George J. Hanna

Low-level viremia persists for at least 7 years in patients on suppressive antiretroviral therapy

Residual viremia can be detected in most HIV-1-infected patients on antiretroviral therapy despite suppression of plasma RNA to <50 copies per ml, but the source and duration of this viremia is currently unknown. Therefore, we analyzed longitudinal plasma samples from 40 patients enrolled in the Abbott M97-720 trial at baseline (pretherapy) and weeks 60 to 384 by using an HIV-1 RNA assay with single-copy sensitivity. All patients were on therapy (lopinavir/ritonavir, stavudine, and lamivudine) with plasma HIV RNA <50 copies per ml by week 96 of the study and thereafter. Single-copy assay results revealed that 77% of the patient samples had detectable low-level viremia (≥1 copy per ml), and all patients had at least one sample with detectable viremia. A nonlinear mixed effects model revealed a biphasic decline in plasma RNA levels occurring over weeks 60 to 384: an initial phase of decay with a half-life of 39 weeks and a subsequent phase with no perceptible decay. The level of pretherapy viremia extrapolated for each phase of decay was significantly correlated with total baseline viremia for each patient (R2 = 0.27, P = 0.001 and R2 = 0.19, P < 0.005, respectively), supporting a biological link between the extent of overall baseline viral infection and the infection of long-lived reservoirs. These data suggest that low-level persistent viremia appears to arise from at least two cell compartments, one in which viral production decays over time and a second in which viral production remains stable for at least 7 years.

Genotypic Correlates of Phenotypic Resistance to Efavirenz in Virus Isolates from Patients Failing Nonnucleoside Reverse Transcriptase Inhibitor Therapy

ABSTRACT Efavirenz (also known as DMP 266 or SUSTIVA) is a potent nonnucleoside inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) activity and of HIV-1 replication in vitro and in vivo. Most patients on efavirenz-containing regimens have sustained antiviral responses; however, rebounds in plasma viral load have been observed in some patients in association with the emergence of mutant strains of HIV-1. Virus isolates from the peripheral blood mononuclear cells (PBMCs) of patients with such treatment failures, as well as recombinant viruses incorporating viral sequences derived from patient plasma, show reduced in vitro susceptibility to efavirenz in association with mutations in the RT gene encoding K103N, Y188L, or G190S/E substitutions. Patterns of RT gene mutations and in vitro susceptibility were similar in plasma virus and in viruses isolated from PBMCs. Variant strains of HIV-1 constructed by site-directed mutagenesis confirmed the role of K103N, G190S, and Y188L substitutions in reduced susceptibility to efavirenz. Further, certain secondary mutations (V106I, V108I, Y181C, Y188H, P225H, and F227L) conferred little resistance to efavirenz as single mutations but enhanced the level of resistance of viruses carrying these mutations in combination with K103N or Y188L. Viruses with K103N or Y188L mutations, regardless of the initial selecting nonnucleoside RT inhibitor (NNRTI), exhibited cross-resistance to all of the presently available NNRTIs (efavirenz, nevirapine, and delavirdine). Some virus isolates from nevirapine or delavirdine treatment failures that lacked K103N or Y188L mutations remained susceptible to efavirenz in vitro, although the clinical significance of this finding is presently unclear.

The tablet formulation of lopinavir/ritonavir provides similar bioavailability to the soft-gelatin capsule formulation with less pharmacokinetic variability and diminished food effect.

Lopinavir, an HIV protease inhibitor, is coformulated with ritonavir to enhance the bioavailability and pharmacokinetics of lopinavir. The original solid oral formulation of lopinavir/ritonavir, a soft-gelatin capsule (SGC), requires refrigerated storage, is taken as 6 capsules daily at the recommended adult dose, and is administered with food to maximize the bioavailability of lopinavir. Melt extrusion technology was used to produce a tablet formulation reducing the number of dosage units administered per day and simplifying storage requirements. Three studies assessed the bioavailability of tablet doses of lopinavir/ritonavir at 800/200 mg or 400/100 mg under different meal conditions compared with equal doses of the SGC after a moderate-fat meal. The tablet was bioequivalent to the SGC after a moderate-fat meal with respect to lopinavir and ritonavir areas under the concentration-time curve. Compared with the SGC formulation, the tablet formulation resulted in more consistent lopinavir and ritonavir exposures within and across studies and across meal conditions. The diminished food effect and decreased variability of the tablet are likely to result in more consistent lopinavir and ritonavir exposures, minimizing the likelihood of extreme high or low values compared with the SGC.

