Impact of adding maraviroc to antiretroviral regimens in patients with full viral suppression but impaired CD4 recovery

Definition of Immunological Nonresponse to Antiretroviral Therapy: A Systematic Review

BACKGROUND

Terms and criteria to classify people living with HIV on antiretroviral therapy who fail to achieve satisfactory CD4 T-cell counts are heterogeneous, and need revision and summarization.

METHODS

We performed a systematic review of PubMed original research articles containing a set of predefined terms, published in English between January 2009 and September 2018. The search retrieved initially 1360 studies, of which 103 were eligible. The representative terminology and criteria were extracted and analyzed.

RESULTS

Twenty-two terms and 73 criteria to define the condition were identified. The most frequent term was "immunological nonresponders" and the most frequent criterion was "CD4 T-cell count <350 cells/µL after ≥24 months of virologic suppression." Most criteria use CD4+ T-cell counts as a surrogate, either as an absolute value or as a change after a defined period of time [corrected]. Distinct values and time points were used. Only 9 of the 73 criteria were used by more than one independent research team. Herein we propose 2 criteria that could help to reach a consensus.

CONCLUSIONS

The high disparity in terms and criteria here reported precludes data aggregation and progression of the knowledge on this condition, because it renders impossible to compare data from different studies. This review will foster the discussion of terms and criteria to achieve a consensual definition.

High Virologic Failure Rates with Maraviroc-Based Salvage Regimens Among Indian Patients: A Preliminary Analysis-Maraviroc Effectiveness in HIV-1 Subtype C

BACKGROUND

There is no information on the clinical effectiveness of Maraviroc (MVC) amongst People Living with HIV (PLHIV) in India infected with HIV-1 Subtype C viruses.

METHODS

We conducted a retrospective chart review of adult PLHIV on MVC based Antiretroviral (ARV) regimens for at least 6 months. Maraviroc was initiated amongst PLHIV with documented R5 tropic viruses (determined by in-house population sequencing of the V3 loop in triplicate and interpreted using the Geno2Pheno algorithm) in combination with an Optimized Background regimen (designed using genotypic resistance testing and past ARV history). Plasma viral loads (PVL) are performed 6 months post-initiation and annually thereafter. Primary outcome d. Median duration on MVC treatment was 1.8 years (range 1-2.9 years) while median duration of ART prior to switching to MVC was 13 years. Maraviroc was combined with Darunavir/ritonavir (DRV/r) (n=10), Atazanavir/r (ATV/r) (n=2) and Lopinavir/r (LPV/r) (n=1). All PLHIV were infected with HIV-1 Subtype C. Only 23.3% PLHIV achieved virologic suppression at 6 months and sustained it for 2.3 years. Median CD4 count change from baseline was +117 (n=13), +228 (n=10), +253 (n=9), and +331 (n=4) at 6, 12, 18 and 24 months respectively. Repeat tropism among patients with virologic failure demonstrated R5 virus.

CONCLUSIONS

High rates of virologic failure was seen when MVC was used amongst treatment experienced PLHIV infected with HIV-1 Subtype C in India. was the proportion of PLHIV with virologic success (PVL<50 copies/ml) at last follow up visit.

RESULTS

Data on 13 PLHIV were analyze.

Chemokine receptor CCR5 correlates with functional CD8+ T cells in SIV-infected macaques and the potential effects of maraviroc on T-cell activation

