Intensification of a triple-nucleoside regimen with tenofovir or efavirenz in HIV-1-infected patients with virological suppression

Comparative effectiveness of tenofovir in HIV-infected treatment-experienced patients: systematic review and meta-analysis

BACKGROUND

Antiretroviral therapy (ART) regimens for HIV infection are frequently changed. We conducted a systematic review of randomized trials (RCTs) on the benefits and harms of switching to tenofovir disoproxil fumarate (TDF)-based regimens in ART-experienced patients.

METHODS

We included RCTs in HIV-infected adults comparing switching to a TDF-containing regimen with maintaining or switching to another regimen. We searched MEDLINE, EMBASE, CENTRAL, LILACS, SCI, and the WHO Global Health Library. We assessed bias with the Cochrane tool and synthesized data using random-effects meta-analyses and Peto's approach. For further analyses, we added data from a previous systematic review in treatment-naïve patients.

RESULTS

17 RCTs with 2210 patients were included. All but one study had a high risk of bias. There was no significant association of switching to TDF-based regimens with mortality, fractures, CD4-cell count, body fat, virological failure, LDL-, and HDL-cholesterol. TDF-based regimens decreased total cholesterol (mean difference -12.05 mg/dL; 95% CI -20.76 to -3.34), trigylcerides (-14.33 mg/dL; -23.73 to -4.93), and bone mineral density (BMD; hip: -2.46%; -3.9 to -1.03; lumbar spine -1.52%; -2.69 to -0.34). Effects on estimated glomerular filtration (eGFR) were inconsistent and depended on the measurement. Adding 22 RCTs from 8297 treatment-naïve patients gave consistent results with then significant reductions of LDL (-7.57 mg/dL; -10.37 to -4.78), HDL (-2.38 mg/dL; -3.83 to -0.93), and eGFR (-3.49 ml/min; -5.56 to -1.43).

CONCLUSIONS

Switching to TDF-based regimens is associated with reductions of BMD and lipid levels and possibly lowered kidney function. The evidence is limited by the high risk of bias.

Simplified Maintenance Therapy with Abacavir/Lamivudine/Zidovudine plus Tenofovir After Sustained HIV Load Suppression: Four Years of Follow-up

PURPOSE

To assess the virologic and immunologic outcome of a treatment simplification strategy based on the substitution of protease inhibitor (PI)-based regimen with abacavir/lamivudine/zidovudine (ABC/3TC/ZDV, also known as trizivir or TZV) plus tenofovir (TDF) in viral-suppressed patients.

METHOD

The study population included 17 HIV-infected patients with undetectable viral loads over 12 months of a stable PI-based therapy. Patients were switched to a combination of TZV (2 pills twice a day) plus TDF (1 pill once a day) and were followed up for 48 months. They were studied for intracellular HIV DNA, CD4 cell count, HIV RNA levels, and lipid metabolism.

RESULTS

All patients had undetectable HIV RNA for the entire period of the follow-up. After 24 months of treatment with TZV plus TDF, the levels of cellular HIV DNA significantly decreased (p = .021). When we stratified the patients on the basis of HIV DNA outcome, we observed a significant increase of CD4 count only in patients who had undetectable HIV DNA after 24 months of TZV/TDF treatment. On the contrary, the CD4 count did not change in patients whose HIV DNA was still detectable at 24 months. The percentage of patients taking lipid-lowering agents declined significantly after switching to TZV/TDF.

CONCLUSION

This small pilot study suggests that a single-class quadruple regimen of TZV/TDF may represent a safe and appealing approach in the setting of simplification/switching antiretroviral strategies.

Maraviroc as intensification strategy in HIV-1 positive patients with deficient immunological response: an Italian randomized clinical trial

BACKGROUND

Immunological non-responders (INRs) lacked CD4 increase despite HIV-viremia suppression on HAART and had an increased risk of disease progression. We assessed immune reconstitution profile upon intensification with maraviroc in INRs.

