Maraviroc (UK-427,857; brand-named Selzentry, or Celsentri outside the U.S) is a selective CCR5 antagonist with potent anti-human immunodeficiency virus type 1 (HIV-1) activity and favorable pharmacological properties. Maraviroc is the product of a medicinal chemistry effort initiated following identification of an imidazopyridine CCR5 ligand from a high-throughput screen of the Pfizer compound file. Selzentry, in combination with other antiretroviral agents, is indicated for adult patients infected with only CCR5-tropic HIV-1. This indication is based on analyses of plasma HIV-1 RNA levels in two controlled trials of SELZENTRY in treatment-experienced subjects and one trial in treatment-naive subjects. Maraviroc selectively binds to the human chemokine receptor CCR5 present on the cell membrane, preventing the interaction of HIV-1 gp120 and CCR5 necessary for CCR5-tropic HIV-1 to enter cells. CXCR4-tropic and dual-tropic HIV-1 entry is not inhibited by maraviroc. Antiviral Activity in Cell Culture Maraviroc inhibits the replication of CCR5-tropic laboratory strains and primary isolates of HIV-1 in models of acute peripheral blood leukocyte infection. The mean EC50 value (50% effective concentration) for maraviroc against HIV-1 group M isolates (subtypes A to J and circulating recombinant form AE) and group O isolates ranged from 0.1 to 4.5 nM (0.05 to 2.3 ng per mL) in cell culture. When used with other antiretroviral agents in cell culture, the combination of maraviroc was not antagonistic with NNRTIs (delavirdine, efavirenz, and nevirapine), NRTIs (abacavir, didanosine, emtricitabine, lamivudine, stavudine, tenofovir, zalcitabine, and zidovudine), or protease inhibitors (amprenavir, atazanavir, darunavir, indinavir, lopinavir, nelfinavir, ritonavir, saquinavir, and tipranavir). Maraviroc was not antagonistic with the HIV fusion inhibitor enfuvirtide. Maraviroc was not active against CXCR4-tropic and dual-tropic viruses (EC50 value greater than 10 µM). The antiviral activity of maraviroc against HIV-2 has not been evaluated. Maraviroc can cause serious, life-threatening side effects such as, liver problems, skin reactions, and allergic reactions.

Cenicriviroc (also referred to as TBR-652 and TAK-652) is an orally active, potent inhibitor of ligand binding to C-C chemokine receptor type 2 (CCR2) and C-C chemokine receptor type 5 (CCR5). Cenicriviroc does not inhibit ligand binding to CCR1 (an alternative target of CCR5 ligands). The mean half-life in healthy volunteers is 35 to 40 hours, which allows daily dosing of the drug. Due to its CCR5 blocking activity, Cenicriviroc has initially been tested as a drug against CCR5-tropic HIV infection. In a double-blind placebo-controlled trial involving 54 HIV infected participants, Cenicriviroc monotherapy at different doses (25, 50, 75, 100, or 150 mg) led to a dose-dependent reduction in HIV-1 RNA levels and concomitant increases in circulating levels of the CCR2 ligand monocyte chemoattractant protein 1 (MCP-1, or CCL2), suggesting potent CCR2 and CCR5 inhibition in vivo. According to clinical trials, Cenicriviroc is a very safe drug with a wide therapeutic range and fairly low pharmacokinetic variability. In animal models of liver diseases, Cenicriviroc potently inhibits macrophage accumulation in the liver and ameliorates fibrosis. In a phase 2b clinical trial on 289 patients with NASH and fibrosis, Cenicriviroc consistently demonstrated liver fibrosis improvement after 1 year of therapy and had an excellent safety profile.

DAPTA (D-ala-peptide T-amide) is a synthetic peptide that prevents HIV entry by blocking binding of HIV gp120 protein with CCR5 receptor. In a small clinical study of internasal formulation of DAPTA in long-term infected HIV patients, administration of DAPTA led to decrease in the amount of virus isolated from white blood cells, an increase in gamma-interferon secreting T-cells in the absense of drug-related toxicity. In another clinical study DAPTA in combination with antiretroviral therapy reduced the peripheral (plasma and serum) viral load, but did not reduce the CSF viral load.

Vicriviroc or SCH 417690 is a potent and selective antagonist of the CCR5 receptor. vicriviroc binds specifically to the CCR5 receptor and prevents infection of target cells by CCR5-tropic HIV-1 isolates. In antiviral assays, vicriviroc showed potent, broad-spectrum activity against genetically diverse and drug-resistant HIV-1 isolates and was consistently more active than SCH-C in inhibiting viral replication. This compound demonstrated synergistic anti-HIV activity in combination with drugs from all other classes of approved antiretrovirals. Competition binding assays revealed that vicriviroc binds with higher affinity to CCR5 than SCH-C. Functional assays, including inhibition of calcium flux, guanosine 5'-[35S]triphosphate exchange, and chemotaxis, confirmed that vicriviroc acts as a receptor antagonist by inhibiting signaling of CCR5 by chemokines. Finally, vicriviroc demonstrated diminished affinity for the human ether a-go-go related gene transcript ion channel compared to SCH-C, suggesting a reduced potential for cardiac effects. Vicriviroc represented a promising new candidate for the treatment of HIV-1 infection. Vicriviroc for HIV treatment was previously in Phase III studies but has since been discontinued.

TAK-779 is a selective antagonist of CCR5 receptor, which was initially developed by Takeda for the treatment of HIV infection. However, the development was terminated due to poor oral bioavailability. Also, TAK-779 demonstrated the ability to protect the brain against focal cerebral ischemia in mice.

UCB35625 is a potential inhibitor of chemokine/eosinophil interactions. UCB35625 is a trans-isomer of a compound J113863, which was originally identified by scientists at Banyu Pharmaceutical Company as a candidate small molecule chemokine receptor antagonist. UCB35625 initially identified as CCR1 and CCR3 antagonists also bind to CCR2 and CCR5 and act as full agonist, partial agonist or antagonist according to the nature of the receptor and the signaling pathway investigated. UCB35625 shows promise as a lead compound for the design of future therapeutics, which may be of use in the treatment of allergic inflammatory diseases such as asthma and also the blockade of viral entry by HIV strains that utilize CCR3.

J 113863 is a potent and high selective CKR-1 (CCR1) and CKR-3 (CCR3) chemokine receptor antagonist, which is also behaved as a full agonist of CCR2 and as a very partial agonist of CCR5. This compound was investigated for the treatment of multiple sclerosis and rheumatoid arthritis, but the status of these studies are not known.