Virologic response, early HIV-1 decay, and maraviroc pharmacokinetics with the nucleos(t)ide-free regimen of maraviroc plus darunavir/ritonavir in a pilot study

No Clinical Impact of CYP3A5 Gene Polymorphisms on the Pharmacokinetics and/or Efficacy of Maraviroc in Healthy Volunteers and HIV-1-Infected Subjects

Maraviroc is a C-C chemokine receptor type-5 antagonist approved for the treatment of HIV-1. Previous studies show that cytochrome P450 3A5 (CYP3A5) plays a role in maraviroc metabolism. CYP3A5 is subject to a genetic polymorphism. The presence of 2 functional alleles (CYP3A5*1/*1) confers the extensive metabolism phenotype, which is rare in whites but common in blacks. The effect of CYP3A5 genotype on maraviroc and/or metabolite pharmacokinetics was evaluated in 2 clinical studies: a post hoc analysis from a phase 2b/3 study (NCT00098293) conducted in 494 HIV-1-infected subjects (study 1) in which the impact on maraviroc efficacy in 303 subjects was also assessed, and a study conducted in 47 healthy volunteers (study 2). In study 2 (NCT02625207), extensive metabolizers had 26% to 37% lower mean area under the concentration-time curve compared with poor metabolizers (no CYP3A5*1 alleles). This effect diminished to 17% in the presence of potent CYP3A inhibition. The effect of CYP3A5 genotype was greatest in the formation of the metabolite (1S,2S)-2-hydroxymaraviroc. In study 1, the CYP3A5*1/*1 genotype unexpectedly had higher maraviroc area under the curve predictions (20%) compared with those with no CYP3A5*1 alleles. The reason for this disparity remains unclear. The proportions of subjects with viral loads <50 and <400 copies/mL for maraviroc were comparable among all 3 CYP3A5 genotypes. In both studies maraviroc exposures were in the range of near-maximal viral inhibition in the majority of subjects. These results demonstrate that although CYP3A5 contributes to the metabolism of maraviroc, CYP3A5 genotype does not affect the clinical response to maraviroc in combination treatment of HIV-1 infection at approved doses.

Nucleoside reverse transcriptase inhibitor-reducing strategies in HIV treatment: assessing the evidence

Antiretroviral (ARV) therapy, comprising a backbone of two nucleos(t)ide reverse transcriptase inhibitors (NRTIs) plus another ARV, is the recognized standard of care (SOC), which has helped extend life expectancy in people living with HIV. In a quest to reduce lifelong drug exposure and minimize or avoid the toxicity of NRTIs, "NRTI-reducing" regimens have been investigated. This descriptive review assessing the results of NRTI-reducing strategies from the largest randomized trials focuses on virological efficacy, resistance, regimen safety (in terms of bone mineral density, renal function, lipids and central nervous system function) and simplicity. The review considers efficacy across various NRTI-sparing strategies, for example an integrase strand transfer inhibitor (INSTI) plus a ritonavir-boosted protease inhibitor (PI/r) or PI/r + lamivudine (3TC), in both naïve and switch regimes. Of 10 key studies in treatment-naïve adults assessing five NRTI-reducing strategies, only four studies demonstrated noninferiority vs. SOC [GARDEL, NEAT 001, AIDS Clinical Trials Group 5142 and PROGRESS]. In switch settings, 17 studies (10 randomized) were reviewed that used four strategies, including three studies assessing an INSTI plus a nonnucleoside reverse transcriptase inhibitor . Noninferiority of the NRTI-reducing arm was shown in six of 10 studies (ATLAS-M, SALT, DUAL, OLE, LATTE-2 and SWORD). In general, NRTI-reducing therapy did not always result in an improvement in short- or long-term adverse events; however, in many cases, these endpoints were not reported. Some of these studies reported higher virological failure rates with more frequent emergence of resistance mutations. None of these NRTI-reducing strategies has been compared against a single-pill regimen, including those containing tenofovir alafenamide. Only strategies demonstrating noninferior efficacy, a benefit in safety/tolerability, and a favourable cost-efficacy ratio, preferably in a single pill, will eventually match the current SOC of triple ARV therapy.

