Identification of nectin-4 oncoprotein as a diagnostic and therapeutic target for lung cancer

Targeting nectin-4 by antibody-drug conjugates for the treatment of urothelial carcinoma

INTRODUCTION

Nectin-4 is a tumor-associated antigen overexpressed in urothelial carcinoma and several other malignancies. It has emerged as a compelling target for novel tumor-directed therapies, particularly as a component of antibody-drug conjugates (ADCs), a growing class of anti-cancer therapeutic agents. Development of nectin-4-directed therapies has been led by enfortumab vedotin (EV), an ADC comprised of a fully human monoclonal antibody specific for nectin-4 conjugated via a cleavable linker to the microtubule inhibitor MMAE. EV was approved in 2019 as a first-in-class agent for the treatment of urothelial carcinoma.

AREAS COVERED

This article discusses general principles relevant to ADC design and our current understanding of nectin-4 in normal physiology and malignancy, followed by a review of the development of EV as well as additional drug conjugate strategies targeting nectin-4.

EXPERT OPINION

EV offers proof-of-concept for the clinical utility of nectin-4-directed therapies and provides further support for ADCs as an important class of anti-cancer agents. Future development of nectin-4-targeted approaches will benefit from a deeper understanding of nectin-4 biology in both health and disease, as well as a detailed exploration of the mechanisms underlying therapeutic activity and resistance.

Treating Bladder Cancer: Engineering of Current and Next Generation Antibody-, Fusion Protein-, mRNA-, Cell- and Viral-Based Therapeutics

Bladder cancer is a frequent malignancy and has a clinical need for new therapeutic approaches. Antibody and protein technologies came a long way in recent years and new engineering approaches were applied to generate innovative therapeutic entities with novel mechanisms of action. Furthermore, mRNA-based pharmaceuticals recently reached the market and CAR-T cells and viral-based gene therapy remain a major focus of biomedical research. This review focuses on the engineering of biologics, particularly therapeutic antibodies and their application in preclinical development and clinical trials, as well as approved monoclonal antibodies for the treatment of bladder cancer. Besides, newly emerging entities in the realm of bladder cancer like mRNA, gene therapy or cell-based therapeutics are discussed and evaluated. As many discussed molecules exhibit unique mechanisms of action based on innovative protein engineering, they reflect the next generation of cancer drugs. This review will shed light on the engineering strategies applied to develop these next generation treatments and provides deeper insights into their preclinical profiles, clinical stages, and ongoing trials. Furthermore, the distribution and expression of the targeted antigens and the intended mechanisms of action are elucidated.

Emerging agents for the treatment of metastatic urothelial cancer

Over the past few decades, platinum-based combination chemotherapy (PBCC) has been the preferred initial therapy for metastatic urothelial cancer (mUC). However, despite a response rate of approximately 50%, a small proportion of patients with distant metastases may be cured by cisplatin-based combination chemotherapy (CBCC). In addition, up to 50% of patients are not eligible for CBCC due to age or comorbidities. Furthermore, adverse effects from PBCC are a major concern. The emergence of check-point inhibitors (CPIs), particularly those with antibodies directed against programmed cell death 1 protein (PD-1) or its ligand (PD-L1), advanced the treatment of mUC. Avelumab switch-maintenance therapy is recommended in patients with locally advanced or mUC who did not progress on initial PBCC. With the recent advances in tumor molecular biology and the discovery of actionable therapeutic targets, the clinical application of targeted therapy is now being explored for mUC. Erdafitinib, a tyrosine kinase inhibitor of FGFR1-4, has shown positive outcomes in patients with advanced UC with FGFR alterations. Another recent technological development is antibody-drug conjugates (ADCs), which are complex molecules composed of an antibody linked to a biologically active cytotoxic drug (payload) that targets and kills tumor cells while sparing healthy cells. Enfortumab vedotin, a monoclonal antibody targeting nectin-4 conjugated to monomethyl auristatin E, has demonstrated clinically significant efficacy in patients who do not respond to both cytotoxic chemotherapy and CPIs. In this review, we describe switch-maintenance therapies using CPI, various targeted agents, and ADCs that have been investigated for mUC treatment.

Nectin-4 and p95-ErbB2 cooperatively regulate Hippo signaling-dependent SOX2 gene expression, enhancing anchorage-independent T47D cell proliferation

Nectin-4, upregulated in various cancer cells, cis-interacts with ErbB2 and its trastuzumab-resistant splice variants, p95-ErbB2 and ErbB2∆Ex16, enhancing DNA synthesis through the PI3K-AKT signaling in human breast cancer T47D cells in an adherent culture. We found here that nectin-4 and p95-ErbB2, but not nectin-4 and either ErbB2 or ErbB2∆Ex16, cooperatively enhanced SOX2 gene expression and cell proliferation in a suspension culture. This enhancement of T47D cell proliferation in a suspension culture by nectin-4 and p95-ErbB2 was dependent on the SOX2 gene expression. In T47D cells, nectin-4 and any one of p95-ErbB2, ErbB2, or ErbB2∆Ex16 cooperatively activated the PI3K-AKT signaling, known to induce the SOX2 gene expression, to similar extents. However, only a combination of nectin-4 and p95-ErbB2, but not that of nectin-4 and either ErbB2 or ErbB2∆Ex16, cooperatively enhanced the SOX2 gene expression. Detailed studies revealed that only nectin-4 and p95-ErbB2 cooperatively activated the Hippo signaling. YAP inhibited the SOX2 gene expression in this cell line and thus the MST1/2-LATS1/2 signaling-mediated YAP inactivation increased the SOX2 gene expression. These results indicate that only the combination of nectin-4 and p95-ErbB2, but not that of nectin-4 and either ErbB2 or ErbB2∆Ex16, cooperatively regulates the Hippo signaling-dependent SOX2 gene expression, enhancing anchorage-independent T47D cell proliferation.

PARP inhibitor Veliparib (ABT-888) enhances the anti-angiogenic potentiality of Curcumin through deregulation of NECTIN-4 in oral cancer: Role of nitric oxide (NO)

Concurrent use of DNA damaging agents with PARP inhibitors contribute to the effectiveness of the anticancer therapy. But there is a dearth of reports on the antiangiogenic effects of PARP inhibitors and the suppression of angiogenesis by this drug combination is not yet reported. For the successful development of cancer therapeutics, anti-cancer drugs ought to have anti-angiogenic potentiality along with their DNA damaging abilities. In this current piece of work, we investigated the in vitro and in ovo anti-angiogenic effect of Curcumin and Veliparib (a PARP inhibitor) in oral cancer. Recent evidences suggest an involvement of the NECTIN-4 in cancer angiogenesis and the exact molecular pathway of this involvement remains to be delineated. We observed that the soluble NECTIN-4 secreted from H357 oral cancer cells enhanced the angiogenesis of endothelial cells (HUVECs) and this was inhibited by Curcumin-Veliparib combination. NECTIN-4 enhanced vascularization, induced vasodilation and triggered the angiogenic sprouting via endothelial tip cell filopodia. Data indicated that NECTIN-4 mediated angiogenesis is associated with PI3K-AKT-mediated nitric oxide (NO) formation. A noticeable increase in the NO enhanced epithelial NO level through HIF-1α mediated iNOS activation. We observed that increased NO enhanced the NECTIN-4 mediated eNOS expression and thereby elicited further angiogenesis. Curcumin antagonised the NECTIN-4-induced angiogenesis through inhibition of PI3K-AKT mediated eNOS pathway and Veliparib synergized the effect of Curcumin. Our observations indicate that NO is cardinal in inducing NECTIN-4 mediated angiogenesis in H357 cells. Thus, Curcumin-Veliparib combination suppresses angiogenesis through deregulation of the PI3K-AKT-eNOS pathway downstream to the NECTIN-4.

The biology and rationale of targeting nectin-4 in urothelial carcinoma

Bladder cancer is the tenth most common cancer type worldwide. Urothelial carcinoma is the most common type of bladder cancer and accounts for 90% of bladder cancer cases in the USA and Europe. Novel approaches are needed to improve patient outcomes. Nectin-4 is a tumour-associated antigen found on the surface of most urothelial carcinoma cells. In the antibody-drug conjugate enfortumab vedotin, human anti-nectin-4 antibody is linked to the cytotoxic microtubule-disrupting agent monomethyl auristatin E. In ongoing phase I, II and III clinical trials, enfortumab vedotin has been evaluated as a monotherapy and in combination with a checkpoint inhibitor and/or chemotherapy in locally advanced and metastatic urothelial carcinoma. Encouraging data from the phase II study resulted in the FDA granting accelerated approval for enfortumab vedotin in December 2019 for patients with locally advanced or metastatic urothelial carcinoma who were previously treated with platinum and a checkpoint inhibitor therapy. Moreover, data from a phase I study led to the FDA granting breakthrough therapy designation to enfortumab vedotin combined with pembrolizumab as a first-line treatment in February 2020 for cisplatin-ineligible patients with locally advanced or metastatic urothelial carcinoma. Results of ongoing and future combination studies of enfortumab vedotin with immunotherapy and other novel agents are eagerly awaited.

