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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Enfuvirtide (T-20) is a novel antiretroviral agent that blocks HIV-1 cell fusion. A 28-day randomized dose-comparison study was conducted to determine the safety, pharmacokinetics, and antiviral activity of enfuvirtide in 78 HIV-infected adults, most with extensive treatment experience. Patients received enfuvirtide, added to a failing regimen, either by continuous subcutaneous infusion (CSI: 12.5, 25, 50 or 100 mg/day) or by subcutaneous (SC) injection (50 or 100 mg twice daily). Dose-related decreases in viral load were observed, with a maximum mean reduction from baseline of 1.6 log(10) copies/ml (p< 0.001) seen in the 100 mg bid SC group. Most responses diminished by 28 days. Plasma pharmacokinetics and antiviral responses were more consistent for SC injection than for CSI because of technical difficulties experienced with CSI. Injection site reactions were common but generally mild. These results indicate that enfuvirtide is a promising new therapeutic agent for HIV-infected patients, including those with prior antiretroviral treatment.
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PMID:The safety, plasma pharmacokinetics, and antiviral activity of subcutaneous enfuvirtide (T-20), a peptide inhibitor of gp41-mediated virus fusion, in HIV-infected adults. 1216 74

Despite the overall success of antiretroviral medications in reducing the morbidity and mortality associated with HIV infection, many patients on treatment suffer progressive disease due to intolerance or the development of resistant viral strains. Consequently, considerable research focuses on the development of new classes of antiretroviral agents with mechanisms of action different to the current classes. Enfuvirtide (T-20, pentafuside, Fuzeon), the first drug of a new class of antiretroviral medications known as fusion inhibitors, blocks the fusion of the virus particle with the host target cell. The viral entry process begins with the attachment of viral surface glycoprotein gp120 to the host cell CD4 and chemokine receptor sites. Viral gp41 then undergoes a conformational change enabling fusion of both membranes, a critical step in the viral life cycle. Enfuvirtide is a synthetic peptide that binds to gp41, preventing the conformational change required for membrane fusion. Based on potent in vitro activity, a Phase I clinical trial of intravenous enfuvirtide was conducted that demonstrated a substantial decline in HIV plasma viral load in the highest dose group and no serious adverse effects. Phase II trials evaluated regimens of both continuous subcutaneous infusions and intermittent subcutaneous injections. Intermittent injections were pharmacokinetically superior to continuous infusions and were associated with fewer administration difficulties. For some subjects who added enfuvirtide monotherapy to an already failing regimen, the beneficial effect on viral load reduction appeared short-lived, suggesting the development of resistance. Two large randomised clinical trials comparing "optimised background" (best available, individualised regimens based on patient history and resistance assays) versus optimised background plus enfuvirtide have recently shown a significant virological advantage (approximately 1 log(10) difference from controls) at 24 weeks. In all trials to date, very few significant adverse effects have been seen--minor injection site reactions are frequent, but rarely treatment limiting. Based on these studies, enfuvirtide will likely play a significant role in the treatment of patients with limited treatment options.
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PMID:Enfuvirtide. 1245 43

The most significant new information about anti-HIV drugs offered in Barcelona concerned those drugs that are either already available or which will soon be available. This includes new information about T-20 (now called enfuvirtide or Fuzeon) and atazanavir--two drugs which will likely be approved within the next six months. Another new drug likely to be approved soon is FTC (Coviracil), a close relative of 3TC (lamivudine, Epivir), though its importance is less certain than that of enfuvirtide and atazanavir. Important new information was also released about tenofovir (Viread), a drug approved by the FDA late in 2001. Equally important were new observations about some older drugs, particularly the combination of ddI and d4T. Many comparative studies of different drug combinations were also reported, offering new information about the relative value of a number of treatment strategies.
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PMID:Anti-HIV drug updates--three drugs on the near horizon. 1264 72