Two-Drug Treatment Approaches in HIV: Finally Getting Somewhere?

The advent of combination antiretroviral therapy (ART) has significantly decreased AIDS-related morbidity and mortality. Nevertheless, the benefits of ART are only realized through adherence to lifelong treatment. Though contemporary antiretroviral (ARV) drugs have fewer adverse effects in comparison to older ARV drugs, many agents are associated with negative or unknown long-term effects. There is increasing evidence that two-drug (dual-therapy) regimens may be an effective alternative to the currently recommended three-drug (triple-therapy) regimens. In this review, we provide a comprehensive and critical review of recently completed and ongoing trials of dual-therapy regimens in treatment-naïve and treatment-experienced HIV-1-infected patients. We also review current HIV/AIDS society recommendations regarding dual therapy as well as future therapeutic possibilities.

Once-daily maraviroc versus tenofovir/emtricitabine each combined with darunavir/ritonavir for initial HIV-1 treatment

Objective:

The aim of this study was to evaluate the efficacy of maraviroc along with darunavir/ritonavir, all once daily, for the treatment of antiretroviral-naive HIV-1 infected individuals.

Design:

MODERN was a multicentre, double-blind, noninferiority, phase III study in HIV-1 infected, antiretroviral-naive adults with plasma HIV-1 RNA at least 1000 copies/ml and no evidence of reduced susceptibility to study drugs.

Methods:

At screening, participants were randomized 1 : 1 to undergo either genotypic or phenotypic tropism testing. Participants with CCR5-tropic HIV-1 were randomized 1 : 1 to receive maraviroc 150 mg once daily or tenofovir/emtricitabine once daily each with darunavir/ritonavir once daily for 96 weeks. The primary endpoint was the proportion of participants with HIV-1 RNA less than 50 copies/ml (Food and Drug Administration snapshot algorithm) at Week 48. A substudy evaluated bone mineral density, body fat distribution and serum bone turnover markers.

Results:

Seven hundred and ninety-seven participants were dosed (maraviroc, n = 396; tenofovir/emtricitabine, n = 401). The Data Monitoring Committee recommended early study termination due to inferior efficacy in the maraviroc group. At Week 48, the proportion of participants with HIV-1 RNA less than 50 copies/ml was 77.3% for maraviroc and 86.8% for tenofovir/emtricitabine [difference of −9.54% (95% confidence interval: −14.83 to −4.24)]. More maraviroc participants discontinued for lack of efficacy, which was not associated with non-R5 tropism or resistance. Discontinuations for adverse events, Category C events, Grade 3/4 adverse events and laboratory abnormalities were similar between groups.

Conclusion:

A once-daily nucleos(t)ide-sparing two-drug regimen of maraviroc and darunavir/ritonavir was inferior to a three-drug regimen of tenofovir/emtricitabine and darunavir/ritonavir in antiretroviral-naive adults.

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.

Safety, efficacy and indications of prescription of maraviroc in clinical practice: Factors associated with clinical outcomes

