Effect of Anti-CD4 Antibody UB-421 on HIV-1 Rebound after Treatment Interruption.

Background: Administration of a single broadly neutralizing human immunodeficiency virus (HIV)-specific antibody to HIV-infected persons leads to the development of antibody-resistant virus in the absence of antiretroviral therapy (ART). It is possible that monotherapy with UB-421, an antibody that blocks the virus-binding site on human CD4+ T cells, could induce sustained virologic suppression without induction of resistance in HIV-infected persons after analytic treatment interruption.

Methods: We conducted a nonrandomized, open-label, phase 2 clinical study evaluating the safety, pharmacokinetics, and antiviral activity of UB-421 monotherapy in HIV-infected persons undergoing analytic treatment interruption.

Effect of scavenger receptor class B type I antagonist ITX5061 in patients with hepatitis C virus infection undergoing liver transplantation.

Hepatitis C virus (HCV) entry inhibitors have been hypothesized to prevent infection of the liver after transplantation. ITX5061 is a scavenger receptor class B type I antagonist that blocks HCV entry and infection in vitro. We assessed the safety and efficacy of ITX5061 to limit HCV infection of the graft.

Successful anti-scavenger receptor class B type I (SR-BI) monoclonal antibody therapy in humanized mice after challenge with HCV variants with in vitro resistance to SR-BI-targeting agents.

Unlabelled: Hepatitis C virus (HCV)-induced endstage liver disease is currently a major indication for liver transplantation. After transplantation the donor liver inevitably becomes infected with the circulating virus. Monoclonal antibodies (mAbs) against the HCV coreceptor scavenger receptor class B type I (SR-BI) inhibit HCV infection of different genotypes, both in cell culture and in humanized mice.

Safety and antiviral activity of the HCV entry inhibitor ITX5061 in treatment-naive HCV-infected adults: a randomized, double-blind, phase 1b study.

Background: Hepatitis C virus (HCV) entry involves scavenger receptor B1 (SRB1). In vitro, SRB1 inhibition by ITX5061 impedes HCV replication.

Methods: Multicenter study to assess safety/activity of ITX5061 in previously untreated, noncirrhotic, HCV genotype 1 infected adults.

ITX 5061 quantitation in human plasma with reverse phase liquid chromatography and mass spectrometry detection.

Background: ITX 5061 is a highly potent small molecule inhibitor of scavenger receptor-B1, an integral transmembrane protein that is found in liver cells and is actively involved in the transport of HCV into hepatocytes. Currently, ITX 5061 is being investigated in monoinfected hepatitis C patients in a proof-of-concept clinical trial carried out by the AIDS Clinical Trial Group (ACTG).

Methods: To provide quantitative results in human plasma for pharmacokinetic analysis, an assay for ITX 5061 was validated.

Discovery of ITX 4520: a highly potent orally bioavailable hepatitis C virus entry inhibitor.

The manuscript reports an identification of a highly potent, orally bioavailable hepatitis C virus entry inhibitor through optimization of a previously reported class of molecules (1) that were not stable in the rat plasma. Compound 39 (ITX 4520) exhibited an excellent PK profile in both rats and dogs with good oral exposure, half-life and oral bioavailability. The compound is also well-tolerated in the preliminary in vivo toxicity studies and has been selected as a pre-clinical candidate for our HCV clinical pipeline.

A plant-derived flavonoid inhibits entry of all HCV genotypes into human hepatocytes.

Background & Aims: Interferon-based therapies for hepatitis C virus (HCV) infection are limited by side effects and incomplete response rates, particularly among transplant recipients. We screened a library of plant-derived small molecules to identify HCV inhibitors with novel mechanisms.

Methods: We isolated phenolic compounds from Marrubium peregrinum L (Lamiaceae).

Evaluation of ITX 5061, a scavenger receptor B1 antagonist: resistance selection and activity in combination with other hepatitis C virus antivirals.

