6504 ORAL Safety and Efficacy of Epirubicin, Cisplatin, and Capecitabine (ECX) Plus Rilotumumab (R) as First-line Treatment for Unresectable Locally Advanced (LA) or Metastatic (M) Gastric or Esophagogastric Junction (EGJ) Adenocarcinoma

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.

How prognostic and predictive biomarkers are transforming our understanding and management of advanced gastric cancer

BACKGROUND

Gastric cancer (GC) is the second leading cause of cancer death worldwide. GC is a heterogeneous disease in terms of histology, anatomy, and epidemiology. There is also wide variability in how GC is treated in both the resectable and unresectable settings. Identification of prognostic and predictive biomarkers is critical to help direct and tailor therapy for this deadly disease.

METHODS

A literature search was done using Medline and MeSH terms for GC and predictive biomarkers and prognostic biomarkers. The search was limited to human subjects and the English language. There was no limit on dates. Published data and unpublished abstracts with clinical relevance were included.

RESULTS

Many potential prognostic and predictive biomarkers have been assessed for GC, some of which are becoming practice changing. This review is focused on clinically relevant biomarkers, including EGFR, HER2, various markers of angiogenesis, proto-oncogene MET, and the mammalian target of rapamycin.

CONCLUSION

GC is a deadly and heterogeneous disease for which biomarkers are beginning to change our understanding of prognosis and management. The recognition of predictive biomarkers, such as HER2 and vascular endothelial growth factor, has been an exciting development in the management of GC, validating the use of targeted drugs trastuzumab and ramucirumab. MET is another potential predictive marker that may be targeted in GC with drugs such as rilotumumab, foretinib, and crizotinib. Further identification and validation of prognostic and predictive biomarkers has the potential transform how this deadly disease is managed.

Met, IGF1R, and other new targets in upper GI malignancies

OPINION STATEMENT

Upper gastrointestinal (GI) malignancies comprise some of the most aggressive human cancers. Expanding knowledge of molecular mechanisms is finally translating into clinical application, and this has occurred at a relatively rapid rate in the past several years. However, despite recent advances in targeted therapies in upper GI cancers our overall success with targeted therapeutics in this disease area remains dismal. This statement is particularly troubling given some sobering facts: upper GI malignancies are prevalent as well as aggressive with a high morbidity and mortality. Esophagus and gastric cancer combined have an annual global incidence of over 1.2 million new cases annually while median survival is less than 1 year for most patients with metastatic disease. Progress has been limited due to several factors including: disease heterogeneity and variance of phenotype across the globe, clinical trial design strategies that have not yet incorporated selective mechanisms to afford individualized matching of drug to tumor molecular profile and last, a lack of validated predictive markers. Nevertheless there is evidence that many targeted agents can be administered safely at doses that achieve the required effect at the protein level. Several drugs that have negative early trial results can be potentially vital therapeutic agents if patient selection is appropriate.

MET overexpression assessed by new interpretation method predicts gene amplification and poor survival in advanced gastric carcinomas

The establishment of better selection criteria for identifying sub-populations that may benefit from treatment is a key aspect of the development and success of targeted therapy. To investigate methods for assessing MET overexpression in gastric cancer, we conducted immunohistochemistry using a new anti-Total MET monoclonal antibody in a single-institution cohort of 495 patients. As antibody is directed against a membranous and/or cytoplasmic epitope, two interpretation methods were used: (1) membranous and cytoplasmic and (2) membranous alone. In selected 120 cases, copy number gain and mRNA expression levels were measured using quantitative real-time PCR. Further in situ hybridization confirmed the presence of MET gene amplification. Among the 495 gastric cancers, simultaneous membranous and cytoplasmic overexpression of MET was found in 108 cases (21.8%) and membranous alone overexpression was observed in 40 cases (8.1%). The highest correlation was observed in membranous and cytoplasmic staining of MET: MET expression scores correlated significantly with high MET mRNA levels (r=0.465, P<0.0001), increased copy number gain (r=0.393, P=0.000002) and amplification of MET gene. Moreover, patients with MET overexpression showed shorter overall survival (HR, 1.781; 95% CI, 1.324-2.395; P<0.001) and disease-free survival (HR, 1.765; 95% CI, 1.227-2.541; P=0.002) compared with patients without MET overexpression. However, membranous overexpression of MET did not highly correlate with mRNA level (r=0.274, P=0.002), copy number gain or survival (P>0.05). We developed highly correlating interpretation methods of MET immunohistochemistry in gastric carcinomas. MET overexpression is an independent prognostic factor and could be a potential target and predictor of benefit for targeted therapy with MET inhibitors.

cMET as a potential therapeutic target in gastric cancer (Review)

Gastric cancer is one of the most common malignancies worldwide. Despite improvements in surgery and chemotherapy, the outcomes in patients with advanced gastric cancer remain poor. cMET is a member of the receptor tyrosine kinase family, and plays a key role in tumor survival, growth, angiogenesis and metastasis. cMET overexpression and/or gene amplification occurs in a significant proportion of gastric cancers. cMET is associated with a high tumor stage and poor prognosis. Several cMET inhibitors have been investigated in clinical trials, and the initial results are encouraging. It has become increasingly apparent that cMET is a promising therapeutic target in gastric cancer. In this review, we summarize the development of cMET inhibitors in the preclinical and clinical environment. In addition, we discuss the challenges of cMET-targeted therapy in gastric cancer and explore possible solutions.