C-C chemokine receptor 5 (CCR5) plays an essential role in HIV pathogenesis as the major coreceptor on CD4⁺ T cells used by HIV, yet the function of CCR5 on CD8 T cells is not well understood. Furthermore, the immunologic effects of the CCR5 inhibitor maraviroc (MVC), despite approval for clinical use, have not yet been well evaluated for their potential effects on cytotoxic T-cell responses. In this study, we characterized the development and function of CCR5⁺CD8⁺ T cells in rhesus macaques with or without Simian immunodeficiency virus (SIV) infection. We also investigated the effects of the CCR5 antagonist MVC on functional CCR5⁺CD8⁺ T-cell responses in vitro. The data show that CCR5⁺CD8⁺ T cells have an effector memory phenotype and increase with age in systemic and mucosal lymphoid tissues as a heterogeneous population of polyfunctional CD8 T cells. In addition, CCR5 is highly expressed on SIV gag-specific (CM9⁺) CD8⁺ T cells in SIV-infected macaques, yet CCR5⁺CD8⁺ T cells are significantly reduced in mucosal lymphoid tissues with disease progression. Furthermore, in vitro MVC treatment reduced activation and cytokine secretion of CD8⁺ T cells via a CCR5-independent pathway. These findings suggest that surface CCR5 protein plays an important role in differentiation and activation of CD8⁺ T cells. Although MVC may be helpful in reducing chronic inflammation and activation, it may also inhibit virus-specific CD8⁺ T-cell responses. Thus optimal use of CCR5 antagonists either alone or in combination with other drugs should be defined by further investigation.-Wang, X., Russell-Lodrigue, K. E., Ratterree, M. S., Veazey, R. S., Xu, H. Chemokine receptor CCR5 correlates with functional CD8⁺ T cells in SIV-infected macaques and the potential effects of maraviroc on T-cell activation.

Maraviroc: a review of its use in HIV infection and beyond

The human immunodeficiency virus-1 (HIV-1) enters target cells by binding its envelope glycoprotein gp120 to the CD4 receptor and/or coreceptors such as C-C chemokine receptor type 5 (CCR5; R5) and C-X-C chemokine receptor type 4 (CXCR4; X4), and R5-tropic viruses predominate during the early stages of infection. CCR5 antagonists bind to CCR5 to prevent viral entry. Maraviroc (MVC) is the only CCR5 antagonist currently approved by the United States Food and Drug Administration, the European Commission, Health Canada, and several other countries for the treatment of patients infected with R5-tropic HIV-1. MVC has been shown to be effective at inhibiting HIV-1 entry into cells and is well tolerated. With expanding MVC use by HIV-1-infected humans, different clinical outcomes post-approval have been observed with MVC monotherapy or combination therapy with other antiretroviral drugs, with MVC use in humans infected with dual-R5- and X4-tropic HIV-1, infected with different HIV-1 genotype or infected with HIV-2. This review discuss the role of CCR5 in HIV-1 infection, the development of the CCR5 antagonist MVC, its pharmacokinetics, pharmacodynamics, drug–drug interactions, and the implications of these interactions on treatment outcomes, including viral mutations and drug resistance, and the mechanisms associated with the development of resistance to MVC. This review also discusses available studies investigating the use of MVC in the treatment of other diseases such as cancer, graft-versus-host disease, and inflammatory diseases.

The efficacy and safety of maraviroc addition to a stable antiretroviral regimen in subjects with suppressed plasma HIV-RNA is not influenced by age

There are few data about the immunovirological efficacy, safety/tolerability, and durability of maraviroc (MVC) addition to aging patients on suppressive antiretroviral therapy (cART) and undetectable viral load (<50 copies/ml). The aging population is underrepresented in most HIV clinical trials. This study included 80 patients aged ≥50 years and 161 aged <50 years and showed that after 48 weeks of treatment, there was no between-group differences in the median increase of CD4(+) T cells or the virological suppression rate. Safety and tolerability were also comparable. In multivariable analysis, the effect of age was not modified and was independent of the response to MVC. An immunological recovery of ≥100 CD4(+) T cells was significantly less common in those with a longer HIV history (≥15 years) (OR 0.43; p=0.016) or having <200/mm(3) CD4(+) T cells at MVC initiation (OR 0.27; p=0.004). Meanwhile, achieving a CD4/CD8 ratio ≥0.5 at week 48 was less likely in those with CD4(+) T cell counts <200 at MVC initiation (OR 0.09; p<0.0001) or with a previous AIDS event (OR 0.43; p=0.028). In summary, the immunovirological efficacy, safety/tolerability, and durability of MVC addition in patients virologically suppressed were independent of the patient's age at treatment onset.

