Phase I study of matuzumab in combination with 5-fluorouracil, leucovorin and cisplatin (PLF) in patients with advanced gastric and esophagogastric adenocarcinomas. Invest New Drugs. 2013;31:642-652. [PMID: 22763610 DOI: 10.1007/s10637-012-9848-0]

EGFR targeting for cancer therapy: Pharmacology and immunoconjugates with drugs and nanoparticles

The epidermal growth factor receptor (EGFR) belongs to the tyrosine kinase receptors family and is present in the epithelial cell membrane. Its endogenous activation occurs through the binding of different endogenous ligands, including the epidermal growth factor (EGF), leading to signaling cascades able to maintain normal cellular functions. Although involved in the development and maintenance of tissues in normal conditions, when EGFR is overexpressed, it stimulates the growth and progression of tumors, resulting in angiogenesis, invasion and metastasis, through some main cascades such as Ras/Raf/MAPK, PIK-3/AKT, PLC-PKC and STAT. Besides, considering the limitations of conventional chemotherapy that result in high toxicity and low tumor specificity, EGFR is currently considered an important target. As a result, several monoclonal antibodies are currently approved for use in cancer treatment, such as cetuximab (CTX), panitumumab, nimotuzumab, necitumumab and others are in clinical trials. Aiming to combine the chemotherapeutic agent toxicity and specific targeting to EGFR overexpressing tumor tissues, two main strategies will be discussed in this review: antibody-drug conjugates (ADCs) and antibody-nanoparticle conjugates (ANCs). Briefly, ADCs consist of antibodies covalently linked through a spacer to the cytotoxic drug. Upon administration, binding to EGFR and endocytosis, ADCs suffer chemical and enzymatic reactions leading to the release and accumulation of the drug. Instead, ANCs consist of nanotechnology-based formulations, such as lipid, polymeric and inorganic nanoparticles able to protect the drug against inactivation, allowing controlled release and also passive accumulation in tumor tissues by the enhanced permeability and retention effect (EPR). Furthermore, ANCs undergo active targeting through EGFR receptor-mediated endocytosis, leading to the formation of lysosomes and drug release into the cytosol. Herein, we will present and discuss some important aspects regarding EGFR structure, its role on internal signaling pathways and downregulation aspects. Then, considering that EGFR is a potential therapeutic target for cancer therapy, the monoclonal antibodies able to target this receptor will be presented and discussed. Finally, ADCs and ANCs state of the art will be reviewed and recent studies and clinical progresses will be highlighted. To the best of our knowledge, this is the first review paper to address specifically the EGFR target and its application on ADCs and ANCs.

The Latest Battles Between EGFR Monoclonal Antibodies and Resistant Tumor Cells

Epidermal growth factor receptor (EGFR) is a tyrosine kinase receptor involved in homeostatic regulation of normal cells and carcinogenesis of epithelial malignancies. With rapid development of the precision medicine era, a series of new therapies targeting EGFR are underway. Four EGFR monoclonal antibody drugs (cetuximab, panitumumab, nimotuzumab, and necitumumab) are already on the market, and a dozen other EGFR monoclonal antibodies are in clinical trials. Here, we comprehensively review the newly identified biological properties and anti-tumor mechanisms of EGFR monoclonal antibodies. We summarize recently completed and ongoing clinical trials of the classic and new EGFR monoclonal antibodies. More importantly, according to our new standard, we re-classify the complex evolving tumor cell resistance mechanisms, including those involving exosomes, non-coding RNA and the tumor microenvironment, against EGFR monoclonal antibodies. Finally, we analyzed the limitations of EGFR monoclonal antibody therapy, and discussed the current strategies overcoming EGFR related drug resistance. This review will help us better understand the latest battles between EGFR monoclonal antibodies and resistant tumor cells, and the future directions to develop anti-tumor EGFR monoclonal antibodies with durable effects.