METHODS

We designed a multi-centric, randomized, parallel, open label, phase 4 superiority trial. We enrolled 97 patients on HAART with CD4+<200/µL and/or CD4+ recovery ≤ 25% and HIV-RNA<50 cp/mL. Patients were randomized 1:1 to HAART+maraviroc or continued HAART. CD4+ and CD8+ CD45+RA/RO, Ki67 expression and plasma IL-7 were quantified at W0, W12 and W48.

RESULTS

By W48 both groups displayed a CD4 increase without a significant inter-group difference. A statistically significant change in CD8 favored patients in arm HAART+maraviroc versus HAART at W12 (p=.009) and W48 (p=.025). The CD4>200/µL and CD4>200/µL + CD4 gain ≥ 25% end-points were not satisfied at W12 (p=.24 and p=.619) nor at W48 (p=.076 and p=.236). Patients continuing HAART displayed no major changes in parameters of T-cell homeostasis and activation. Maraviroc-receiving patients experienced a significant rise in circulating IL-7 by W48 (p=.01), and a trend in temporary reduction in activated HLA-DR+CD38+CD4+ by W12 (p=.06) that was not maintained at W48.

CONCLUSIONS

Maraviroc intensification in INRs did not have a significant advantage in reconstituting CD4 T-cell pool, but did substantially expand CD8. It resulted in a low rate of treatment discontinuations.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00884858 http://clinicaltrials.gov/show/NCT00884858.

Assessing adherence to antiretroviral therapy in randomized HIV clinical trials: a review of currently used methods

Antiretroviral therapy for the treatment of HIV infection requires high levels of adherence to both maintain plasma HIV RNA at undetectable levels and prevent the emergence of drug resistance. As adherence to treatment is a major criterion for the evaluation of therapeutic outcomes, randomized clinical trials (RCTs) conducted among HIV-infected patients commonly include an assessment of adherence. However, there is still no gold-standard tool for assessing adherence behaviors in HIV RCTs. The methods currently used to collect and analyze adherence data are varied, which makes the comparison of results between studies difficult. The scope of this article is to review and discuss the range of adherence measures currently used in RCTs conducted among HIV-infected adults.

Incarceration predicts virologic failure for HIV-infected injection drug users receiving antiretroviral therapy

BACKGROUND

Incarceration may lead to interruptions in antiretroviral therapy (ART) for persons receiving treatment for human immunodeficiency virus (HIV) infection. We assessed whether incarceration and subsequent release were associated with virologic failure for injection drug users (IDUs) who were previously successfully treated with ART.

METHODS

ALIVE is a prospective, community-based cohort study of IDUs in Baltimore, Maryland. IDUs receiving ART during 1998-2009 who successfully achieved an HIV RNA level below the limit of detection (<400 copies/mL) were followed up for development of virologic failure at the subsequent semiannual study visit. Logistic regression with generalized estimating equations was used to assess whether incarceration was independently associated with virologic failure.

RESULTS

Of 437 HIV-infected IDUs who achieved undetectable HIV RNA for at least one study visit, 69% were male, 95% were African-American, and 40% reported at least one incarceration during follow-up. Virologic failure occurred at 26.3% of visits after a median of 6 months since achieving undetectable HIV RNA. In multivariate analysis accounting for demographic characteristics, drug use, and HIV disease stage, brief incarceration was strongly associated with virologic failure (adjusted odds ratio, 7.7; 95% confidence interval, 3.0-19.7), although incarceration lasting >30 days was not (odds ratio, 1.4; 95% confidence interval, .8-2.6).

CONCLUSIONS

Among IDUs achieving viral suppression while receiving ART, virologic failure occurred with high frequency and was strongly associated with brief incarceration. Efforts should be made to ensure continuity of care both during and after incarceration to improve treatment outcomes and prevent viral resistance in this vulnerable population.

A randomized, placebo-controlled trial of abacavir intensification in HIV-1-infected adults with virologic suppression on a protease inhibitor-containing regimen

BACKGROUND AND OBJECTIVE

Maximizing the durability of viral suppression is a key goal of antiretroviral therapy. The objective of AIDS Clinical Trials Group Study 372A was to determine whether the intensification strategy of adding abacavir to an effective indinavir-dual nucleoside regimen would delay the time to virologic failure.