Maraviroc Intensification of cART in Patients with Suboptimal Immunological Recovery: A 48-Week, Placebo-Controlled Randomized Trial

OBJECTIVE

The immunomodulatory effects of the CCR5-antagonist maraviroc might be beneficial in patients with a suboptimal immunological response, but results of different cART (combination antiretroviral therapy) intensification studies are conflicting. Therefore, we performed a 48-week placebo-controlled trial to determine the effect of maraviroc intensification on CD4+ T-cell counts and immune activation in these patients.

DESIGN

Double-blind, placebo-controlled, randomized trial.

METHODS

Major inclusion criteria were 1. CD4+ T-cell count <350 cells/μL while at least two years on cART or CD4+ T-cell count <200 cells/μL while at least one year on cART, and 2. viral suppression for at least the previous 6 months. HIV-infected patients were randomized to add maraviroc (41 patients) or placebo (44 patients) to their cART regimen for 48 weeks. Changes in CD4+ T-cell counts (primary endpoint) and other immunological parameters were modeled using linear mixed effects models.

RESULTS

No significant differences for the modelled increase in CD4+ T-cell count (placebo 15.3 CD4+ T cells/μL (95% confidence interval (CI) [1.0, 29.5] versus maraviroc arm 22.9 CD4+ T cells/μL (95% CI [7.4, 38.5] p = 0.51) or alterations in the expression of markers for T-cell activation, proliferation and microbial translocation were found between the arms. However, maraviroc intensification did increase the percentage of CCR5 expressing CD4+ and CD8+ T-cells, and the plasma levels of the CCR5 ligand MIP-1β. In contrast, the percentage of ex-vivo apoptotic CD8+ and CD4+ T-cells decreased in the maraviroc arm.

CONCLUSIONS

Maraviroc intensification of cART did not increase CD4+ T-cell restoration or decrease immune activation as compared to placebo. However, ex-vivo T-cell apoptosis was decreased in the maraviroc arm.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00875368.

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.

Maraviroc intensification of stable antiviral therapy in HIV-1-infected patients with poor immune restoration: MARIMUNO-ANRS 145 study

OBJECTIVE

To address the ability of a 24-week Maraviroc (MVC) intensification of a stable antiretroviral therapy (cART) to significantly increase the CD4 cell count slope.

METHODS

Patients were eligible if they had CD4 <350 cells/mm, a CD4 slope <50 cells/mm per year, and sustained plasma HIV-RNA <50 copies/mL over the last 2 years, while receiving a stable cART. Patients harboring pure X4-using viruses by a phenotypic tropism assay were excluded. MVC was added to cART for 24 weeks, at the recommended dosage per drug-drug interactions. The primary endpoint was a significant positive difference in CD4 slopes (with MVC- pre-MVC, paired t test).

RESULTS

Sixty patients (55 men), with median age 51 years, baseline CD4 238 cells/mm, and slope before intensification +14.1 cells/mm per year were included. CD4 nadir was <50/mm in 47% of the population. The full set of patients (N = 57) completed week 24, and the on-treatment patients (N = 48) did not discontinue MVC. The median CD4 slope difference from baseline was +22.6 cells/mm per year (P = 0.08) in full set and +22.6 cells/mm per year (P = 0.04) in on-treatment. Slope evolution was not different according to baseline tropism, CD4 nadir, or ongoing cART regimen. No drug-related severe adverse events were recorded during intensification. MVC plasma concentrations were significantly different depending on drug-drug interaction with ongoing cART regimen and tended to be correlated with CD4 cells increase.

CONCLUSION

In this study, MVC intensification of stable cART over 24 weeks was able to enhance CD4 cell slopes in patients with prior insufficient immune restoration despite long-term virological control.

Treating HIV-1 Infection: What Might the Future Hold?

