Caroline E. Ridgway

Maraviroc for Previously Treated Patients with R5 HIV-1 Infection

BACKGROUND CC chemokine receptor 5 antagonists are a new class of antiretroviral agents. METHODS We conducted two double-blind, placebo-controlled, phase 3 studies--Maraviroc versus Optimized Therapy in Viremic Antiretroviral Treatment-Experienced Patients (MOTIVATE) 1 and MOTIVATE 2--with patients who had R5 human immunodeficiency virus type 1 (HIV-1) only. They had been treated with or had resistance to three antiretroviral-drug classes and had HIV-1 RNA levels of more than 5000 copies per milliliter. The patients were randomly assigned to one of three antiretroviral regimens consisting of maraviroc once daily, maraviroc twice daily, or placebo, each of which included optimized background therapy (OBT) based on treatment history and drug-resistance testing. Safety and efficacy were assessed after 48 weeks. RESULTS A total of 1049 patients received the randomly assigned study drug; the mean baseline HIV-1 RNA level was 72,400 copies per milliliter, and the median CD4 cell count was 169 per cubic millimeter. At 48 weeks, in both studies, the mean change in HIV-1 RNA from baseline was greater with maraviroc than with placebo: -1.66 and -1.82 log(10) copies per milliliter with the once-daily and twice-daily regimens, respectively, versus -0.80 with placebo in MOTIVATE 1, and -1.72 and -1.87 log(10) copies per milliliter, respectively, versus -0.76 with placebo in MOTIVATE 2. More patients receiving maraviroc once or twice daily had HIV-1 RNA levels of less than 50 copies per milliliter (42% and 47%, respectively, vs. 16% in the placebo group in MOTIVATE 1; 45% in both maraviroc groups vs. 18% in MOTIVATE 2; P<0.001 for both comparisons in each study). The change from baseline in CD4 counts was also greater with maraviroc once or twice daily than with placebo (increases of 113 and 122 per cubic millimeter, respectively, vs. 54 in MOTIVATE 1; increases of 122 and 128 per cubic millimeter, respectively, vs. 69 in MOTIVATE 2; P<0.001 for both comparisons in each study). Frequencies of adverse events were similar among the groups. CONCLUSIONS Maraviroc, as compared with placebo, resulted in significantly greater suppression of HIV-1 and greater increases in CD4 cell counts at 48 weeks in previously treated patients with R5 HIV-1 who were receiving OBT. (ClinicalTrials.gov numbers, NCT00098306 and NCT00098722.)

Efficacy of short-term monotherapy with maraviroc, a new CCR5 antagonist, in patients infected with HIV-1

We assessed the efficacy and safety of 10-d monotherapy with the orally administered CCR5 antagonist maraviroc in 63 HIV-1-positive individuals prescreened for the absence of CXCR4-using virus. Maximum reduction in viral load occurred at a median of 10–15 d, with a mean reduction of ≥1.6 log10 copies/ml at all twice daily doses ≥100 mg. These results provide proof of concept that CCR5 antagonism is a viable antiretroviral therapeutic approach.

Subgroup analyses of maraviroc in previously treated R5 HIV-1 infection.

BACKGROUND We conducted subanalyses of the combined results of the Maraviroc versus Optimized Therapy in Viremic Antiretroviral Treatment-Experienced Patients (MOTIVATE) 1 and MOTIVATE 2 studies to better characterize the efficacy and safety of maraviroc in key subgroups of patients. METHODS We analyzed pooled data from week 48 from the two studies according to sex, race or ethnic group, clade, CC chemokine receptor 5 (CCR5) delta32 genotype, viral load at the time of screening, the use or nonuse of enfuvirtide in optimized background therapy (OBT), the baseline CD4 cell count, the number of active antiretroviral drugs coadministered, the first use of selected background agents, and tropism at baseline. Changes in viral tropism and the CD4 count at treatment failure were evaluated. Data on aminotransferase levels in patients coinfected with hepatitis B virus (HBV) or hepatitis C virus (HCV) were also analyzed. RESULTS A treatment benefit of maraviroc plus OBT over placebo plus OBT was shown in all subgroups, including patients with a low CD4 cell count at baseline, those with a high viral load at screening, and those who had not received active agents in OBT. Analyses of the virologic response according to the first use of selected background drugs showed the additional benefit of adding a potent new drug to maraviroc at the initiation of maraviroc therapy. More patients in whom maraviroc failed had a virus binding to the CXC chemokine receptor 4 (CXCR4) at failure, but there was no evidence of a decrease in the CD4 cell count at failure in such patients as compared with those in whom placebo failed. Subanalyses involving patients coinfected with HBV or HCV revealed no evidence of excess hepatotoxic effects as compared with baseline. CONCLUSIONS Subanalyses of pooled data from week 48 indicate that maraviroc provides a valuable treatment option for a wide spectrum of patients with R5 HIV-1 infection who have been treated previously. (ClinicalTrials.gov numbers, NCT00098306 and NCT00098722.)

