First prospective comparison of genotypic versus phenotypic tropism assays in predicting virologic responses to maraviroc in a phase 3 study.

Maraviroc (MVC, a CCR5 antagonist) is only fully active against CCR5 tropic [R5] HIV-1, and tropism testing is required prior to initiating treatment. The MODERN study prospectively compared genotypic (GTT) and phenotypic (Trofile®) tropism testing with treatment-naive HIV-1-infected participants randomized 1:1 to either GTT or Trofile tropism assessments. Participants with R5 virus were randomized 1:1 to receive darunavir/ritonavir (DRV/r) with either MVC or tenofovir/emtricitabine. Screening samples were also retrospectively tested using the alternative assay. Positive predictive values (PPVs) for each assay were estimated using both the observed MVC+DRV/r response rate (HIV-1 RNA <50 copies/mL at Week 48) and model-based response estimates. The observed MVC+DRV/r response rate was 146/181 (80.7%) for GTT versus 160/215 (74.4%) for Trofile, with a stratification adjusted difference of 6.6% (95% CI, -1.5% to 14.7%) in favor of GTT. The model-based PPV estimates (±standard error) were 80.5% (±2.38) and 78.0% (±2.35) for GTT and Trofile, respectively (difference, 2.5%; 95% CI, -2.0% to 7.0%). Most participants had R5 results using both assays (285/396; 72%) and, of those, 79.3% (226/285) had HIV-1 RNA <50 copies/mL at Week 48. Both the genotypic and phenotypic tropism assays evaluated can effectively predict treatment response to MVC.

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.

Pharmacokinetics, safety and efficacy of maraviroc in treatment-experienced pediatric patients Infected with CCR5-tropic HIV-1

BACKGROUND: Maraviroc is a CC-chemokine receptor 5 antagonist approved to treat adults infected with CC-chemokine receptor 5-tropic (R5) HIV-1. Study A4001031 was conducted to evaluate the pharmacokinetics, safety and efficacy of maraviroc in combination with optimized background therapy in treatment-experienced pediatric patients infected with R5 HIV-1 and support registration of maraviroc for pediatric use. METHODS: This is an open-label, 2-stage, age-stratified, noncomparative multicenter study. One-hundred and three participants were enrolled into 4 age/formulation cohorts and dosed twice daily. Initial doses were determined by body surface area and optimized background therapy, based on drug interactions with maraviroc in adults. Dose adjustment and pharmacokinetic reevaluation occurred if the average concentrations (Cavg) at Week 2 were <100 ng/mL (Stage 1-dose finding). RESULTS: Data from the Week 48 analysis demonstrated that 49/50 Stage 1 participants rolling over into Stage 2 (safety and efficacy) achieved Cavg ≥100 ng/mL. Doses were identified that achieved similar concentration ranges to those seen in adults. The majority (90/103) received optimized background therapy containing potent cytochrome P450 3A inhibitors. Maraviroc was well tolerated and the safety and efficacy were comparable to those of adults. All cohorts had a mean decrease from baseline in HIV-1 RNA of >1 log10. Increases from baseline in the median CD4+ cell count and percentage were seen for all age groups. CONCLUSIONS: The maraviroc dosing strategy resulted in participants achieving the target Cavg, with exposure ranges similar to those observed in adults on approved doses. The safety and efficacy of maraviroc in this pediatric population were comparable to those seen in adults

Pharmacokinetics, Safety and Efficacy of Maraviroc in Treatment-experienced Pediatric Patients Infected With CCR5-Tropic HIV-1.