Advances in antiretroviral combination therapy lasting the past two decades have transformed HIV-1 infection from a fatal disease into a chronic medical condition that in many cases does not compromise life quality. There are 25 different antiretroviral agents available currently, allowing for patient-centered, individualized management of HIV-1 infection, and ongoing progress in HIV-1 virology and antiretroviral pharmacology is likely to expand treatment options further in the future. Nevertheless, antiretroviral therapy continues to have limitations, including insufficient immunological reconstitution, selection of drug resistance, ongoing abnormal immune activation despite effective suppression of HIV-1 viremia, and the inability to target latently infected cells that are responsible for long-term viral persistence. Owing to these shortcomings, the theoretical ability of antiretroviral therapy to extend life expectancy to normal levels is not realized in many cases. Strategies to address these limitations are a matter of active ongoing research and will be summarized in this article.

In vitro effects of the CCR5 inhibitor maraviroc on human T cell function

BACKGROUND

Several potential immunological benefits have been observed during treatment with the CC chemokine receptor 5 (CCR5) antagonist maraviroc, in addition to its antiviral effect. Our objective was to analyse the in vitro effects of CCR5 blockade on T lymphocyte function and homeostasis.

METHODS

Peripheral blood mononuclear cells (PBMCs) from both HIV-negative (n=28) and treated HIV-positive (n=27) individuals were exposed in vitro to different concentrations of maraviroc (0.1-100 μM). Effects on T cell activation were analysed by measuring the expression of the CD69, CD38, HLA-DR and CD25 receptors as well as CCR5 density using flow cytometry. Spontaneous and chemokine-induced chemotaxis were measured by transwell migration assays, and polyclonal-induced proliferation was assessed by a lymphoproliferation assay and carboxyfluorescein succinimidyl ester staining.

RESULTS

Maraviroc increases CCR5 surface expression on activated T cells, even at low doses (0.1 μM). Slight differences were detected in the frequency and mean fluorescence intensity of activation markers at high concentrations of maraviroc. Expression of CD25, CD38 and HLA-DR tended to decrease in both CD4+ and CD8+ T lymphocytes, whereas expression of CD69 tended to increase. Maraviroc clearly inhibits T cell migration induced by chemokines in a dose-dependent manner. Moreover, at 100 μM, maraviroc tends to inhibit T cell proliferation.

CONCLUSIONS

These data showed that in vitro exposure to maraviroc decreases some activation expression markers on T lymphocytes and also migration towards chemoattractants. These results support the additional immunological effects of CCR5 blockade and suggest that maraviroc might have potential capacity to inhibit HIV-associated chronic inflammation and activation, both by directly affecting T cell activation and by reducing entrapment of lymphocytes in lymph nodes.

Immunologic effectiveness of maraviroc- and raltegravir-containing regimens (R+M+) versus raltegravir-based regimens that do not include maraviroc (R+M-)

OBJECTIVE

To compare the immunologic effectiveness of raltegravir-maraviroc (R+M+)-based regimens with raltegravir-based regimens that do not include maraviroc (R+M-) in treatment-experienced patients in clinical practice.

METHODS

We conducted a retrospective study of treatment-experienced HIV-infected adults receiving either R+M+- or R+M--based therapy. Longitudinal CD4 counts were analyzed using a linear mixed model.

RESULTS

One hundred and fifty-six patients were included in the analysis, of whom 32 were receiving R+M+ and 124 R+M-. Mean baseline CD4 counts in patients on R+M+ and R+M- were 463.8 and 442.3 cells/mm(3), respectively (P = .67). In multivariable mixed models, a baseline viral load ≥50 copies/mL was significantly associated with CD4 change during follow-up (P < .0001). No difference between R+M+ and R+M- was observed during follow-up (P = .81).

CONCLUSION

CD4 cell recovery was similar among patients receiving either R+M+- or R+M--based therapy during a 24-month period of follow-up.

T-cell changes after a short-term exposure to maraviroc in HIV-infected patients are related to antiviral activity

OBJECTIVES

Analyze the short-term immunological effect directly attributable to MRV without interference of other drugs.

