, significantly improved overall survival (OS) in first-line therapy (13.8 vs. 11.1 months). Angiogenesis also was targeted with MoAbs (bevacizumab and ramucirumab); ramucirumab, a vascular endothelial growth factor-receptor 2 antagonist, enhanced OS in two phase III studies in the first (9.6 vs. 7.4 months) and subsequent lines of treatment (5.2 vs. 3.8 months), while the bevacizumab study was negative. TKIs (sunitinib, sorafenib, regorafenib, apatinib) were tested in this setting in phase II studies in the second/third line, only showing modest antitumor activity. The hepatocyte growth factor receptor (MET) was targeted in untreated patients in a phase III trial with MoAb rilotumumab, with or without CT, but the study was stopped because of mortality excess in the rilotumumab arm. Mammalian target of rapamycin (MTOR) pathway inhibition with everolimus was tested in pretreated patients in a placebo-controlled phase III trial who failed to improve OS (5.4 vs. 4.3 months). In conclusion, considering the modest survival gain obtained overall, the high cost of these therapies and the quality of life issue must be primarily considered in treating these patients.

MET tyrosine kinase receptor expression and amplification as prognostic biomarkers of survival in gastroesophageal adenocarcinoma

BACKGROUND

MET gene amplification and Met protein overexpression may be associated with a poor prognosis. The MET/Met status is typically determined with fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC), respectively. Targeted proteomics uses mass spectrometry–based selected reaction monitoring (SRM) to accurately quantitate Met expression. FISH, IHC, and SRM analyses were compared to characterize the prognostic value of MET/Met in gastroesophageal adenocarcinoma (GEC).

METHODS

Samples from 447 GEC patients were analyzed for MET gene amplification (FISH) and Met protein expression (IHC and SRM). Cox proportional hazards models and Kaplan‐Meier estimates were applied to explore relations between Met, overall survival (OS), and clinical/pathological characteristics. Spearman's rank coefficient was used to assess the correlation between parameters.

RESULTS

Patients with MET‐amplified tumors had worse OS when: the MET/centromere enumeration probe for chromosome 7 FISH ratio was ≥ 2 (hazard ratio [HR], 3.13; 95% confidence interval [CI], 1.84‐5.33), the MET gene copy number was ≥5 (HR, 2.51; 95% CI, 1.45‐4.34), or ≥ 10% of the cells had ≥15 copies (HR, 4.28; 95% CI, 2.18‐8.39). Similar observations were made with Met protein overexpression by IHC (≥1 + intensity in ≥ 25% of the tumor cell membrane: HR, 1.39; 95% CI, 1.04‐1.86) or SRM (≥400 amol/μg: HR, 1.76; 95% CI, 1.06‐2.90). A significant correlation was observed between MET FISH/Met IHC, MET FISH/Met SRM, and Met IHC/Met SRM; only MET FISH and Met SRM were independent negative prognostic biomarkers in multivariate analyses.

CONCLUSIONS

MET amplification and overexpression, assessed by multiple methods, were associated with a worse prognosis in univariate analyses. However, only MET amplification by FISH and Met expression by SRM were independent prognostic biomarkers. Compared with IHC, SRM may provide an added benefit for informed decisions about Met‐targeted therapy. Cancer 2017;123:1061–70. © 2016 American Cancer Society.

In a large study, MET gene amplification, Met protein overexpression, or both, as assessed by various assays, are associated with a poor prognosis in univariate analyses. However, only MET amplification by fluorescence in situ hybridization and Met expression by selected reaction monitoring mass spectrometry are independent prognostic biomarkers; compared with immunohistochemistry, selected reaction monitoring may provide an added benefit for informed decisions about Met‐targeted therapy.

Molecular targets of luteolin in cancer

Many food-derived phytochemical compounds and their derivatives represent a cornucopia of new anticancer compounds. Despite extensive study of luteolin, the literature has no information on the exact mechanisms or molecular targets through which it deters cancer progression. This review discusses existing data on luteolin's anticancer activities and then offers possible explanations for and molecular targets of its cancer-preventive action. Luteolin prevents tumor development largely by inactivating several signals and transcription pathways essential for cancer cells. This review also offers insights into the molecular mechanisms and targets through which luteolin either prevents cancer or mediates cancer cell death.