BACKGROUND: Maraviroc is a CC-chemokine receptor 5 antagonist approved to treat adults infected with CC-chemokine receptor 5-tropic (R5) HIV-1. Study A4001031 was conducted to evaluate the pharmacokinetics, safety and efficacy of maraviroc in combination with optimized background therapy in treatment-experienced pediatric patients infected with R5 HIV-1 and support registration of maraviroc for pediatric use. METHODS: This is an open-label, 2-stage, age-stratified, noncomparative multicenter study. One-hundred and three participants were enrolled into 4 age/formulation cohorts and dosed twice daily. Initial doses were determined by body surface area and optimized background therapy, based on drug interactions with maraviroc in adults. Dose adjustment and pharmacokinetic reevaluation occurred if the average concentrations (Cavg) at Week 2 were <100 ng/mL (Stage 1-dose finding). RESULTS: Data from the Week 48 analysis demonstrated that 49/50 Stage 1 participants rolling over into Stage 2 (safety and efficacy) achieved Cavg ≥100 ng/mL. Doses were identified that achieved similar concentration ranges to those seen in adults. The majority (90/103) received optimized background therapy containing potent cytochrome P450 3A inhibitors. Maraviroc was well tolerated and the safety and efficacy were comparable to those of adults. All cohorts had a mean decrease from baseline in HIV-1 RNA of >1 log10. Increases from baseline in the median CD4+ cell count and percentage were seen for all age groups. CONCLUSIONS: The maraviroc dosing strategy resulted in participants achieving the target Cavg, with exposure ranges similar to those observed in adults on approved doses. The safety and efficacy of maraviroc in this pediatric population were comparable to those seen in adults.

Hepatic safety of maraviroc in patients with HIV-1 and hepatitis C and/or B virus: 144-week results from a randomized, placebo-controlled trial.

BACKGROUND: In the primary 48-week analysis of a hepatic safety trial in patients with HIV-1 coinfected with HBV and/or HCV, maraviroc-containing treatment regimens were not associated with increased hepatotoxicity. METHODS: In this randomized, double-blind, placebo-controlled, multicentre study, patients received maraviroc twice daily (n=70) or placebo (n=67) with concomitant antiretroviral therapy for 144 weeks (Clinicaltrials.gov identifier, NCT01327547). The primary end point was the proportion of patients with protocol-defined Grade 3/4 alanine aminotransferase (ALT) abnormalities through week 48. Key secondary end points included 144-week analysis of Grade 3/4 ALT abnormalities and liver fibrosis by enhanced liver fibrosis (ELF) testing, hepatic elastography and an optional biopsy substudy. RESULTS: Through 144 weeks of treatment, two (maraviroc) and three (placebo) patients met the protocol-defined Grade 3/4 ALT end point. Similar to the 48-week results, there were no statistically significant differences between groups in change from baseline in ELF or hepatic elastography. However, decreased elastography scores were noted in the maraviroc group. Blinded pathologist review suggested that 2 of 11 paired biopsies (both on maraviroc) showed signs of decreased fibrosis. One (maraviroc) and two (placebo) patients experienced treatment-related hepatobiliary adverse events (AEs). Five patients in the maraviroc group discontinued because of treatment-related AEs versus three in the placebo group. One death in the maraviroc group and two deaths in the placebo group were reported. CONCLUSIONS: Use of maraviroc did not increase hepatotoxicity in this population through 144 weeks. Further investigation regarding possible beneficial effects of maraviroc on liver fibrosis may be warranted.

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.

Development of maraviroc, a CCR5 antagonist for treatment of HIV, using a novel tropism assay.

Assays to identify infectious organisms are critical for diagnosis and enabling the development of therapeutic agents. The demonstration that individuals with a 32-bp deletion within the CCR5 locus were resistant to human immunodeficiency virus (HIV) infection, while those heterozygous for the mutation progressed more slowly, led to the discovery of maraviroc (MVC), a CCR5 antagonist. As MVC is only active against CCR5-tropic strains of HIV, it was critical to develop a diagnostic assay to identify appropriate patients. Trofile™, a novel phenotypic tropism assay, was used to identify patients with CCR5-tropic virus for the MVC development program. Results of these clinical studies demonstrated that the assay correctly identified patients likely to respond to MVC. Over time, the performance characteristics of the phenotypic assay were enhanced, necessitating retesting of study samples. Genotypic tropism tests that have the potential to allow for local use and more rapid turnaround times are also being developed.

Hepatic safety in subjects with HIV-1 and hepatitis C and/or B virus: a randomized, double-blind study of maraviroc versus placebo in combination with antiretroviral agents.