The emerging role of MET/HGF inhibitors in oncology

The N-methyl-N'-nitroso-guanidine human osteosarcoma transforming gene (MET) receptor tyrosine kinase and its ligand hepatocyte growth factor (HGF) control cellular signaling cascades that direct cell growth, proliferation, survival, and motility. Aberrant MET/HGF activation has been observed in many tumor types, can occur by multiple mechanisms, and promotes cellular proliferation and metastasis via growth factor receptors and other oncogenic receptor pathways. Thus, MET/HGF inhibition has emerged as targeted anticancer therapies. Preclinically, neoplastic and metastatic phenotypes of several tumor cells, including non-small cell lung cancer, hepatocellular carcinoma, and gastric cancer, were abrogated by MET inhibition. Ongoing clinical development with tivantinib, cabozantinib, onartuzumab, crizotinib, rilotumumab, and ficlatuzumab has shown encouraging results. These trials have established a key role for MET in a variety of tumor types. Evidence is emerging for identification of aberrant MET activity biomarkers and selection of patient subpopulations that may benefit from targeted MET and HGF inhibitor treatment.

Seminars in clinical pharmacology: an introduction to MET inhibitors for the medical oncologist

MET is a tyrosine kinase receptor for hepatocyte growth factor (HGF), primarily expressed on epithelial cells; the activation of MET induces several biological responses relevant for the development and growth of many human cancers. Several human malignancies present altered expression of MET and this is usually associated with poor prognosis and aggressive phenotype. The majority of MET inhibitors in clinical development target directly the receptor through the use of monoclonal antibodies (MAbs) or through small molecule inhibitors of MET kinase activity; small molecule inhibitors are very potent but less specific than MAbs. MET inhibitors are of great clinical interest because of the extensive crosstalk of the HGF/MET axis with many other signaling pathways, including growth factor-dependent pathways (like PI3K/AKT/mTOR,RAS/RAF/ERK) and vascular endothelial growth factor (VEGF) axis. In preclinical studies, the treatment with MET inhibitors could prevent or reverse resistance to inhibitors of growth factor-dependent signaling; this hypothesis is currently tested in phase III trials with anti-epidermal growth factor receptor (EGFR) inhibitors in non-small-cell lung cancer (NSCLC). Based on preclinical and preliminary clinical results, a rational strategy for the clinical development of MET antagonists should include a selection of the tumors with MET overexpression, the identification of prognostic/predictive biomarkers, the evaluation of combinations with anti-VEGF compounds.

Current questions for the treatment of advanced gastric cancer

BACKGROUND

Gastric cancer remains a major health problem worldwide. Treatment of advanced gastric cancer is controversial and there is no standard regimen for first- or second-line chemotherapy (CT). This review aims to give an overview of the hot topics concerning treatment, prognostic factors and new strategies in advanced gastric cancer.

MATERIAL AND METHODS

Seven questions of special clinical interest have been formulated previously to the literature review. With the aim of answering each of these questions, a specific search of the relevant trials and meta-analyses published or communicated from 1990 to date was performed.

RESULTS

Patients treated with CT have a survival benefit over those treated with only best supportive care (BSC). Such active cytotoxic drugs as cisplatin or docetaxel and targeted agents as trastuzumab showed superiority in randomized trials. Other agents such as oxaliplatin, oral fluoropyrimidines and irinotecan showed non-inferiority or less toxic results, positioning them as valuable alternatives to classical schedules. Combination regimens seem to be an improvement over single agent therapy. However, increased toxicity of some regimens makes their general use difficult. Second-line CT is of value for selected patients with good performance status. Trastuzumab is the only targeted agent showing better survival when added to chemotherapy in HER2-driven tumors.

CONCLUSIONS

With the introduction of new agents, management of advanced gastric cancer has experienced important changes. First and second-line CT improve survival in patients with good performance status. Future trials should address how to better select patients for new, targeted agents, based upon validated predictive biomarkers.

Targeting MET in cancer: rationale and progress

Uncontrolled cell survival, growth, angiogenesis and metastasis are essential hallmarks of cancer. Genetic and biochemical data have demonstrated that the growth and motility factor hepatocyte growth factor/scatter factor (HGF/SF) and its receptor, the tyrosine kinase MET, have a causal role in all of these processes, thus providing a strong rationale for targeting these molecules in cancer. Parallel progress in understanding the structure and function of HGF/SF, MET and associated signalling components has led to the successful development of blocking antibodies and a large number of small-molecule MET kinase inhibitors. In this Review, we discuss these advances, as well as results from recent clinical studies that demonstrate that inhibiting MET signalling in several types of solid human tumours has major therapeutic value.