Antibody-drug conjugates in solid tumors: a look into novel targets

Antibody-drug conjugates (ADCs) are a relatively new class of anticancer agents designed to merge the selectivity of monoclonal antibodies with cell killing properties of chemotherapy. They are commonly described as the "Trojan Horses" of therapeutic armamentarium, because of their capability of directly conveying cytotoxic drug (payloads) into the tumor space, thus transforming chemotherapy into a targeted agent. Three novel ADCs have been recently approved, i.e., trastuzumab deruxtecan, sacituzumab govitecan and enfortumab vedotin, respectively, targeting HER2, Trop2 and Nectin4. Thanks to progressive advances in engineering technologies these drugs rely on, the spectrum of diseases sensitive to these drugs as well as their indications are in continuous expansion. Several novel ADCs are under evaluation, exploring new potential targets along with innovative payloads. This review aims at providing a summary of the technology behind these compounds and at presenting the latest ADCs approved in solid tumors, as well as at describing novel targets for ADCs under investigation and new strategies to optimize their efficacy in solid tumors.

Ursolic Acid and Its Nanoparticles Are Potentiators of Oncolytic Measles Virotherapy against Breast Cancer Cells

Simple Summary

Despite the advancing treatments, female breast cancer is one of the most common cancers and a leading cause of cancer deaths in women. To help broaden the therapeutic spectrum of breast cancer, we identified the natural compound ursolic acid (UA) as a potentiator that enhances the oncolytic activity of measles virus (MV) against breast cancer cells through the induction of apoptosis. In addition, to increase clinical applicability, we further generated UA nanoparticles that achieved improved solubility. UA nanoparticles similarly synergized with MV in killing breast cancer cells by triggering apoptosis, and this synergistic anticancer effect was also observed in various breast cancer cell types. This study demonstrates for the first time that UA and its nanoparticles enhance MV’s oncolytic activity in breast cancer cells, suggesting that such combinations may be worth further exploring as an anticancer strategy against breast cancer.

Abstract

Oncolytic viruses (OVs) and phytochemical ursolic acid (UA) are two efficacious therapeutic candidates in development against breast cancer, the deadliest women’s cancer worldwide. However, as single agents, OVs and UA have limited clinical efficacies. As a common strategy of enhancing monotherapeutic anticancer efficacy, we explored the combinatorial chemovirotherapeutic approach of combining oncolytic measles virus (MV), which targets the breast tumor marker Nectin-4, and the anticancer UA against breast adenocarcinoma. Our findings revealed that in vitro co-treatment with UA synergistically potentiated the killing of human breast cancer cells by oncolytic MV, without UA interfering the various steps of the viral infection. Mechanistic studies revealed that the synergistic outcome from the combined treatment was mediated through UA’s potentiation of apoptotic killing by MV. To circumvent UA’s poor solubility and bioavailability and strengthen its clinical applicability, we further developed UA nanoparticles (UA-NP) by nanoemulsification. Compared to the non-formulated UA, UA-NP exhibited improved drug dissolution property and similarly synergized with oncolytic MV in inducing apoptotic breast cancer cell death. This oncolytic potentiation was partly attributed to the enhanced autophagic flux induced by the UA-NP and MV combined treatment. Finally, the synergistic effect from the UA-NP and MV combination was also observed in BT-474 and MDA-MB-468 breast cancer cells. Our study thus highlights the potential value of oncolytic MV and UA-based chemovirotherapy for further development as a treatment strategy against breast cancer, and the feasibility of employing nanoformulation to enhance UA’s applicability.

Recombinant SLAMblind Measles Virus Is a Promising Candidate for Nectin-4-Positive Triple Negative Breast Cancer Therapy

One of the most refractory breast cancer types is triple negative (TN) breast cancer, in which cells are resistant to both hormone and Herceptin treatments and, thus, often cause recurrence and metastasis. Effective treatments are needed to treat TN breast cancer. We previously demonstrated that rMV-SLAMblind, a recombinant measles virus, showed anti-tumor activity against breast cancer cells. Here, we examined whether rMV-SLAMblind is effective for treating TN breast cancer. Nectin-4, a receptor for rMV-SLAMblind, was expressed on the surface of 75% of the analyzed TN breast cancer cell lines. rMV-SLAMblind infected the nectin-4-expressing TN breast cancer cell lines, and significantly decreased the viability in half of the analyzed cell lines in vitro. Additionally, intratumoral injection of rMV-SLAMblind suppressed tumor growth in xenografts of MDA-MB-468 and HCC70 cells. To assess treatment for metastatic breast cancer, we performed intravenous administration of the luciferase-expressing-rMV-SLAMblind to MDA xenografted mice. Virus replicated in the tumor and resulted in significant suppression of the tumor growth. The safety of the virus was tested by its intravenous injection into healthy cynomolgus monkeys, which did not cause any measles-like symptoms. These results suggest that rMV-SLAMblind is a promising candidate as a therapeutic agent for treating metastatic and/or TN type breast cancer.

Prospects for Using Expression Patterns of Paramyxovirus Receptors as Biomarkers for Oncolytic Virotherapy

Simple Summary

Some non-pathogenic viruses that do not cause serious illness in humans can efficiently target and kill cancer cells and may be considered candidates for cancer treatment with virotherapy. However, many cancer cells are protected from viruses. An important goal of personalized cancer treatment is to identify viruses that can kill a certain type of cancer cells. To this end, researchers investigate expression patterns of cell entry receptors, which viruses use to bind to and enter host cells. We summarized and analyzed the receptor expression patterns of two paramyxoviruses: The non-pathogenic measles and the Sendai viruses. The receptors for these viruses are different and can be proteins or lipids with attached carbohydrates. This review discusses the prospects for using these paramyxovirus receptors as biomarkers for successful personalized virotherapy for certain types of cancer.

Abstract

The effectiveness of oncolytic virotherapy in cancer treatment depends on several factors, including successful virus delivery to the tumor, ability of the virus to enter the target malignant cell, virus replication, and the release of progeny virions from infected cells. The multi-stage process is influenced by the efficiency with which the virus enters host cells via specific receptors. This review describes natural and artificial receptors for two oncolytic paramyxoviruses, nonpathogenic measles, and Sendai viruses. Cell entry receptors are proteins for measles virus (MV) and sialylated glycans (sialylated glycoproteins or glycolipids/gangliosides) for Sendai virus (SeV). Accumulated published data reviewed here show different levels of expression of cell surface receptors for both viruses in different malignancies. Patients whose tumor cells have low or no expression of receptors for a specific oncolytic virus cannot be successfully treated with the virus. Recent published studies have revealed that an expression signature for immune genes is another important factor that determines the vulnerability of tumor cells to viral infection. In the future, a combination of expression signatures of immune and receptor genes could be used to find a set of oncolytic viruses that are more effective for specific malignancies.

Pseudotyping Lentiviral Vectors: When the Clothes Make the Virus

Delivering transgenes to human cells through transduction with viral vectors constitutes one of the most encouraging approaches in gene therapy. Lentivirus-derived vectors are among the most promising vectors for these approaches. When the genetic modification of the cell must be performed in vivo, efficient specific transduction of the cell targets of the therapy in the absence of off-targeting constitutes the Holy Grail of gene therapy. For viral therapy, this is largely determined by the characteristics of the surface proteins carried by the vector. In this regard, an important property of lentiviral vectors is the possibility of being pseudotyped by envelopes of other viruses, widening the panel of proteins with which they can be armed. Here, we discuss how this is achieved at the molecular level and what the properties and the potentialities of the different envelope proteins that can be used for pseudotyping these vectors are.