ITX 5061 is a scavenger receptor B1 antagonist that has entered phase 1 clinical trials in hepatitis C virus (HCV)-infected humans. We evaluated ITX 5061 in combination with interferon-α, ribavirin, and HCV protease and polymerase inhibitors in a genotype 2a infectious virus system. ITX 5061 is a potent inhibitor of HCV replication and is additive to synergistic with interferon-α, ribavirin, BILN2061, VX950, VX1, and 2'-C-methyladenosine.

Discovery of highly potent small molecule Hepatitis C Virus entry inhibitors.

Novel, highly potent small molecule HCV entry inhibitors are reported. The SAR exploration of a hit molecule identified from screening of a compound library led to the identification of highly potent compounds with IC(50) values of <5 nM in the tissue culture HCV infectious assay.

Neutralizing antibody-resistant hepatitis C virus cell-to-cell transmission.

Hepatitis C virus (HCV) can initiate infection by cell-free particle and cell-cell contact-dependent transmission. In this study we use a novel infectious coculture system to examine these alternative modes of infection. Cell-to-cell transmission is relatively resistant to anti-HCV glycoprotein monoclonal antibodies and polyclonal immunoglobulin isolated from infected individuals, providing an effective strategy for escaping host humoral immune responses.

Small molecule scavenger receptor BI antagonists are potent HCV entry inhibitors.

Background And Aims: ITX 5061 is a clinical stage small molecule compound that promotes high-density lipoprotein (HDL) levels in animals and patients by targeting the scavenger receptor BI protein pathway. Since SR-BI is a known co-receptor for HCV infection, we evaluated these compounds for their effects on HCV entry.

Methods: We obtained ITX 5061 and related compounds to characterize their interaction with SR-BI and effects on HCV entry and infection.

Targeting HCV entry for development of therapeutics.

Recent progress in defining the molecular mechanisms of Hepatitis C Virus (HCV) entry affords the opportunity to exploit new viral and host targets for therapeutic intervention. Entry inhibitors would limit the expansion of the infected cell reservoir, and would complement the many replication inhibitors now under development. The current model for the pathway of entry involves the initial docking of the virus onto the cell surface through interactions of virion envelope and associated low density lipoproteins (LDL) with cell surface glycosaminoglycans and lipoprotein receptors, followed by more specific utilization with other hepatocyte membrane proteins: Scavenger Receptor Class B type 1 (SR-BI), CD81, Claudin 1 (CLDN1) and Occludin (OCLN).

Hepatitis C virus infection of neuroepithelioma cell lines.

Background & Aims: Hepatitis C virus (HCV) establishes chronic infections in 3% of the world's population. Infection leads to progressive liver disease; hepatocytes are the major site of viral replication in vivo. However, chronic infection is associated with a variety of extrahepatic syndromes, including central nervous system (CNS) abnormalities.

A method for detecting and preventing negative RNA interference in preparation of lentiviral vectors for siRNA delivery.

The lentiviral vector is a useful tool for delivery of hairpin siRNA (shRNA) into mammalian cells. However, the efficiency of this system for carrying double-stranded siRNA (dsRNA) has not been explored. In this study we cloned the two forms of siRNA-coding sequence, a palindromic DNA with a spacer loop for shRNA and a double-stranded DNA with opposing Pol III promoters for dsRNA, into lentiviral DNA vectors, and compared their viral vector production yields.

Pyrvinium targets the unfolded protein response to hypoglycemia and its anti-tumor activity is enhanced by combination therapy.

We identified pyrvinium pamoate, an old anthelminthic medicine, which preferentially inhibits anchorage-independent growth of cancer cells over anchorage-dependent growth (approximately 10 fold). It was also reported by others to have anti-tumor activity in vivo and selective toxicity against cancer cells under glucose starvation in vitro, but with unknown mechanism. Here, we provide evidence that pyrvinium suppresses the transcriptional activation of GRP78 and GRP94 induced by glucose deprivation or 2-deoxyglucose (2DG, a glycolysis inhibitor), but not by tunicamycin or A23187.

Screening of small-molecule compounds as inhibitors of HCV entry.