METHODS

Zidovudine-experienced subjects (n=229) on therapy with indinavir + zidovudine + lamivudine with plasma HIV-1 RNA levels<500 copies/mL were randomized to abacavir 300 mg twice daily or placebo. The primary endpoint was the time to treatment failure, defined as a composite of confirmed virologic failure (2 consecutive HIV-1 RNAs>200 copies/mL) and treatment discontinuation.

RESULTS

At baseline, the study population was 88% male with a median age of 41 years and median CD4 cell count of 250/mm3. Median follow-up was 4.4 years. The primary endpoint was reached in 61/116 of abacavir versus 62/113 of placebo recipients (P=.77); virologic failure occurred in 34/116 and 42/113 patients, respectively (P=.22). There were no differences in the proportions of subjects with plasma HIV-1 RNA levels below 50 copies/mL, in CD4 cell count increases, nor adverse events between the arms. In the study, 17% of subjects developed nephrolithiasis, 2% experienced abacavir hypersensitivity, and 4.8% experienced at least 1 serious cardiovascular event (7 [6%] in the abacavir arm, 4 [3.5%] in the placebo arm). In additional secondary and post hoc analyses, rates of intermittent viremia, suppression below a plasma HIV-1 RNA level of 6 copies/mL, and HIV-1 proviral DNA levels in peripheral blood mononuclear cells were not significantly different in the 2 arms.

CONCLUSIONS

The strategy of intensification with abacavir in patients who are virologically suppressed on a stable antiretroviral regimen does not confer a clinical or virologic benefit. As antiretroviral regimens have become more potent since this trial was completed, it will be even more difficult to prove that late intensification of already virologically suppressed patients will add benefit. However, studies are warranted with drugs with new mechanisms of action to determine whether the level of persistent viremia below 50 copies/ mL can be further reduced and what influence this may have on latent HIV reservoirs.

HIV persistence and the prospect of long-term drug-free remissions for HIV-infected individuals

HIV infection can persist in spite of efficacious antiretroviral therapies. Although incomplete inhibition of viral replication may contribute to this phenomenon, this is largely due to the early establishment of a stable reservoir of latently infected cells. Thus, life-long antiviral therapy may be needed to control HIV. Such therapy is prone to drug resistance and cumulative side effects and is an unbearable financial burden for regions of the world hit hardest by the epidemic. This review discusses our current understanding of HIV persistence and the limitations of potential approaches to eradicate the virus and accordingly pleads for a joint multidisciplinary effort toward two highly related goals: the development of an HIV prophylactic vaccine and the achievement of long-term drug-free remissions in HIV-infected individuals.

Methodological issues in the use of composite endpoints in clinical trials: examples from the HIV field

BACKGROUND

In many fields, the choice of a primary endpoint for a trial is not always the ultimate clinical endpoint of interest, but rather some surrogate endpoint believed to be relevant for predicting the effect of the intervention on the clinical endpoint. The classic example of such a field is clinical HIV treatment research, where a variety of primary endpoints are used to evaluate the efficacy of new antiretroviral drugs or new combinations of existing drugs. The choice of endpoint reflects either the goal of therapy as recommended by treatment guidelines (e.g. rapid virological suppression) or the licensing requirements of official drug approval organizations (e.g. time to loss of virological response [TLOVR]).

PURPOSE

To review the diversity of endpoints used in recent clinical trials in HIV infection and highlight the methodological issues.

METHODS

We identified articles relating to antiretroviral therapy by searching PubMed and through hand searches of relevant conference abstracts. We restricted the search to randomized controlled trials conducted in HIV-infected adults published/presented from January 2005 until March 2008.

RESULTS

We identified 28 trials in antiretroviral-naive patients (i.e. patients who were starting antiretroviral therapy for the first time at the time of randomization) and 23 trials in antiretroviral-experienced patients. Most trials were performed for purposes of drug licensing, but others were focused on strategies of using approved drugs. Most trials (40 of 51) used a composite primary endpoint (TLOVR in 13). Of note, 22 of these 40 studies reported that they had used a purely virological efficacy endpoint, but the primary endpoint was actually a composite one due to the way in which missing data and treatment switches were considered as failures.

LIMITATIONS

Examples are restricted to HIV clinical trials.