Infection by human immunodeficiency virus type 1 (HIV-1) has been associated with increased cell death of both infected and bystander cells. The envelope glycoprotein complex appears to play an active role in HIV-induced death of bystander cells. We quantified cell-to-cell fusion, single cell death and membrane lipid mixing in cocultures of effector, HIV-1 envelope-expressing cells with peripheral blood mononuclear cells or purified CD4 T lymphocytes from HIV-negative donors, in the presence or the absence of the fusion inhibitor enfuvirtide (T-20, pentafuside, Fuzeon). T-20, which blocks gp41-dependent virus-cell fusion, showed a complete and dose-dependent inhibition of syncytium formation in cocultures of envelope-expressing cells with uninfected cells. Similarly, T-20 totally abrogated death of single bystander CD4 T cells with an IC50 of 0.04 microg/ml. Membrane lipid mixing, as a measure of interaction between envelope-expressing cells and CD4 cells, was also dose-dependently inhibited by T-20. Moreover, effector cells chronically infected with a T-20-resistant virus recovered the ability to induce bystander cell death in the presence of the drug, supporting the role of gp41 in single cell death. In conclusion, T-20 is able to protect CD4 T cells from envelope presentation with a dual effect: inhibition of virus replication and blockade of HIV-1 envelope-induced cell death of bystander CD4 T cells. Protection of cells prior to infection from HIV envelope-dependent bystander effect could lead to a better immune restoration of HIV-1-infected patients that are treated with T-20.
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PMID:Anti-HIV-1 activity of enfuvirtide (T-20) by inhibition of bystander cell death. 1274 28

Despite the success of combination HAART in improving the clinical prognosis of HIV-infected patients, therapeutic options are limited for many patients, particularly those with extensive treatment experience. Resistance, cross-resistance, and toxicity combine to threaten the durability of antiviral response, necessitating the development of novel agents. The HIV life cycle has many potential targets for inhibition in addition to the current reverse transcriptase and protease targets. These include the HIV integrase, nucleocapsid, and Tat proteins and the viral entry process. Entry inhibitors can be classified as attachment, coreceptor, and fusion inhibitors, according to the stage in the entry process at which they act. Most advanced in development of these is the fusion inhibitor enfuvirtide. Enfuvirtide is a potent inhibitor of HIV fusion whose novel mechanism of action and extracellular nature mean that it will induce limited cross-resistance to currently approved antiretrovirals and fewer toxicities.
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PMID:New classes of HIV drugs on the horizon. A review of the presentation at the satellite symposium "New hope: advancing care in HIV infection" at the 15th annual Association of Nurses in AIDS Care conference, November 2002. 1276 59

Enfuvirtide (T-20) is the lead compound of the new class of antiretroviral drugs called fusion inhibitors. T-20 resistance-associated mutations located in the heptad repeat 1 (HR-1) domain of gp41 have been described in vitro and in clinical trials. In this study, the authors investigated the primary genotypic T-20 resistance in subtype B and non-B HIV-1 strains from patients at the beginning of their follow-up in the Luxembourg HIV Cohort as well as the emergence of primary resistance to T-20 in patients who had long-term infection with subtype B HIV-1 strains. HR-1 fragments including the gp41 amino acid 36-45, T-20-sensitive region were screened for amino acid variation. No classic T-20 resistance-associated mutations were identified in subtype B or non-B isolates. However, several uncommon mutations were found at residues 37, 39, and 42 for subtype B isolates and at residue 42 for a subtype non-B isolate. The results indicate that primary genotypic T-20 resistance seems to be rare in HIV-1, regardless of subtype or prior antiretroviral therapy (excluding fusion inhibitors). However, episodic variation within HR-1 can occur and needs further phenotypic evaluation in accurate fusion inhibitor resistance assays.
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PMID:Uncommon mutations at residue positions critical for enfuvirtide (T-20) resistance in enfuvirtide-naive patients infected with subtype B and non-B HIV-1 strains. 1279 44

The large-scale commercial production of a 36-amino-acid peptide by chemical synthesis has been demonstrated in the development of enfuvirtide (T-20 or Fuzeon), a first-in-class membrane fusion inhibitor for the treatment of HIV. The rationale behind route selection and the scale-up of the process used to manufacture enfuvirtide are discussed.
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PMID:Large-scale manufacture of peptide therapeutics by chemical synthesis. 1281 83

The replicative cycle of the human immunodeficiency virus (HIV) can be interrupted at several stages. Until recently only the viral reverse transcriptase and protease were the only enzymes targeted by antiretroviral agents. However, the first HIV entry inhibitor (T-20, Enfuvirtide, Fuseon) to be used in humans has been approved by the Food and Drug Administration (FDA). The HIV entry process is considered as an attractive target for chemotherapeutic intervention, as blocking HIV entry into its target cell leads to suppression of viral infectivity, replication and the cytotoxicity induced by virus-cell contacts. HIV-1 entry into target cells is a multistep process: virus attachment is initiated by the binding of trimeric envelope glycoprotein gp120 complexes on the virions to glycosylated T-cell surface receptor (CD4) and HIV GPCR coreceptors (CCR5 or CXCR4) leading to envelope glycoprotein gp41-dependent fusion-pore formation and membrane fusion. A number of compounds are being developed to specifically target each of these steps leading to virus entry and some compounds have reached early clinical development. Conversely, agents such as the CCR5 antagonist Tak-779 and the CXCR4 antagonist AMD3100 are not longer being thought as relevant anti-HIV agents but have given way to new analogues with improved properties. This review summarizes the current state of HIV entry inhibitors, their mechanisms of action and their therapeutic value against HIV infection and AIDS.
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PMID:Virus entry as a target for anti-HIV intervention. 1287 Nov 11

