Characterization of clinical envelopes with lack of sensitivity to the HIV-1 inhibitors temsavir and ibalizumab.

Previous data suggest a lack of cross-resistance between the gp120-directed attachment inhibitor temsavir (active moiety of fostemsavir) and the CD4-directed post-attachment inhibitor ibalizumab. Recently, analysis of HIV-1 envelopes with reduced sensitivity to both inhibitors was undertaken to determine whether they shared genotypic correlates of resistance. Sequences from 2 envelopes with reduced susceptibility to both agents were mapped onto a temsavir-bound gp120 structure.

Week 240 Efficacy and Safety of Fostemsavir Plus Optimized Background Therapy in Heavily Treatment-Experienced Adults with HIV-1.

Introduction: Efficacy and safety of the attachment inhibitor fostemsavir + optimized background therapy (OBT) were evaluated through 48 and 96 weeks in the phase 3 BRIGHTE trial in heavily treatment-experienced (HTE) adults failing their current antiretroviral regimen. Here, we report 240-week efficacy and safety of fostemsavir + OBT in adults with multidrug-resistant human immunodeficiency virus (HIV)-1 in BRIGHTE.

Methods: Heavily treatment-experienced adults failing their current regimen entered the randomized cohort (RC; 1-2 fully active antiretrovirals available) or non-randomized cohort (NRC; no fully active antiretrovirals available) and received open-label fostemsavir + OBT (starting Day 8 in RC and Day 1 in NRC).

Week 96 Genotypic and Phenotypic Results of the Fostemsavir Phase 3 BRIGHTE Study in Heavily Treatment-Experienced Adults Living with Multidrug-Resistant HIV-1.

In the phase 3 BRIGHTE study in heavily treatment-experienced adults with multidrug-resistant HIV-1, fostemsavir plus optimized background therapy (OBT) resulted in sustained rates of virologic suppression through 96 weeks. HIV-1 RNA <40 copies/mL was achieved in 163/272 (60%) Randomized Cohort (RC) participants (with 1 or 2 remaining approved fully active antiretrovirals) and 37/99 (37%) Non-randomized Cohort (NRC) participants (with 0 fully active antiretrovirals). Here we report genotypic and phenotypic analyses of HIV-1 samples from 63/272 (23%) RC participants and 49/99 (49%) NRC participants who met protocol-defined virologic failure (PDVF) criteria through Week 96.

Clinical evidence for a lack of cross-resistance between temsavir and ibalizumab or maraviroc.

Background: Temsavir (TMR), the active agent of the gp120-directed attachment inhibitor fostemsavir (FTR), the CD4-directed attachment inhibitor ibalizumab (IBA), and the CCR5 antagonist maraviroc (MVC) are antiretroviral agents that target steps in HIV-1 viral entry. Although mechanisms of inhibition of the three agents are different, it is important to understand whether there is potential for cross-resistance between these agents, as all involve interactions with gp120.

Methods: Envelopes derived from plasma samples from participants in the BRIGHTE study who experienced protocol-derived virologic failure (PDVF) and were co-dosed with FTR and either IBA or MVC were analyzed for susceptibility to the agents.

Prevalence of gp160 polymorphisms known to be related to decreased susceptibility to temsavir in different subtypes of HIV-1 in the Los Alamos National Laboratory HIV Sequence Database.

Background: Fostemsavir, a prodrug of the gp120-directed attachment inhibitor temsavir, is indicated for use in heavily treatment-experienced individuals with MDR HIV-1. Reduced susceptibility to temsavir in the clinic maps to discrete changes at amino acid positions in gp160: S375, M426, M434 and M475.

Objectives: To query the Los Alamos National Laboratory (LANL) HIV Sequence Database for the prevalence of polymorphisms at gp160 positions of interest.

Susceptibility of global HIV-1 clinical isolates to fostemsavir using the PhenoSense® Entry assay.

Background: Fostemsavir is a prodrug of a first-in-class HIV-1 attachment inhibitor, temsavir, that binds to gp120 and blocks attachment to the host-cell CD4 receptor, preventing entry and infection of the target cell. Previous studies using a limited number of clinical isolates showed that there was intrinsic variability in their susceptibility to temsavir.

Objectives: Here, an analysis was performed using all clinical isolates analysed in the Monogram Biosciences PhenoSense® Entry assay as part of the development programme.

Safety and efficacy of the HIV-1 attachment inhibitor prodrug fostemsavir in heavily treatment-experienced individuals: week 96 results of the phase 3 BRIGHTE study.

Background: Fostemsavir, a prodrug of the first-in-class attachment inhibitor, temsavir, is indicated for heavily treatment-experienced individuals with multidrug-resistant HIV-1. We previously reported superior efficacy of fostemsavir versus placebo in the randomised cohort of the BRIGHTE study after 8-day functional monotherapy (primary endpoint); here we report planned interim analyses through week 96.

