The design of 8-hydroxyquinoline tetracyclic lactams as HIV-1 integrase strand transfer inhibitors.

A novel series of HIV-1 integrase strand transfer inhibitors were designed using the venerable two-metal binding pharmacophore model and incorporating structural elements from two different literature scaffolds. This manuscript describes a number of 8-hydroxyquinoline tetracyclic lactams with exceptional antiviral activity against HIV-1 and little loss of potency against the IN signature resistance mutations Q148K and G140S/Q148H.

Biological and Structural Characterization of Rotamers of C-C Chemokine Receptor Type 5 (CCR5) Inhibitor GSK214096.

We recently reported the discovery of preclinical CCR5 inhibitor GSK214096, 1 (J. Med. Chem. 2011, 54, 756). Detailed characterization of 1 revealed that it exists as a mixture of four separable atropisomers A-D. The two slow-interconverting pairs of rotamers A + B and C + D were separated and further characterized. HIV and CCR5-mediated chemotaxis data strongly suggest that the antiviral potency of 1 is due to rotamers A + B and not C + D. Furthermore, integrated UV, vibrational circular dichroism VCD and computational approach allowed to determine the M chirality in C + D (and P chirality in A + B). These findings imply additional avenues to be pursued toward new CCR5 antagonists.

Blockade of X4-tropic HIV-1 cellular entry by GSK812397, a potent noncompetitive CXCR4 receptor antagonist.

GSK812397 is a potent entry inhibitor of X4-tropic strains of HIV-1, as demonstrated in multiple in vitro cellular assays (e.g., in peripheral blood mononuclear cells [PBMCs] and a viral human osteosarcoma [HOS] assay, mean 50% inhibitory concentrations [IC50s]+/-standard errors of the means were 4.60+/-1.23 nM and 1.50+/-0.21 nM, respectively). The primary in vitro potency of GSK812397 was not significantly altered by the addition of serum proteins (2.55 [+/-0.12]-fold shift in the presence of human serum albumin and alpha-acid glycoprotein in the PBMC assay). Pharmacological characterization of GSK812397 in cell-based functional assays revealed it to be a noncompetitive antagonist of the CXCR4 receptor, with GSK812397 producing a concentration-dependent decrease in both an SDF-1-mediated chemotaxis and intracellular calcium release (IC50s were 0.34+/-0.01 nM and 2.41+/-0.50 nM, respectively). With respect to the antiviral activity of GSK812397, it was effective against a broad range of X4- and X4R5-utilizing clinical isolates. The potency and efficacy of GSK812397 were dependent on the individual isolate, with complete inhibition of infection observed with 24 of 30 isolates. GSK812397 did not show any detectable in vitro cytotoxicity and was highly selective for CXCR4, as determined using a wide range of receptors, enzymes, and transporters. Moreover, GSK812397 demonstrated acceptable pharmacokinetic properties and bioavailability across species. The data demonstrate that GSK812397 has antiviral activity against a broad range of X4-utilizing strains of HIV-1 via a noncompetitive antagonism of the CXCR4 receptor.

Mutation rate of the hepatitis C virus NS5B in patients undergoing treatment with ribavirin monotherapy.

BACKGROUND & AIMS: Error catastrophe from an increase in mutation rate may be a possible mechanism of action of ribavirin in chronic hepatitis C (CHC). We sought to evaluate the mutagenic potential of ribavirin in vivo and to determine if conserved regions of hepatitis C virus (HCV) NS5B are mutated during ribavirin therapy. METHODS: Thirty-one patients with CHC genotype 1 who participated in a randomized, placebo-controlled trial of ribavirin for 48 weeks were studied. After 48 weeks, patients on placebo were crossed-over to open-label ribavirin for 48 weeks. Viral RNA was extracted from paired, stored sera at day 0 and week 24 during the randomized phase and weeks 48, 52, and 72 during the cross-over phase. The entire NS5B region was sequenced and the mutation rates were calculated. RESULTS: An increase in mutation rate was observed after 4 weeks (4.4 x 10(-2) vs 2.1 x 10(-3) per site/y, P = .02) but not after 24 weeks (4.0 x 10(-3) vs. 5.5 x 10(-3) per site/y, P = .1) in patients who crossed over to ribavirin. Similarly, during the randomized phase no increase in the number of mutations or the mutation rate was observed at week 24 between the ribavirin- and placebo-treated patients 6.6 vs 4.3 x 10(-3) per site/y, respectively (P = .4). No mutations were observed in conserved regions of NS5B. CONCLUSIONS: Ribavirin therapy is associated with an early, transient increase in the mutation rate of HCV. Lethal mutagenesis and error catastrophe is unlikely to be the sole mechanism of action of ribavirin during therapy for CHC.