Maraviroc is approved for treatment-experienced HIV+ adults in twice-daily administration. Limited data are available on safety, efficacy and use in routine clinical practice, outside of restrictive clinical trials. This retrospective multicenter (27 centers) study included 667 subjects starting a regimen with maraviroc. The primary endpoint was plasma HIV-RNA <50copies/mL and CD4(+) cell count change at 48 and 96weeks (FDA snapshot analysis). 94.4% had CCR5 tropism (58.3% Trofile™, 29.2% population genotype, and 12% genotyping proviral DNA). Half of the subjects received the drug in scenarios or dosages outside the initial approval. Maraviroc was prescribed for salvage in 346 (51.9%) individuals, as a switch strategy due to toxicity in 135 (38.7%), for immune discordance in 75 (11.2%), and for simplification in 48 (7.2%). After salvage therapy, 223 (64.5%) subjects had HIV-RNA <50copies/mL at 48weeks, and 178 (51.4%) at 96weeks. Darunavir/r was included in 224 (64.7%) subjects and associated with higher rates of virological and immunologic efficacy (p<0.001). In multivariate analysis MSM (OR 2.25; 95%CI 1.29-3.94) and baseline HIV-RNA <100,000copies/mL (OR 1.96; 1.06-3.70) were associated with virological suppression. An increase in CD4(+) counts was seen at 48 and 96weeks in subjects with immune discordance (p<0.001). Maraviroc was used once-daily in 142 (21.3%) subjects overall, and 68 (57.4%) in switch/simplification. No new safety signals were identified. Besides in salvage regimens, maraviroc was frequently used in switch due to toxicity, simplification, and immune discordance. The efficacy in salvage in clinical practice was higher than in phase III clinical trials, likely due to availability of new active drugs in the regimen. These results increase our understanding of the efficacy, safety, and conditions of prescription of maraviroc beyond the initial registrational trials and the early manufacturer pharmacovigilance programs.

The Intelence aNd pRezista Once A Day Study (INROADS): a multicentre, single-arm, open-label study of etravirine and darunavir/ritonavir as dual therapy in HIV-1-infected early treatment-experienced subjects

OBJECTIVES

Following antiretroviral therapy failure, patients are often treated with a three-drug regimen that includes two nucleoside/tide reverse transcriptase inhibitors [N(t)RTIs]. An alternative two-drug nucleoside-sparing regimen may decrease the pill burden and drug toxicities associated with the use of N(t)RTIs. The Intelence aNd pRezista Once A Day Study (INROADS; NCT01199939) evaluated the nucleoside-sparing regimen of etravirine 400 mg with darunavir/ritonavir 800/100 mg once-daily in HIV-1-infected treatment-experienced subjects or treatment-naïve subjects with transmitted resistance.

METHODS

In this exploratory phase 2b, single-arm, open-label, multicentre, 48-week study, the primary endpoint was the proportion of subjects who achieved HIV-1 RNA < 50 copies/mL at week 48 [confirmed virological response (CVR), non-virological failure (VF) censored]. Key secondary endpoints included assessments of changes from baseline to week 48 in viral load, immunological response, pharmacokinetics/pharmacodynamics, safety, tolerability, metabolic and bone markers and body fat.

RESULTS

Forty-one of the 54 enrolled subjects completed the study. Adverse events (7%) and VF (7%) were the most common reasons for discontinuation. The week 48 CVR rate in the intent-to-treat (ITT) non-VF censored population was 89% (primary endpoint). Seven subjects experienced VF. Common adverse events were diarrhoea (15%), rash (15%) and upper respiratory tract infection (11%). Mild/moderate lipid elevations, minimal changes in limb fat distribution and bone mineral density and no clinically relevant changes in glucose metabolism were observed.

CONCLUSIONS

Etravirine 400 mg and darunavir/ritonavir 800/100 mg as a two-drug once-daily regimen in treatment-experienced subjects or treatment-naïve subjects with transmitted resistance was virologically efficacious and well tolerated.

Maraviroc 150 mg daily plus lopinavir/ritonavir, a nucleoside/nucleotide reverse transcriptase inhibitor-sparing regimen for HIV-infected naive patients: 48-week final results of VEMAN study

