Genetic activation of the MET pathway and prognosis of patients with high-risk, radically resected gastric cancer

Ferroptosis regulating lipid peroxidation metabolism in the occurrence and development of gastric cancer

BACKGROUND

Gastric cancer is one of the most common malignant tumors in the world, and its occurrence and development involve complex biological processes. Iron death, as a new cell death mode, has attracted wide attention in recent years. However, the regulatory mechanism of iron death in gastric cancer and its effect on lipid peroxidation metabolism remain unclear.

AIM

To explore the role of iron death in the development of gastric cancer, reveal its relationship with lipid peroxidation, and provide a new theoretical basis for revealing the molecular mechanism of the occurrence and development of gastric cancer.

METHODS

The process of iron death in gastric cancer cells was simulated by cell culture model, and the occurrence of iron death was detected by fluorescence microscopy and flow cytometry. The changes of gene expression related to iron death and lipid peroxidation metabolism were analyzed by high-throughput sequencing technology. In addition, a mouse model of gastric cancer was established, and the role of iron death in vivo was studied by histology and immunohistochemistry, and the level of lipid peroxidation was detected. These methods comprehensively and deeply reveal the regulatory mechanism of iron death on lipid peroxidation metabolism in the occurrence and development of gastric cancer.

RESULTS

Iron death was significantly activated in gastric cancer cells, and at the same time, associated lipid peroxidation levels increased significantly. Through high-throughput sequencing analysis, it was found that iron death regulated the expression of several genes related to lipid metabolism. In vivo experiments demonstrated that increased iron death in gastric cancer mice was accompanied by a significant increase in lipid peroxidation.

CONCLUSION

This study confirmed the important role of iron death in regulating lipid peroxidation metabolism in the occurrence and development of gastric cancer. The activation of iron death significantly increased lipid peroxidation levels, revealing its regulatory mechanism inside the cell.

Expressions and Clinical Significance of Met and YAP in Gastric Cancer Tissue Microarray

Objective

This study is aimed at investigating the expression of Met and YAP in gastric cancer and their impact on clinical prognosis.

Methods

Tissue samples and clinical data were collected from 89 patients with gastric cancer. Immunohistochemistry was performed to quantify the expression of Met and YAP using tissue microarray. The correlation between the expressions of Met, YAP, and clinicopathological characteristics of patients was determined using a chi-square test. Survival analysis was conducted using the Kaplan-Meier method, while multivariate survival analysis was performed using the Cox proportional hazard model. Bioinformatics analysis was carried out by downloading chip data from TCGA.

Results

The expression levels of both Met and YAP were significantly higher in gastric cancer tissues compared to adjacent tissues (P < 0.001). Met expression showed a positive association with P53 and CD133, whereas YAP expression correlated positively with tumor grade and CD133 (P < 0.05). Pearson's analysis revealed a significant correlation between Met expression and VEGFR as well as CD133, while YAP expression correlated with Ki67 and VEGFR (P < 0.05). Patients with high levels of both Met and YAP exhibited decreased survival time (P < 0.01). Furthermore, Met expression, N stage, and VEGFR were identified as independent risk factors for gastric cancer prognosis (P < 0.05), whereas no such association was observed for YAP expression. Bioinformatics analysis demonstrated a significant correlation between the expressions of Met and YAP; both proteins were highly expressed in gastric cancer patients accompanied by markedly reduced survival time.

Conclusion

The expressions of Met and YAP are closely associated with the survival outcomes as well as clinicopathological features in patients with gastric cancer. Moreover, our findings highlight that Met serves as an independent prognostic factor for gastric cancer.

The MET Oncogene: Thirty Years of Insights into Molecular Mechanisms Driving Malignancy

The discovery and subsequent research on the MET oncogene's role in cancer onset and progression have illuminated crucial insights into the molecular mechanisms driving malignancy. The identification of MET as the hepatocyte growth factor (HGF) receptor has paved the path for characterizing the MET tyrosine kinase activation mechanism and its downstream signaling cascade. Over the past thirty years, research has established the importance of HGF/MET signaling in normal cellular processes, such as cell dissociation, migration, proliferation, and cell survival. Notably, genetic alterations that lead to the continuous activation of MET, known as constitutive activation, have been identified as oncogenic drivers in various cancers. The genetic lesions affecting MET, such as exon skipping, gene amplification, and gene rearrangements, provide valuable targets for therapeutic intervention. Moreover, the implications of MET as a resistance mechanism to targeted therapies emphasize the need for combination treatments that include MET inhibitors. The intriguing "flare effect" phenomenon, wherein MET inhibition can lead to post-treatment increases in cancer cell proliferation, underscores the dynamic nature of cancer therapeutics. In human tumors, increased protein expression often occurs without gene amplification. Various mechanisms may cause an overexpression: transcriptional upregulation induced by other oncogenes; environmental factors (such as hypoxia or radiation); or substances produced by the reactive stroma, such as inflammatory cytokines, pro-angiogenic factors, and even HGF itself. In conclusion, the journey to understanding MET's involvement in cancer onset and progression over the past three decades has not only deepened our knowledge, but has also paved the way for innovative therapeutic strategies. Selective pharmacological inactivation of MET stands as a promising avenue for achieving cancer remission, particularly in cases where MET alterations are the primary drivers of malignancy.

Comprehensive Multiomics Analyses Establish the Optimal Prognostic Model for Resectable Gastric Cancer : Prognosis Prediction for Resectable GC

BACKGROUND

Prognostic models based on multiomics data may provide better predictive capability than those established at the single-omics level. Here we aimed to establish a prognostic model for resectable gastric cancer (GC) with multiomics information involving mutational, copy number, transcriptional, methylation, and clinicopathological alterations.

PATIENTS AND METHODS

The mutational, copy number, transcriptional, methylation data of 268, 265, 226, and 252 patients with stages I-III GC were downloaded from the TCGA database, respectively. Alterations from all omics were characterized, and prognostic models were established at the individual omics level and optimized at the multiomics level. All models were validated with a cohort of 99 patients with stages I-III GC.

RESULTS

TTN, TP53, and MUC16 were among the genes with the highest mutational frequency, while UBR5, ZFHX4, PREX2, and ARID1A exhibited the most prominent copy number variations (CNVs). Upregulated COL10A1, CST1, and HOXC10 and downregulated GAST represented the biggest transcriptional alterations. Aberrant methylation of some well-known genes was revealed, including CLDN18, NDRG4, and SDC2. Many alterations were found to predict the patient prognosis by univariate analysis, while four mutant genes, two CNVs, five transcriptionally altered genes, and seven aberrantly methylated genes were identified as independent risk factors in multivariate analysis. Prognostic models at the single-omics level were established with these alterations, and optimized combination of selected alterations with clinicopathological factors was used to establish a final multiomics model. All single-omics models and the final multiomics model were validated by an independent cohort. The optimal area under the curve (AUC) was 0.73, 0.71, 0.71, and 0.85 for mutational, CNV, transcriptional, and methylation models, respectively. The final multiomics model significantly increased the AUC to 0.92 (P < 0.05).

CONCLUSIONS

Multiomics model exhibited significantly better capability in predicting the prognosis of resectable GC than single-omics models.