The hepatitis C virus (HCV) has infected some 170 million people worldwide, and is expected to pose a significant medical problem for the foreseeable future. No vaccine is presently available, and the current antiviral therapies (pegylated interferon-alpha and ribavirin) are characterized by limited efficacy, high costs, and substantial side effects. Initiation of infection requires attachment of the HCV virus to the cell surface followed by viral entry and represents a critical determinant of tissue tropism and pathogenesis.

Comparisons of RNAi approaches for validation of human RNA helicase A as an essential factor in hepatitis C virus replication.

A major issue of current virology concerns the characterization of cellular proteins that operate as functional components of the viral multiplication process. RNAi is a powerful tool to elucidate gene functions. In this study three RNAi approaches (transient transfection, stable transduction and inducible RNAi) were assessed to validate human RNA helicase A (RHA) as an essential factor in hepatitis C virus (HCV) replication.

Toxicity and intraocular properties of a novel long-acting anti-proliferative and anti-angiogenic compound IMS2186.

Purpose: To investigate the intraocular properties and toxicity of IMS2186, a small molecule developed as an anti-choroidal neovascularization (anti-CNV) drug.

Materials And Methods: Cellular toxicity and mechanism of action was tested on cell lines in vitro. Intraocular studies used rabbits for drug dissolution as well as toxicity and rats for the treatment study as well as the toxicity confirmation study.

Oncolytic virotherapy as a personalized cancer vaccine.

Oncolytic virotherapy has demonstrated multimodal antitumor mechanisms in both preclinical and clinical settings for cancer treatment, including antitumor immunity. Compared with conventional immunotherapy, oncolytic viruses have the advantages of simultaneous cytoreduction and conferring personalized anticancer immunity, but without the need of personalized manufacture. Additionally, oncolytic viruses can be further engineered to delete immunosuppressive viral components and to insert transgenes that enhance antitumor immunity.

Biochemical characterization of genetic mutations of GPR56 in patients with bilateral frontoparietal polymicrogyria (BFPP).

Bilateral frontoparietal polymicrogyria (BFPP) is a rare genetic disease characterized by cortical malformation associated with GPR56 mutations of frameshift, splicing, and point mutations (Science 303:2033). All the missense point mutations are located in the regions predicted to be exposed at the cell surface, e.g.

Isoginkgetin enhances adiponectin secretion from differentiated adiposarcoma cells via a novel pathway involving AMP-activated protein kinase.

Adiponectin is an anti-diabetic hormone secreted by adipocytes. Circulating adiponectin levels are lower in obese and type II diabetic patients than in healthy people. Weight loss or thiazolidinedione treatment increases plasma adiponectin levels.

A more efficient RNAi inducible system for tight regulation of gene expression in mammalian cells and xenograft animals.

Two types of tetracycline-controlled inducible RNAi expression systems have been developed that generally utilize multiple tetracycline operators (TetOs) or repressor fusion proteins to overcome the siRNA leakiness. Here, we report a novel system that overexpresses the tetracycline repressor (TetR) via a bicistronic construct to control siRNA expression. The high level of TetR expression ensures that the inducible promoter is tightly bound, with minimal basal transcription, allowing for regulation solely dependent on TetR rather than a TetR fusion protein via a more complicated mechanism.

Orphan G protein-coupled receptor GPR56 plays a role in cell transformation and tumorigenesis involving the cell adhesion pathway.

GPR56 is an orphan G protein - coupled receptor, mutations of which have recently been associated with bilateral frontoparietal polymicrogyria, a rare neurologic disease that has implications in brain development. However, no phenotype beyond central nervous system has yet been described for the GPR56-null mutations despite abundant GPR56 expression in many non - central nervous system adult tissues. In the present study, we show that higher GPR56 expression is correlated with the cellular transformation phenotypes of several cancer tissues compared with their normal counterparts, implying a potential oncogenic function.

Ribozyme technology for cancer gene target identification and validation.

Ribozymes are naturally occurring RNAs with catalytic activities including cis- or trans- cleavage of RNA at predefined sequence sites. This activity has been exploited for specific gene inactivation in cells during the last two decades, and ribozymes have been important functional genomics tools, especially in the pre-RNAi era. It has also been broadly applied in drug target identification and validation in pharmaceutical R&D.