Wnt/β-catenin, an oncogenic pathway targeted by H. pylori in gastric carcinogenesis

A section of gastric cancers presents nuclear β-catenin accumulation correlated with H. pylori infection. H. pylori stimulate Wnt/β-catenin pathway by activating oncogenic c-Met and epidermal growth factor receptor (EGFR), or by inhibiting tumor suppressor Runx3 and Trefoil factor 1 (TFF1). H. pylori also trigger Wnt/β-catenin pathway by recruiting macrophages. Moreover, Wnt/β-catenin pathway is found involved in H. pylori-induced gastric cancer stem cell generation. Recently, by using gastroids, researchers have further revealed that H. pylori induce gastric epithelial cell proliferation through β-catenin. These findings indicate that Wnt/β-catenin is an oncogenic pathway activated by H. pylori. Therefore, this pathway is a potential therapy target for H. pylori-related gastric cancer.

Humanized anti-hepatocyte growth factor (HGF) antibody suppresses innate irinotecan (CPT-11) resistance induced by fibroblast-derived HGF

The growth factors derived from the microenvironment create an environment conducive to tumor growth and survival. HGF deprivation using neutralizing antibody enhanced chemosensitivity in colorectal cancer cells (CRC). We determined secreted HGF in fibroblast conditioned medium (CM). Combination treatment of anti-HGF antibody and irinotecan (CPT-11) directly enhanced CPT-11 sensitivity in CRC. We generated xenograft in NOD/SCID mice inoculating HCT-116 human colorectal cancer cells subcutaneously with or without fibroblast. We found that the combination of CPT-11 and anti-HGF antibody induced marked suppression of tumor development. These results suggest that HGF produced by fibroblast induce CPT-11 resistance, and that anti-HGF antibody abrogate such resistance in vivo. fibroblast-derived HGF is important determinant of chemoresistance. Anti-HGF monoclonal antibody treatment confirmed the importance of this growth factor for chemoresistance in CRC. These results present new options toward the early diagnosis of chemoresistance and suggest novel combinations of chemotherapy and anti-HGF agents to prevent or significantly delay the onset of therapy resistance.

Molecular classification of gastric cancer: Towards a pathway-driven targeted therapy

Gastric cancer (GC) is the third leading cause of cancer mortality worldwide. Although surgical resection is a potentially curative approach for localized cases of GC, most cases of GC are diagnosed in an advanced, non-curable stage and the response to traditional chemotherapy is limited. Fortunately, recent advances in our understanding of the molecular mechanisms that mediate GC hold great promise for the development of more effective treatment strategies. In this review, an overview of the morphological classification, current treatment approaches, and molecular alterations that have been characterized for GC are provided. In particular, the most recent molecular classification of GC and alterations identified in relevant signaling pathways, including ErbB, VEGF, PI3K/AKT/mTOR, and HGF/MET signaling pathways, are described, as well as inhibitors of these pathways. An overview of the completed and active clinical trials related to these signaling pathways are also summarized. Finally, insights regarding emerging stem cell pathways are described, and may provide additional novel markers for the development of therapeutic agents against GC. The development of more effective agents and the identification of biomarkers that can be used for the diagnosis, prognosis, and individualized therapy for GC patients, have the potential to improve the efficacy, safety, and cost-effectiveness for GC treatments.

Quantitative imaging for development of companion diagnostics to drugs targeting HGF/MET

The limited clinical success of anti-HGF/MET drugs can be attributed to the lack of predictive biomarkers that adequately select patients for treatment. We demonstrate here that quantitative digital imaging of formalin fixed paraffin embedded tissues stained by immunohistochemistry can be used to measure signals from weakly staining antibodies and provides new opportunities to develop assays for detection of MET receptor activity. To establish a biomarker panel of MET activation, we employed seven antibodies measuring protein expression in the HGF/MET pathway in 20 cases and up to 80 cores from 18 human cancer types. The antibodies bind to epitopes in the extra (EC)- and intracellular (IC) domains of MET (MET4^EC, SP44_MET^IC, D1C2_MET^IC), to MET-pY1234/pY1235, a marker of MET kinase activation, as well as to HGF, pSFK or pMAPK. Expression of HGF was determined in tumour cells (T_HGF) as well as in stroma surrounding cancer (St_HGF). Remarkably, MET4^EC correlated more strongly with pMET (r = 0.47) than SP44_MET^IC (r = 0.21) or D1C2_MET^IC (r = 0.08) across 18 cancer types. In addition, correlation coefficients of pMET and T_HGF (r = 0.38) and pMET and pSFK (r = 0.56) were high. Prediction models of MET activation reveal cancer-type specific differences in performance of MET4^EC, SP44_MET^IC and anti-HGF antibodies. Thus, we conclude that assays to predict the response to HGF/MET inhibitors require a cancer-type specific antibody selection and should be developed in those cancer types in which they are employed clinically.