MET alterations detection platforms and clinical implications in solid tumors: a comprehensive review of literature

MET alterations, including MET exon 14 skipping variants, MET amplification, MET overexpression, and MET fusion, play pivotal roles in primary tumorigenesis and acquired resistance to targeted therapies, especially EGFR tyrosine kinase inhibitors. They represent important diagnostic, prognostic, and predictive biomarkers in many solid tumor types. However, the detection of MET alterations is challenging due to the complexity of MET alterations and the diversity of platform technologies. Therefore, techniques with high sensitivity, specificity, and reliable molecular detection accuracy are needed to overcome such hindrances and aid in biomarker-guided therapies. The current review emphasizes the role of MET alterations as oncogenic drivers in a variety of cancers and their involvement in the development of resistance to targeted therapies. Moreover, our review provides an overview of and recommendations on the selection of various cross-platform technologies for the detection of MET exon 14 skipping variants, MET amplification, MET overexpression, and MET fusion. Furthermore, challenges and hurdles underlying these common detection platforms are discussed.

Chromosomal Instability in Gastric Cancer: Role in Tumor Development, Progression, and Therapy

According to the Cancer Genome Atlas (TCGA), gastric cancers are classified into four molecular subtypes: Epstein-Barr virus-positive (EBV+), tumors with microsatellite instability (MSI), tumors with chromosomal instability (CIN), and genomically stable (GS) tumors. However, the gastric cancer (GC) with chromosomal instability remains insufficiently described and does not have effective markers for molecular and histological verification and diagnosis. The CIN subtype of GC is characterized by chromosomal instability, which is manifested by an increased frequency of aneuploidies and/or structural chromosomal rearrangements in tumor cells. Structural rearrangements in the CIN subtype of GC are not accidental and are commonly detected in chromosomal loci, being abnormal because of specific structural organization. The causes of CIN are still being discussed; however, according to recent data, aberrations in the TP53 gene may cause CIN development or worsen its phenotype. Clinically, patients with the CIN subtype of GC demonstrate poor survival, but receive the maximum benefit from adjuvant chemotherapy. In the review, we consider the molecular mechanisms and possible causes of chromosomal instability in GC, the common rearrangements of chromosomal loci and their impact on the development and clinical course of the disease, as well as the driver genes, their functions, and perspectives on their targeting in the CIN subtype of GC.

An Overview of Current Biomarkers, the Therapeutic Implications, and the Emerging Role of hERG1 Expression in Gastric Cancer: A Literature Review

Gastric cancer remains one of the most commonly diagnosed cancers in the world. It carries a high mortality rate, with cases being more prevalent in the developing world, and has been linked to diet and Helicobacter pylori infection. It is a highly heterogeneous disease, with most cases being of a sporadic nature. Most patients present at an advanced stage due to the asymptomatic nature of the early stages of the disease. A multidisciplinary approach is often best implemented to help decide how to best manage individual cases. However, the overall clinical outcome and survival of patients with advanced gastric cancer remain poor. Recent therapeutic advancements focus on the identification of molecular biomarkers associated with gastric cancer that have predictive, diagnostic, and prognostic implications. This enables the development of specific targeted therapies that have shown efficacy in numerous trials, either as monotherapy or in combination with standard chemotherapy. Despite this, tumour heterogeneity and treatment resistance are still issues leading to poor survival outcomes. An emerging approach is focusing efforts on the bidirectional crosstalk between tumour cells and the microenvironment through targeting ion channels. A key player in this is human ether-á-go-go-related gene 1 (hERG1). This voltage-gated potassium ion channel has been shown to have predictive, diagnostic, and prognostic significance, enabling the stratification of high-risk individuals. In addition, targeting hERG1 in combination with chemotherapy has been shown to potentiate tumour regression. This comprehensive literature review will aim to consolidate our understanding of current biomarkers in gastric cancer. The relevance of hERG1 in gastric cancer as a useful novel biomarker and the potential therapeutic implications as targeted therapy will be explored. This offers a new and personalised approach to helping to manage patients with gastric cancer.

An Observatory for the MET Oncogene: A Guide for Targeted Therapies

The MET proto-oncogene encodes a pivotal tyrosine kinase receptor, binding the hepatocyte growth factor (HGF, also known as scatter factor, SF) and governing essential biological processes such as organogenesis, tissue repair, and angiogenesis. The pleiotropic physiological functions of MET explain its diverse role in cancer progression in a broad range of tumors; genetic/epigenetic alterations of MET drive tumor cell dissemination, metastasis, and acquired resistance to conventional and targeted therapies. Therefore, targeting MET emerged as a promising strategy, and many efforts were devoted to identifying the optimal way of hampering MET signaling. Despite encouraging results, however, the complexity of MET's functions in oncogenesis yields intriguing observations, fostering a humbler stance on our comprehension. This review explores recent discoveries concerning MET alterations in cancer, elucidating their biological repercussions, discussing therapeutic avenues, and outlining future directions. By contextualizing the research question and articulating the study's purpose, this work navigates MET biology's intricacies in cancer, offering a comprehensive perspective.

Targeting MET Amplification: Opportunities and Obstacles in Therapeutic Approaches

The MET gene plays a vital role in cellular proliferation, earning it recognition as a principal oncogene. Therapies that target MET amplification have demonstrated promising results both in preclinical models and in specific clinical cases. A significant obstacle to these therapies is the ability to distinguish between focal amplification and polysomy, a task for which simple MET copy number measurement proves insufficient. To effectively differentiate between the two, it is crucial to utilize comparative measures, including in situ hybridization (ISH) with the centromere or next generation sequencing (NGS) with adjacent genes. Despite the promising potential of MET amplification treatment, the judicious selection of patients is paramount to maximize therapeutic efficacy. The effectiveness of MET inhibitors can fluctuate depending on the extent of MET amplification. Future research must seek to establish the ideal threshold value for MET amplification, identify the most efficacious combination therapies, and innovate new targeted treatments for patients exhibiting MET amplification.

An mTOR feedback loop mediates the 'flare' ('rebound') response to MET tyrosine kinase inhibition

Targeted therapy significantly impairs tumour growth but suffers from limitations, among which the 'flare' ('rebound') effect. Among cancers driven by tyrosine kinase receptors, those relying on alterations of the MET oncogene benefit from treatment by specific inhibitors. Previously, we reported that discontinuation of MET tyrosine kinase receptor inhibition causes 'rebound' activation of the oncogene, with a post-treatment transient hyperphosphorylation phase that culminates into a dramatic increase in cancer cell proliferation. The molecular mechanisms behind the 'MET burst' after treatment cessation are unknown but critically important for patients. Here we identify a positive feedback loop mediated by the AKT/mTOR pathway leading to (a) enhanced MET translation by activating p70S6K and 4EBP1 and (b) MET hyper-phosphorylation by inactivation of the tyrosine-phosphatase PTP1B. The latter effect is due to m-TOR-driven PTP1B phosphorylation of the inhibitory residues Ser⁵⁰ and Ser³⁷⁸. These data provide in vitro evidence for the use of mTOR inhibitors to prevent the 'flare effect' in MET targeted therapy, with potential applicative ramifications for patient clinical management.

MET Amplification as a Resistance Driver to TKI Therapies in Lung Cancer: Clinical Challenges and Opportunities

Targeted therapy has emerged as an important pillar for the standard of care in oncogene-driven non-small cell lung cancer (NSCLC), which significantly improved outcomes of patients whose tumors harbor oncogenic driver mutations. However, tumors eventually develop resistance to targeted drugs, and mechanisms of resistance can be diverse. MET amplification has been proven to be a driver of resistance to tyrosine kinase inhibitor (TKI)-treated advanced NSCLC with its activation of EGFR, ALK, RET, and ROS-1 alterations. The combined therapy of MET-TKIs and EGFR-TKIs has shown outstanding clinical efficacy in EGFR-mutated NSCLC with secondary MET amplification-mediated resistance in a series of clinical trials. In this review, we aimed to clarify the underlying mechanisms of MET amplification-mediated resistance to tyrosine kinase inhibitors, discuss the ways and challenges in the detection and diagnosis of MET amplifications in patients with metastatic NSCLC, and summarize the recently published clinical data as well as ongoing trials of new combination strategies to overcome MET amplification-mediated TKI resistance.