FDA Approval Summary: Enfortumab Vedotin for Locally Advanced or Metastatic Urothelial Carcinoma

On December 18, 2019, the FDA granted accelerated approval to enfortumab vedotin-ejfv (PADCEV; Astellas and Seattle Genetics) for treatment of patients with locally advanced or metastatic urothelial cancer who have previously received a programmed cell death protein 1 or programmed death ligand 1 inhibitor, and a platinum-containing chemotherapy in the neoadjuvant/adjuvant, locally advanced or metastatic setting. Substantial evidence of effectiveness for this application is obtained from Cohort 1 of the single-arm, multicenter Study EV-201. Patients received enfortumab vedotin (EV) 1.25 mg/kg (up to a maximum dose of 125 mg) intravenously on days 1, 8, and 15 of 28-day cycles until disease progression or unacceptable toxicity. Confirmed objective response rate in the 125-patient efficacy population determined by blinded independent central review was 44% [95% confidence interval (CI), 35.1-53.2], with complete responses in 12%. Median response duration was 7.6 months (95% CI, 6.3-not estimable). Grade 3-4 adverse reactions occurred in 73% of patients. Hyperglycemia, peripheral neuropathy, ocular disorders, skin reactions, infusion site extravasations, and embryo-fetal toxicity are labeled as warnings and precautions for EV. The article summarizes the data and the FDA thought process supporting accelerated approval of EV. This approval may be contingent upon verification and description of clinical benefit in confirmatory trial(s).

Enfortumab Vedotin-ejfv: A First-in-Class Anti-Nectin-4 Antibody-Drug Conjugate for the Management of Urothelial Carcinoma

OBJECTIVE

To evaluate the pharmacology, pharmacokinetics, clinical efficacy, safety, dosing, cost, and clinical implications of enfortumab vedotin-ejfv (EV) in the treatment of locally advanced or metastatic urothelial carcinoma (UC).

DATA SOURCES

A literature search of PubMed (inception to August 2020) was conducted using the terms enfortumab, vedotin, Padcev, and Nectin. Data were also obtained from package inserts, meeting abstracts, and ongoing studies from ClinicalTrials.gov.

STUDY SELECTION AND DATA EXTRACTION

All relevant published articles, package inserts, and meeting abstracts evaluating EV for the treatment of UC were analyzed.

DATA SYNTHESIS

Antibody-drug conjugates (ADCs) deliver potent cytotoxic agents using highly selective monoclonal antibodies. Targeting the near-universal expression of Nectin-4 on UC cells is a viable therapeutic strategy. In a pivotal phase II trial, EV demonstrated an overall response rate of 44%, and a median duration of response of 7.6 months. Estimated overall survival was 11.7 months with a median estimated progression-free survival of 5.6 months. Results were similar among difficult-to-treat patients, including those with liver metastases. Unique toxicity concerns with EV require careful consideration and monitoring.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

EV, a first-in-class anti-Nectin-4 ADC, provides impressive response rates with manageable toxicities, making it a promising treatment option for patients with multiply relapsed or refractory UC.

CONCLUSION

The US Food and Drug Administration-approved EV demonstrates antitumor activity in heavily pretreated patients with UC but harbors important adverse effects and financial concerns. Additional studies are required to identify the optimal sequencing, patient population, and place in therapy for EV.

The emerging role of antibody-drug conjugates in urothelial carcinoma

INTRODUCTION

In December 2019, the US Food and Drug Administration granted accelerated approval to the novel nectin-4-targeting antibody-drug conjugate, enfortumab vedotin, for the treatment of platinum-refractory and immune checkpoint blockade-refractory locally advanced or metastatic urothelial carcinoma. Antibody-drug conjugates represent a new therapeutic modality in urothelial cancer; and beyond nectin-4, agents targeting Trop-2, HER2, and EpCAM are also in clinical development.

AREAS COVERED

This review outlines the biologic rationale and the clinical development of novel antibody-drug conjugates for the treatment of urothelial cancer across the spectrum of disease from non-muscle-invasive bladder cancer through treatment-refractory metastatic disease.

EXPERT OPINION

The high response rates observed with enfortumab vedotin - both as monotherapy and in combination with checkpoint blockade immunotherapy - suggest this and other antibody-drug conjugates may have efficacy similar to or even exceeding that of traditional cytotoxic chemotherapy. Ongoing clinical development of antibody-drug conjugates in urothelial cancer will address the optimal combination or sequencing strategy with anti-PD-1/L1 immunotherapy and platinum-based chemotherapy.

Pathological and genetic aspects of spontaneous mammary gland tumor in Tupaia belangeri (tree shrew)

Mammary gland cancer is the most common cancer occurring in women globally. Incidences of this cancer in Japan are on the increase. Annually, more than 70,000 new cases are recorded in Japan and about 1.7 million in the world. Many cases are still difficult to cure completely, and animal models are required for the characterization of the biology, therapeutic strategy, and preventive measures for spontaneous mammary tumor. The mouse model used currently has some limitations owing to structural differences between mouse and human mammary glands. Tupaia belangeri (tree shrew), which belongs to the Tupaiidae family, shows relatively high genetic homology and structural similarity to human mammary glands. Here, we characterized the spontaneous mammary tumors in 61 female tree shrews of different ages. The incidence rate was 24.6% (15/61), and the rate of simultaneous or metachronous multiplex tumors was 60% (9/15). From the incidence pattern, some cases seemed to be of familial mammary gland tumor, as the offspring of female tree shrews No. 3 and 9 and male tree shrew No. 11 showed a high incidence rate, of 73.3% (11/15). Average incidence age for tumor development was 2 years and 3 months, and the earliest was 10 months. Histochemical analysis indicated that spontaneous mammary gland tumors in the tree shrew show the features of intraductal papillary adenomas (22 cases), except 2 tubulopapillary carcinoma cases (No. 75 and 131). All the cases were positive for the progesterone receptor, whereas 91.3% were positive for the estrogen receptor, and 4.3% were HER-2 positive. We have also confirmed the expression of nectin-4 in some mammary tumor cells. Additionally, we subjected tree shrews to cytodiagnosis or X-ray CT. Thus, the findings of this study highlight the potential of the tree shrew as a valuable new animal model for mammary gland tumor study.

Characterization of KIF20A as a prognostic biomarker and therapeutic target for different subtypes of breast cancer

The aim of the present study was to identify novel prognostic biomarkers and therapeutic targets for breast cancer; thus, genes that are frequently overexpressed in several types of breast cancer were screened. Kinesin family member 20A (KIF20A) was identified as a candidate molecule during this process. Immunohistochemical staining performed using tissue microarrays from 257 samples of different breast cancer subtypes revealed that KIF20A was expressed in 195 (75.9%) of these samples, whereas it was seldom expressed in normal breast tissue. KIF20A protein was expressed in all types of breast cancer observed. However, it was more frequently expressed in human epidermal growth factor receptor 2 (HER2)‑positive and triple‑negative breast cancer than in the luminal type. Moreover, KIF20A expression was significantly associated with the poor prognosis of patients with breast cancer. A multivariate analysis indicated that KIF20A expression was an independent prognostic factor for patients with breast cancer. The suppression of endogenous KIF20A expression using small interfering ribonucleic acids or via treatment with paprotrain, a selective inhibitor of KIF20A, significantly inhibited breast cancer cell growth through cell cycle arrest at the G2/M phase and subsequent mitotic cell death. These results suggest that KIF20A is a candidate prognostic biomarker and therapeutic target for different types of breast cancer.

Viral Pathogenesis, Recombinant Vaccines, and Oncolytic Virotherapy: Applications of the Canine Distemper Virus Reverse Genetics System

Canine distemper virus (CDV) is a highly contagious pathogen transmissible to a broad range of terrestrial and aquatic carnivores. Despite the availability of attenuated vaccines against CDV, the virus remains responsible for outbreaks of canine distemper (CD) with significant morbidity and mortality in domesticated and wild carnivores worldwide. CDV uses the signaling lymphocytic activation molecule (SLAM, or CD150) and nectin-4 (PVRL4) as entry receptors, well-known tumor-associated markers for several lymphadenomas and adenocarcinomas, which are also responsible for the lysis of tumor cells and apparent tumor regression. Thus, CDV vaccine strains have emerged as a promising platform of oncolytic viruses for use in animal cancer therapy. Recent advances have revealed that use of the CDV reverse genetic system (RGS) has helped increase the understanding of viral pathogenesis and explore the development of recombinant CDV vaccines. In addition, genetic engineering of CDV based on RGS approaches also has the potential of enhancing oncolytic activity and selectively targeting tumors. Here, we reviewed the host tropism and pathogenesis of CDV, and current development of recombinant CDV-based vaccines as well as their use as oncolytic viruses against cancers.