Patterns of Resistance Mutations Selected by Treatment of Human Immunodeficiency Virus Type 1 Infection with Zidovudine, Didanosine, and Nevirapine

Resistance mutations selected in reverse transcriptase (RT) by incompletely suppressive therapy with combination zidovudine and didanosine with or without nevirapine were identified in 141 human immunodeficiency virus type 1 isolates from peripheral blood mononuclear cells of 57 individuals in the AIDS Clinical Trials Group protocol 241. After prolonged treatment (16-48 weeks), the most common nevirapine-selected mutations were RT 181C (15/30 isolates [50%]), 190A (15/30 [50%]), and 101E (9/30 [30%]). RT 103N and 188L, which individually confer cross-resistance to all nonnucleoside RT inhibitors, were seen in a minority of viruses (6/30 [20%] and 4/30 [13%], respectively). Didanosine-resistance mutations arose rarely. A newly recognized mutation, RT 44D, was selected by the nucleosides. Two distinct zidovudine-resistance mutational patterns were noted. Mutations selected during treatment with zidovudine, didanosine, and nevirapine differed among individuals and changed over time. Resistance testing is necessary to identify which mutations are selected by nevirapine-containing combinations.

A once-daily lopinavir/ritonavir-based regimen provides noninferior antiviral activity compared with a twice-daily regimen.

Objective:To evaluate the safety and noninferiority and to explore the efficacy of administration of once-daily versus twice-daily lopinavir/ritonavir (LPV/r) in antiretroviral-naive HIV-1-infected subjects. Design:Randomized, open-label, multicenter, comparative study. Methods:One hundred ninety antiretroviral-naive subjects with plasma HIV-1 RNA level >1000 copies/mL and any CD4+ cell count were randomized to lopinavir/ritonavir at a dose of 800/200 mg administered once daily (n = 115) or lopinavir/ritonavir at a dose of 400/100 mg administered twice daily (n = 75). Subjects also received tenofovir disoproxil fumarate (TDF) at a dose of 300 mg and emtricitabine (FTC) at a dose of 200 mg administered once daily. Results:The median baseline plasma HIV-1 RNA level and CD4+ count were 4.8 log10 copies/mL and 216 cells/mm3, respectively. Before week 48, 20% (once daily) and 29% (twice daily) subjects discontinued. Virologic responses of the subjects through 48 weeks were comparable; 70% (once daily) and 64% (twice daily) achieved an HIV-1 RNA level <50 copies/mL by intent-to-treat, noncompleter = failure analysis. No subject demonstrated LPV or TDF resistance, but 3 subjects (2 in the once-daily group, 1 in the twice-daily group) demonstrated FTC resistance. Mean increases in CD4 count were similar. Diarrhea (16% in the once-daily group, 5% in the twice-daily group; P = 0.036) was the most common moderate or severe study drug-related adverse event. Conclusions:Through 48 weeks, a once-daily regimen of lopinavir/ritonavir + TDF + FTC appears to have similar virologic and immunologic responses in antiretroviral-naive subjects as the same regimen with lopinavir/ritonavir administered twice daily. Both regimens were relatively well tolerated, and no LPV or TDF resistance was observed.

A 96-Week Comparison of Lopinavir-Ritonavir Combination Therapy Followed by Lopinavir-Ritonavir Monotherapy versus Efavirenz Combination Therapy

Antiretroviral-naive HIV-1-infected volunteers received zidovudine/lamivudine plus either lopinavir/ritonavir (n=104) or efavirenz (n=51). Lopinavir/ritonavir-treated subjects demonstrating 3 consecutive monthly HIV-1 RNA levels <50 copies/mL started lopinavir/ritonavir monotherapy. In previous-failure=failure analysis, 48% (lopinavir/ritonavir) and 61% (efavirenz) maintained HIV-1 RNA at <50 copies/mL through week 96, (P= .17; 95% confidence interval [CI] for the difference, -29% to 4%); in noncompletion=failure analysis, 60% (lopinavir/ritonavir) and 63% (efavirenz) maintained HIV-1 RNA at <50 copies/mL at week 96 (P= .73; 95% CI for the difference, -19% to 13%). Significant sparing of peripheral lipoatrophy was noted in the lopinavir/ritonavir simplification strategy. This study has provided important information for future studies using treatment simplified to lopinavir/ritonavir monotherapy.

Clinical Use of Genotypic and Phenotypic Drug Resistance Testing to Monitor Antiretroviral Chemotherapy

Assays that detect antiretroviral drug resistance in human immunodeficiency virus have recently become available to clinicians. Phenotypic assays measure the drug susceptibility of the virus by determining the concentration of drug that inhibits viral replication in tissue culture. Genotypic assays determine the presence of mutations that are known to confer decreased drug susceptibility. Although each type of assay has specific advantages, limitations associated with these tests often complicate the interpretation of results. Several retrospective clinical trials have suggested that resistance testing may be useful in the assessment of the success of salvage antiretroviral therapy. Prospective, controlled trials have demonstrated that resistance testing improves short-term virological response. Resistance testing is currently recommended to help guide the choice of new drugs for patients after treatment has failed and for pregnant women. Resistance testing should also be considered for treatment-naïve patients, to detect transmission of resistant virus.

