Combination antiretroviral therapy without a nucleoside reverse transcriptase inhibitor: experience from 334 patients in three cohorts

A lipid index for risk of hyperlipidemia caused by anti-retroviral drugs

HIV-associated lipodystrophy has been reported in people taking anti-retroviral therapy (ART). Lipodystrophy can cause cardiovascular diseases, affecting the quality of life of HIV-infected individuals. In this study, we propose a pharmacological lipid index to estimate the risk of hyperlipidemia caused by anti-retroviral drugs. Lipid droplets were stained in cells treated with anti-retroviral drugs and cyclosporin A. Signal intensities of lipid droplets were plotted against the drug concentrations to obtain an isodose of 10 μM of cyclosporin A, which we call the Pharmacological Lipid Index (PLI). The PLI was then normalized by EC50. PLI/EC50 values were low in early proteinase inhibitors and the nucleoside reverse transcriptase inhibitor, d4T, indicating high risk of hyperlipidemia, which is consistent with previous findings of hyperlipidemia. In contrast, there are few reports of hyperlipidemia for drugs with high PLI/EC50 scores. Data suggests that PLI/EC50 is a useful index for estimating the risk of hyperlipidemia.

Nucleoside-sparing antiretroviral regimens

Nucleoside reverse transcriptase inhibitors (NRTIs) were the first drugs approved for use as antiretroviral therapy in patients infected with HIV. Despite the introduction of other classes of antiretroviral drugs, they remain an important component of combination regimens as recommended by many treatment guidelines. They also continue to be used in prevention of disease from mother to child, postexposure prophylaxis, and more recently for preexposure prophylaxis. Unfortunately, the toxicities associated with this class of drugs can limit their use. Although NRTI-sparing regimens are not currently recommended for first-line therapy there is an increasing amount of data supporting their use in both treatment-naive and in treatment-experienced patients.

Polymeric nanoparticles containing combination antiretroviral drugs for HIV type 1 treatment

The use of combination antiretroviral nanoparticles (cART NPs) was investigated as a novel treatment approach for the inhibition of HIV-1 replication. We developed nanoparticles of biodegradable polymer, poly-(dl-lactide-co-glycolic acid; PLGA) containing efavirenz (EFV) and boosted lopinavir (lopinavir/ritonavir; LPV/r) by a high-pressure homogenization method. The method resulted in >79% drug entrapment efficiency for each of the three drugs. The average size of cART NPs was 138.3±55.4 nm as measured by dynamic light scanning, confirmed by scanning electron microscopy (SEM) with an average surface charge of -13.7±4.5. Lissamine-rhodamine-labeled fluorescent PLGA NPs exhibited efficient uptake in nonimmune (HeLa cells) and immune (H9 T cells) cells as measured by confocal microscopy. Cells treated with cART NPs resulted in minimal loss of cell viability over 28 days. Subcellular fractionation studies demonstrated that HIV-1-infected H9 monocytic cells treated with cART NPs contained significantly (p<0.05) higher nuclear, cytoskeleton, and membrane antiretroviral drug levels compared to cells treated with drug solutions alone. Finally, cART NPs efficiently inhibited HIV-1 infection and transduction. The IC50 for each of the three drugs in the cART NPs was <31 nM. These experiments demonstrate the efficacy of a novel PLGA NPs formulation for the delivery of cART to inhibit HIV-1 replication.

The pharmacokinetics of lersivirine (UK-453,061) and HIV-1 protease inhibitor coadministration in healthy subjects

OBJECTIVE

Lersivirine (UK-453,061) is a next-generation nonnucleoside reverse transcriptase inhibitor, active against wild-type HIV-1 and several nonnucleoside reverse transcriptase inhibitor-resistant strains. Four studies evaluated the pharmacokinetic (PK) interactions between lersivirine and various HIV-1 protease inhibitors.

METHODS

Four phase I trials were conducted to assess the PK of lersivirine when coadministered with lopinavir/ritonavir, darunavir/ritonavir, or atazanavir with/without ritonavir, and to examine the effects of lersivirine on the PK of atazanavir with/without ritonavir. PK data included the area under the plasma concentration-time profile from time zero to the end of the dosing interval (AUC24), maximum plasma concentration (Cmax), minimum plasma concentration (Cmin, C24, or Ctrough), and time to Cmax (Tmax). Safety was assessed by recording adverse events, vital signs, and laboratory data.

RESULTS

Coadministration of lersivirine with lopinavir/ritonavir, darunavir/ritonavir, or atazanavir/ritonavir decreased mean plasma lersivirine AUC24 by 43%, 22%, and 19%, respectively. Atazanavir had no effect on lersivirine exposure, except for a 16% decrease in lersivirine C24. Lersivirine had no effect on atazanavir AUC24 or Cmax, although Ctrough was reduced by 18% in the absence of ritonavir.