Disease progression in HIV-infected patients treated with stavudine vs. zidovudine.

BACKGROUND AND OBJECTIVES: This prospective, observational study compared disease progression and death in HIV-1 patients treated with stavudine vs. zidovudine in the Collaborations in HIV Outcomes Research/U.S. (CHORUS) cohort. METHODS: Patients with a first occurrence of CD4 count <500 cells/microL (n=3301) were grouped as: no nucleoside reverse transcriptase inhibitor (NRTI) use; other NRTI without stavudine or zidovudine; stavudine with no zidovudine, with or without other NRTIs; and zidovudine with no stavudine, with or without other NRTIs. The risk for death or disease progression was evaluated in unadjusted analyses and using a Cox proportional hazards model, adjusting for: study site, age, gender, race, route of HIV infection, previous AIDS-defining conditions, number of previous antiretroviral regiments, CD4 count, HIV-1 RNA, and treatment variables. Sensitivity analyses were conducted to determine the sensitivity of the results to major modeling assumptions. A landmark analysis was conducted to determine the absolute difference in time to event. RESULTS: During a median follow-up of 2.4 years, there were 57 deaths and 348 AIDS-defining conditions in 405 patients. Stavudine treatment compared with zidovudine resulted in a greater percentage of patients with AIDS-defining events (14.5 vs. 10.9%; P=.013), and an increased risk of disease progression (HR=1.30; 95% CI: 1.01,1.7; P=.04). This result was not sensitive to modeling assumptions. Landmark analysis demonstrated an absolute difference in time to 95% event-free survival of 2.7 months for those with a CD4< or =200 cells/microL and 11 months for those 6 months after model entry. CONCLUSIONS: In unadjusted and adjusted analyses of 3301 HIV-1 infected patients, stavudine containing combination therapy was associated with an increased risk of disease progression or death compared to therapy containing zidovudine. Most of the difference was attributable to new cases of wasting.

Pharmacodynamic effects of zidovudine 600 mg once/day versus 300 mg twice/day in therapy-naïve patients infected with human immunodeficiency virus.

STUDY OBJECTIVE: To compare the virologic activity of zidovudine monotherapy administered as 600 mg once/day versus 300 mg twice/day. DESIGN: Phase II, randomized (1:1), open-label study. SETTING: Thirteen medical centers in the United States. PATIENTS: Thirty-two antiretroviral-naive patients infected with human immunodeficiency virus (HIV). INTERVENTION: Patients were administered either zidovudine 600 mg every 24 hours (16 patients) or 300 mg every 12 hours (16 patients) for 13 days. MEASUREMENTS AND MAIN RESULTS: Plasma HIV-1 RNA concentration was measured daily. Study end points were between-group differences in change from baseline of log10-transformed HIV-1 RNA and in rates of viral load decline measured by the slope of HIV-1 RNA over time. At baseline, mean HIV-1 RNA was similar in the once/day and twice/day groups (4.33 and 4.40 log10 copies/ml, respectively). At day 14, a trend toward lower mean reduction in HIV-1 RNA from baseline was observed in the once/day group (-0.585, 95% confidence interval [CI] -0.728 to -0.442 log10 copies/ml) compared with the twice/day group (-0.849, 95% CI -1.067 to -0.630 log10 copies/ml, p=0.056). Viral load reduction also tended to be slower in the once/day group, as indicated by the smaller slope of viral load decline in the once/day group than in the twice/day group during days 1-14 (-0.045 vs -0.065 logic copies/ml/day, p=0.065). Both zidovudine regimens were similarly well tolerated. CONCLUSION: Zidovudine 600 mg once/day has antiviral activity, although less pronounced and more slowly achieved than that seen with zidovudine 300 mg twice/day. No differences were observed between the two treatment groups with respect to safety profile or tolerability

Compact quadruple therapy with the lamivudine/zidovudine combination tablet plus abacavir and efavirenz, followed by the lamivudine/zidovudine/abacavir triple nucleoside tablet plus efavirenz in treatment-naïve HIV-infected adults.