[Research Progress of Acquired Resistance Mediated by MET Amplification in Advanced Non-small Cell Lung Cancer]

Mesenchymal-epithelial transition factor (MET) amplification is an important driver of resistance in epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC), and the combination of MET proto-oncogene (MET) and EGFR-tyrosine kinase inhibitors (TKIs) has shown promise in overcoming this molecularly defined acquired resistance. Emerging data also demonstrate MET amplification as a resistance driver to TKIs-treated anaplastic lymphoma kinase (ALK)-, RET-, and ROS1-fusion NSCLC. Here, we review the literature on recent research progress of MET amplification as a resistance driver to targeted therapy in oncogene-driven NSCLC and summarize the progress of clinical strategies to overcome the resistance mechanism.
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Receptor Tyrosine Kinases Amplified in Diffuse-Type Gastric Carcinoma: Potential Targeted Therapies and Novel Downstream Effectors

Simple Summary

Diffuse-type gastric carcinoma (DGC) is an aggressive subtype of gastric carcinoma with an extremely poor prognosis due to frequent peritoneal metastasis and high probability of recurrence. Its pathogenesis is poorly understood, and consequently, no effective molecular targeted therapy is available. The importance of oncogenic receptor tyrosine kinase (RTK) signaling has been recently demonstrated in the malignant progression of DGC. In particular, RTK gene amplification appears to accelerate peritoneal metastasis. In this review, we provide an overview of RTK gene amplification in DGC and the potential of related targeted therapies.

Abstract

Gastric cancer (GC) is a major cause of cancer-related death worldwide. Patients with an aggressive subtype of GC, known as diffuse-type gastric carcinoma (DGC), have extremely poor prognoses. DGC is characterized by rapid infiltrative growth, massive desmoplastic stroma, frequent peritoneal metastasis, and high probability of recurrence. These clinical features and progression patterns of DGC substantially differ from those of other GC subtypes, suggesting the existence of specific oncogenic signals. The importance of gene amplification and the resulting aberrant activation of receptor tyrosine kinase (RTK) signaling in the malignant progression of DGC is becoming apparent. Here, we review the characteristics of RTK gene amplification in DGC and its importance in peritoneal metastasis. These insights may potentially lead to new targeted therapeutics.

Targeting MET amplification in Gastro-oesophageal (GO) malignancies and overcoming MET inhibitor resistance: challenges and opportunities

INTRODUCTION

MET, the hepatocyte growth factor receptor is amplified in 8% of gastroesophageal (GO) malignancies and associated with poor prognosis. Therapeutic targeting of MET amplification and MET mutations has the potential to improve outcomes for patients with GO cancers (GOC).

AREAS COVERED

The efficacy of MET inhibition (METi) in preclinical studies has yet to translate into meaningful improvements in the treatment paradigm for unselected GOC. MET amplification has been proposed as a superior modality for patient selection; however even if confirmed, frequency and duration of response to METi are limited by rapid activation of primary and secondary resistance pathways. These observations illustrate the challenges inherent in the application of precision oncology predicated on the theory of oncogenic addiction.

EXPERT OPINION

A standardized definition of MET positivity is critical to enhance patient selection. Early successes targeting the METex14 skipping mutation demonstrate the potent therapeutic effects of METi in a clearly molecularly defined cohort. There is robust preclinical rationale and early-phase data supporting exploitation of immune system interaction with MET. Pragmatic investigation of rational therapeutic combinations based on molecular profiling of both primary and metastatic disease sites with sequential circulating tumor DNA analysis can inform successful clinical development of METi agents in GOC.

CircATIC Contributes to Multiple Myeloma Progression via miR-324-5p-Dependent Regulation of HGF

Circular RNA (circRNA) 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase (circATIC; hsa_circ_0058058) was observed to be upregulated in multiple myeloma (MM) by former article. However, the function and exact mechanism of circATIC in MM development remain barely known. CircRNA-microRNA (miRNA)-messenger RNA (mRNA) axis was established through using bioinformatic databases (starbase, Circinteractome, and microT-CDS). Dual-luciferase reporter assay, RNA immunoprecipitation assay, and RNA-pull down assay were utilized to verify the target relationship between microRNA-324-5p (miR-324-5p) and circATIC or hepatocyte growth factor (HGF). CircATIC expression was upregulated in MM patients and cell lines. CircATIC interference notably hampered cell proliferation, migration, invasion, and glycolysis and induced cell apoptosis of MM cells. MiR-324-5p was a target of circATIC. CircATIC silencing-mediated effects in MM cells were largely overturned by the knockdown of miR-324-5p. HGF was a target of miR-324-5p, and circATIC upregulated the expression of HGF partly through sponging miR-324-5p in MM cells. MiR-324-5p suppressed the malignant behaviors of MM cells, which were largely counteracted by the overexpression of HGF in MM cells. CircATIC accelerated the proliferation, migration, invasion, and glycolysis and suppressed the apoptosis of MM cells through mediating miR-324-5p/HGF signaling.

Case Report: Prompt Response to Savolitinib in a Case of Advanced Gastric Cancer With Bone Marrow Invasion and MET Abnormalities

Gastric cancer is one of the most common malignant tumors and patients show a short survival, those combined with bone marrow invasion have a median survival of only 37 days. Here we reported the treatment of a 47-year-old male with advanced gastric cancer and complicated with bone marrow invasion and extensive metastases, who did not tolerate chemotherapy, under monotherapy with savolitinib, a MET receptor tyrosine kinase inhibitor. Before treatment, the patient was in severe pain and presented with thrombocytopenia and hemorrhagic anemia. Savolitinib was given based on amplification and rearrangement of the MET gene in his tumor. After savolitinib treatment, the patient’s condition promptly improved, efficacy evaluation indicated partial remission, and the patient was alive and remained progression-free at 15 weeks at the time of reporting. No obvious adverse reactions occurred. Besides, another case of a female gastric cancer patient with MET amplification who received savolitinib monotherapy as a third-line treatment that remained progression-free at 12 weeks was also reported. This report provides a new reference for understanding MET abnormalities in gastric cancer and offers a possibility for future application of MET tyrosine kinase inhibitors in the therapy of gastric cancer with MET abnormalities. Also, it suggests that sequencing of MET can be considered a routine target in advanced gastric cancer patients.

Molecularly Targeted Therapies for Gastric Cancer. State of the Art

Many phase III trials failed to demonstrate a survival benefit from the addition of molecular therapy to conventional chemotherapy for advanced and metastatic gastric cancer, and only three agents were approved by the FDA. We examined the efficacy and safety of novel drugs recently investigated. PubMed, Embase and Cochrane Library were searched for phase III randomized controlled trials published from January 2016 to December 2020. Patients in the experimental arm received molecular therapy with or without conventional chemotherapy, while those in the control arm had conventional chemotherapy alone. The primary outcomes were overall and progression-free survival. The secondary outcomes were the rate of tumor response, severe adverse effects, and quality of life. Eight studies with a total of 4223 enrolled patients were included. The overall and progression-free survival of molecular and conventional therapy were comparable. Most of these trials did not find a significant difference in tumor response rate and in the number of severe adverse effects and related deaths between the experimental and control arms. The survival benefits of molecular therapies available to date for advanced and metastatic gastric cancer are rather unclear, mostly due to inaccurate patient selection, particularly concerning oncogene amplification and copy number.