Non-conventional strategies with nucleoside/nucleotide reverse transcriptase inhibitor-sparing regimens in antiretroviral naive human immunodeficiency virus (HIV) -infected patients have been explored in clinical trials. A prospective, open-label, randomized (1:1), multicentre, proof-of-concept trial (VEMAN study, EUDRACT number 2008-006287-11) was conducted assigning HIV-infected naive patients to once-daily maraviroc plus lopinavir/ritonavir (MVC group) or to tenofovir/emtricitabine plus lopinavir/ritonavir (TDF/FTC group). Clinical and laboratory data were collected at baseline, and after 4, 12, 24, 36 and 48 weeks with the objective to evaluate the 48-week virological and immunological efficacy. HIV-1 DNA load and CD4(+) T-cell subsets were analysed on frozen peripheral blood mononuclear cells collected at baseline, 4 and 48 weeks to explore the trend in HIV reservoirs. Fifty patients were randomized and included in the analysis. During follow up, HIV-1 RNA decreased similarly in both groups and, at week 48, all patients in the MVC group and 22/24 (96%) in the TDF/FTC group had < 50 copies/ml of HIV-1 RNA. CD4(+) trend during follow up was higher in maraviroc-treated patients (MVC group: 286 (183-343) versus TDF/FTC group: 199 (125-285); Mann-Whitney U-test: p 0.033). A significant 48-week increase of CCR5(+) CD4(+) T cells and CD4(+) effector memory cells was observed among maraviroc-treated patients (Wilcoxon signed rank test: p 0.016 and p 0.007, respectively). No significant variations were found in naive and central memory CD4(+) T cells. Among naive patients with an R5 virus, treatment with maraviroc and lopinavir/ritonavir was shown to provide a virological response compared to a triple therapy and a greater immunological benefit.

Maintenance of virologic efficacy and decrease in levels of β2-microglobulin, soluble CD40L and soluble CD14 after switching previously treated HIV-infected patients to an NRTI-sparing dual therapy

Novel strategies are necessary to decrease inflammatory parameters in successfully treated HIV-infected patients. Our aim was to evaluate the maintenance of viral suppression and potential changes in inflammatory, immune-activation and coagulation biomarkers in virologically suppressed HIV-infected patients switched to a nucleoside reverse transcriptase inhibitor-sparing (NRTI) and maraviroc (MVC)-containing combined antiretroviral therapy (cART). Fifty-eight HIV-infected patients were observed after their treatment regimens were changed to MVC 150mg/once daily plus ritonavir-boosted protease inhibitor therapy. Activation-, inflammation- and coagulation-associated biomarkers and mitochondrial (mt)DNA were analyzed after a median of 24weeks of follow-up. We observed that after changing to an NRTI-sparing regimen, 96.6% of HIV-patients on viral suppressive cART maintained viral suppression and their CD4+ T cell counts did not change significantly (median of 31weeks of follow-up). This cART switch reduced soluble CD40 ligand (p=0.002), beta-2 microglobulin (p=0.025), and soluble CD14 (p=0.009) in patients with higher baseline levels of these inflammation biomarkers after a median of 24weeks of follow-up. The results of our study show that changing to NRTI-sparing dual therapy decreased the levels of inflammatory biomarkers and maintained the immune-virologic efficacy. The potential benefits of this regimen warrant further investigation to uncover the association of this therapy with the potential decrease in the morbidity and mortality of HIV-infected patients from non-AIDS-defining illnesses.

CYP3A5 genotype impacts maraviroc concentrations in healthy volunteers

CYP3A5 plays a prominent role in the metabolism of maraviroc, an approved drug for human immunodeficiency virus (HIV)-1 treatment and a candidate for HIV-1 prevention. We studied the effect of the CYP3A5 genotype on pharmacokinetics of maraviroc and a primary CYP3A5-dependent metabolite of maraviroc denoted as metabolite 1 (M1). Volunteers were screened for health status and CYP3A5 genotype (wild-type allele *1 and dysfunctional alleles *2, *3, *6, and *7) to obtain 24 evaluable subjects in three groups (n = 8 each): homozygous dysfunctional (two dysfunctional alleles), heterozygous (one *1 allele and one dysfunctional allele), and homozygous wild-type (two *1 alleles). Subjects received 300 mg maraviroc orally followed by blood collection for 32 hours. The homozygous wild-type group exhibited lower mean plasma maraviroc concentrations at almost all sampling times. The median (interquartile range) maraviroc area under the plasma concentration-time curves from time 0 to infinity (AUC0-inf) were 2099 (1422-2568) ng⋅h/ml, 1761 (931-2640) ng⋅h/ml, and 1238 (1065-1407) ng⋅h/ml for the homozygous dysfunctional, heterozygous, and homozygous wild-type groups, respectively. The homozygous wild-type group had 41% lower maraviroc AUC0-inf and 66% higher apparent clearance compared with the homozygous dysfunctional group (P = 0.02). The AUC0-inf ratios of maraviroc to M1 in heterozygous and homozygous wild-type subjects were lower by 51 and 64% relative to the homozygous dysfunctional group, respectively (P < 0.001). In conclusion, the lower maraviroc concentrations in the homozygous wild-type group indicate that maraviroc may be underdosed in people homozygous for the CYP3A5*1 allele, including almost one-half of African Americans.