BACKGROUND: One of the more clinically relevant co-morbidities in HIV-infected patients is the development of progressive liver disease due to hepatitis B virus (HBV) or hepatitis C virus (HCV). In addition, hepatotoxicity has been observed with prolonged use of antiretroviral agents. OBJECTIVE: To evaluate the hepatic safety of maraviroc in combination with other antiretroviral agents in HIV-1-infected subjects co-infected with HCV and/or HBV. METHODS: In this 148-week randomized, double-blind, placebo-controlled, multicentre study (NCT01327547), subjects received maraviroc twice daily (n = 70) or placebo (n = 67) in combination with other antiretroviral agents. PRIMARY ENDPOINT: the percentage at week 48 of subjects with Grade 3 and Grade 4 ALT abnormalities, defined as >5 × upper limit of normal (ULN) if baseline ALT ≤ ULN or >3.5 × baseline if baseline ALT>ULN in the maraviroc versus the placebo arm. RESULTS: At week 48, one subject in each group had met the primary endpoint definition. No subjects met protocol-defined liver stopping criteria and there were no cases of Hy's law or treatment-related hepatobiliary serious adverse events. No significant difference in change from baseline in enhanced liver fibrosis or hepatic elastography was observed between groups. Treatment-related hepatobiliary adverse events were reported in one and two subjects receiving maraviroc and placebo, respectively; discontinuations due to treatment-related AEs occurred in four and two subjects receiving maraviroc and placebo, respectively; two deaths were reported in the placebo group. CONCLUSIONS: The use of maraviroc does not increase hepatotoxicity in HIV-1-infected subjects co-infected with HCV and/or HBV through 48 weeks of treatment.

The maraviroc expanded access program - safety and efficacy data from an open-label study.

PURPOSE: The maraviroc (MVC) expanded access program (EAP) was initiated to increase MVC availability to patients with limited treatment options. Darunavir (DRV), raltegravir (RAL), and etravirine (ETV) were either recently approved or under regulatory review at study initiation and available for coadministration with MVC. Thus, the safety of MVC in combination with new antiretroviral therapies (ARVs) could be assessed. This open-label safety study of MVC was conducted at 262 sites worldwide in 1032 R5 HIV-positive treatment-experienced patients with limited/no therapeutic options. METHODS: Study visits included screening, baseline, end of study or early discontinuation, and follow-up 30 days after last dose. Interim visits for HIV-1 RNA and CD4 cell counts occurred according to local HIV infection management guidelines. Safety data were analyzed overall and by subgroup based on ARV combination [MVC+optimized background therapy (OBT), MVC ± OBT+DRV/r, MVC ± OBT+RAL, MVC ± OBT+RAL+DRV/r, MVC ± OBT+RAL+ETV ± DRV/r]. RESULTS: Most (90.3%) adverse events (AEs) were of mild or moderate severity with few grade 3/4 events, discontinuations, or temporary discontinuations/dose reductions due to AEs or serious AEs. Similar results were observed across subgroups. Of treated patients, 79.9% and 50% had HIV-1 RNA < 400 copies/ml and < 50 copies/ml respectively, at the end of the study, early termination visits, or at last known status. Tropism changes and selection of MVC-resistant R5 virus, including high-level MVC dependence, were mechanisms of viral escape. CONCLUSION: MVC was well tolerated with virologic suppression observed in most patients.

First prospective comparison of genotypic vs phenotypic tropism assays in predicting virologic responses to Maraviroc (MVC) in a phase 3 study: MODERN.