The Activity of Crizotinib in Chemo-Refractory MET-Amplified Esophageal and Gastric Adenocarcinomas: Results from the AcSé-Crizotinib Program

Background

The AcSé-crizotinib program provides extensive screening of crizotinib-targeted genomic alteration in several malignancies. We here report the results in patients with esogastric MET-amplified adenocarcinomas.

Objective

The objective of the study was to evaluate the efficacy and tolerability of crizotinib in patients with pretreated esogastric MET-amplified adenocarcinoma who have no alternative treatment options.

Patients and Methods

MET expression was evaluated by fluorescence in situ hybridization in tumor samples with immunohistochemistry scores ≥ 2+. Patients with chemo-refractory tumors showing ≥ 6 MET copies were eligible for crizotinib 250 mg twice daily. The primary efficacy outcome was the objective response rate after two cycles of crizotinib.

Results

MET was prospectively analyzed in 570 esogastric adenocarcinomas. Amplifications were found in 35/570 adenocarcinomas (29/523 gastric and 6/47 esophageal). Nine patients were treated with crizotinib. The objective response rate after two cycles was 33.3% (95% CI 7.5–70), the best overall response rate was 55.6% (95% CI 21.2–86.3), with median progression-free survival of 3.2 months (95% CI 1.0–5.4), and overall survival of 8.1 months (95% CI 1.7–24.6). Safety was consistent with that previously reported for crizotinib.

Conclusions

Large-scale screening for MET-amplified esogastric adenocarcinomas is feasible. MET amplification was observed in 5.5% of gastric and 12.8% of esophageal adenocarcinomas. Crizotinib shows encouraging results in selected patients. Thus, c-MET inhibition for MET-amplified tumors deserves further evaluation.

Trial Registration Number

NCT02034981.

Date of Registration

14 January 2014.

Chromosome X aneusomy and androgen receptor gene copy number aberrations in apocrine carcinoma of the breast

Carcinomas with apocrine differentiation (CAD) of the breast are rare tumours typically presenting high immunohistochemical expression of androgen receptor (AR) which is a target molecule for personalised therapy. To date, no studies have evaluated the genetic changes that are associated with AR immunohistochemical expression in CADs. The present work aims to characterise AR status in CADs. Twenty CAD tumours were studied with immunohistochemistry, in situ fluorescence hybridization and DNA methylation analysis, to evaluate AR expression and its regulator status. All tumours demonstrated high AR immunohistochemical expression, with over 95% of the neoplastic cells showing AR positivity in 19/20 cases. CADs showed AR gene copy loss in a percentage of neoplastic cells ranging from 5 to 84% (mean 48.93%). AR regulator genes, including the MAGE family, UXT and FLNA, presented variable methylation levels, but were mainly hypomethylated and therefore all transcriptionally active. The results of this study indicate that CADs present AR monosomy, paralleled by higher transcriptional activity of the gene with potential to influence response to AR deprivation therapy.

MET deletion is a frequent event in gastric/gastroesophageal junction/esophageal cancer: a cross-sectional analysis of gene status and signal distribution in 1,580 patients

Background

MET gene aberrations are found in several human cancers including gastric, ovarian and lung. In a large multinational cohort of patients with gastric/gastroesophageal junction/esophageal (G/GEJ/E) adenocarcinoma we assessed the MET status with respect to amplification and deletion and correlate the results with the phenotypical gene signal distribution pattern.

Methods

Tissue specimens from 1,580 patients were analyzed using a novel fluorescence in situ hybridization (FISH) assay employing a MET/CEN-7 IQFISH Probe Mix. MET amplification and deletions were defined as a MET/CEN-7 ratio ≥2.0 and a MET/CEN-7 ratio <0.8, respectively. Furthermore, the link between the MET gene status and the phenotypical signal distribution was investigated.

Results

The prevalence of MET amplification and deletions was found to be 7.2% and 8.7%, respectively. Significant differences were observed with regard to geographic regions and sex. The Asian population had the highest percentage of MET amplification (9.4%) and the lowest percentage of deletions (3.2%). MET deletions was found more frequently among males (10.1%) compared to females (5.3%) and in esophagus (17.6%) compared to the stomach (5.7%). More than 50% of the patients who harbored MET gene amplification had a heterogeneous distribution of the FISH signals. Patients with a focal signal distribution were solely to be found among the MET amplified population. MET deletion were mainly observed in the group of patients with a homogenous signal distribution.

Conclusions

The screening data from this cross-sectional study showed that MET deletion and amplification are frequent events in G/GEJ/E cancer, which are linked to different phenotypical signal distribution patterns. The role of MET deletion in relation to tumor development is not fully understood but it is likely to play a role in the oncogenic transformation of the cells.

Revisiting MET: Clinical Characteristics and Treatment Outcomes of Patients with Locally Advanced or Metastatic, MET-Amplified Esophagogastric Cancers

BACKGROUND

Metastatic esophagogastric cancers (EGCs) have a poor prognosis with an approximately 5% 5-year survival. Additional treatment approaches are needed. c-MET gene-amplified tumors are an uncommon but potentially targetable subset of EGC. Clinical characteristics and outcomes were evaluated in patients with MET-amplified EGC and compared with those without MET amplification to facilitate identification of these patients and possible treatment approaches.

PATIENTS AND METHODS

Patients with locally advanced or metastatic MET-amplified EGC at Massachusetts General Hospital (MGH) were identified using fluorescent in situ hybridization analysis, with a gene-to-control ratio of ≥2.2 defined as positive. Non-MET-amplified patients identified during the same time period who had undergone tumor genotyping and treatment at MGH were evaluated as a comparison group.

RESULTS

We identified 233 patients evaluated for MET amplification from 2002 to 2019. MET amplification was seen in 28 (12%) patients versus 205 (88%) patients without amplification. Most MET-amplified tumors occurred in either the distal esophagus (n = 9; 32%) or gastroesophageal junction (n = 10; 36%). Of MET-amplified patients, 16 (57%) had a TP53 mutation, 5(18%) had HER2 co-amplification, 2 (7.0%) had EGFR co-amplification, and 1 (3.5%) had FGFR2 co-amplification. MET-amplified tumors more frequently had poorly differentiated histology (19/28, 68.0% vs. 66/205, 32%; p = .02). Progression-free survival to initial treatment was substantially shorter for all MET-amplified patients (5.6 vs. 8.8 months, p = .026) and for those with metastatic disease at presentation (4.0 vs. 7.6 months, p = .01). Overall, patients with MET amplification had shorter overall survival (19.3 vs. 24.6 months, p = .049). No difference in survival was seen between low MET-amplified tumors (≥2.2 and <25 MET copy number) compared with highly amplified tumors (≥25 MET copy number).

CONCLUSION

MET-amplified EGC represents a distinct clinical entity characterized by rapid progression and short survival. Ideally, the identification of these patients will provide opportunities to participate in clinical trials in an attempt to improve outcomes.

IMPLICATIONS FOR PRACTICE

This article describes 233 patients who received MET amplification testing and reports (a) a positivity rate of 12%, similar to the rate of HER2 positivity in this data set; (b) the clinical characteristics of poorly differentiated tumors and nodal metastases; and (c) markedly shorter progression-free survival and overall survival in MET-amplified tumors. Favorable outcomes are reported for patients treated with MET inhibitors. Given the lack of published data in MET-amplified esophagogastric cancers and the urgent clinical importance of identifying patients with MET amplification for MET-directed therapy, this large series is a valuable addition to the literature and will have an impact on future practice.