Depletion of FOXM1 via MET Targeting Underlies Establishment of a DNA Damage-Induced Senescence Program in Gastric Cancer

PURPOSE

Deregulated signaling via the MET receptor tyrosine kinase is abundant in gastric tumors, with up to 80% of cases displaying aberrant MET expression. A growing body of evidence suggests MET as a potential target for tumor radiosensitization.

EXPERIMENTAL DESIGN

Cellular proliferation and DNA damage-induced senescence were studied in a panel of MET-overexpressing human gastric cancer cell lines as well as in xenograft models after MET inhibition and/or ionizing radiation. Pathways activation and protein expression were assessed by immunoblotting and immunohistochemistry. Tumor tissue microarrays (91 gastric cancer patients) were generated and copy number alteration (178 patients) and gene expression (373 patients) data available at The Cancer Genome Atlas were analyzed to assess the coalterations of MET and FOXM1.

RESULTS

MET targeting administered before ionizing radiation instigates DNA damage-induced senescence (∼80%, P < 0.001) rather than cell death. MET inhibition-associated senescence is linked to the blockade of MAPK pathway, correlates with downregulation of FOXM1, and can be abrogated (11.8% vs. 95.3%, P < 0.001) by ectopic expression of FOXM1 in the corresponding gastric tumor cells. Cells with ectopic FOXM1 expression demonstrate considerable (∼20%, P < 0.001) growth advantage despite MET targeting, suggesting a novel clinically relevant resistance mechanism to MET inhibition as the copresence of both MET and FOXM1 protein (33%) and mRNA (30%) overexpression as well as gene amplification (24,7%) are common in patients with gastric cancer.

CONCLUSIONS

FOXM1, a negative regulator of senescence, has been identified as a key downstream effector and potential clinical biomarker that mediates MET signaling following infliction of DNA damage in gastric tumors. Clin Cancer Res; 22(21); 5322-36. ©2016 AACR.

Gene of the month: HGF

Hepatocyte growth factor (HGF) is a multifunctional cytokine with important roles in cell proliferation, survival, motility and morphogenesis. Secreted by cells of mesenchymal origin, HGF is the specific ligand for the tyrosine-kinase receptor c-MET (cellular mesenchymal-epithelial transition), also called MET, which is expressed in different types of epithelial, endothelial and haematopoietic progenitor cells. The HGF/MET axis is involved in several biological processes, such as embryogenesis, organogenesis, adult tissue regeneration (including wound healing and liver regeneration) and carcinogenesis, for both solid and haematological malignancies.1 2 HGF and its particular interaction with the MET receptor have been extensively investigated in the last decades and remain the focus of numerous clinical trials.3–8 This short review focuses on HGF structure and function, as well as its roles in liver regeneration and different types of tumours.

Serum level of hepatocyte growth factor is a novel marker of predicting the outcome and resistance to the treatment with trastuzumab in HER2-positive patients with metastatic gastric cancer

HER2-overexpression in tumor tissue is observed in 6 to 23% of advanced gastric cancer (GC) cases, and trastuzumab is an active molecular drug for these patients. There are no data available on whether serum levels of ligands are associated with the response and resistance to trastuzumab in HER2-positive patients with metastatic GC. HER2 screening of 502 patients with advanced gastric cancer was performed in our institution. Among these patients, 84 patients (16.8%) were diagnosed as HER2-positive, and those who were treated with trastuzumab and met the inclusion criteria were enrolled in the present study. Serum levels of ligands that affect the HER2 signal pathway were measured by an enzyme-linked immunosorbent assay. Forty-six HER2-positive patients were enrolled in this study, and 26 patients (56.5%) achieved a partial response to treatment with trastuzumab. Among several ligands, the serum level of hepatocyte growth factor (HGF) was significantly lower in responders compared with that in non-responders (p = 0.014). Multivariate analyses showed that a high level of serum HGF was a poor prognostic factor for overall survival (OS) compared with low levels of HGF (adjusted HR: 3.857, 95% CI: 1.309-11.361, p = 0.014). Among 25 patients without initial disease progression on the treatment with trastuzumab, the mean value of serum HGF at disease progression was significantly higher than that at pre-treatment (p = 0.041). As novel findings, our study indicated that serum level of HGF was associated with tumor shrinkage and time to progression of trastuzumab in HER2-positive patients with metastatic GC.