The promising role of monoclonal antibodies for gastric cancer treatment

Gastric cancer (GC) is the second leading cause of cancer-related death world-wide. Despite improvements in prevention, early detection and various therapeutic options, the prognosis is still poor. GC is often diagnosed at an advanced stage with survivals less than 1 year. Chemotherapy as the mainstay of treatment in advanced stage is not of notable advantages, underlining the need for novel more effective therapeutic options. Based on current knowledge of molecular and cellular mechanisms, a number of novel biologic approaches such as monoclonal antibodies have been recently introduced for cancer treatment that mainly affect the immune system or target signaling pathways playing role in cancer and metastasis development. In this review, various monoclonal antibodies for GC therapy were explained.

Monoclonal antibody-based therapeutics, targeting the epidermal growth factor receptor family: from herceptin to Pan HER

Objectives

Monoclonal antibody-based of cancer therapy has been considered as one of the most successful therapeutic strategies for both haematologic malignancies and solid tumours in the last two decades. Epidermal growth factor receptor (EGFR) family signalling pathways play a key role in the regulation of cell proliferation, survival and differentiation. Hence, anti-EGFR family mAbs is one of the most promising approaches in cancer therapy.

Key findings

Here, recent advances in anti-EGFR mAb including approved or successfully tested in preclinical and clinical studies have been reviewed. Although we focus on monoclonal antibodies against the EGF receptor, but the mechanisms underlying the effects of EGFR-specific mAb in cancer therapy, to some extend the resistance to existing anti-EGFR therapies and some therapeutic strategies to overcome resistance such as combination of mAbs on different pathways are briefly discussed as well.

Summary

The EGFR family receptors, is considered as an attractive target for mAb development to inhibit their consecutive activities in tumour growth and resistance. However, due to resistance mechanisms, the combination therapies may become a good candidate for targeting EGFR family receptors.

Genetics of Gastric Cancer

Gastric cancer represents a major cause of cancer mortality worldwide despite a declining incidence. New molecular classification schemes developed from genomic and molecular analyses of gastric cancer have provided a framework for understanding this heterogenous disease, and early findings suggest these classifications will be relevant for designing and implementing new targeted therapies. The success of targeted therapy and immunotherapy in breast cancer and melanoma, respectively, has not been duplicated in gastric cancer, but trastuzumab and ramucirumab have demonstrated efficacy in select populations. New markers that predict therapeutic response are needed to improve patient selection for both targeted and immunotherapies.

Targeted therapy in esophageal cancer

An increasing number of patients are diagnosed with esophageal cancer at an advanced stages, and only a small group of them can benefit from the traditional chemotherapy and radiotherapy. So far, multiple monoclonal antibodies and tyrosine kinase inhibitors have been developed, alone or in combination with traditional therapy, to improve the prognosis of patients with advanced esophageal cancer. This review summarizes the recent advances of targeted therapies against EGFR, HER2, VEGFR and c-MET in esophageal cancer. More clinical trials should be performed to evaluate the efficacy and safety of various targeted therapy regimens. Future basic research should focus on investigating the molecular mechanisms of therapeutic targets in esophageal cancer.

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.

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.

Molecular targeting to treat gastric cancer

Trastuzumab that targets human epidermal growth factor receptor 2 (HER2) protein is the only approved molecular targeting agent for treating gastric cancer in Japan and the outcomes have been favorable. However, trastuzumab is effective for only 10% to 20% of the population with gastric cancer that expresses HER2 protein. Molecular targeting therapy with bevacizumab against vascular endothelial growth factors (VEGF) and with cetuximab and panitumumab against the epidermal growth factors pathway that have been approved for treating colorectal cancer are not considered effective for treating gastric cancer according to several clinical trials. However, ramucirumab that targets VEGF receptor-2 prolonged overall survival in a large phase III clinical trial and it might be an effective molecular targeting therapy for gastric cancer. The significance of molecular targeting therapy for gastric cancer remains controversial. A large-scale randomized clinical trial of novel molecular targeting agents with which to treat gastric cancer is needed.

Investigational therapies targeting the ErbB family in oesophagogastric cancer

INTRODUCTION

The prognosis for patients with oesophagogastric (OG) cancer remains poor, with a median survival of approximately 9 - 11 months for patients with metastatic disease. However, a more personalised approach to treatment, using drugs tailored to the molecular characteristics of patients' tumours, has the potential to improve patient outcomes. Drugs targeting the ErbB family of receptors have been developed, but these have had varying degrees of success in clinical practice.