PURPOSE: To assess efficacy, safety, and adherence with compact quadruple therapy comprising one lamivudine 150-mg/zidovudine 300-mg tablet (COM) twice daily + one abacavir (ABC) 300-mg tablet twice daily + three efavirenz (EFV) 200-mg capsules at bedtime for 24 weeks, followed by one lamivudine 150-mg/zidovudine 300-mg/ABC 300-mg triple nucleoside tablet (TZV) twice daily + three EFV 200-mg capsules at bedtime for 24 weeks. METHOD: A pilot 48-week, prospective, open-label trial in which 38 antiretroviral-naïve HIV-infected adults (baseline median HIV-1 RNA 5.1 log(10) copies/mL, CD4+ cell count 285/microL) received the above treatment and were monitored regularly with respect to plasma HIV-1 RNA levels, CD4+ cell counts, T-cell receptor excision circles (TRECs), adherence, and adverse events. RESULTS: At Week 48, intent-to-treat, switch-included analysis showed plasma HIV-1 RNA levels <400 copies/mL in 100% (29/29) of patients and <50 copies/mL in 93% (27/29); 59% of patients who achieved <50 copies/mL had <3 copies/mL (16/27). Similar virologic suppression was observed in patients with baseline HIV-1 RNA above or below 100000 copies/mL. HIV-1 RNA and CD4+ cell counts changed from baseline by a median of -3.4 log(10) copies/mL and +172 cells/microL, respectively. One virologic failure occurred at Week 16. Median TRECs/100000 peripheral blood lymphocytes increased 6-fold between baseline and Week 48. Median adherence rates were consistently 100% by self-report and 94% by pill count. Grade 2-4 treatment-related adverse events included dreams (16%), nausea (13%), decreased white cells (8%), dizziness (8%), sleep disorders (8%), and malaise and fatigue (8%). A suspected ABC hypersensitivity reaction occurred in 8% (3/38) of patients. CONCLUSION: COM/ABC/EFV or TZV/EFV produced potent, durable virologic suppression and immunologic benefits, was associated with high adherence rates, and was generally well tolerated.

Effect of combination antiretroviral therapy on cerebrospinal fluid HIV RNA, HIV resistance, and clinical manifestations of encephalopathy.

OBJECTIVES: This study evaluated the effect of treatment with abacavir/lamivudine/zidovudine versus lamivudine/zidovudine on cerebrospinal fluid (CSF) human immunodeficiency virus (HIV) RNA and clinical manifestations of HIV encephalopathy in children. STUDY DESIGN: HIV-infected children 7 months to 10 years of age (n = 23) were studied. CSF and plasma were obtained at baseline and weeks 8, 16, and 48. Genotype analysis of HIV was attempted at baseline and week 48. Neurologic evaluations were performed at baseline and weeks 16, 32, and 48. RESULTS: At baseline, 83% of children had >2.00 log(10) copies/mL HIV RNA in CSF, but only 10% had HIV RNA measurable at week 48. Among children in whom paired genotyping of HIV was possible, 8 of 11 had identical patterns in both CSF and plasma at baseline, whereas at week 48, only 1 of 9 children had similar patterns. Neurologic abnormalities were observed in 83% of children at baseline but only 35% of children at week 48 (P =.004), suggesting a benefit of treatment. CONCLUSIONS: Antiretroviral therapy was associated with a decline in CSF HIV RNA and an improvement in neurologic status. The development of genotypic mutations was different in CSF and plasma, suggesting discordant viral evolution. These results suggest that antiretroviral treatment in children should include agents with activity in the CNS.