White Coat Compliance Limits the Reliability of Therapeutic Drug Monitoring in HIV-1-Infected Patients

Abstract Purpose: To analyze the extent of improved adherence preceding a clinic visit (”white coat compliance„) in a clinical trial and its potential impact on the utility of therapeutic drug monitoring (TDM). Method: In this randomized, open-label trial, 190 antiretroviral-naïve, HIV-1—infected subjects received lopinavir/ritonavir capsules, once or twice daily, with tenofovir DF and emtricitabine (both once daily) for 96 weeks. Lopinavir/ritonavir compliance was assessed using MEMS®. Results: 178 subjects (107 once daily, 71 twice daily) had plasma samples collected for lopinavir concentration resulting in 768 visits with pharmacokinetic (PK) assessment. The results were not used to provide feedback or recommend dose changes. For 239 (31%) of these visits, drug intake was perfect 1–3 days before PK sampling, whereas compliance during the remainder of the inter-PK visit period was ≤95%. This phenomenon was noted in 66% of subjects, more frequently among twice-daily than once-daily subjects (85% vs. 54%; p < .0001), and may have led to determination of “therapeutic” drug levels despite overall adherence ≤95%. The opposite phenomenon (>95% compliance reported during the inter-PK visit period, yet a dose missed the day before PK sampling) was observed for 1% of PK visits and clustered in 5% of subjects. Conclusions: In a substantial portion of visits and a majority of subjects, a white coat compliance pattern was observed. Drug concentration results obtained at these visits could deliver unreliable estimates of long-term drug exposure.

Seven-Year Efficacy of a Lopinavir/Ritonavir- Based Regimen in Antiretroviral-Naïve HIV-1-Infected Patients

Abstract Objective: Evaluate efficacy and tolerability of lopinavir/ritonavir (LPV/r) plus stavudine and lamivudine long term in antiretroviral-naïve patients. Design: Open-label follow-up of prospective, randomized, multicenter trial. Method: Antiretroviral-naïve HIV—infected subjects (N = 00) received of 3 doses of LPV/r plus stavudine and lamivudine for 48 weeks then received LPV/r soft-gel capsules 400/00 mg plus stavudine and lamivudine. After 6 years, subjects replaced stavudine with tenofovir. Results: At 7 years, by intent-to-treat analysis, 61 % had plasma HIV-RNA <400 copies/mL and 59% had < 50 copies/mL. Thirty-nine subjects discontinued treatment due to adverse events (n = 6), personal/other reasons (0), loss to follow-up (9), and noncompliance (4). Among 28 subjects qualifying for drug resistance testing, no protease inhibitor or stavudine resistance was observed and 4 showed lamivudine resistance. Most common drug-related moderate or severe adverse events were diarrhea (28%), nausea (6%), and abdominal pain (11 %). Subjects who received stavudine (median 6.6 years) and switched to tenofovir demonstrated significant improvements in total cholesterol (p = .009), triglycerides (p = .023), apolipoprotein C-III (p < .001 ), adiponectin (p = .008), fasting insulin (p = .04), and leptin (p = .03). Conclusion: LPV/r-based therapy demonstrated sustained efficacy with no protease inhibitor or stavudine resistance through 7 years in antiretroviral-naïve patients. Switching from stavudine to tenofovir resulted in significant improvements in multiple metabolic parameters.

Pharmacodynamics, safety, and pharmacokinetics of BMS-663068, an oral HIV-1 attachment inhibitor in HIV-1-infected subjects.

BACKGROUND BMS-663068 is a prodrug of the small-molecule inhibitor BMS-626529, which inhibits human immunodeficiency virus type 1 (HIV-1) infection by binding to gp120 and interfering with the attachment of virus to CD4+ T-cells. METHODS Fifty HIV-1-infected subjects were randomized to 1 of 5 regimen groups (600 mg BMS-663068 plus 100 mg ritonavir every 12 hours [Q12H], 1200 mg BMS-663068 plus 100 mg ritonavir every bedtime, 1200 mg BMS-663068 plus 100 mg ritonavir Q12H, 1200 mg BMS-663068 Q12H plus 100 mg ritonavir every morning, or 1200 mg BMS-663068 Q12H) for 8 days in this open-label, multiple-dose, parallel study. The study assessed the pharmacodynamics, pharmacokinetics, and safety of BMS-663068. RESULTS The maximum median decrease in plasma HIV-1 RNA load from baseline ranged from 1.21 to 1.73 log(10) copies/mL. Plasma concentrations of BMS-626529 were not associated with an antiviral response, while low baseline inhibitory concentrations and the minimum and average steady-state BMS-626529 plasma concentrations, when adjusted by the baseline protein binding-adjusted 90% inhibitory concentration (inhibitory quotient), were linked with antiviral response. BMS-663068 was generally well tolerated. CONCLUSIONS Administration of BMS-663068 for 8 days with or without ritonavir resulted in substantial declines in plasma HIV-1 RNA levels and was generally well tolerated. Longer-term clinical trials of BMS-663068 as part of combination antiretroviral therapy are warranted. Clinical Trials Registration.NCT01009814.