CONCLUSIONS

Lersivirine exposure was reduced when coadministered with ritonavir-boosted protease inhibitors; a dose adjustment may be warranted. Unboosted atazanavir had no effect on lersivirine exposure, except for a small decrease in lersivirine C24. Lersivirine had no effect on atazanavir (with/without ritonavir) exposure, except for a decrease in Ctrough. Caution should be applied when unboosted atazanavir is coadministered with lersivirine. Coadministration of lersivirine with lopinavir/ritonavir, darunavir/ritonavir, or atazanavir with/without ritonavir seems to be generally well tolerated.

Viral suppression rates in salvage treatment with raltegravir improved with the administration of genotypic partially active or inactive nucleoside/tide reverse transcriptase inhibitors

BACKGROUND

Nucleoside reverse transcriptase inhibitors (NRTIs) are often administered in salvage therapy even if genotypic resistance tests (GRTs) indicate high-level resistance, but little is known about the benefit of these additional NRTIs.

METHODS

The effect of <2 compared with 2 NRTIs on viral suppression (HIV-1 RNA < 50 copies/mL) at week 24 was studied in salvage patients receiving raltegravir. Intent-to-treat and per-protocol analyses were performed; last observation carried forward imputation was used to deal with missing information. Logistic regressions were weighted to create a pseudopopulation in which the probability of receiving <2 and 2 NRTIs was unrelated to baseline factors predicting treatment response.

RESULTS

One-hundred thirty patients were included, of whom 58.5% (n = 76) received <2 NRTIs. NRTIs were often replaced by other drug classes. Patients with 2 NRTIs received less additional drug classes compared with patients with <2 NRTIs [median (IQR): 1 (1-2) compared with 2 (1-2), P Wilcoxon < 0.001]. The activity of non-NRTI treatment components was lower in the 2 NRTIs group compared with the <2 NRTIs group [median (IQR) genotypic sensitivity score: 2 (1.5-2.5) compared with 2.5 (2-3), P Wilcoxon < 0.001]. The administration of <2 NRTIs was associated with a worse viral suppression rate at week 24. The odds ratios were 0.34 (95% confidence interval: 0.13 to 0.89, P = 0.027) and 0.19 (95% confidence interval: 0.05 to 0.79, P = 0.023) when performing the last observation carried forward and the per-protocol approach, respectively.

CONCLUSIONS

Our findings showed that partially active or inactive NRTIs contribute to treatment response, and thus the use of 2 NRTIs in salvage regimens that include raltegravir seems warranted.

Antiretroviral release from poly(DL-lactide-co-glycolide) nanoparticles in mice

OBJECTIVES

Free ritonavir, lopinavir and efavirenz injected intraperitoneally were compared with antiretroviral (AR) nanoparticles (NPs).

METHODS

This is a prospective study in BALB/c mice comparing the pharmacokinetics of free drugs with AR NPs. All animals received free drugs or AR NPs (20 mg/kg) in PBS. In vitro replication assays were used for determination of the anti-HIV efficacy of NP formulations. At specific times (free drugs 0.08, 0.125, 0.25, 0.33, 1, 2 and 3 days; AR NPs 0.125, 0.33, 1, 2, 4, 7, 14, 21, 28, 35 and 42 days) mice were euthanized and serum and organs were harvested for determination of AR concentrations by HPLC. Single treatment of monocyte-derived macrophages (MDMs) infected with HIV-1(ada) compared AR NPs (0.005-0.05 mg/mL) with free efavirenz or lopinavir/ritonavir (0.01-0.1 mg/mL), blank NPs and controls. Results are presented as means ± SEM.

RESULTS

Serum free AR drug concentrations peaked 4 h post-injection (ritonavir 3.9 ± 3.05, lopinavir 3.4 ± 2.5 and efavirenz 1.8 ± 0.63 µg/mL) and were eliminated by 72 h. Poly(dl-lactide-co-glycolide) NP animals had detectable ritonavir, lopinavir and efavirenz concentrations in all tissues for 28 days. Treatment of MDMs with AR NPs resulted in sustained inhibition of HIV-1(ada) replication.

CONCLUSIONS

AR drug concentrations from NPs are sustained for 28 days in vivo and anti-HIV inhibition was comparable to that of free drugs in vitro and could be a sustained treatment for delivery of AR drugs.

Mathematical modelling of the impact of haematopoietic stem cell-delivered gene therapy for HIV

BACKGROUND

Gene therapy represents a new treatment paradigm for HIV that is potentially delivered by a safe, once-only therapeutic intervention.