AREAS COVERED

The authors provide an overview of the ErbB receptor family with regard to OG cancers. Furthermore, they evaluate the evidence from preclinical and clinical trials of therapeutics targeting this family, including monoclonal antibodies, tyrosine kinase inhibitors and novel agents.

EXPERT OPINION

Drugs targeting the ErbB family have been evaluated in OG cancer, with a notable success story in the case of trastuzumab, although there have been disappointing failures with anti-EGFR therapy. The response to targeted treatment remains variable and further biomarker research is essential to identify patients most likely to benefit from these therapies. The treatment of OG cancer remains challenging, but new anti-HER2 therapies and combination therapies hold promise for the future.

Expression of the EGF family in gastric cancer: downregulation of HER4 and its activating ligand NRG4

Gastric cancer is a major cause of cancer-related deaths in both men and women. The epidermal growth factor receptors are EGFR, HER2, HER3 and HER4. Of the four epidermal growth factor receptors, EGFR and HER2 are well-known oncogenes involved in gastric cancer. Little, however, is known about the role played by HER3 and HER4 in this disease. We obtained paired samples from the tumor and the adjacent normal tissue from the same patient undergoing surgery for gastric cancer. Using RT-qPCR, we quantified the mRNA expression of the four receptors including the HER4 splicing isoforms and all the ligands activating these receptors. Using immunohistochemistry, the protein expression of HER4 was also quantified. We found that HER2 mRNA expression was upregulated in the tumor tissue compared to the matched normal tissue (p = 0.0520). All ligands with affinity for EGFR were upregulated, whereas the expression of EGFR was unchanged. Interestingly, we found the mRNA expression of HER4 (p = 0.0002) and its ligand NRG4 (p = 0.0009) to be downregulated in the tumor tissue compared to the matched normal tissue. HER4 downregulation was demonstrated for all the alternatively spliced isoforms of this receptor. These results support the involvement of EGFR and HER2 in gastric cancer and suggest an interesting association of reduced HER4 expression with development of gastric cancer.

Targeted therapies in gastroesophageal cancer

Gastroesophageal cancers comprising gastric cancer (GC), and cancers of the distal oesophagus and gastroesophageal junction (GEJ) are a global health threat. In Western populations the incidence of GC is declining which has been attributed to effective strategies of eradicating Helicobacter pylori infection. To the contrary, GEJ cancers are on the rise, with obesity and reflux disease being viewed as major risk factors. During the past decade perioperative chemotherapy, pre- or postoperative radio-chemotherapy, and, in Asian populations, adjuvant chemotherapy have been shown to improve the outcome of patients with advanced GC and GEJ cancers suited for surgery. Less progress has been made in the treatment of metastatic disease. The introduction of trastuzumab in combination with platinum/fluoropyrimidine-based chemotherapy for patients with HER2-positive disease has marked a turning point. Recently, several novel agents targeting growth factor receptors, angiogenic pathways, adhesion molecules and mediators of intracellular signal transduction have been clinically explored. Here we summarise the current status and future developments of molecularly targeted therapies in GC and GEJ cancer.

The rugged road to targeted therapy for gastric cancer

Gastric cancer is the second leading cause of cancer related-death. Most patients with gastric cancer present with an advanced stage of the disease that has a poor prognosis. Molecularly targeted drugs combined with chemotherapy have been becoming the main treatment for advanced gastric cancer. A number of targeted agents modulating different signal transduction pathways are currently entering clinical trials, such as angiogenesis inhibitors and agents targeting epidermal growth factor receptor, hepatocyte growth factor, cell cycle, or matrix metalloproteinases. However, disappointing results were achieved in most phase III clinical trials, in which special patient selection by molecular biomarkers was not conducted. This systematic review synthesizes most of the data available from clinical trials, evaluates the efficacy and safety of molecularly targeted drugs and explores the rugged road to targeted therapy for advanced gastric cancer.