METHODS

MRV group included experienced HIV-infected patients undergoing an 8-day MRV monotherapy. A comparison population included naïve HIV-infected patients starting combined antiretroviral therapy (cART group). Absolute CD4(+) and CD8(+) T-cells and T-lymphocyte subsets were determined at day 0 and 8.

RESULTS

Fifty-nine patients who underwent MRV monotherapy and 28 naïve patients were analyzed. Forty-one patients in the MRV group experienced a significant viral load decrease (MRV positive subgroup). Virological response and CD4(+) T-cell change were comparable in the MRV positive and cART groups. CD8(+) T-cell increase in the MRV positive subgroup showed a trend toward superiority when compared with the cART group. T-lymphocyte subset changes showed a similar profile in the MRV positive and cART groups with a differential effect in the TemRA cells related to MRV. No immunological effect (absolute lymphocyte counts or subsets) was observed in patients without virological response to MRV.

CONCLUSIONS

MRV produced CD4(+) and CD8(+) T-cell gains related to antiviral activity and comparable or even superior in terms of CD8(+) T-cells to naïve patients starting cART. No immunological effect occurred in subjects without virological response to MRV.

Drug safety evaluation of maraviroc for the treatment of HIV infection

INTRODUCTION

Maraviroc is the only C-chemokine receptor 5 (CCR5) antagonist approved for the treatment of infection with HIV. This article reviews the safety and efficacy of maraviroc in the treatment of HIV infection.

AREAS COVERED

The PubMed database was searched using the keywords 'maraviroc' and 'HIV'. In addition, conference proceedings from CROI, IAS and EACS meetings were searched for maraviroc clinical trials. The PubMed search revealed one Phase IIb - III clinical trial in treatment-naive HIV(+) patients (MERIT) and three Phase IIb - III randomized clinical trials (RCTs) in treatment-experienced patients (MOTIVATE 1 and 2, A4001029). All RCTs showed an excellent safety profile for maraviroc in the treatment of HIV-1 infection. However, long-term (> 3 years) safety data generated on maraviroc therapy are still scarce. Based on the findings from RCTs so far, no relevant toxicities and co-morbidities such as coronary heart disease or hepatotoxicity have been described. The overall CD4(+) cell count increase resulting from a maraviroc-containing regimen appears to be higher than those seen with other antiretroviral regimens. However, the significance remains controversial. To date, maraviroc has shown a potent and durable virological efficacy profile for the treatment of HIV-1 infection. The only use of maraviroc depends on pretreatment testing for CCR5 tropism.

EXPERT OPINION

Maraviroc is a generally safe and well-tolerated medication for the treatment of HIV-1 infection with a unique mechanism of action. Long-term (i.e., > 5 years) risks are not known and have to be carefully monitored.

Efficacy of new antiretroviral drugs in treatment-experienced HIV-infected patients: a systematic review and meta-analysis of recent randomized controlled trials

OBJECTIVES

We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) to assess the overall efficacy of new antiretroviral drugs, as well as the factors associated with increased efficacy. We compared CD4 cell count increases associated with chemokine (C-C motif) receptor 5 (CCR5) inhibitors or other new drugs, using indirect comparison.

METHODS

We included RCTs published in 2003-2010 that assessed the 48-week immunological and virological efficacy of adding new antiretroviral drugs vs. placebo to optimized background therapy (OBT) in treatment-experienced subjects. These drugs included maraviroc, vicriviroc, enfuvirtide, raltegravir, etravirine, tipranavir and darunavir. We collected baseline descriptive characteristics, CD4 cell count changes and virological suppression proportions (percentage with HIV RNA <50 HIV-1 RNA copies/mL).