Identifying novel genetic alterations in pediatric acute lymphoblastic leukemia based on copy number analysis

Copy number variations (CNVs) analysis may reveal molecular biomarkers and provide information on the pathogenesis of acute lymphoblastic leukemia (ALL). We investigated the gene copy number in childhood ALL by microarray and select three new recurrent CNVs to evaluate by real-time PCR assay: DMBT1, KIAA0125 and PRDM16 were selected due to high frequency of CNVs in ALL samples and based on their potential biological functions in carcinogenesis described in the literature. DBMT1 deletion was associated with patients with chromosomal translocations and is a potential tumor suppressor; KIAA0125 and PRDM16 may act as an oncogene despite having a paradoxical behavior in carcinogenesis. This study reinforces that microarrays/aCGH is it is a powerful tool for detection of genomic aberrations, which may be used in the risk stratification.

A dual MET/AXL small-molecule inhibitor exerts efficacy against gastric carcinoma through killing cancer cells as well as modulating tumor microenvironment

The receptor tyrosine kinases MET and AXL have been implicated in tumorigenesis and aggressiveness of multiple malignancies. We performed this study to evaluate the antitumor impact of LY2801653, a dual MET and AXL inhibitor on gastric cancer and to elucidate the underlying mechanisms. In the present study, tissue microarrays containing gastric cancer tissues were stained with MET and AXL antibodies, which showed the prognostic values of MET and AXL. Administration of LY2801653 inhibited cell proliferation, migration, epithelial‐mesenchymal transition, induced apoptosis, and cell cycle arrest. Xenograft mouse models showed suppressed cell proliferation of tumors in high MET and AXL expression cells. LY2801653 also inhibited the growth of MET and AXL‐independent cells at higher but clinically relevant doses through decreased angiogenesis and M2 macrophages in the tumor microenvironment. In conclusion, our study provides evidence for MET and AXL as prognostic biomarkers and potential therapeutic targets in gastric cancer. The dual MET/AXL inhibitor LY2801653 represents a promising therapeutic strategy for the treatment of patients with gastric carcinoma.

MET-dependent solid tumours - molecular diagnosis and targeted therapy

Attempts to develop MET-targeted therapies have historically focused on MET-expressing cancers, with limited success. Thus, MET expression in the absence of a genomic marker of MET dependence is a poor predictor of benefit from MET-targeted therapy. However, owing to the development of more sensitive methods of detecting genomic alterations, high-level MET amplification and activating MET mutations or fusions are all now known to be drivers of oncogenesis. MET mutations include those affecting the kinase or extracellular domains and those that result in exon 14 skipping. The activity of MET tyrosine kinase inhibitors varies by MET alteration category. The likelihood of benefit from MET-targeted therapies increases with increasing levels of MET amplification, although no consensus exists on the optimal diagnostic cut-off point for MET copy number gains identified using fluorescence in situ hybridization and, in particular, next-generation sequencing. Several agents targeting exon 14 skipping alterations are currently in clinical development, with promising data available from early-phase trials. By contrast, the therapeutic implications of MET fusions remain underexplored. Here we summarize and evaluate the utility of various diagnostic techniques and the roles of different classes of MET-targeted therapies in cancers with MET amplification, mutation and fusion, and MET overexpression.

Tivantinib inhibits the VEGF signaling pathway and induces apoptosis in gastric cancer cells with c-MET or VEGFA amplification

Tivantinib has been described as a selective inhibitor of c-Met and is being studied in various types of cancer. In this study, we evaluated the effects of tivantinib on the suppression of gastric cancer (GC) cell migration and apoptosis. We also examined the mechanism of action of tivantinib by oncogenic pathway analysis. We applied an RNA-sequencing approach in 34 GC patients to identify oncogenes that are differentially expressed in GC tissues. To examine the inhibitory effect of tivantinib on GC cells, we conducted apoptosis analysis using an annexin V-APC/PI apoptosis detection kit and trans-well migration assay with human GC cell lines. For oncogenic pathway analysis, Western blot and quantitative real-time PCR analysis were used to detect the expression of proteins and genes before and after tivantinib exposure. In the RNA-sequencing analysis of 34 GC patients, c-Met and VEGFA genes were expressed and positively correlated with each other. Cell migration and apoptosis analysis demonstrated that tivantinib induced the best inhibition effect in SNU620, MKN45 (carries VEGFB mutation), AGS, and MKN28 cells, but not in KATO III (carries VEGFB and VEGFC mutations) cells. Oncogenic pathway analysis showed that tivantinib, in addition to c-Met signaling pathway inhibition, also inhibits VEGF signaling and MYC expression in VEGFA-expressing GC cells. We found that tivantinib has anti-cancer activity not only in GC cells overexpressing c-Met but also in non-c-Met GC cells by inhibition of the VEGF signaling pathway.

Real-World Outcomes and Factors Associated With the Second-Line Treatment of Patients With Gastric, Gastroesophageal Junction, or Esophageal Adenocarcinoma

This retrospective observational study was designed to evaluate overall survival in a real-world patient population and to identify predictive factors associated with receipt of second-line therapy. A retrospective analysis of electronic medical records (Flatiron Health, New York) was conducted among patients initiating first-line therapy from January 1, 2013, through April 30, 2018. Eligible patients were diagnosed with advanced gastric, gastroesophageal junction, or esophageal adenocarcinoma and ≥18 years of age at the time of treatment initiation. Patients alive 45 days after discontinuation of first-line therapy were considered potentially eligible for continued therapy and were categorized into those who received and those who did not receive second-line therapy. Survival analyses were conducted using Kaplan-Meier method and log-rank test without adjusting for any baseline covariates. Factors associated with further treatment were evaluated using logistic regression. A total of 3850 patients met eligibility criteria. Among the 2516 patients available to receive second-line therapy, 1515 (60.2%) received second-line therapy and 1001 (39.8%) did not receive further therapy. Among those potentially eligible to receive second-line therapy, median survival was 15.4 months (95% confidence interval [CI]: 14.6-16.0) from initiation of first-line therapy for those who received second-line therapy and 10.0 months (95% CI: 9.3-10.7) for those who did not. Longer duration of first-line therapy (≥169 vs ≤84 days), HER2-positive tumors, initially diagnosed with stage IV disease, less weight loss during first-line therapy, and younger age were associated with receipt of second-line therapy (all P < .001). Longer survival was associated with multiple lines of therapy; however, these results should be interpreted with caution, and no causal relationship can be inferred.

Clinical significance of MET gene amplification in metastatic or locally advanced gastric cancer treated with first-line fluoropyrimidine and platinum combination chemotherapy

Objective

To investigate the clinical significance of MET gene amplification in patients with gastric cancer in the palliative setting.

Methods

MET amplification was assessed using fluorescence in situ hybridization (FISH) in 50 patients and quantitative polymerase chain reaction (qPCR) in 326 patients; 259 patients treated with first-line fluoropyrimidine and platinum were included for survival analysis.

Results

The results of FISH and qPCR indicated that the c-MET/CEP7 ratio was correlated with gene copy number. The optimal cutoff value for the copy number using qPCR to detect MET gene amplification with FISH was 5 (κ=0.778, P<0.001). Twenty-one out of 326 patients (6.4%) were identified asMET amplification with a copy number of >5 detected by qPCR. MET-amplified gastric cancer was associated with an Eastern Cooperative Oncology Group (ECOG) performance status (PS) score of ≥2 (33.3% vs. 10.5% P=0.007), peritoneal metastasis (76.2% vs. 46.2%, P=0.008), and elevated bilirubin levels (28.6% vs. 7.3%, P=0.006). The median overall survival (OS) and progression-free survival (PFS) were 11.9 and 5.6 months, respectively. MET-amplified gastric cancer was not associated with survival outcomes [hazard ratio (HR)=0.68, 95% confidence interval (95% CI): 0.35−1.32, P=0.254 for PFS; HR=0.68, 95% CI: 0.35−1.32, P=0.251 for OS].