MET gene exon 14 deletion created using the CRISPR/Cas9 system enhances cellular growth and sensitivity to a MET inhibitor

BACKGROUND

MET splice site mutations resulting in an exon 14 deletion have been reported to be present in about 3% of all lung adenocarcinomas. Patients with lung adenocarcinoma and a MET splice site mutation who have responded to MET inhibitors have been reported. The CRISPR/Cas9 system is a recently developed genome-engineering tool that can easily and rapidly cause small insertions or deletions.

MATERIALS AND METHODS

We created an in vitro model for MET exon 14 deletion using the CRISPR/Cas9 system and the HEK293 cell line. The phenotype, which included MET inhibitor sensitivity, was then investigated in vitro. Additionally, MET splice site mutations were analyzed in several cancers included in The Cancer Genome Atlas (TCGA) dataset.

RESULTS

An HEK293 cell line with a MET exon 14 deletion was easily and rapidly created; this cell line had a higher MET protein expression level, enhanced MET phosphorylation, and prolonged MET activation. In addition, a direct comparison of phenotypes using this system demonstrated enhanced cellular growth, colony formation, and MET inhibitor sensitivity. In the TCGA dataset, lung adenocarcinomas had the highest incidence of MET exon 14 deletions, while other cancers rarely carried such mutations. Approximately 10% of the lung adenocarcinoma samples without any of driver gene alterations carried the MET exon 14 deletion.

CONCLUSIONS

These findings suggested that this system may be useful for experiments requiring the creation of specific mutations, and the present experimental findings encourage the development of MET-targeted therapy against lung cancer carrying the MET exon 14 deletion.

c-Met as a Target for Personalized Therapy

MET and its ligand HGF are involved in many biological processes, both physiological and pathological, making this signaling pathway an attractive therapeutic target in oncology. Downstream signaling effects are transmitted via mitogen-activated protein kinase (MAPK), PI3K (phosphoinositide 3-kinase protein kinase B)/AKT, signal transducer and activator of transcription proteins (STAT), and nuclear factor-κB. The final output of the terminal effector components of these pathways is activation of cytoplasmic and nuclear processes leading to increases in cell proliferation, survival, mobilization and invasive capacity. In addition to its role as an oncogenic driver, increasing evidence implicates MET as a common mechanism of resistance to targeted therapies including EGFR and VEGFR inhibitors. In the present review, we summarize the current knowledge on the role of the HGF-MET signaling pathway in cancer and its therapeutic targeting (HGF activation inhibitors, HGF inhibitors, MET antagonists and selective/nonselective MET kinase inhibitors). Recent advances in understanding the role of this pathway in the resistance to current anticancer strategies used in lung, kidney and pancreatic cancer are discussed.

c-Met as a Target for Personalized Therapy

MET and its ligand HGF are involved in many biological processes, both physiological and pathological, making this signaling pathway an attractive therapeutic target in oncology. Downstream signaling effects are transmitted via mitogen-activated protein kinase (MAPK), PI3K (phosphoinositide 3-kinase protein kinase B)/AKT, signal transducer and activator of transcription proteins (STAT), and nuclear factor-κB. The final output of the terminal effector components of these pathways is activation of cytoplasmic and nuclear processes leading to increases in cell proliferation, survival, mobilization and invasive capacity. In addition to its role as an oncogenic driver, increasing evidence implicates MET as a common mechanism of resistance to targeted therapies including EGFR and VEGFR inhibitors. In the present review, we summarize the current knowledge on the role of the HGF-MET signaling pathway in cancer and its therapeutic targeting (HGF activation inhibitors, HGF inhibitors, MET antagonists and selective/nonselective MET kinase inhibitors). Recent advances in understanding the role of this pathway in the resistance to current anticancer strategies used in lung, kidney and pancreatic cancer are discussed.