RESULTS

We identified 10 studies which included a total of 6401 patients. New drugs were associated with increased virological suppression (pooled odds ratio 2.97) and larger CD4 count increases (pooled nonstandardized difference 39 cells/μL) compared with placebo. OBT genotypic sensitivity scores (GSSs) were also associated with larger differences in virological suppression (P<0.001 for GSS=0,≤1 and ≤2) and CD4 cell count increase (GSS=0, P<0.001; GSS ≤1, P=0.002; GSS ≤2, P=0.015) between the two groups. CCR5 inhibitors were not associated with significant gains in CD4 cell counts (P=0.22) compared with other new drugs.

CONCLUSIONS

Our study confirmed the overall immunological and virological efficacy of new antiretroviral drugs in treatment-experienced patients, compared with placebo. The main predictive factor for efficacy was the number of fully active drugs. CCR5 inhibitors did not increase CD4 cell count to a greater extent than other new drugs.

Treatment intensification with raltegravir in subjects with sustained HIV-1 viraemia suppression: a randomized 48-week study

BACKGROUND

Residual viraemia is a major obstacle to HIV-1 eradication in subjects receiving HAART. The intensification with raltegravir could impact latent reservoirs and might lead to a reduction of plasma HIV-1 viraemia (viral load [VL]), complementary DNA intermediates and immune activation.

METHODS

This was a prospective, open-label, randomized study comprising 69 individuals on suppressive HAART randomly assigned 2:1 to add raltegravir during 48 weeks.

RESULTS

Total and integrated HIV-1 DNA, and ultrasensitive VL remained stable despite intensification. There was a significant increase in episomal HIV DNA at weeks 2-4 in the raltegravir group returning to baseline levels at week 48. Median CD4(+) T-cell counts increased 124 and 80 cells/µl in the intensified and control groups after 48 weeks (P=0.005 and P=0.027, respectively), without significant differences between groups. No major changes were observed in activation of CD4(+) T-cells. Conversely, raltegravir intensification significantly reduced activation of CD8(+) T-cells at week 48 (HLA-DR(+)CD38(+), P=0.005), especially in the memory compartment (CD38(+) of CD8(+)CD45RO(+), P<0.0001). Linear mix models also depicted a larger decrease in CD8(+) T-cell activation in the intensification group (P=0.036 and P=0.010, respectively). Raltegravir intensification was not associated to any particular adverse event.

CONCLUSIONS

Intensification of HAART with raltegravir during 48 weeks was safe and associated with a significant decrease in CD8(+) T-cell activation, and a transient increase of episomal HIV-1 DNA. However, raltegravir did not significantly contribute to changes in CD4(+) T-cell counts, ultrasensitive VL, and total and integrated HIV-1 DNA. These findings suggest that raltegravir impacts residual HIV-1 replication and support new strategies to impair HIV-1 persistence. ClinicalTrials.gov identifier: NCT00554398.

Intensification of antiretroviral therapy with raltegravir or addition of hyperimmune bovine colostrum in HIV-infected patients with suboptimal CD4+ T-cell response: a randomized controlled trial

BACKGROUND

Despite virally suppressive combination antiretroviral therapy (cART), some HIV-infected patients exhibit suboptimal CD4(+) T-cell recovery. This study aimed to determine the effect of intensification of cART with raltegravir or addition of hyperimmune bovine colostrum (HIBC) on CD4(+) T-cell count in such patients.

METHODS

We randomized 75 patients to 4 treatment groups to receive raltegravir, HIBC, placebo, or both raltegravir and HIBC in a factorial, double-blind study. The primary endpoint was time-weighted mean change in CD4(+) T-cell count from baseline to week 24. T-cell activation (CD38(+) and HLA-DR(+)), plasma markers of microbial translocation (lipopolysaccharide, 16S rDNA), monocyte activation (soluble (s) CD14), and HIV-RNA (lowest level of detection 4 copies/mL) were monitored. Analysis was performed using linear regression methods.