Development of Entry-Targeted Oncolytic Measles Viruses

This chapter describes the development of recombinant oncolytic measles viruses (MeV) that selectively enter and destroy tumor cells. The envelope of MeV is a favorable targeting substrate because receptor attachment and membrane fusion functions are separated on two proteins: the hemagglutinin (H) that binds receptors, and the fusion (F) protein that fuses the viral envelope with the cell membrane. The cell entry process, which depends on receptor recognition and occurs at the plasma membrane at neutral pH, results in the delivery of encapsidated genomes to the cytoplasm, where they replicate. Towards improving cancer specificity of oncolytic MeV, two types of cell entry targeting have been achieved. First, entry has been redirected through cancer-specific cell surface proteins. This was done by displaying specificity domains on H while also ablating binding to its natural receptors. Second, activation of the F protein was made dependent on secreted cancer proteases, while also interfering with F cleavage/activation by a ubiquitous intracellular protease. This chapter describes how entry-targeted MeV are produced: In short, gene cassettes with modified H or F coding regions are generated, and then introduced into the viral genome available on plasmid DNA. Such full-length genome plasmids are transfected in cell lines expressing, stably or transiently, the three viral proteins necessary for genome replication. Infectious centers form among these "rescue" cells, which allow isolation of clonal recombinant viruses. These are amplified, characterized in vitro, and then evaluated for their oncolytic activity in appropriate preclinical animal models.

Clinical significance of a pvrl 4 encoded gene Nectin-4 in metastasis and angiogenesis for tumor relapse

PURPOSE

In the present study, we have systematically examined the clinical significance of Nectin-4 (encoded by the PVRL-4 gene), a marker for breast cancer stem cells (CSCs), in cancer metastasis and angiogenesis using a variety of human specimens, including invasive duct carcinoma (IDC) with multiple grades, several types of primary tumors to local and distant relapses, lymph node metastases and circulating tumor cells (CTCs).

METHODS

Nectin-4 was overexpressed in more than 92% of samples with 65.2% Nectin-4-positive cells. The level of expression was increased with increasing tumor grade (GI-III) and size (T1-4) of IDC specimens.

RESULTS

More induction of Nectin-4 was noted in relapsed samples from a variety of tumors (colon, tongue, liver, kidney, ovary, buccal mucosa) in comparison to primary tumors, while paired adjacent normal tissues do not express any Nectin-4. A high expression of Nectin-4 along with other representative markers in CTCs and lymph node metastasis was also observed in cancer specimens. An increased level of Nectin-4 along with representative metastatic (CD-44, Sca1, ALDH1, Nanog) and angiogenic (Ang-I, Ang-II, VEGF) markers were noted in metastatic tumors (local and distant) in comparison to primary tumors that were correlated with different grades of tumor progression. In addition, greater expression of Nectin-4 was observed in secondary tumors (distant metastasis, e.g., breast to liver or stomach to gall bladder) in comparison to primary tumors.

CONCLUSION

Our study demonstrated a significant correlation between Nectin-4 expression and tumor grade as well as stages (p < 0.001), suggesting its association with tumor progression. Nectin-4 was overexpressed at all stages of metastasis and angiogenesis, thus appearing to play a major role in tumor relapse through the PI3K-Akt-NFκβ pathway.

The Prognostic Role of Expression of Nectin-4 in Esophageal Cancer

BACKGROUND Nectin-4 is overexpressed in several human malignant tumors. This study aimed to investigate the expression of Nectin-4 in esophageal cancer tissues compared with adjacent normal esophageal tissue and its association with clinicopathological parameters and prognosis. MATERIAL AND METHODS Nectin-4 expression in esophageal cancer tissues was compared with adjacent normal esophageal tissue from 94 patients using immunohistochemistry, Western blot, and quantitative reverse transcription-polymerase chain reaction (RT-qPCR). The chi-squared (χ²) test and Fisher's exact test compared categorical variables. The log-rank test and Kaplan-Meier survival analysis assessed the relationship between Nectin-4 expression and overall survival (OS). Univariate and multivariate Cox proportional risk models compared Nectin-4 expression, patient prognosis, and clinicopathological parameters. RESULTS Nectin-4 expression was significantly increased in esophageal cancer tissue compared with normal tissue (P<0.001), tumor size ≥4.5 cm, and tumor invasion in T3/T4 compared with T1/T2 stage. Kaplan-Meier survival analysis showed that the OS of patients with increased Nectin-4 expression was significantly reduced compared with patients with low levels of Nectin-4 expression. Patient prognosis in men was less than women, tumor diameter ≥4.5 cm, lymph node involvement, and depth of invasion were associated with poor prognosis. Independent prognostic factors were Nectin-4 expression, lymph node involvement, and depth of invasion. CONCLUSIONS In patients with esophageal cancer, the expression levels of Nectin-4, lymph node involvement, and depth of tumor invasion were independent prognostic factors. Further studies should be performed to evaluate the diagnostic and prognostic roles of Nectin-4 and its potential role as a therapeutic target.

Nectin-4 cis-interacts with ErbB2 and its trastuzumab-resistant splice variants, enhancing their activation and DNA synthesis

Nectin-4 cell adhesion molecule and ErbB2 tyrosine kinase receptor are upregulated in many cancers, including breast cancer, and promote cancer cell proliferation and metastasis. Using human breast cancer cell lines T47D and SUM190-PT, in which both nectin-4 and ErbB2 were upregulated, we showed here that nectin-4 cis-interacted with ErB2 and enhanced its dimerization and activation, followed by the activation of the phosphoinositide 3-kinase-AKT signalling pathway for DNA synthesis. The third immunoglobulin-like domain of nectin-4 cis-interacted with domain IV of ErbB2. This region differs from the trastuzumab-interacting region but is included in the trastuzumab-resistant splice variants of ErbB2, p95-ErbB2 and ErbB2ΔEx16. Nectin-4 also cis-interacted with these trastuzumab-resistant splice variants and enhanced the activation of the phosphoinositide 3-kinase-AKT signalling pathway for DNA synthesis. In addition, nectin-4 enhanced the activation of the p95-ErbB2-induced JAK-STAT3 signalling pathway, but not the ErbB2- or ErbB2ΔEx16-induced JAK-STAT3 signalling pathway. These results indicate that nectin-4 cis-interacts with ErbB2 and its trastuzumab-resistant splice variants and enhances the activation of these receptors and downstream signalling pathways in a novel mechanism.

Nectin-4 Expression Is an Independent Prognostic Biomarker and Associated With Better Survival in Triple-Negative Breast Cancer

Background: Triple-negative breast cancer (TNBC) represents about 10-20% of all invasive breast cancers and is associated with a poor prognosis. The nectin cell adhesion protein 4 (Nectin-4) is a junction protein involved in the formation and maintenance of cell junctions. Nectin-4 has previously shown to be expressed in about 60% of TNBC as well as in TNBC metastases, but to be absent in normal breast tissue, which makes it a potential specific target for TNBC therapy. Previous studies have shown an association of Nectin-4 protein expression with worse prognosis in TNBC in a small patient cohort. The aim of our study was to explore the role of Nectin-4 in TNBC and confirm its impact on survival in a larger TNBC patient cohort.

Material and Methods: We performed immunohistochemical staining for Nectin-4 on a tissue microarray encompassing 148 TNBC cases with detailed clinical annotation and outcomes data.

Results: A high expression of Nectin-4 was present in 86 (58%) of the 148 TNBC cases. In multivariate survival analysis, high expression of Nectin-4 was associated with a significantly better overall survival when compared with low expression of Nectin-4 (p < 0.001). Nectin-4-high expression was also significantly associated with a lower tumor stage (p = 0.025) and pN0 lymph node stage (p = 0.034).

Conclusion: Our results confirm that expression of Nectin-4 serves as a potential prognostic marker in TNBC and is associated with a significantly better overall survival. In addition, Nectin-4 represents a potential target in TNBC, and its role in molecular defined breast cancer subtype should be investigated in larger patient cohorts.

Pivotal Trial of Enfortumab Vedotin in Urothelial Carcinoma After Platinum and Anti-Programmed Death 1/Programmed Death Ligand 1 Therapy

PURPOSE

Locally advanced or metastatic urothelial carcinoma is an incurable disease with limited treatment options, especially for patients who were previously treated with platinum and anti–programmed death 1 or anti–programmed death ligand 1 (PD-1/L1) therapy. Enfortumab vedotin is an antibody–drug conjugate that targets Nectin-4, which is highly expressed in urothelial carcinoma.