CONCLUSIONS

Whilst most current HIV clinical trials use composite primary endpoints, there are substantial differences in the components that make up these endpoints. In HIV and other fields where precise definitions are variable, guidelines for standardization of definition and reporting would greatly improve the ability to compare trial results.

Expanding antiretroviral options in resource-limited settings--a cost-effectiveness analysis

BACKGROUND

Current World Health Organization (WHO) guidelines for treatment of HIV in resource-limited settings call for 2 antiretroviral regimens. The effectiveness and cost-effectiveness of increasing the number of antiretroviral regimens is unknown.

METHODS

Using a simulation model, we compared the survival and costs of current WHO regimens with two 3-regimen strategies: an initial regimen of 3 nucleoside reverse transcriptase inhibitors followed by the WHO regimens and the WHO regimens followed by a regimen with a second-generation boosted protease inhibitor (2bPI). We evaluated monitoring with CD4 counts only and with both CD4 counts and viral load. We used cost and effectiveness data from Cape Town and tested all assumptions in sensitivity analyses.

RESULTS

Over the lifetime of the cohort, 25.6% of individuals failed both WHO regimens by virologic criteria. However, when patients were monitored using CD4 counts alone, only 6.5% were prescribed additional highly active antiretroviral therapy due to missed and delayed detection of failure. The life expectancy gain for individuals who took a 2bPI was 6.7-8.9 months, depending on the monitoring strategy. When CD4 alone was available, adding a regimen with a 2bPI was associated with an incremental cost-effectiveness ratio of $2581 per year of life gained, and when viral load was available, the ratio was $6519 per year of life gained. Strategies with triple-nucleoside reverse transcriptase inhibitor regimens in initial therapy were dominated. Results were sensitive to the price of 2bPIs.

CONCLUSIONS

About 1 in 4 individuals who start highly active antiretroviral therapy in sub-Saharan Africa will fail currently recommended regimens. At current prices, adding a regimen with a 2bPI is cost effective for South Africa and other middle-income countries by WHO standards.

Modulation of K65R selection by zidovudine inclusion: analysis of HIV resistance selection in subjects with virologic failure receiving once-daily abacavir/lamivudine/zidovudine and tenofovir DF (study COL40263)

COL40263 was a pilot 48-week, open-label, multicenter study evaluating the efficacy and safety of once-daily coformulated abacavir/lamivudine/zidovudine plus tenofovir in ART-naive, HIV-infected subjects. We examined the patterns of resistance that were selected on-therapy through 48 weeks in subjects with virologic nonresponse (VF). A total of 123 antiretroviral-naive HIV-1-infected subjects with plasma HIV-1 RNA > or = 30,000copies/ml were enrolled. For subjects with confirmed VF (HIV-1 RNA > or = 400 copies/ml at week 24 or later), HIV population genotypic and phenotypic analysis was performed. Of the 123 enrolled subjects, 14 (11%) had confirmed plasma HIV-1 RNA > or = 400 copies/ml through week 48. Of these subjects, 3/14 had evidence of drug resistance at baseline: 2/14 had HIV with K103N, Y188F/H/L/Y, and/or T215A and 1/14 had reduced zidovudine susceptibility. At the last time point analyzed, 4/14 subjects had wild-type HIV, while 10/14 subjects had HIV with either thymidine analogue mutations (TAMS) alone (3/10), TAMS + M184V (4/10), M184V only (1/10), or K65R/K (2/10). Matched phenotype was obtained for 13/14 subjects and 8/13 (62%) subjects had reduced susceptibility to one or more study drugs: 2/13 tenofovir, 3/13 abacavir, 4/13 zidovudine, and 7/13 lamivudine. The resistance pattern in COL40263 subjects with VF differs significantly from that reported for tenofovir-containing triple-nucleoside regimens. TAMs were detected in the majority (7/10) of samples from subjects with VF who selected any resistance mutation. These data suggest that TAMs selection is a preferred resistance route of this combination, with zidovudine modulating the resistance pathway against selection for K65R.