INTRODUCTION: MODERN (A4001095) was the first prospective phase 3 study comparing genotype vs phenotype (Trofile™) tropism assessments. MATERIALS AND METHODS: Treatment-naïve adults with HIV-1 RNA >1000 copies/mL were randomized 1:1 at screening to either genotype or Trofile for tropism assessment. Genotype was determined using the geno2pheno algorithm to assess triplicate HIV-1 gp120 V3 loop sequences (plasma); false-positive rate=10%. R5-virus-infected subjects were then randomized 1:1 to receive Maraviroc (MVC) 150 mg QD or Truvada 200/300 mg QD each with DRV/r 800/100 mg QD. Tropism of screening samples from enrolled subjects was also retrospectively determined using the alternate testing method. Positive predictive values (PPV) were estimated by%R5 subjects with Week 48 HIV-1 RNA < 50 c/mL. PPV for each assay was estimated using the response rate among those randomized to that assay and using model-based response estimates in those with R5 by that assay (at screening or retest). RESULTS: The observed response rate was 146/181 (80.7%) for genotype vs 160/215 (74.4%) for Trofile (stratification adjusted difference=6.9%, 95% CI 1.3% to 15%). The model-based estimates of PPV (±SE) were 79.1% (±2.42) and 76.3% (±2.38), respectively (difference = 2.8%, 95% CI -2.1% to 7.2%). There was no difference in response rate between assays in the Truvada arm (observed difference=- 0.1%, 95% CI -6.8% to 6.6%). Most enrolled subjects had R5 results at screening using both assays (285/396 (72%)), and of these subjects, 79.3% (226/285) had HIV-1 RNA <50 c/mL at week 48 (Table 1). The few subjects classified as non-R5 by the alternate assay had similar virologic responses to the concordant R5 group. CONCLUSION: There was a higher MVC response rate and model-based positive predictive value with genotype compared to Trofile, but this difference did not reach statistical significance. The majority of subjects had concordant R5 tropism results. Either phenotype or genotype can effectively predict MVC response.

Efficacy and safety of lersivirine versus etravirine for the treatment of HIV-1 infection in patients with prior non-nucleoside reverse transcriptase inhibitor (NNRTI) use and evidence of NNRTI resistance: a randomized phase 2B trial.

OBJECTIVE: To assess the efficacy and safety of lersivirine versus etravirine in patients with HIV-1 and prior non-nucleoside reverse transcriptase inhibitor (NNRTI) use and evidence of NNRTI resistance. METHODS: In this 96-week, phase 2b study, 97 patients were randomized and treated with lersivirine 750 mg qd (n = 31), lersivirine 1,000 mg qd (n = 32), and etravirine 200 mg bid (n = 34), plus one optimized nucleoside reverse transcriptase inhibitor and darunavir/ritonavir 600/100 mg bid. The primary endpoint was the percentage of patients with HIV-1 RNA <50 copies/mL at week 24. RESULTS: At week 24, HIV-1 RNA <50 copies/mL was achieved by fewer patients receiving lersivirine 750 mg (48.4%) and 1,000 mg (43.8%) qd compared with etravirine 200 mg qd (67.7%) (intention to treat [ITT], missing/switch/discontinuation equals failure [MSDF]). At week 48, HIV-1 RNA <50 copies/mL and <400 copies/mL were also achieved by fewer patients receiving lersivirine 750 mg (41.9% and 41.9%, respectively) and 1,000 mg (31.3% and 34.4%, respectively) qd compared with etravirine 200 mg bid (61.8% and 70.6%, respectively) (ITT, MSDF). Least squares means (SE) change from baseline in log transformed HIV-1 RNA at week 48 was -1.42 (0.27) and -0.95 (0.28) copies/mL for lersivirine 750 mg and 1,000 mg qd, respectively, versus -2.02 (0.26) copies/mL for etravirine 200 mg bid (ITT). Lersivirine and etravirine were generally safe and well-tolerated. CONCLUSIONS: Lersivirine 750 mg and 1,000 mg qd was associated with lower rates of viral suppression at week 24 and week 48 versus etravirine in patients with prior NNRTI use and evidence of NNRTI resistance. No new safety signals were detected.

Efficacy and safety of maraviroc vs. efavirenz in treatment-naive patients with HIV-1: 5-year findings.