RESULTS

Compared with placebo, the addition of neither raltegravir nor HIBC to cART for 24 weeks resulted in a significant change in CD4(+) T-cell count (mean difference, 95% confidence interval [CI]: 3.09 cells/μL, -14.27; 20.45, P = .724 and 9.43 cells/μL, -7.81; 26.68, P = .279, respectively, intention to treat). There was no significant interaction between HIBC and raltegravir (P = .275). No correlation was found between CD4(+) T-cell count and plasma lipopolysaccharide, 16S rDNA, sCD14, or HIV-RNA.

CONCLUSION

The determinants of poor CD4(+) T-cell recovery following cART require further investigation.

CLINICAL TRIALS REGISTRATION

ClinicalTrials.gov identifier: NCT00772590, Australia New Zealand Clinical Trials Registry: ACTRN12609000575235.

Maraviroc: the first chemokine coreceptor 5 inhibitor

HIV viral entry occurs via viral interaction with host cell CD4 receptors and a second coreceptor, most commonly chemokine coreceptor (CCR)5. As a result, CCR5 antagonists have been developed to block HIV entry into CD4+ cells, thereby inhibiting viral replication. The first CCR5 inhibitor approved for use in the treatment of HIV was maraviroc. Maraviroc has been shown to be successful in reducing HIV replication in both antiretroviral treatment-experienced and treatment-naive populations. Since maraviroc is only efficacious against CCR5-tropic HIV virus, it is imperative to perform viral tropism testing prior to initiation of maraviroc. The currently available enhanced sensitivity Trofile™ assay (Monogram Biosciences, CA, USA) is the reference standard of tropism tests. Although it is highly sensitive, it remains a barrier to maraviroc use because it is expensive and has a long turnaround time. The development of simpler tropism assays may allow for more widespread use of maraviroc in the future. At present, maraviroc remains a highly useful drug in the management of HIV-infected persons infected with CCR5-tropic viruses.

Novel antiretroviral combinations in treatment-experienced patients with HIV infection: rationale and results

Novel antiretroviral drugs offer different degrees of improvement in activity against drug-resistant HIV, short- and long-term tolerability, and dosing convenience compared with earlier drugs. Those drugs approved more recently and commonly used in treatment-experienced patients include the entry inhibitor enfuvirtide, protease inhibitors (PIs) [darunavir and tipranavir], a C-C chemokine receptor (CCR) type 5 antagonist (maraviroc), an integrase inhibitor (raltegravir) and etravirine, a non-nucleoside reverse transcriptase inhibitor (NNRTI). Novel agents in earlier stages of development include a CCR5 monoclonal antibody (PRO 140) administered subcutaneously once weekly, once-daily integrase inhibitors (elvitegravir and S/GSK1349572), and several nucleoside (nucleotide) reverse transcriptase inhibitors and NNRTIs. Bevirimat, a maturation inhibitor, has compromised activity in the presence of relatively common Gag polymorphisms. Viral suppression is necessary to control the evolution of drug resistance, reduce chronic immune activation that probably underlies the excess morbidity and mortality in HIV-infected patients, and reduce viral transmission, including transmitted drug resistance. In general, the proportion of viraemic patients who achieve suppression increases with the number of active pharmacokinetically compatible antiretroviral drugs in the regimen. In the ANRS139-TRIO trial, 86% of highly treatment-experienced patients treated with darunavir-ritonavir, etravirine and raltegravir had HIV RNA <50 copies/mL at 48 weeks. In patients who had received at least 12 weeks of a stable regimen and had no darunavir resistance-associated mutations, once-daily darunavir boosted with ritonavir 100 mg was virologically noninferior with better lipid effects than with the twice-daily dosing, which requires a 200 mg total daily dose of ritonavir. Raltegravir plus a boosted PI is being investigated for second-line therapy in patients not responding to NNRTI-based first-line treatment in resource-limited settings (RLS). However, concerns about this potential strategy include the low barrier against resistance of raltegravir, limited penetration of some PIs into the CNS and the unknown impact of integrase polymorphisms seen more commonly in non-B subtype HIV-1. In patients who have already achieved viral suppression, novel agents may be used to simplify the dosing schedule, lower costs (such as by switching to boosted PI monotherapy), reduce adverse events or preserve antiretroviral drug options, especially since the absence of an HIV eradication strategy implies the need for life-long combination antiretroviral therapy. Switching enfuvirtide to raltegravir eliminated painful injection-site reactions without compromising virological suppression. Two studies found different virological outcomes when patients were switched from lopinavir/ritonavir to raltegravir, but there was an improvement in the lipid profile. Simplifying to darunavir-ritonavir monotherapy after suppression of plasma HIV RNA to <50 copies/mL has been found to be safe with no emergence of resistance in cases of viral rebound, but longer-term data are needed. The initial suggestion that maraviroc may possess unique CD4+ T-cell boosting effects was not confirmed in several clinical trials. Improved understanding of HIV pathogenesis has opened new frontiers for research such as identifying the sources, consequences and optimal management of residual viraemia in those with plasma HIV RNA <50 copies/mL. Globally, however, one of the most urgent priorities is providing the increasing number of treatment-experienced virologically failing patients in RLS with access to optimal treatment, including those treatments based on novel antiretroviral agents.