Modeling HIV persistence, the latent reservoir, and viral blips

HIV-1 eradication from infected individuals has not been achieved with the prolonged use of highly active antiretroviral therapy (HAART). The cellular reservoir for HIV-1 in resting memory CD4(+) T cells remains a major obstacle to viral elimination. The reservoir does not decay significantly over long periods of time but is able to release replication-competent HIV-1 upon cell activation. Residual ongoing viral replication may likely occur in many patients because low levels of virus can be detected in plasma by sensitive assays and transient episodes of viremia, or HIV-1 blips, are often observed in patients even with successful viral suppression for many years. Here we review our current knowledge of the factors contributing to viral persistence, the latent reservoir, and blips, and mathematical models developed to explore them and their relationships. We show how mathematical modeling has helped improve our understanding of HIV-1 dynamics in patients on HAART and of the quantitative events underlying HIV-1 latency, reservoir stability, low-level viremic persistence, and emergence of intermittent viral blips. We also discuss treatment implications related to these studies.

Patients presenting with AIDS in the HAART era: a collaborative cohort analysis

OBJECTIVE

Many patients infected with HIV still present with an AIDS diagnosis. The aim of this study was to evaluate the virological, immunological and clinical outcomes of HAART in these patients.

DESIGN

The present study was a multi-cohort study. All patients with an AIDS diagnosis between 30 days before and 14 days after HIV diagnosis, recruited between 1997 and 2004 from eight hospital cohorts, were evaluated.

RESULTS

A total of 760 patients were included [268 (35.3%) had pneumocystis and 168 (22.1%) tuberculosis]. Six hundred and twenty-four patients (82.1%) started HAART a median of 31 days after HIV diagnosis. One hundred and fifty-three patients started a nonnucleoside transcriptase inhibitor-based regimen (20.1%), 409 a protease inhibitor-based regimen (53.8%) and 62 other regimens (8.2%). In adjusted analyses, HAART was started sooner in more recent years, in patients with lower CD4 cell count and in those with Kaposi's sarcoma, whereas it was started later in those with tuberculosis. Five hundred and five patients (89%) attained a viral load of less than 500 copies/ml. The factors associated with a better virological response were later calendar year, lower initial viral load and cytomegalovirus disease. Virological rebound was more common in those receiving nucleoside reverse transcriptase inhibitor-based regimens, in those with tuberculosis and in earlier calendar years. One hundred and twenty-five (16%) patients died; 61 had received HAART (48.6%). Mortality was more likely in those who were older, those with a higher viral load at diagnosis, those with nonsexual HIV risks and those with lower CD4 cell count and haemoglobin levels over follow-up.

CONCLUSION

Virological suppression was achieved in most AIDS patients, though mortality remains high in these individuals.

Quadruple Nucleoside Therapy with Zidovudine, Lamivudine, Abacavir and Tenofovir in the Treatment of HIV

Highly active antiretroviral therapy (HAART) has significantly reduced morbidity and mortality in HIV-infected patients. However, problems such as short-term or long-term toxicity and the development of drug resistance could necessitate a change in the therapy regimen. Whereas various HAART options with low pill burden and favourable long-term tolerability profiles are available for naive patients, treatment of experienced patients tends to be more complex and remains a challenge. Treatment with class sparing nucleoside-only regimens could be an option in this context, but the combination of zidovudine (AZT), lamivudine (3TC) and abacavir (ABC) has shown to be inferior in terms of virological efficacy compared with the standard regimen. More promising data were obtained when AZT, 3TC and ABC were intensified with tenofovir (TDF), resulting in a quadruple nucleoside therapy. This regimen has demonstrated comparable potency to a standard regimen with AZT, 3TC and efavirenz in treatment-naive patients. Additionally, it has shown to be an efficient treatment option especially in moderately pretreated patients. This is accredited to the potency of the single components and the antagonistic selection pressure of AZT and TDF. The presence of L210W, or at least two of the mutations 41L, 67N, 70R, 215F/Y or 219Q/E, at or before baseline seems to be a predictor of non-response, whereas the presence of M184V does not impede virological response and might even be advantageous. This review summarizes current data on the combined use of AZT, 3TC, ABC and TDF in regard to virological and immunological outcome as well as genotypic predictors of response.