Methods: BRIGHTE (NCT02362503) is an ongoing multicentre, two-cohort, phase 3 trial, done at 108 centres in 22 countries.

Fostemsavir in Adults with Multidrug-Resistant HIV-1 Infection.

Background: Among some patients with human immunodeficiency virus type 1 (HIV-1) infection who have undergone multiple antiretroviral therapies and have limited options for treatment, new classes of antiretroviral drugs with novel mechanisms of action are needed. Fostemsavir is the prodrug of temsavir, a first-in-class investigational HIV-1 attachment inhibitor.

Methods: In this ongoing phase 3 trial in 23 countries, we enrolled patients with multidrug-resistant HIV-1 infection in two cohorts, according to their remaining treatment options.

Safety, efficacy, and dose response of the maturation inhibitor GSK3532795 (formerly known as BMS-955176) plus tenofovir/emtricitabine once daily in treatment-naive HIV-1-infected adults: Week 24 primary analysis from a randomized Phase IIb trial.

GSK3532795 (formerly known as BMS-955176) is a second-generation maturation inhibitor targeting a specific Gag cleavage site between capsid p24 and spacer peptide 1 of HIV-1. Study 205891 (previously AI468038) investigated the efficacy, safety, and dose response of GSK3532795 in treatment-naive, HIV-1-infected participants. Study 205891 (NCT02415595) was a Phase IIb, randomized, active-controlled, double-blind, international trial.

A Phenotypic High-Throughput Screen with RSV-Infected Primary Human Small Airway Epithelial Cells (SAECs).

Respiratory syncytial virus (RSV) is a commonly occurring pathogen that can cause severe disease in children, the elderly, and immunocompromised individuals with a large, unmet clinical need. We developed a high-throughput, primary cell-based antiviral RSV assay to enable identification of small molecules using cytopathic effect (CPE) as a phenotypic end point. To provide increased biological relevance, we developed our assay with primary human small airway epithelial cells (SAECs), which originate from known sites of RSV infection and replication instead of a more traditional immortalized cell line.

Discovery of novel P3-oxo inhibitor of hepatitis C virus NS3/4A serine protease.

A novel series of P3 oxo-modified macrocyclic hepatitis C virus NS3/4A serine protease inhibitor was designed, synthesized and biologically evaluated. The hydroxy-substituted inhibitor 10 demonstrated high potency in genotype 1a and 1b replicon and in the panel of HCV protease mutants. Interestingly, the t-butyl carbonate analog 9c, while not the most potent one in this series, exhibited a virtually flat potency profile in the panel of HCV protease mutants, thus providing opportunity for further optimization.

GSK983: a novel compound with broad-spectrum antiviral activity.

GSK983, a novel tetrahydrocarbazole, inhibits the replication of a variety of unrelated viruses in vitro with EC(50) values of 5-20 nM. Both replication of the adenovirus Ad-5 and the polyoma virus SV-40, and episomal maintenance of human papillomaviruses (HPV) and Epstein-Barr virus (EBV) are susceptible to GSK983. The compound does not inhibit all viruses; herpes simplex virus (HSV-1), human immunodeficiency virus (HIV), and lytic replication of EBV were not susceptible at concentrations below 1 microM.

Potent inhibitors of HIV-1 integrase display a two-step, slow-binding inhibition mechanism which is absent in a drug-resistant T66I/M154I mutant.

Two-metal binding HIV-1 integrase inhibitors (INIs) are potent inhibitors of HIV-1 in vitro and in patients. We report here for the first time the kinetics of inhibition of integrase-catalyzed strand transfer. First, the IC(50) values for each of six structurally distinct INIs decreased when a preincubation was included: S-1360 (1.

The naphthyridinone GSK364735 is a novel, potent human immunodeficiency virus type 1 integrase inhibitor and antiretroviral.

The naphthyridinone GSK364735 potently inhibited recombinant human immunodeficiency virus type 1 (HIV-1) integrase in a strand transfer assay (mean 50% inhibitory concentration +/- standard deviation, 8 +/- 2 nM). As expected based on the structure of the drug, it bound competitively with another two-metal binding inhibitor (Kd [binding constant], 6 +/- 4 nM). In a number of different cellular assays, GSK364735 inhibited HIV replication with potency at nanomolar concentrations (e.

The 5' untranslated region of GB virus B shows functional similarity to the internal ribosome entry site of hepatitis C virus.

Since its characterization in 1995, there has been increasing interest in the significance of GB virus B (GBV-B) due to its close phylogenetic relationship to hepatitis C virus (HCV). The genome of GBV-B is similar in length and organization to that of HCV and the two viruses share sequence similarity in their 5' untranslated regions (5'UTR). A secondary structure model of the GBV-B 5'UTR has been proposed by comparative sequence analysis with HCV.