The development of mechanistic insight into the process by which HIV enters host cells has revealed a panoply of targets that offer considerable potential as sites for pharmacological intervention. The gp120/gp41 protein complex, expressed on the virion surface, mediates HIV entry by a process initiated by the engagement of the host cell receptor CD4. Subtle conformational changes triggered by this interaction expose elements of gp120 to the seven-transmembrane, G protein-coupled chemokine receptors CCR5 or CXCR4 expressed on host cells, a contact that relieves constraints imposed on gp41 by gp120. This leads to a major conformational rearrangement of gp41, which results in the insertion of the fusion peptide into the host cell membrane and the assembly of the amino terminus heptad repeat into a trimeric form that is subsequently recognized by the carboxy terminal heptad repeat. The latter process leads to juxtaposition of the viral and host cell membranes, a prelude to fusion. The most prominent strategies and targets that are actively being exploited as drug discovery opportunities are inhibition of the attachment of HIV to host cells, blockade of chemokine receptors and interference with the function of gp41. Inhibitors of each of these steps in the HIV entry process with potential clinical relevance are reviewed in the context of their status in the drug development process. The most significant entity to emerge from this area of research to date is enfuvirtide, a 36-amino acid derivative that interferes with the function of gp41. Enfuvirtide is the first HIV entry inhibitor to be granted a license for marketing (it was approved in the US and Europe in March 2003), and its introduction portends the beginning of what promises to be an exciting new era of HIV therapy.
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PMID:Inhibitors of the entry of HIV into host cells. 1295 8

Enfuvirtide is a novel antiretroviral that blocks HIV-1 cell fusion and viral entry. This Phase II, controlled, open-label, randomized, multicentre dose-ranging trial explored the safety, antiviral activity and pharmacokinetics of enfuvirtide, administered by subcutaneous (s.c.) injection, in 71 HIV-1-infected, protease inhibitor-experienced, non-nucleoside reverse transcriptase inhibitor (NNRTI)-naive adults for 48 weeks. Study participants were randomized to receive enfuvirtide at a deliverable dose of 45, 67.5 or 90 mg twice daily; the 45 mg twice daily dose required 2 injections/day, while the higher doses required 4 injections/day. A background oral antiretroviral (ARV) regimen of abacavir (300 mg twice daily), amprenavir (1200 mg twice daily), ritonavir (200 mg twice daily) and efavirenz (600 mg once daily) was provided with enfuvirtide. A control group received the background ARV regimen alone. All potential participants underwent an HIV genotype at screen to ensure a homogenous population and to exclude patients with evidence of genotypic resistance to NNRTIs. Overall, the tolerability of the combination of abacavir, amprenavir, ritonavir, efavirenz and enfuvirtide was generally comparable to control through 48 weeks. No enfuvirtide dose-dependent adverse events (AEs) were observed across treatment groups. Injection site reactions (ISRs) occurred at least once in 68.5% of the enfuvirtide-treated population, and most ISRs were mild to moderate in severity, with no apparent dose relationship. Excluding ISRs, the most common treatment-emergent AEs were nausea, diarrhoea, dizziness and fatigue; with no clinically significant differences in the incidence of AEs observed between the control and enfuvirtide groups. Each treatment group benefited from ARV therapy, with a trend of increasing antiviral and immunological activity associated with increasing enfuvirtide dose. At 48 weeks, the median HIV-1 RNA change from baseline for the ITT population was -2.24 log10 copies/ml for the combined enfuvirtide groups compared with -1.87 log10 copies/ml for the control group. In addition, 54.9% of patients in the enfuvirtide group achieved HIV-1 RNA < or = 400 copies/ml versus 36.8% of patients in the control group. These results indicate that enfuvirtide has a favourable safety profile and is a promising new antiviral agent for HIV-infected patients who have been on previously failing ARV regimens.
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PMID:A controlled Phase II trial assessing three doses of enfuvirtide (T-20) in combination with abacavir, amprenavir, ritonavir and efavirenz in non-nucleoside reverse transcriptase inhibitor-naive HIV-infected adults. 1451 96


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