Pharmacokinetics and pharmacodynamics of boosted once-daily darunavir

The ability to dose antiretroviral agents once daily simplifies the often complex therapeutic regimens required for the successful treatment of HIV infection. Thus, once-daily dosing can lead to improved patient adherence to medication and, consequently, sustained virological suppression and reduction in the risk of emergence of drug resistance. Several trials have evaluated once-daily darunavir/ritonavir in combination with other antiretrovirals (ARTEMIS and ODIN trials) or as monotherapy (MONET, MONOI and PROTEA trials) in HIV-1-infected adults. Data from ARTEMIS and ODIN demonstrate non-inferiority of once-daily darunavir/ritonavir against a comparator and, together with pharmacokinetic data, have established the suitability of once-daily darunavir/ritonavir for treatment-naive and treatment-experienced patients with no darunavir resistance-associated mutations. The findings of ARTEMIS and ODIN have led to recent updates to treatment guidelines, whereby once-daily darunavir/ritonavir, given with other antiretrovirals, is now a preferred treatment option for antiretroviral-naive adult patients and a simplified treatment option for antiretroviral-experienced adults who have no darunavir resistance-associated mutations. Once-daily dosing with darunavir/ritonavir is an option for treatment-naive and for treatment-experienced paediatric patients with no darunavir resistance-associated mutations based on the findings of the DIONE trial and ARIEL substudy. This article reviews the pharmacokinetics, efficacy, safety and tolerability of once-daily boosted darunavir. The feasibility of darunavir/ritonavir monotherapy as a treatment approach for some patients is also discussed. Finally, data on a fixed-dose combination of 800/150 mg of darunavir/cobicistat once daily are presented, showing comparable darunavir bioavailability to that obtained with 800/100 mg of darunavir/ritonavir once daily.

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.

Antiretroviral regimens sparing agents from the nucleoside(tide) reverse transcriptase inhibitor class: a review of the recent literature

The nucleoside(tide) reverse transcriptase inhibitors (NRTIs) have traditionally been an important 'back-bone' of an antiretroviral therapy (ART) regimen. However all agents have been associated with both short- and long-term toxicity. There have also been concerns regarding the efficacy and safety of a treatment sequencing strategy in which those with past exposure and/or resistance to one or more NRTIs are re-exposed to 'recycled' NRTIs in subsequent ART regimens. Newer, potent and possible safer, agents from various ART classes continue to become available. There has therefore been growing interest in evaluating NRTI-sparing regimens. In this review, we examined studies of NRTI-sparing regimens in adult HIV-positive patients with varying degrees of ART experience. We found that in treatment experienced patients currently on a failing regimen with detectable viral load, there now exists a robust evidence for the use of NRTI-sparing regimens including raltegravir with a boosted-protease inhibitor with or without a third agent. In those on a virologically suppressive regimen switching to a NRTI-sparing regimen or in those ART-naïve patients initiating an NRTI-sparing regimen, evidence is sparse and largely comes from small exploratory trials or observational studies. Overall, these studies suggest that caution needs to be exercised in carefully selecting the right candidate and agents, especially in the context of a dual-therapy regimen, to minimise the risks of virological failure. There is residual toxicity conferred by the ritonavir boost in protease-inhibitor containing NRTI-sparing regimens. Fully-powered studies are needed to explore the place of N (t)RTI-sparing regimens in the sequencing of ART. Additionally research is required to explore how to minimise the adverse effects associated with ritonavir-based pharmacoenhancement.