OBJECTIVE: Maraviroc, a chemokine co-receptor type 5 (CCR5) antagonist, has demonstrated comparable efficacy and safety to efavirenz, each in combination with zidovudine/lamivudine, over 96 weeks in the Maraviroc vs. Efavirenz Regimens as Initial Therapy (MERIT) study. Here we report 5-year findings. DESIGN: A randomized, double-blind, multicenter phase IIb/III study with an open-label extension phase. METHODS: Treatment-naive patients with CCR5-tropic HIV-1 infection (Trofile) received maraviroc 300 mg twice daily or efavirenz 600 mg once daily, and zidovudine/lamivudine 300 mg/150 mg twice daily. After the last patient's week 96 visit, the study was unblinded and patients could enter a nominal 3-year open-label phase. Endpoints at the 5-year nominal visit (week 240) included proportion of patients (CCR5 tropism re-confirmed by enhanced sensitivity Trofile) with viral load (plasma HIV-1 RNA) below 50 and 400 copies/ml, and change from baseline in CD4(+) cell count, as well as safety. RESULTS: The proportion of patients maintaining viral load below 50 copies/ml was similar between treatment arms throughout the study and at week 240 (maraviroc 50.8% vs. efavirenz 45.9%). Maraviroc-treated patients had a greater increase from baseline in mean CD4(+) cell count than efavirenz-treated patients at week 240 (293 vs. 271 cells/µl, respectively). Fewer patients on maraviroc vs. efavirenz experienced treatment-related adverse events (68.9 vs. 81.7%) and discontinued as a result of any adverse event (10.6 vs. 21.3%). CONCLUSION: Maraviroc maintained similar long-term antiviral efficacy to efavirenz over 5 years in treatment-naive patients with CCR5-tropic HIV-1. Maraviroc was generally well tolerated with no unexpected safety findings or evidence of long-term safety concerns.

Five-year safety evaluation of maraviroc in HIV-1-infected treatment-experienced patients.

BACKGROUND: Maraviroc is unique among approved antiretroviral drugs in targeting the host-cell chemokine coreceptor type-5 receptor. With its novel mechanism of action, we sought to describe the 5-year safety profile of maraviroc. METHODS: Two large phase 3 studies of maraviroc enrolled HIV-infected treatment-experienced patients and followed them up for 5 or more years. Survival and selected clinical end points were identified and assessed. RESULTS: A total of 938 enrolled patients received maraviroc-containing regimens. Rates of death and selected clinical events (eg, hepatic failure, malignancy, and myocardial infarction) were low during follow-up. CONCLUSIONS: Maraviroc was generally safe in treatment-experienced participants for >5 years.

The effects of boceprevir and telaprevir on the pharmacokinetics of maraviroc: an open-label, fixed-sequence study in healthy volunteers.

OBJECTIVE: To evaluate the effects of boceprevir (BOC) and telaprevir (TVR) on the pharmacokinetics (PK) of maraviroc (MVC) in healthy volunteers. METHODS: In this open-label, fixed-sequence study, 14 volunteers received MVC 150 mg twice daily alone for 5 days (period 1), followed by MVC + BOC 800 mg 3 times daily and MVC + TVR 750 mg 3 times daily, each for 10 days in periods 2 and 3, respectively, with a ≥10-day wash-out. PK was analyzed on day 5 of period 1 and day 10 of periods 2 and 3. Safety was also assessed. RESULTS: Ratios of the adjusted geometric means (90% confidence intervals) for MVC area under the curve from predose to 12 hours, maximum plasma concentration, and plasma concentration at 12 hours were 3.02 (2.53 to 3.59), 3.33 (2.54 to 4.36), and 2.78 (2.40 to 3.23), respectively, for MVC + BOC versus MVC alone, and 9.49 (7.94 to 11.34), 7.81 (5.92 to 10.32), and 10.17 (8.73 to 11.85), respectively, for MVC + TVR versus MVC alone. PK profiles for MVC + BOC or TVR were consistent with historic values for BOC and TVR monotherapy. Adverse event incidence was higher with MVC + BOC and MVC + TVR versus MVC alone. Dysgeusia (50%) and pruritus (29%) occurred most commonly with MVC + BOC, and fatigue (46%) and headache (31%) with MVC + TVR. There were no serious adverse events. CONCLUSIONS: MVC exposures were significantly increased with BOC or TVR, therefore MVC should be dosed at 150 mg twice daily when coadministered with these newly approved hepatitis C protease inhibitors. No dose adjustment for BOC or TVR is warranted with MVC. MVC + BOC or TVR was generally well tolerated with no unexpected safety findings.