METHODS

Using mathematical modelling, we assessed the possible impact of autologous haematopoietic stem cell (HSC) delivered, anti-HIV gene therapy. The therapy comprises a ribozyme construct (OZ1) directed to a conserved region of HIV-1 delivered by transduced HSC (OZ1+HSC). OZ1+HSC contributes to the CD4+ T lymphocyte and monocyte/macrophage cell pools that preferentially expand under the selective pressure of HIV infection. The model was used to predict the efficacy of OZ1 in a highly active antiretroviral therapy (HAART) naïve individual and a HAART-experienced individual undergoing two structured treatment operations. In the standard scenario, OZ1+HSC was taken as 20% of total body HSC.

RESULTS

For a HAART-naïve individual, modelling predicts a reduction of HIV RNA at 1 and 2 years post-OZ1 therapy of 0.5 log(10) and 1 log(10), respectively. Eight years after OZ1 therapy, the CD4+ T-lymphocyte count was 271 cells/mm(3) compared to 96 cells/mm(3) for an untreated individual. In a HAART-experienced individual HIV RNA was reduced by 0.34 log(10) and 0.86 log(10) at 1 and 2 years. The OZ1 effect was maximal when both CD4+ T lymphocytes and monocytes/macrophages were protected from successful, productive infection by OZ1.

CONCLUSIONS

The modelling indicates a single infusion of HSC cell-delivered gene therapy can impact on HIV viral load and CD4 T-lymphocyte count. Given that gene therapy avoids the complications associated with HAART, there is significant potential for this approach in the treatment of HIV.

Nucleoside and nucleotide HIV reverse transcriptase inhibitors: 25 years after zidovudine

Twenty-five years ago, nucleoside analog 3'-azidothymidine (AZT) was shown to efficiently block the replication of HIV in cell culture. Subsequent studies demonstrated that AZT acts via the selective inhibition of HIV reverse transcriptase (RT) by its triphosphate metabolite. These discoveries have established the first class of antiretroviral agents: nucleoside and nucleotide reverse transcriptase inhibitors (NRTIs). Over the years that followed, NRTIs evolved into the main component of antiretroviral drug combinations that are now used for the treatment of all populations of HIV infected patients. A total of thirteen NRTI drug products are now available for clinical application: eight individual NRTIs, four fixed-dose combinations of two or three NRTIs, and one complete fixed-dose regimen containing two NRTIs and one non-nucleoside RT inhibitor. Multiple NRTIs or their prodrugs are in various stages of clinical development and new potent NRTIs are still being identified through drug discovery efforts. This article will review basic principles of the in vitro and in vivo pharmacology of NRTIs, discuss their clinical use including limitations associated with long-term NRTI therapy, and describe newly identified NRTIs with promising pharmacological profiles highlighting those in the development pipeline. This article forms part of a special issue of Antiviral Research marking the 25th anniversary of antiretroviral drug discovery and development, volume 85, issue 1, 2010.

Current and future antiretroviral treatment options in paediatric HIV infection

Because of a lack of prevention policies or problems in implementing prevention of mother-to-child transmission (P-MTCT), most of the 1500 daily new HIV infections in children aged<15 years are caused by MTCT. Fifteen percent of all HIV-infected individuals are children, but the vast majority lack access to highly active antiretroviral therapy (HAART), which can drastically reduce morbidity and mortality. There are 22 antiretroviral drugs currently approved by the US FDA for use in the treatment of HIV-infected adults and adolescents, but only 12 of these drugs are approved for use in children. Antiretroviral drugs belong to four major classes: nucleoside and nucleotide analogue reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), protease inhibitors and fusion inhibitors. According to international guidelines developed by organizations including WHO, the Paediatric European Network for Treatment of AIDS (PENTA) and the US National Institutes of Health (US-NIH), the treatment of choice for HIV-infected children and adults is a combination of two NRTIs (backbone treatment) plus a third potent agent from a different class, either an NNRTI or a ritonavir-boosted protease inhibitor. There are specific challenges in treating HIV-infected children, including uncertainty about the best time to start treatment, the need for more paediatric formulations, the lack of pharmacokinetic studies for new drugs, and incomplete dosing guidelines. Furthermore, the most appropriate regimen for an individual child depends on a variety of factors, including the age of the child; the availability of appropriate drug formulations; the potency, complexity and toxicity of the drug regimen; the home situation; the child and caregiver's ability to adhere to the regimen; and the child's antiretroviral treatment history. In addition, antiretroviral drugs are not licensed for all age groups and the drugs are often not affordable. This review describes NNRTI and protease inhibitors as key components of first- and second-line antiretroviral therapy (ART), focusing on the rationale for choosing an NNRTI- versus protease inhibitor-based regimen based on the results of available phase II and III studies. Some of the new agents available for children as second-line and salvage therapy both on- and off-label are also discussed. The drug regimens described in this review are relevant to clinicians in developed and developing countries. The availability of new, potent compounds with different resistance and toxicity profiles may represent an alternative option to interclass switching and could redefine ART strategy, including the option of first-line NRTI-sparing regimens.