Conclusions

qPCR can be used to detect MET gene amplification. MET amplification was not a predictor of poor prognosis in patients with metastatic or unresectable gastric cancer.

Downregulation of lncRNA UCA1 facilitates apoptosis and reduces proliferation in multiple myeloma via regulation of the miR-1271-5p/HGF axis

BACKGROUND

Long noncoding RNAs (lncRNAs) are considered to be a novel prognostic and therapeutic target in many cancers. This study identified dysregulation of lncRNA urothelial carcinoma associated 1 (UCA1) and hepatocyte growth factor (HGF) mRNA via the Gene Expression Omnibus (GEO) database, which was traced to the mutual target miRNA, miR-1271-5p, and their effects were explored in multiple myeloma (MM).

METHODS

RNA expression profiles of MM were downloaded from the GEO database and analyzed using R packages. The expression of RNAs in MM tissue samples and cells was evaluated through quantificational real-time polymerase chain reaction (qRT-PCR). A luciferase reporter assay was utilized to confirm the binding relationships between UCA1/HGF and miR-1271-5p. To assess cell proliferation and apoptosis, CCK-8 assays and flow cytometry were conducted. Additionally, tumor progression was demonstrated in vivo.

RESULTS

LncRNA UCA1 and HGF expression was higher in the cells and samples of patients with MM than in normal plasma cells. miR-1271-5p was confirmed to be the target of lncRNA UCA1 and HGF and to be negatively correlated with them. Moreover, downregulation of lncRNA UCA1 and HGF inhibited cell proliferation and facilitated cell apoptosis in RPMI 8226 cells (human MM cell line). However, miR-1271-5p overexpression affected the proliferation decrease and apoptosis increase. Moreover, in vivo experiments indicated that down or upregulation of lncRNA UCA1 repressed or enhanced the tumor growth of MM, respectively, in xenograft models.

CONCLUSION

LncRNA UCA1 promoted proliferation and inhibited apoptosis by regulating miR-1271-5p and HGF in the human MM cell line RPMI 8226. Our investigations might contribute to a better understanding of the lncRNA UCA1/miR-1271-5p/HGF axis as a potential therapeutic strategy in MM.

Identification of HGF as a novel target of miR-15a/16/195 in gastric cancer

Background Gastric malignancy is the third most frequently encountered cancer globally and have been documented to confer extremely poor prognosis, given their limited treatment options. The up-regulation of hepatocyte growth factor (HGF) has been found in various tumor tissues, including GC tissue, and has been linked with tumor development. Nevertheless, the pathways leading to HGF upregulation have yet to be fully explored. Methods Immunohistochemistry (IHC) assay was used to detect HGF expression in human gastric tumor tissues, while western blotting allowed quantification of protein levels. Bioinformatics tools were used to predict potential miRNA that may target HGF mRNA. Relative levels of miR-15a/16/195 as well as the target mRNA levels were analyzed with qRT-PCR. Direct targeting between miRNA and mRNA was then validated by luciferase assay. Finally, a mouse xenograft tumor model was selected to demonstrate the in vivo effects of miR-15a/16/195. Results HGF protein expressions were markedly raised, while miR-15a/16/195 levels were dramatically down-regulated in tumor tissues of GC. miR-15a/16/195 were shown to directly bind with the 3'-UTR of HGF mRNA. This study demonstrated that HGF can be repressed by overexpressed miR-15a/16/195, which resulted in the suppression of GC cell proliferation and migration. Furthermore, in the xenograft mouse model, miR-15a/16/195 were also found to have a tumor growth suppression effect. Conclusions miR-15a/16/195 suppresses tumorigenesis by targeting HGF and may have a potential therapeutic application in the clinical treatment of GC.

New drug developments in metastatic gastric cancer

Metastatic gastric cancer is associated with a poor prognosis and novel treatment options are desperately needed. The development of targeted therapies heralded a new era for the management of metastatic gastric cancer, however results from clinical trials of numerous targeted agents have been mixed. The advent of immune checkpoint inhibitors has yielded similar promise and results from early trials are encouraging. This review provides an overview of the systemic treatment options evaluated in metastatic gastric cancer, with a focus on recent evidence from clinical trials for targeted therapies and immune checkpoint inhibitors. The failure to identify appropriate predictive biomarkers has hampered the success of many targeted therapies in gastric cancer, and a deeper understanding of specific molecular subtypes and genomic alterations may allow for more precision in the application of novel therapies. Identifying appropriate biomarkers for patient selection is essential for future clinical trials, for the most effective use of novel agents and in combination approaches to account for growing complexity of treatment options.

[Metastatic stomach cancer: Clinical trials in Asia and in Occident]

Although cytotoxic chemotherapy is the main therapeutic option to treat gastric cancer in the metastatic setting, molecular targeted agents have recently been introduced in an effort to improve survival outcomes which in average do not exceed 1 year. Trastuzumab and ramucirumab, antibodies directed against HER2 and VEGFR2, respectively, may provide clinical benefit for some patients. Results of clinical studies show that Asian patients have increased survival compared to Caucasian patients. Differences between populations, and in particular the presence of polymorphisms capable of influencing the availability of fluorouracil, have been suggested as possible explanations. Other factors including histology, surgical procedures, administration of neoadjuvant chemotherapy in Western countries and screening programs in Asia have also been suggested. However, none of these elements can fully explain this phenomenon. The aim of this article is to present the main protocols used in clinical practice, the perspectives of metastatic gastric cancer treatment and the particularities observed in Asian and Caucasian patients.

Evaluation of GWAS-Identified Genetic Variants for Gastric Cancer Survival

BACKGROUNDS

Genome-wide association studies (GWASs) have identified several gastric cancer (GC) susceptibility loci in Asians, but their effects on disease outcome are still unknown. This study aimed to investigate whether these GWAS-identified genetic variants could serve as robust prognostic biomarkers for GC.

METHODS

A multistage clinical cohort, including a total of 2432 GC patients in the Chinese population, was used to identify the association between GWAS-identified risk variants and overall survival of GC. Hazard ratios (HRs) and 95% confidence intervals (CIs) were computed by Cox regression analysis, and the log-rank P was calculated by the log-rank test with the Kaplan-Meier method.

RESULTS

We found that rs2274223 A>G in PLCE1 was associated with increased GC survival in both training set (P = .011), which was independently replicated in validation set 1 (P = .045), but not in validation set 2. The area under the curve (AUC) from receiver-operator characteristic (ROC) curve showed this clinical relevance with onset age-dependence, especially in the subgroup of early-onset cases. Moreover, a significant improvement in overall survival prediction was identified when the rs2274223 genetic effect was included in the estimation; this result was also supported by the prognostic nomogram. In addition, patients with lower expression of PLCE1 showed benefits via longer survival, potentially due to the functional effect of rs2274223.

INTERPRETATION

This preliminary study suggests that a GWAS-identified genetic variant in PLCE1 may serve as a potential biomarker for GC survival. Additional replication with larger samples size is warranted to further investigation.

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.