METHODS

EV-201 is a global, phase II, single-arm study of enfortumab vedotin 1.25 mg/kg (intravenously on days 1, 8, and 15 of every 28-day cycle) in patients with locally advanced or metastatic urothelial carcinoma who were previously treated with platinum chemotherapy and anti–PD-1/L1 therapy. The primary end point was objective response rate per Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 by blinded independent central review. Key secondary end points were duration of response, progression-free survival, overall survival, safety, and tolerability.

RESULTS

Enfortumab vedotin was administered to 125 patients with metastatic urothelial carcinoma. Median follow-up was 10.2 months (range, 0.5 to 16.5 months). Confirmed objective response rate was 44% (95% CI, 35.1% to 53.2%), including 12% complete responses. Similar responses were observed in prespecified subgroups, such as those patients with liver metastases and those with no response to prior anti–PD-1/L1 therapy. Median duration of response was 7.6 months (range, 0.95 to 11.30+ months). The most common treatment-related adverse events were fatigue (50%), any peripheral neuropathy (50%), alopecia (49%), any rash (48%), decreased appetite (44%), and dysgeusia (40%). No single treatment-related adverse events grade 3 or greater occurred in 10% or more of patients.

CONCLUSION

Enfortumab vedotin demonstrated a clinically meaningful response rate with a manageable and tolerable safety profile in patients with locally advanced or metastatic urothelial carcinoma who were previously treated with platinum and anti–PD-1/L1 therapies.

Upregulation of nectin-4 is associated with ITGB1 and vasculogenic mimicry and may serve as a predictor of poor prognosis in colorectal cancer

Colorectal cancer (CRC) is one of the most common malignancies worldwide. Unlike endothelium-dependent vasculature, vasculogenic mimicry (VM) is an alternative type of blood supply in tumors that is frequently associated with poor patient outcome. Nectin-4 serves a vital role in the formation and maintenance of adherens junctions; integrin β-1 (ITGB1) promotes tumor invasion, metastasis and VM formation. In the present study, the analysis of nectin-4 mRNA expression in a database of The Cancer Genome Atlas (TCGA) was combined with that of another non-overlapping cohort of 68 patients with CRC. TCGA data were used to examine nectin-4 mRNA expression in CRC and its correlation with the clinicopathological features of patients. Data from the non-overlapping cohort of patients was used to determine nectin-4 and ITGB1 protein expression in CRC by immunohistochemical (IHC) staining. Cluster of differentiation 34/periodic acid-Schiff double staining was performed to validate the presence of VM formation. The association with, and significance of combining nectin-4, ITGB1 protein expression and VM formation for predicting patient prognosis was evaluated. The TCGA dataset demonstrated that nectin-4 mRNA was upregulated in CRC, which was significantly relate to lymph node metastasis (P=0.0017), distant metastasis (P=0.0045), and tumor-node-metastasis (TNM) stage (P=0.0015). Of the 68 patients analyzed by IHC staining, 48 (70.6%) were positive for nectin-4, 46 (67.6%) for ITGB1 and 17 (25%) for VM formation. Nectin-4 protein expression was associated with ITGB1 protein expression (P<0.01) and VM formation (P<0.05). Nectin-4, ITGB1 expression and VM formation were associated with distant metastasis stage (P<0.05) and TNM stage (P<0.05). Based on these findings it was concluded that nectin-4 was upregulated in CRC tissues compared with normal mucosal tissues, and was associated with ITGB1 expression and VM formation. Furthermore, nectin-4 and ITGB1 protein expression, together with VM formation may be used to predict poor prognosis in CRC.

Clinical Trials with Oncolytic Measles Virus: Current Status and Future Prospects

Attenuated Edmonston lineage measles virus (MV-Edm) vaccine strains can preferentially infect and lyse a wide variety of cancer cells. Oncolytic MV-Edm derivatives are genetically engineered to express the human carcinoembryonic antigen (MV-CEA virus) or the human sodium iodide symporter (MV-NIS virus) and are currently being tested in clinical trials against ovarian cancer, glioblastoma multiforme, multiple myeloma, mesothelioma, head and neck cancer, breast cancer and malignant peripheral nerve sheath tumors. This review describes the basic and preclinical data that facilitated the clinical translation of MV-Edm strains, and summarizes the clinical results of this oncolytic platform to date. Furthermore, we discuss the latest clinically relevant MV-Edm vector developments and creative strategies for future translational steps.

Chemovirotherapeutic Treatment Using Camptothecin Enhances Oncolytic Measles Virus-Mediated Killing of Breast Cancer Cells

Oncolytic virotherapy represents an emerging development in anticancer therapy. Although it has been tested against a variety of cancers, including breast cancer, the efficacy of oncolytic viral vectors delivered as a monotherapy is limited. Enhancing viral oncolytic therapies through combination treatment with anticancer agents is a feasible strategy. In this study, we considered a chemovirotherapeutic approach for treating breast adenocarcinoma using oncolytic measles virus (MV) and the chemotherapeutic agent camptothecin (CPT). Our results demonstrated that co-treatment of MV with CPT yielded enhanced cytotoxicity against breast cancer cells. Low dosage CPT combined with MV was also found to elicit the same therapeutic effect as high doses of CPT. At the lower dosage used, CPT did not inhibit the early stages of MV entry, nor reduce viral replication. Further studies revealed that co-treatment induced significantly enhanced apoptosis of the breast cancer cells compared to either MV or CPT alone. Overall, our findings demonstrate the potential value of MV plus CPT as a novel chemovirotherapeutic treatment against breast cancer and as a strategy to enhance MV oncolytic activity.

Targeting advanced urothelial carcinoma-developing strategies

PURPOSE OF REVIEW

Advanced urothelial carcinoma is a heterogeneous disease with high burden of morbidity, mortality, and cost. Significant progress has been made in understanding the biology of the disease and the development of immunotherapies and targeted therapies. In this review, we summarize the current and future therapeutic approaches in the management of urothelial carcinoma.

RECENT FINDINGS

Advances in immune checkpoint inhibitors resulted in the Food and Drug Administration (FDA) approvals of atezolizumab in 2016, and pembrolizumab, avelumab, durvalumab, and nivolumab in 2017 for the treatment of advanced urothelial carcinoma. More recently, development of inhibitors targeting the fibroblast growth factor receptor genetic alterations and antibody-drug conjugates targeting specific cell surface antigens (trop2, nectin4, and SLITRK6) resulted in several FDA breakthrough designations for urothelial carcinoma.

CONCLUSION

The development of novel therapies targeting the immune and molecular pathways of advanced urothelial carcinoma is promising for the improvement of outcomes in this lethal disease. Ongoing efforts are poised to optimize therapeutic options in the post-chemotherapy arena. In the era of precision medicine, the future of urothelial carcinoma lies in using less cytotoxic chemotherapy, more targeted therapy and immunotherapy, and possibly a combination of these therapeutic approaches.

Over-expression of Nectin-4 promotes progression of esophageal cancer and correlates with poor prognosis of the patients

Background

Nectin-4, also known as PVRL4 (poliovirus-receptor-like 4), is specifically expressed in the embryo and placenta. Recent studies have reported that the Nectin-4 is over-expressed in multiple human cancers, and such abnormal expression is associated with cancer progression and poor prognosis of the patients. In the present study, we aimed to characterize the expression pattern of Nectin-4 in human esophageal cancer (EC) tissues, and to investigate its clinical implications, prognostic value and regulatory effects on cellular functions of EC cells.

Methods

In the present study, we first examined Nectin-4 expression in human EC tissues by using immunohistochemistry (IHC) assay and analyzed the clinical associations. Then the cellular studies in vitro and the nude mice tumor model in vivo were used to examine the regulatory role of Nectin-4 in the progression of EC.

Results

Our results demonstrated that over-expression of Nectin-4 in human EC tissues was significantly associated with tumor size, depth of tumor invasion, and poor prognosis of the patients. The intervention of Nectin-4 expression in EC cell lines showed that the increased Nectin-4 expression could significantly promote the cell viability, migration, invasion and tumor formation.

Conclusions

Our present data unveiled that Nectin-4 played an important role in tumor biology and could serve as a useful prognostic predictor of human EC.