Genotypic analysis of the V3 region of HIV from virologic nonresponders to maraviroc-containing regimens reveals distinct patterns of failure.

Changes in HIV tropism from R5 to non-R5 or development of drug resistance is often associated with virologic failure in patients treated with maraviroc, a CCR5 antagonist. We sought to examine changes in HIV envelope sequences and inferred tropism in patients who did not respond to maraviroc-based regimens. We selected 181 patients who experienced early virologic failure on maraviroc-containing therapy in the MOTIVATE trials. All patients had R5 HIV by the original Trofile assay before entry. We used population-based sequencing methods and the geno2pheno algorithm to examine changes in tropism and V3 sequences at the time of failure. Using deep sequencing, we assessed whether V3 sequences observed at failure emerged from preexisting subpopulations. From population genotyping data at failure, 90 patients had R5 results, and 91 had non-R5 results. Of the latter group, the geno2pheno false-positive rate (FPR) value fell from a median of 20 at screening to 1.1 at failure. By deep sequencing, the median percentage of non-R5 variants in these patients rose from 1.4% to 99.5% after a median of 4 weeks on maraviroc. In 70% of cases, deep sequencing could detect a pretreatment CXCR4-using subpopulation, which emerged at failure. Overall, there were two distinct patterns of failure of maraviroc. Patients failing with R5 generally had few V3 substitutions and low non-R5 prevalence by deep sequencing. Patients with non-R5 HIV who were failing developed very-high-prevalence non-R5 HIV (median, 99%) and had very low geno2pheno values.

Pharmacokinetic interaction between maraviroc and fosamprenavir-ritonavir: an open-label, fixed-sequence study in healthy subjects.

This open-label, fixed-sequence, phase 1 study evaluated the pharmacokinetic interaction between maraviroc (MVC) and ritonavir-boosted fosamprenavir (FPV/r) in healthy subjects. In period 1, subjects received 300 mg of MVC twice daily (BID; cohort 1) or once daily (QD; cohort 2) for 5 days. In period 2, cohort 1 subjects received 700/100 mg of FPV/r BID alone on days 1 to 10 and then FPV/r at 700/100 mg BID plus MVC at 300 mg BID on days 11 to 20; cohort 2 subjects received FPV/r at 1,400/100 mg QD alone on days 1 to 10 and then FPV/r at 1,400/100 mg QD plus MVC at 300 mg QD on days 11 to 20. Pharmacokinetic parameters, assessed on day 5 of period 1 and on days 10 and 20 of period 2, included the maximum plasma concentration (Cmax), the concentration at end of dosing interval (Cτ), and the area under the curve over dosing interval (AUCτ). Safety and tolerability were also assessed. MVC geometric mean AUCτ, Cmax, and Cτ were increased by 149, 52, and 374%, respectively, after BID dosing with FPV/r, and by 126, 45, and 80%, respectively, after QD dosing. Amprenavir (the active form of the prodrug fosamprenavir) and ritonavir exposures were decreased in the presence of MVC with amprenavir AUCτ, Cmax, and Cτ decreased by 34 to 36% in the presence of FPV/r plus maraviroc BID and by 15 to 30% with FPV/r plus MVC QD both compared to FPV/r alone. The overall all-causality adverse-event (AE) incidence rate was 96.4%; all AEs were of mild or moderate severity. Commonly reported treatment-related AEs (>20% of patients overall) included diarrhea, fatigue, abdominal discomfort, headache, and nausea. No serious AEs or deaths occurred. In summary, maraviroc exposure increased in the presence of FPV/r, whereas MVC coadministration decreased amprenavir and ritonavir exposures. MVC dosed at 300 mg BID with FPV/r is not recommended due to concerns of lower amprenavir exposures; however, no dose adjustment is warranted with MVC at 150 mg BID in combination with FPV/r based on the available clinical data. MVC plus FPV/r was generally well tolerated; no new safety signals were detected.