Discontinuous Schedule of Bevacizumab in Colorectal Cancer Induces Accelerated Tumor Growth and Phenotypic Changes

Antiangiogenics administration in colorectal cancer patients seemed promising therapeutic approach. Inspite of early encouraging results, it however gave only modest clinical benefits. When AAG was administered with discontinuous schedule, the disease showed acceleration in certain cases. Though resistance to AAG has been extensively studied, it is not documented for discontinuous schedules. To simulate clinical situations, we subjected a patient-derived CRC subcutaneous xenograft in mice to three different protocols: 1) AAG (bevacizumab) treatment for 30 days (group A) (group B was the control), 2) bevacizumab treatment for 50 days (group C) and bevacizumab for 30 days and 20 without treatment (group D), and 3) bevacizumab treatment for 70 days (group E) and 70 days treatment with a drug-break period between day 30 and 50 (group F). The tumor growth was monitored, and at sacrifice, the vascularity of tumors was measured and the proangiogenic factors quantified. Tumor phenotype was studied by quantifying cancer stem cells. Interrupting bevacizumab during treatment accelerated tumor growth and revascularization. A significant increase of proangiogenic factors was observed when therapy was stopped. On withdrawal of bevacizumab, as also after the drug-break period, the plasmatic VEGF increased significantly. Similarly, a notable increase of CSCs after the withdrawal and drug-break period of bevacizumab was observed (P<.01). The present study indicates that bevacizumab treatment needs to be maintained because discontinuous schedules tend to trigger tumor regrowth, and increase tumor resistance and CSC heterogeneity.

Biomarker-driven targeted therapies for gastric/gastro-esophageal junction malignancies

Gastroesophageal malignancies often contain high amounts of genetic and molecular alterations that result in an aggressive disease capable of rapidly metastasizing to distant organs and early development of drug resistance. Most patients in the Western hemisphere present with locally advanced or metastatic disease that is treated with systemic chemotherapy used either in the neoadjuvant or palliative setting, respectively. This article will review the various recent advances in the development of targeted therapies for the treatment of advanced gastric and gastroesophageal cancer.

Bright-field in situ hybridization detects gene alterations and viral infections useful for personalized management of cancer patients

INTRODUCTION

Bright-field in situ hybridization (ISH) methods detect gene alterations that may improve diagnostic precision and personalized management of cancer patients. Areas covered: This review focuses on some bright-field ISH techniques for detection of gene amplification or viral infection that have already been introduced in tumor pathology, research and diagnostic practice. Other emerging ISH methods, for the detection of translocation, mRNA and microRNA have recently been developed and need both an optimization and analytical validation. The review also deals with their clinical applications and implications on the management of cancer patients. Expert commentary: The technology of bright-field ISH applications has advanced significantly in the last decade. For example, an automated dual-color assay was developed as a clinical test for selecting cancer patients that are candidates for personalized therapy. Recently an emerging bright-field gene-protein assay has been developed. This method simultaneously detects the protein, gene and centromeric targets in the context of tissue morphology, and might be useful in assessing the HER2 status particularly in equivocal cases or samples with heterogeneous tumors. The application of bright-field ISH methods has become the gold standard for the detection of tumor-associated viral infection as diagnostic or prognostic factors.

MET overexpression, gene amplification and relevant clinicopathological features in gastric adenocarcinoma

This study was conducted to investigate the expression of MET in Chinese gastric adenocarcinoma cohort, the correlation between MET overexpression and clinical pathological features, HER2 expression and MET gene amplification. A total of 816 gastric adenocarcinoma patients were included and MET and HER2 immunohistochemical (IHC) staining were performed. IHC and dual-color silver in situ hybridization analysis were performed in the tissue microarrays, constructed from the 240 patients who were randomly selected. MET overexpression (IHC 3+) was observed in 6.0% (49/816) of the cohort. MET overexpression rate was higher in patients with poor prognostic factors, such as clinical stages III/IV (p =0.012) and pathologic stages T3/T4 (p =0.027). The HER2 overexpression (IHC 3+) rate was 8.8% (72/816) and MET overexpression rate was higher in HER2 positive patients (9.7%, 7/72). A high concordance rate (94.6%) between MET overexpression and gene amplification was demonstrated. Therefore, MET overexpression could serve as a prognostic biomarker and a potential therapeutic target for gastric cancer.

A Phase 1/1b tolerability study of rilotumumab alone or in combination with cisplatin and capecitabine in Japanese patients with gastric cancer

Objective

To evaluate the safety (including adverse events and dose-limiting toxicities [DLTs]), tolerability, pharmacokinetics and antitumor activity of the investigational MET inhibitor rilotumumab alone in patients with advanced solid tumors (Part 1) or in combination with cisplatin plus capecitabine (CX) in patients with MET-positive advanced gastric or gastroesophageal junction cancer (Part 2).

Methods

Adult patients received 10 or 20 mg/kg intravenous (IV) rilotumumab every 2 weeks (Part 1) or 15 mg/kg IV rilotumumab every 3 weeks plus 80 mg/m2 cisplatin on Day 1 and 1000 mg/m2 capecitabine twice daily on Days 1-14 of every 21-day cycle (Part 2).

Results

Nine patients enrolled in Part 1; 12 patients enrolled in Part 2. One DLT occurred (Grade 3 decreased appetite and stomatitis [Part 2]). Adverse events related to any treatment occurred in 17 patients (81%) and were Grade ≥3 in nine patients (43%). Rilotumumab pharmacokinetics appeared linear, and exposure was unaffected by CX. No patient who received rilotumumab monotherapy in Part 1 had a response. In Part 2, five of eight patients (63%) with measureable disease at baseline had a partial response and two patients (25%) had stable disease; median (95% CI) progression-free survival was 7.0 (2.4-15.4) months; overall survival was 18.2 (5.6-20.4) months.

Conclusions

In combination with CX, rilotumumab appeared tolerable and showed antitumor activity in Japanese patients with MET-positive gastric/gastroesophageal junction cancer. However, owing to the results of recent Phase 3 trials of MET inhibitors (including rilotumumab), further development of rilotumumab in this setting is not being pursued. ClinicalTrials.gov Identifier: NCT01791374.

Detection of MET amplification in gastroesophageal tumor specimens using IQFISH

Background

The gene mesenchymal epithelial transition factor (MET) is a proto-oncogene that encodes a transmembrane receptor with intrinsic tyrosine kinase activity known as Met or cMet. MET is found to be amplified in several human cancers including gastroesophageal cancer.

Methods

Here we report the MET amplification prevalence data from 159 consecutive tumor specimens from patients with gastric (G), gastroesophageal junction (GEJ) and esophageal (E) adenocarcinoma, using a novel fluorescence in situ hybridization (FISH) assay, MET/CEN-7 IQFISH Probe Mix [an investigational use only (IUO) assay]. MET amplification was defined as a MET/CEN-7 ratio ≥2.0. Furthermore, the link between the MET signal distribution and amplification status was investigated.

Results

The prevalence of MET amplification was found to be 6.9%. The FISH assay demonstrated a high inter-observer reproducibility. The inter-observer results showed a 100% overall agreement with respect to the MET status (amplified/non-amplified). The inter-observer CV was estimated to 11.8% (95% CI: 10.2-13.4). For the signal distribution, the inter-observer agreement was reported to be 98.7%. We also report an association of MET amplification and a unique signal distribution pattern in the G/GEJ/E tumor specimens. We found that the prevalence of MET amplification was markedly higher in tumors specimens with a heterogeneous (66.7%) versus homogeneous (2.0%) signal distribution. Furthermore, specimens with a heterogeneous signal distribution had a statically significantly higher median MET/CEN-7 ratio (2.35 versus 1.04; P<0.0001).

Conclusions

The novel FISH assay showed a high inter-observer reproducibility both with respect to amplification status and signal distribution. Based on the finding in the study it is suggested that MET amplification mainly is associated with tumor cells that is represented by a heterogonous growth pattern.