NECTIN4 promotes papillary thyroid cancer cell proliferation, migration, and invasion and triggers EMT by activating AKT

Papillary thyroid cancer (PTC) is the most frequent type of malignant thyroid cancer, but its molecular mechanisms remain unknown. To better understand the tumorigenesis and progression of PTC, we conducted a comprehensive analysis of the whole-transcriptome resequencing of paired PTC and normal thyroid tissues. Nectin cell adhesion molecule 4 (NECTIN4) was significantly overexpressed in thyroid carcinoma compared with that in matched normal tissue. We also assessed the relation between the expression level of NECTIN4 and the clinicopathological features of PTC in The Cancer Genome Atlas database, and results showed that upregulated NECTIN4 is associated with lymph node metastasis (P<0.001) and tumor size (P=0.017). The biological function of NECTIN4 was also investigated by using the PTC cell lines TPC-1 and KTC-1. In vitro experiments demonstrated that NECTIN4 downregulation significantly inhibits the colony formation, proliferation, migration, and invasion of PTC cell lines. NECTIN4 could modulate the expression of epithelial-mesenchymal transition-related proteins via the PI3K/AKT pathway, and SC79, an AKT phosphorylation activator, could reverse the si-RNA knockdown effect. In addition, after the use of AKT inhibitors (LY 294,002), we found that SiRNA have similar effect with AKT inhibitors. Taking the results together, the current study shows that NECTIN4 has important biological implications in the tumorigenesis and metastasis of PTC and may be a potential therapeutic target for the disease.

Nanoquinacrine sensitizes 5-FU-resistant cervical cancer stem-like cells by down-regulating Nectin-4 via ADAM-17 mediated NOTCH deregulation

PURPOSE

Cervical cancer is a major cause of cancer-related death in women world-wide. Although the anti-metabolite 5-FU is widely used for its treatment, its clinical utility is limited due to the frequent occurrence of drug resistance during metastasis. Cancer stem-like cells (CSCs), present in the heterogeneous population of CC cells, are thought to contribute to this resistance. Nectin-4, a CSC marker, is known to play an important role in the cellular aggressiveness associated with metastatic CC. This study was designed to assess the role of Nectin-4 in the acquisition of 5-FU resistance by metastatic CC cells, including its relation to the NOTCH signalling pathway.

METHODS

5FU-resistant CC cell lines were deduced from ME-180 and SiHA cells by continuous exposure to a single concentration of 5-FU. Thymidylate synthase (TS) positive cells were isolated from the 5-FU resistant cells, after which a metastatic model was developed. The role of Nectin-4 in the sensitization of 5-FU resistant metastatic CC cells upon incubation with Nano-formulated Quinacrine (NQC) was investigated using multiple bioassays including MTT, FACS, ELISA, immunoflurescence, Western blotting, comet and in vivo plasmid-based short patch and long patch base excision repair assays.

RESULTS

We found that the expression level of Nectin-4, as well as that of other CSC markers (Oct-4, β-catenin, SOX2) and representative NOTCH signalling components (NOTCH-1, Jagged-1, γ-secretase, ADAM-17) were elevated in the 5-FU resistant metastatic cells compared to those in control cells. Increased nuclear translocation of Nectin-4 and increased proliferation and invasion rates were observed after culturing the metastatic cells under hypoxic conditions. Treatment with NQC inhibited the nuclear translocation of Nectin-4 and decreased the proliferation and invasion rates of the cells by inhibiting the induction of base excision repair (BER) pathway components and ADAM-17 expression levels. After combination treatment of Nectin-4 overexpressing metastatic CC cells with a specific ADAM-17 inhibitor (GW280264) and NQC, a decreased Nectin-4 expression, without alterations in BER and/or other NOTCH pathway components, was noted.

CONCLUSION

Our data indicate that Nectin-4 may play a prominent role in 5-FU resistance of metastatic CC cells and that NQC sensitizes these cells by Nectin-4 deregulation through ADAM-17 inhibition, a major component of the NOTCH signalling pathway.

Oncolytic Viruses for Canine Cancer Treatment

Oncolytic virotherapy has been investigated for several decades and is emerging as a plausible biological therapy with several ongoing clinical trials and two viruses are now approved for cancer treatment in humans. The direct cytotoxicity and immune-stimulatory effects make oncolytic viruses an interesting strategy for cancer treatment. In this review, we summarize the results of in vitro and in vivo published studies of oncolytic viruses in different phases of evaluation in dogs, using PubMed and Google scholar as search platforms, without time restrictions (to date). Natural and genetically modified oncolytic viruses were evaluated with some encouraging results. The most studied viruses to date are the reovirus, myxoma virus, and vaccinia, tested mostly in solid tumors such as osteosarcomas, mammary gland tumors, soft tissue sarcomas, and mastocytomas. Although the results are promising, there are issues that need addressing such as ensuring tumor specificity, developing optimal dosing, circumventing preexisting antibodies from previous exposure or the development of antibodies during treatment, and assuring a reasonable safety profile, all of which are required in order to make this approach a successful therapy in dogs.

Potential role for nectin-4 in the pathogenesis of pre-eclampsia: a molecular genetic study

BACKGROUND

Nectins are cell adhesion molecules that play a pivotal role in adherens junctions and tight junctions. Our previous study using whole-genome oligonucleotide microarrays revealed that nectin-4 was upregulated in pre-eclamptic placentas. We investigated the role of nectin-4 in the etiology of pre-eclampsia.

METHODS

We investigated the expression of nectin-4 using real-time RT-PCR, western blot and immunostaining. Additionally, we performed matrigel invasion assay and cytotoxicity assay using cells overexpressing the nectin-4.

RESULTS

NECTIN4 transcripts were elevated in pre-eclamptic placentas relative to uncomplicated pregnancies. Nectin-4 protein levels in pre-eclamptic placentas were higher on a semi-quantitative western blot. Nectin-4 was localized at the apical cell membrane in syncytiotrophoblast cells and not at the adherens junctions. Nectin-4 was also detected in cytotrophoblasts and a subset of cells in the decidua. Nectin-4 overexpressing trophoblast cells migrated normally in the matrix. However, Natural killer (NK) cells showed a strong cytotoxic effect against nectin-4 overexpressing trophoblast cells. No causative genetic variation was evident in the NECTIN4 gene from a pre-eclamptic placenta.

CONCLUSIONS

There are as yet unknown factors that induce nectin-4 overexpression in trophoblast cells that may contribute to abnormal placentation via an aberrant immune response and the onset of a pre-eclamptic pregnancy.

The soluble nectin-4 ecto-domain promotes breast cancer induced angiogenesis via endothelial Integrin-β4

Cancer stem cells secrete diffusible factors into the microenvironment that bind to specific endothelial cell receptors and initiate an angiogenesis cascade. Tumor-induced angiogenesis is an important parameter of tumorigenesis and is critical for tumor growth and metastasis. A pvrl-4 encoded gene, NECTIN-4, has potential roles in cancer cell growth and aggressiveness, and it is only expressed in cancer cells. There is evidence that nectin-4 plays a role in tumorigenesis, but the function of nectin-4 in tumor angiogenesis has lacked thorough evidence of mechanism. Using highly metastatic breast cancer cells and human umbilical vein endothelial cells (HUVECs), we have developed an excellent angiogenesis model and systematically studied the contribution of nectin-4 to angiogenesis. We also provide in-depth in ovo, in vivo and in vivo evidence that nectin-4 causes angiogenesis. Following hypoxia, metastatic breast cancer stem cells (mBCSCs) driven ADAM-17 expression causes the shedding of the ecto-domain of nectin-4 into the microenvironment, which physically interacts with integrin-β4 specifically on endothelial cells. This interaction promotes angiogenesis via the Src, PI3K, AKT, iNOS pathway and not by Phospho-Erk or NF-κβ pathways. In vitro, in ovo and in vivo induction and abrogation of an angiogenesis cascade in the presence and absence of the nectin-4 ecto-domain, respectively, confirms its role in angiogenesis. Thus, disrupting the interaction between nectin-4 ecto-domain and integrin-β4 may provide a means of targeting mBCSC-induced angiogenesis.

Macrophages and Dendritic Cells Are the Predominant Cells Infected in Measles in Humans

Characterization of human measles cases is essential in order to better assess the data generated in model systems of morbillivirus infection. To this end, we collected formalin-fixed tissue samples from 23 natural measles cases from different areas in the world and different phases of disease ranging from prodromal and acute measles to a persistent infection in an immunocompromised subject. We show that the vast majority of measles virus (MV)-infected cells in epithelia were intraepithelial immune cells that were, in most cases, positive for the CD11c myeloid cell marker. Small numbers of measles virus-infected cytokeratin-positive epithelial cells were also detected in bronchial and appendix epithelia. Dissolution and disruption of uninfected and MV-infected alveolar and bronchial epithelia were prominent features of the measles cases, especially in the established and late phases of the disease. In some instances, this was associated with the formation of MV-infected multinucleated giant cells which expressed CD11c and/or macrophage cell marker 68, a pathological feature also prominently observed in closely associated mucosa-associated lymphoid tissue. Collectively, these data show that resident and inflammatory infiltrating immune cells alter the architecture of respiratory tract epithelia and highlight the necessity for additional research into the function(s) and expression of nectin-4 in human tissues.IMPORTANCE We have brought together a unique collection of 23 human cases of measles infection and studied the types of cells that are infected. This work has not been done with modern technologies such as double labeling with antibodies and confocal microscopy in human cases primarily due to the fact that it is difficult to obtain the material because, fortunately, measles is fatal in only a very small fraction of infected patients. During the past decades, the receptors for measles virus have been elucidated and monkey models have been developed. We found that, in most cases, independently of whether the tissues were obtained early or later in the infection, the primary cell types that were infected were those of the immune system such as lymphocytes, macrophages, and dendritic cells. A very small number of epithelial cells were also found to be infected.