Treatment of HIV infection with the CCR5 antagonist maraviroc

IMPORTANCE OF THE FIELD

The emergence of resistance in treatment-experienced HIV patients often limits therapeutic success of the currently available antiretroviral drugs. New drug classes are thus required. Maraviroc is the first chemokine receptor 5 antagonist approved for use in treatment experienced HIV patients with a R5-tropic virus.

AREAS COVERED IN THIS REVIEW

For this review, data from pharmacokinetic, Phase II and III clinical trials were reviewed.

WHAT THE READER WILL GAIN

The objectives of this review were to discuss the pharmacokinetics and clinical efficacy and safety of maraviroc in treatment-experienced and -naive HIV patients with R5-tropic virus. Additionally, tropism testing was discussed.

TAKE HOME MESSAGE

Maraviroc is effective in previously treated patients with R5-tropic virus only. Also, maraviroc will be an attractive option for HIV-1-infected treatment-naive patients with R5-tropic viruses only, once genotypic assays have been validated.

[CCR5-antagonists: contribution of a new antiretroviral class to the management of HIV infection]

Maraviroc, the first approved CCR5-antagonist, is indicated for treatment-experienced adult patients infected with mainly detectable CCR5-tropic HIV-1, which predominates throughout infection. The antiretroviral effectiveness of maraviroc in combination with an optimized ARV therapy has been reported in clinical trials including previously treated patients. The significantly greater increase in CD4 cell counts in patients treated with maraviroc could result from a specific action as well as a better capacity to diffuse in deep compartments. According to available reports, a tropic switch from R5 to X4 induced by maraviroc treatment is not expected. These observations, combined with the predominance of R5-virus throughout the disease, support the early use of maraviroc as soon as patients fail their therapy. Provided genotypic tests assessing R5 tropism are available when the plasma viral load is not detectable, the good safety profile of maraviroc, which includes lipid parameters, could justify its use in patients with successful regimen in order to reduce the subsequent risk of major adverse events.

Optimizing management of treatment-naïve and treatment-experienced HIV+ patients: the role of maraviroc

Maraviroc is the first CCR5 antagonist approved for the treatment of HIV-1 infection. It specifically inhibits the replication of R5 viruses by blocking viral entry. HIV-1 tropism can be estimated accurately and predict viral response to maraviroc. Genotypic tools are increasingly replacing phenotypic assays in most places. The favorable pharmacokinetic properties and the good safety profile of maraviroc may support an earlier use of the drug in HIV-1 infection, as well as favor its consideration as part of switch strategies in patients under suppressive antiret-roviral regimens containing less-well-tolerated drugs. Moreover, a particular immune benefit of maraviroc might encourage its use as part of intensification strategies in HIV-infected patients with impaired CD4 gains despite prolonged suppression of HIV replication with antiretroviral therapy. However, the long-term consequences of using maraviroc must be carefully checked, given its particular mechanism of action, blocking a physiologic cell receptor.