Roles of Fibroblast Activation Protein and Hepatocyte Growth Factor Expressions in Angiogenesis and Metastasis of Gastric Cancer

This study aims to explore the roles of fibroblast activation protein (FAP) and hepatocyte growth factor (HGF) expressions in the angiogenesis and metastasis of gastric cancer (GC). From May 2012 to December 2015, 110 GC patients who received surgical treatment in the First Hospital of Qinhuangdao were selected. The HGF and FAP expressions in 110 cases of GC, 130 cases of normal gastric mucosa and 115 cases of gastric ulcer were detected by streptavidin-perosidase (SP) method. Venous blood HGF level of GC patients was tested by enzyme-linked immunosorbent assay (ELISA). The micro-vessel number of the patients in the three groups were calculated and analyzed. In GC group, positive expression rates of FAP and HGF protein were 61.8% and 67.3% respectively, which were both higher than those in normal gastric mucosa and gastric ulcer groups. The micro-vessel numbers in patients of the normal gastric mucosa and gastric ulcer groups are far less than that in GC group. FAP, HGF and micro-vessel density (MVD) were significantly correlated with infiltration depth, tumor-node-metastasis (TNM) staging, lymph node metastasis (LNM) and distant metastasis. The results of ELISA showed that serum HGF level was related to tumor size, infiltration degree, TNM staging, LNM and distant metastasis. FAP and HGF expressions in GC were positively correlated with MVD, and the expressions of FAP and HGF in GC were in positive correlation. Our study provided evidence that high FAP and HGF expressions may be positively correlated with the angiogenesis and metastasis of GC.

P-REX1 amplification promotes progression of cutaneous melanoma via the PAK1/P38/MMP-2 pathway

P-REX1 (PIP3-dependent Rac exchange factor-1) is a guanine nucleotide exchange factor that activates Rac by catalyzing exchange of GDP for GTP bound to Rac. Aberrant up-regulation of P-REX1 expression has a role in metastasis however, copy number (CN) and function of P-REX1 in cutaneous melanoma are unclear. To explore the role of P-REX1 in melanoma, SNP 6.0 and Exon 1.0 ST microarrays were assessed. There was a higher CN (2.82-fold change) of P-REX1 in melanoma cells than in melanocytes, and P-REX1 expression was significantly correlated with P-REX1 CN. When P-REX1 was knocked down in cells by P-REX1 shRNA, proliferation, colony formation, 3D matrigel growth, and migration/invasiveness were inhibited. Loss of P-REX1 inhibited cell proliferation by inhibiting cyclin D1, blocking cell cycle, and increased cell apoptosis by reducing expression of the protein survivin. Knockdown of P-REX1 expression inhibited cell migration/invasiveness by disrupting P-REX1/RAC1/PAK1/p38/MMP-2 pathway. Assessment of patient tumors and disease outcome demonstrated lower distant metastasis-free survival among AJCC stage I/II/III patients with high P-REX1 expression compared to patients with low P-REX1 expression. These results suggest P-REX1 plays an important role in tumor progression and a potential theranostic target.

Second-line treatments: moving towards an opportunity to improve survival in advanced gastric cancer?

Gastric cancer is the third leading cause of cancer-related death globally with approximately 723 000 deaths every year. Most patients present with advanced unresectable or metastatic disease, only amenable to palliative systemic treatment and a median survival uncommonly exceeding 12 months. Over the last years, the efficacy of chemotherapy combination has plateaued and the introduction of the anti-human epidermal growth factor receptor 2 trastuzumab has resulted in a limited survival gain in the upfront setting. After this positive experience, first-line treatment with new targeted therapies failed to improve the outcome of advanced gastric cancer. On the contrary, second-line options, including monochemotherapy with taxanes or irinotecan and the anti-vascular endothelial growth factor receptor 2 ramucirumab, either alone or combined with paclitaxel, opened new therapeutic rooms for an ever-increasing number of patients who maintain an acceptable performance status across multiple lines. This article provides an updated overview on the current management of advanced gastric cancer and discusses how the different treatment options available may be best combined to favourably impact the outcome of patients following the logic of a treatment strategy.

Pathogenesis of Gastric Cancer: Genetics and Molecular Classification

Gastric cancer is the fifth most incident and the third most common cause of cancer-related death in the world. Infection with Helicobacter pylori is the major risk factor for this disease. Gastric cancer is the final outcome of a cascade of events that takes decades to occur and results from the accumulation of multiple genetic and epigenetic alterations. These changes are crucial for tumor cells to expedite and sustain the array of pathways involved in the cancer development, such as cell cycle, DNA repair, metabolism, cell-to-cell and cell-to-matrix interactions, apoptosis, angiogenesis, and immune surveillance. Comprehensive molecular analyses of gastric cancer have disclosed the complex heterogeneity of this disease. In particular, these analyses have confirmed that Epstein-Barr virus (EBV)-positive gastric cancer is a distinct entity. The identification of gastric cancer subtypes characterized by recognizable molecular profiles may pave the way for a more personalized clinical management and to the identification of novel therapeutic targets and biomarkers for screening, prognosis, prediction of response to treatment, and monitoring of gastric cancer progression.

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.

Autophagy is required for crizotinib-induced apoptosis in MET-amplified gastric cancer cells

MET amplification has been clinically credentialed as a therapeutic target in gastric cancer, but the molecular mechanisms underlying sensitivity and resistance to MET inhibitors are still not well understood. Using whole-genome mRNA expression profiling, we identified autophagy as a top molecular pathway that was activated by the MET inhibitor crizotinib in drug-sensitive human gastric cancer cells, and functional studies confirmed that crizotinib increased autophagy levels in the drug-sensitive cells in a concentration-dependent manner. We then used chemical and molecular approaches to inhibit autophagy in order to define its role in cell death. The clinically available inhibitor of autophagy, chloroquine, or RNAi-mediated knockdown of two obligate components of the autophagy pathway (ATG5 and ATG7) blocked cell death induced by crizotinib or RNAi-mediated knockdown of MET, and mechanistic studies localized the effects of autophagy to cytochrome c release from the mitochondria. Overall, the data reveal a novel relationship between autophagy and apoptosis in gastric cancer cells exposed to MET inhibitors. The observations suggest that autophagy inhibitors should not be used to enhance the effects of MET inhibitors in gastric cancer patients.

The gene copy number of c-MET has a significant impact on progression-free survival in Korean patients with ovarian carcinoma

The aim of this study was to compare the protein overexpression and gene copy number (GCN) of c-MET in ovarian carcinoma and to assess their prognostic roles in Korean women. MET protein expression and GCN status were determined using immunohistochemistry (IHC) and silver in situ hybridization, respectively, in 105 ovarian carcinomas comprising 63 serous, 12 mucinous, 20 clear cell, and 10 endometrioid carcinomas. All cases had been treated and followed up at a single institute in Seoul, Korea. MET protein overexpression was observed in 35 of 105 (33.3%) ovarian carcinomas, with IHC 2+ in 27 and IHC 3+ in 8. The overexpression rates of serous, mucinous, clear cell, and endometrioid carcinomas were 14.3%, 83.3%, 65.0%, and 30.0%, respectively. MET protein overexpression was significant in mucinous carcinoma (P < .001) and was correlated with better progression-free survival (PFS) (P = .028). High polysomy (HP) of chromosome 7 and gene amplification (GA) were found in 10 (9.5%) and 2 (1.9%) of the 105 ovarian carcinomas, respectively. Eleven of 12 cases were high-grade serous carcinomas. The remaining case was clear cell carcinoma. HP and GA were associated with a poor PFS (P = .001). There was no significant correlation between a high level of protein expression and increased GCN of MET (r = -0.127, P = .197). In Korean women, HP and GA of MET were significantly correlated with a poor PFS. MET GCN may serve as a biomarker for poor prognosis in patients with ovarian carcinoma.