Computational Analysis of the Interaction Energies between Amino Acid Residues of the Measles Virus Hemagglutinin and Its Receptors

Measles virus (MV) causes an acute and highly devastating contagious disease in humans. Employing the crystal structures of three human receptors, signaling lymphocyte-activation molecule (SLAM), CD46, and Nectin-4, in complex with the measles virus hemagglutinin (MVH), we elucidated computationally the details of binding energies between the amino acid residues of MVH and those of the receptors with an ab initio fragment molecular orbital (FMO) method. The calculated inter-fragment interaction energies (IFIEs) revealed a number of significantly interacting amino acid residues of MVH that played essential roles in binding to the receptors. As predicted from previously reported experiments, some important amino-acid residues of MVH were shown to be common but others were specific to interactions with the three receptors. Particularly, some of the (non-polar) hydrophobic residues of MVH were found to be attractively interacting with multiple receptors, thus indicating the importance of the hydrophobic pocket for intermolecular interactions (especially in the case of Nectin-4). In contrast, the electrostatic interactions tended to be used for specific molecular recognition. Furthermore, we carried out FMO calculations for in silico experiments of amino acid mutations, finding reasonable agreements with virological experiments concerning the substitution effect of residues. Thus, the present study demonstrates that the electron-correlated FMO method is a powerful tool to search exhaustively for amino acid residues that contribute to interactions with receptor molecules. It is also applicable for designing inhibitors of MVH and engineered MVs for cancer therapy.

High expression of Nectin-4 is associated with unfavorable prognosis in gastric cancer

Nectins are Ca²⁺-independent immunoglobulin-like cell adhesion molecules that belong to a family of four members that function in a number of biological cellular activities. Nectin-4 is overexpressed in several types of human cancer; however, the functional and prognostic significance of Nectin-4 in gastric cancer (GC) remains unclear. In the present study, the reverse transcription-quantitative polymerase chain reaction and tissue microarray immunohistochemical analysis were used to investigate the expression of Nectin-4 in GC as well as its function in the prognosis of patients with GC. The results indicated that mRNA and protein expression of Nectin-4 were increased in tumor tissues compared with the matched non-tumor tissues. Expression of Nectin-4 was closely associated with differentiation (P=0.004), primary tumor (P=0.001), lymph node metastasis (P<0.001) and tumor-node-metastasis (TNM) stage (P<0.001). Positive Nectin-4 expression (P=0.001) and advanced TNM stage (P<0.001) were demonstrated to be associated with overall survival time in multivariate analyses. These results suggest that Nectin-4 may serve a significant function in GC and may serve as a novel clinic pathological biomarker and therapeutic target in GC.

Nectin-4 promotes gastric cancer progression via the PI3K/AKT signaling pathway

Nectin-4, a member of the Nectin family that includes 4 Ca+-independent immunoglobulin-like cell adhesion molecules, plays a carcinogenic role in multiple cancers. However, Nectin-4 expression and its biological role in gastric cancer (GC) remain largely unknown. In this study, quantitative real-time polymerase chain reaction, Western blotting, and immunohistochemistry were used to evaluate the expression patterns of Nectin-4 in GC specimens and cell lines. We observed that high expression of Nectin-4 in GC patients was associated with TNM stage and lymph node metastasis status, and poor prognosis. In addition, cell proliferation and cell migration assays in vitro and tumorigenicity in vivo were performed to observe the effects of up-regulation and down-regulation of Nectin-4 expression on GC cell phenotypes. In further studies, the PI3K/AKT signaling pathway was revealed to be involved in Nectin-4-mediated GC progression. These results demonstrated that Nectin-4 had a promoter effect on human GC cell growth and motility, indicating that Nectin-4 may serve as an effective therapeutic target in GC.

Immunovirotherapy with measles virus strains in combination with anti-PD-1 antibody blockade enhances antitumor activity in glioblastoma treatment

Background

Glioblastoma (GBM) is the most common primary malignant brain tumor and has a dismal prognosis. Measles virus (MV) therapy of GBM is a promising strategy due to preclinical efficacy, excellent clinical safety, and its ability to evoke antitumor pro-inflammatory responses. We hypothesized that combining anti- programmed cell death protein 1 (anti-PD-1) blockade and MV therapy can overcome immunosuppression and enhance immune effector cell responses against GBM, thus improving therapeutic outcome.

Methods

In vitro assays of MV infection of glioma cells and infected glioma cells with mouse microglia ± aPD-1 blockade were established to assess damage associated molecular pattern (DAMP) molecule production, migration, and pro-inflammatory effects. C57BL/6 or athymic mice bearing syngeneic orthotopic GL261 gliomas were treated with MV, aPD-1, and combination treatment. T2* weighted immune cell-specific MRI and fluorescence activated cell sorting (FACS) analysis of treated mouse brains was used to examine adaptive immune responses following therapy.

Results

In vitro, MV infection induced human GBM cell secretion of DAMP (high-mobility group protein 1, heat shock protein 90) and upregulated programmed cell death ligand 1 (PD-L1). MV infection of GL261 murine glioma cells resulted in a pro-inflammatory response and increased migration of BV2 microglia. In vivo, MV+aPD-1 therapy synergistically enhanced survival of C57BL/6 mice bearing syngeneic orthotopic GL261 gliomas. MRI showed increased inflammatory cell influx into the brains of mice treated with MV+aPD-1; FACS analysis confirmed increased T-cell influx predominantly consisting of activated CD8+ T cells.

Conclusions

This report demonstrates that oncolytic measles virotherapy in combination with aPD-1 blockade significantly improves survival outcome in a syngeneic GBM model and supports the potential of clinical/translational strategies combining MV with αPD-1 therapy in GBM treatment.

Cell-surface marker discovery for lung cancer

Lung cancer is the leading cause of cancer deaths in the United States. Novel lung cancer targeted therapeutic and molecular imaging agents are needed to improve outcomes and enable personalized care. Since these agents typically cannot cross the plasma membrane while carrying cytotoxic payload or imaging contrast, discovery of cell-surface targets is a necessary initial step. Herein, we report the discovery and characterization of lung cancer cell-surface markers for use in development of targeted agents. To identify putative cell-surface markers, existing microarray gene expression data from patient specimens were analyzed to select markers with differential expression in lung cancer compared to normal lung. Greater than 200 putative cell-surface markers were identified as being overexpressed in lung cancers. Ten cell-surface markers (CA9, CA12, CXorf61, DSG3, FAT2, GPR87, KISS1R, LYPD3, SLC7A11 and TMPRSS4) were selected based on differential mRNA expression in lung tumors vs. non-neoplastic lung samples and other normal tissues, and other considerations involving known biology and targeting moieties. Protein expression was confirmed by immunohistochemistry (IHC) staining and scoring of patient tumor and normal tissue samples. As further validation, marker expression was determined in lung cancer cell lines using microarray data and Kaplan–Meier survival analyses were performed for each of the markers using patient clinical data. High expression for six of the markers (CA9, CA12, CXorf61, GPR87, LYPD3, and SLC7A11) was significantly associated with worse survival. These markers should be useful for the development of novel targeted imaging probes or therapeutics for use in personalized care of lung cancer patients.