The HGF inhibitory peptide HGP-1 displays promising in vitro and in vivo efficacy for targeted cancer therapy

HGF/MET pathway mediates cancer initiation and development. Thus, inhibition on HGF-initiated MET signaling pathway would provide a new approach to cancer targeted therapeutics. In our study, we identified a targeting peptide candidate binding to HGF which was named HGF binding peptide-1 (HGP-1) via bacterial surface display methods coupled with fluorescence-activated cell sorting (FACS). HGP-1 showed the moderate affinity when determined with surface plasmon resonance (SPR) technique and high specificity in binding to HGF while assessed by fluorescence-based ELISA assay. The results from MTT and in vitro migration assay indicated that HGF-dependent cell proliferation and migration could be inhibited by HGP-1. In vivo administration of HGP-1 led to an effective inhibitory effect on tumor growth in A549 tumor xenograft models. Moreover, findings from Western Blots revealed that HGP-1 could down-regulated the phosphorylation levels of MET and ERK1/2 initiated by HGF, which suggested that HGP-1 could disrupt the activation of HGF/MET signaling to influence the cell activity. All the data highlighted the potential of HGP-1 to be a potent inhibitor for HGF/MET signaling.

c-Met identifies a population of matrix metalloproteinase 9-producing monocytes in peritumoural stroma of hepatocellular carcinoma

Macrophages (Mϕ) are prominent components of solid tumours and exhibit distinct phenotypes in different microenvironments. Previously, we found that tumours could alter the normal developmental process of Mϕ to trigger transient activation of monocytes in the peritumoural stroma of human hepatocellular carcinoma (HCC). In the present study, we showed that a fraction of monocytes in the peritumoural stroma, but not in HCC cancer nests, expressed surface c-Met molecules. Monocytes exposed to tumours strongly expressed c-Met proteins with kinetics similar to their activation status, and significant correlations were found between c-Met levels and HLA-DR expression on tumour-infiltrating monocytes. NF-κB-mediated autocrine TNF-α stimulated the expression of c-Met on activated monocytes, and by interacting with its ligand hepatocyte growth factor (HGF), c-Met increased the motility and matrix metalloproteinase (MMP) 9-producing capacity of tumour-associated monocytes. The intensity of c-Met expression on tumour-infiltrating monocytes was associated with high mortality and reduced survival of patients with HCC. Therefore, the expression of c-Met on activated monocytes/Mϕ may represent a novel mechanism by which a tumour actively and precisely regulates the distribution and functions of these cells to facilitate disease progression.

MET in gastric cancer--discarding a 10% cutoff rule

Aims

We aimed to develop a putative predictive biomarker score for future hepatocyte growth factor receptor (MET)‐targeted therapy of gastric cancer (GC).

Methods and results

MET expression and MET amplification were analysed by immunohistochemistry (IHC) and chromogenic in‐situ hybridization (CISH) in 470 GC patients. Immunostaining was documented with the HistoScore. The percentage area of MET‐amplified tumour cell clones was assessed by virtual microscopy. The expression of MET was heterogeneous in primary and metastatic GC. Immunostaining intensity (MET‐IHC 2+/3+) correlated with MET amplification and a positive MET status was defined by a combination of MET‐IHC 2+ or 3+ with MET amplification, or MET‐IHC 3+ without MET amplification. The prognostic significance of the MET status was independent from the percentage area of positive tumour cells (e.g. <10 versus ≥10%). MET‐positive GCs were microsatellite stable and of KRAS/PIK3CA wild‐type. MET‐positive GCs had a very poor prognosis, with a median survival of 5.4 months and a hazard ratio of 2.126.

Conclusions

A combination of immunohistochemistry and CISH is suitable to assess MET status. If MET status is used as a predictive biomarker, prospective studies should pay specific attention to adequate tissue sampling, should ignore cutoff values for tumour areas, may consider the KRAS and PIK3CA genotype as negative predictive markers and should carry out the analysis expeditiously.

Gene of the month: MET

The MET receptor tyrosine kinase and its ligand hepatocyte growth factor/scatter factor (HGF/SF) are potential therapeutic targets in many human malignancies, making this pathway an important focus of molecular and cancer research. MET mutations have been detected in various tumours. In addition, many tumour types demonstrate MET and HGF/SF overexpression and amplification. The MET signal transduction cascade is complex, and manifests in a broad spectrum of mitogenic and morphogenic functions, affecting cell proliferation, migration, differentiation, morphology and survival. Cancer cells commandeer the physiological functions of this signalling axis to facilitate invasion and metastasis. Significant progress has been made in the development of agents that inhibit MET-HGF/SF signalling. In this article, we outline the key features of the MET gene, its protein product and the ligand HGF/SF, to provide an overview of this important signalling pathway and offer a summary of the relevant pathological and clinical directions of research.