Oncogenic epithelial cell-derived exosomes containing Rac1 and PAK2 induce angiogenesis in recipient endothelial cells

The metastatic cascade describes the escape of primary tumour cells to distant secondary sites. Cells at the leading tumour edge are thought to undergo epithelial-mesenchymal transition (EMT), to enhance their motility and invasion for spreading. Whether EMT cells directly promote tumour angiogenesis, and the role of exosomes (30-150 nm extracellular vesicles) remains largely unknown. We examined the functional effects of exosomes from MDCK cells, MDCK cells stably expressing YBX1 (MDCK^YBX1, intermediate EMT), and Ras-transformed MDCK cells (21D1 cells, complete EMT). 2F-2B cell motility and tube formation (length and branching) was significantly increased following supplementation with MDCK^YBX1 or 21D1 exosomes, but not MDCK exosomes. Next, Matrigel™ plugs containing exosome-supplemented 2F-2B cells were subcutaneously injected into mice. Systemic perfusion was only observed for plugs supplemented with MDCK^YBX1 or 21D1 exosomes. Comparative proteomics revealed that 21D1 exosomes contained VEGF-associated proteins, while MDCK^YBX1 exosomes were enriched with activated Rac1 and PAK2. To validate, 2F-2B cells and HUVECs were pre-treated with PAK inhibitors prior to exosome supplementation. PAK inhibition nullified the effects of MDCK^YBX1 exosomes by reducing the tube length and branching to baseline levels. By contrast, the effects of 21D1 exosomes were not significantly decreased. Our results demonstrate for the first time that oncogenic cells undergoing EMT can communicate with endothelial cells via exosomes, and establish exosomal Rac1/PAK2 as angiogenic promoters that may function from early stages of the metastatic cascade.

Gene isoforms as expression-based biomarkers predictive of drug response in vitro

Next-generation sequencing technologies have recently been used in pharmacogenomic studies to characterize large panels of cancer cell lines at the genomic and transcriptomic levels. Among these technologies, RNA-sequencing enable profiling of alternatively spliced transcripts. Given the high frequency of mRNA splicing in cancers, linking this feature to drug response will open new avenues of research in biomarker discovery. To identify robust transcriptomic biomarkers for drug response across studies, we develop a meta-analytical framework combining the pharmacological data from two large-scale drug screening datasets. We use an independent pan-cancer pharmacogenomic dataset to test the robustness of our candidate biomarkers across multiple cancer types. We further analyze two independent breast cancer datasets and find that specific isoforms of IGF2BP2, NECTIN4, ITGB6, and KLHDC9 are significantly associated with AZD6244, lapatinib, erlotinib, and paclitaxel, respectively. Our results support isoform expressions as a rich resource for biomarkers predictive of drug response.

Targeting tumor multicellular aggregation through IGPR-1 inhibits colon cancer growth and improves chemotherapy

Adhesion to extracellular matrix (ECM) is crucially important for survival of normal epithelial cells as detachment from ECM triggers specific apoptosis known as anoikis. As tumor cells lose the requirement for anchorage to ECM, they rely on cell-cell adhesion 'multicellular aggregation' for survival. Multicellular aggregation of tumor cells also significantly determines the sensitivity of tumor cells to the cytotoxic effects of chemotherapeutics. In this report, we demonstrate that expression of immunoglobulin containing and proline-rich receptor-1 (IGPR-1) is upregulated in human primary colon cancer. Our study demonstrates that IGPR-1 promotes tumor multicellular aggregation, and interfering with its adhesive function inhibits multicellular aggregation and, increases cell death. IGPR-1 supports colon carcinoma tumor xenograft growth in mouse, and inhibiting its activity by shRNA or blocking antibody inhibits tumor growth. More importantly, IGPR-1 regulates sensitivity of tumor cells to the chemotherapeutic agent, doxorubicin/adriamycin by a mechanism that involves doxorubicin-induced AKT activation and phosphorylation of IGPR-1 at Ser220. Our findings offer novel insight into IGPR-1's role in colorectal tumor growth, tumor chemosensitivity, and as a possible novel anti-cancer target.

Prognostic role of Nectin-4 expression in luminal B (HER2 negative) breast cancer

Nectins are Ca2+-independent immunoglobulin (Ig) superfamily proteins that participate in the organization of epithelial and endothelial junctions and regulate several cellular activities including the entry of some viruses. Nectin-4 has recently been shown as a metastasis-associated protein in several cancers. In the following study, we have evaluated the expression of Nectin-4 inthe luminal B HER2 negative subtype breast cancer. The study group consisted of 147 patients presenting with primary unilateral breast carcinoma with no evidence of distant metastases. Nectin-4 protein expression was assessed by immunohistochemistry and the results were correlated with the clinical data using Kaplan-Meier curves, univariate and multivariate stepwise proportional-hazard analysis (Cox model). Nectin-4 overexpression was significantly correlated with the tumour size (p<0.05; Fisher's Exact Test), also Nectin-4 expression was negatively associated with overall survival, disease free survival and distant relapse free survival with the same significance (p<0,001; Kaplan-Meier, Cox model). We did not find statistically significant correlation between Nectin-4 and age, ER, PR, age, lymph node metastasis, tumour differentiation, histologicalsubtype and Ki-67proliferation index. We suggest that Nectin-4 is a relevant prognostic factor and a therapeutic target in luminalB (HER2 negative) breast cancer.

Nectin-4 is a breast cancer stem cell marker that induces WNT/β-catenin signaling via Pi3k/Akt axis

Nectin-4 is well known as a junction protein. Recent reports have implicated it in cancer, but there has been little exploration of its functional significance in metastasis and cancer stem cells. Here, using the breast cancer metastasis model system, we report Nectin-4 is a marker for breast cancer stem cells (BCSCs) and provide experimental evidence suggesting that it utilizes WNT/β-Catenin signaling via Pi3k/Akt axis for self renewal of BCSCs. In vitro, in vivo, ex vivo and clinical pathological data showed upregulated Nectin-4 in breast cancer metastasis and WNT/β-Catenin signaling. Nectin-4 depletion inhibited EMT, metastasis, invasion, and the WNT/β-Catenin pathway; conversely, Nectin-4 overexpression in null cells upregulated EMT and metastasis and also induced WNT/β-Catenin signaling via Pi3k/Akt axis, which in turn, controls cancer stem cell proliferation. Induced Nectin-4 was observed in breast tumor patient samples and in breast tumor metastases to axillary lymph nodes, which indicated that Nectin-4 is not only a BCSC marker but also a breast cancer metastasis marker. The current study provides clear evidence that Nectin-4 is a BCSC marker and is responsible for breast cancer metastasis.

Cap-dependent translational control of oncolytic measles virus infection in malignant mesothelioma

Malignant mesothelioma has a poor prognosis for which there remains an urgent need for successful treatment approaches. Infection with the Edmonston vaccine strain (MV-Edm) derivative of measles virus results in lysis of cancer cells and has been tested in clinical trials for numerous tumor types including mesothelioma. Many factors play a role in MV-Edm tumor cell selectivity and cytopathic activity while also sparing non-cancerous cells. The MV-Edm receptor CD46 (cluster of differentiation 46) was demonstrated to be significantly higher in mesothelioma cells than in control cells. In contrast, mesothelioma cells are not reliant upon the alternative MV-Edm receptor nectin-4 for entry. MV-Edm treatment of mesothelioma reduced cell viability and also invoked apoptotic cell death. Forced expression of eIF4E or translation stimulation following IGF-I (insulin-like growth factor 1) exposure strengthened the potency of measles virus oncolytic activity. It was also shown that repression of cap-dependent translation by treatment with agents [4EASO, 4EGI-1] that suppress host cell translation or by forcing cells to produce an activated repressor protein diminishes the strength of oncolytic viral efficacy.

Nectin spot: a novel type of nectin-mediated cell adhesion apparatus

Nectins are Ca(2+)-independent immunoglobulin (Ig) superfamily cell adhesion molecules constituting a family with four members, all of which have three Ig-like loops at their extracellular regions. Nectins play roles in the formation of a variety of cell-cell adhesion apparatuses. There are at least three types of nectin-mediated cell adhesions: afadin- and cadherin-dependent, afadin-dependent and cadherin-independent, and afadin- and cadherin-independent. In addition, nectins trans-interact with nectin-like molecules (Necls) with three Ig-like loops and other Ig-like molecules with one to three Ig-like loops. Furthermore, nectins and Necls cis-interact with membrane receptors and integrins, some of which are associated with the nectin-mediated cell adhesions, and play roles in the regulation of many cellular functions, such as cell polarization, movement, proliferation, differentiation, and survival, co-operatively with these cell surface proteins. The nectin-mediated cell adhesions are implicated in a variety of diseases, including genetic disorders, neural disorders, and cancers. Of the three types of nectin-mediated cell adhesions, the afadin- and cadherin-dependent apparatus has been most extensively investigated, but the examples of the third type of apparatus independent of afadin and cadherin are recently increasing and its morphological and functional properties have been well characterized. We review here recent advances in research on this type of nectin-mediated cell adhesion apparatus, which is named nectin spot.