Assessment of the absorption, metabolism and absolute bioavailability of maraviroc in healthy male subjects

AIMS Two studies were conducted to: (i) quantify the amount of drug-related radioactivity in blood, plasma, urine and faeces following a (14)C-labelled dose of maraviroc; and (ii) investigate the pharmacokinetics, safety and tolerability of intravenous (i.v.) maraviroc and determine the absolute bioavailability of oral maraviroc. Metabolite profiling was also conducted. Data from both of these studies were used to construct a mass-balance model for maraviroc. METHODS Study 1 was an open-label study in three healthy male subjects. All subjects received a single 300-mg oral solution dose of (14)C-labelled maraviroc. Study 2 included two cohorts of subjects. Cohort 1 involved a double-blind (third party open), four-way crossover study where eight subjects received escalating i.v. doses of maraviroc (3, 10 and 30 mg) with placebo insertion. Cohort 2 involved an open, two-way crossover study where 12 subjects received 30 mg maraviroc by i.v. infusion and 100 mg maraviroc orally in random order. In study 1, blood samples and all urine and faeces were collected up to at least 120 h postdose. In study 2, blood samples were taken at intervals up to 48 h postdose. Urine was also collected up to 24 h postdose in cohort 1 only. RESULTS After oral administration in study 1, maraviroc was rapidly absorbed with a plasma T(max) reached by 2 h postdose for all three subjects. The maximum concentrations of radioactivity also occurred within 2 h for all subjects. There was a higher amount of radioactivity in plasma than in blood (blood/plasma ratio approximately 0.6 for AUC(t) and C(max)). Unchanged maraviroc was the major circulating component in plasma, accounting for approximately 42% of the circulating radioactivity. Following a 300-mg (14)C-labelled maraviroc dose, means of 76.4% and 19.6% of radioactivity were recovered in the faeces and urine, respectively. The mean total recovery of dosed radioactivity was 96%, with the majority of radioactivity being recovered within 96 h postdose. Profiling of the urine and faeces showed similar and extensive metabolism in all subjects. Unchanged maraviroc was the major excreted component (33%). The major metabolic pathways were determined and involved oxidation and N-dealkylation. Intravenous doses of maraviroc (3-30 mg) were well tolerated in study 2, and drug exposure was approximately proportional to dose within the studied range. Approximately 23% of total clearance (44 l h(-1)) was accounted for by renal clearance (10.2 l h(-1)). Mean volume of distribution at steady state was 194 l. Absolute bioavailability of a 100-mg oral tablet dose, by comparison with a 30-mg i.v. dose, was calculated to be 23.1%. CONCLUSIONS Maraviroc is rapidly absorbed and extensively metabolized, although unchanged maraviroc is the major circulating component in plasma and is the major excreted component after oral dosing. The pharmacokinetics of maraviroc after i.v. administration is approximately proportional over the dose range studied. Renal clearance contributes 23% of total clearance. The absolute bioavailability of 100 mg oral maraviroc is 23%.

Assessment of the pharmacokinetics, safety and tolerability of maraviroc, a novel CCR5 antagonist, in healthy volunteers

AIMS To evaluate the pharmacokinetics, safety and tolerability of single and multiple oral doses of maraviroc in healthy volunteers. METHODS Three double-blind, placebo-controlled, dose-escalation studies with either single or multiple doses of maraviroc were conducted in healthy volunteers. Plasma and urine samples were collected to investigate the pharmacokinetics of maraviroc and evaluate any changes with respect to dose and duration/frequency of dosing. Safety and toleration of maraviroc were also assessed. RESULTS Maraviroc is rapidly absorbed following oral administration, and plasma T(max) is achieved within 0.5-4.0 h postdose. Steady-state plasma concentrations are achieved after 7 consecutive days of dosing. Although the pharmacokinetics of maraviroc is nonproportional over the dose range studied (3-1200 mg), the degree of nonproportionality is small at clinically relevant doses. Renal clearance is approximately 10-12 l h(-1) and appears unaffected by increasing maraviroc doses. Maraviroc does not significantly modulate the activity of CYP2D6 or CYP3A4 at clinically relevant doses. There were no serious adverse events in any of these studies, and doses up to 900 mg were generally well tolerated, with postural hypotension being the dose-limiting event. There was no pattern or dose relationship observed with maraviroc with regard to laboratory abnormalities, including hepatic transaminases. No clinically significant increases in QTc were noted at clinically relevant doses. CONCLUSIONS Maraviroc is absorbed into the systemic circulation and reaches steady state by day 7 of multiple dosing. It does not significantly influence the activity of major drug-metabolizing enzymes and is well tolerated at clinically relevant doses, with most adverse events being mild or moderate.

Effects of CYP3A4 inhibitors on the pharmacokinetics of maraviroc in healthy volunteers

AIMS To evaluate the influence of cytochrome P450 (CYP) 3A4 inhibitors on the clinical pharmacokinetics of maraviroc, a novel CCR5 antagonist. METHODS Four open-label, randomized, placebo-controlled studies were conducted in healthy subjects to assess the effect of separate and distinct combinations of CYP3A4 inhibitors on the steady-state pharmacokinetics of maraviroc. Study 1 was a two-way crossover study investigating the influence of saquinavir (SQV; 1200 mg t.i.d.) and ketoconazole (400 mg q.d.) on the pharmacokinetics of maraviroc (100 mg b.i.d.). All subjects received maraviroc for 7 days in both study periods. Cohort 1 subjects also received SQV or placebo and cohort 2 subjects also received ketoconazole or placebo. Study 2 was a parallel-group study including four treatment groups investigating the effects of ritonavir-boosted lopinavir (LPV/r; 400 mg/100 mg b.i.d.), ritonavir-boosted saquinavir (SQV/r; 1000 mg/100 mg b.i.d.), and low-dose ritonavir (RTV; 100 mg b.i.d.) on the steady-state pharmacokinetics of maraviroc (100 mg b.i.d.), and exploring whether maraviroc dose adjustment can compensate for interaction effects. Treatment lasted 28 days and comprised three distinct phases: (i) maraviroc alone on days 1-7; (ii) maraviroc + interactant on days 8-21; and (iii) maraviroc (adjusted dose) + interactant on days 22-28. Study 3 was a two-way crossover study investigating the effects of atazanavir (ATZ; 400 mg q.d.) and ritonavir-boosted atazanavir (ATZ/r; 300 mg/100 mg b.i.d.) on the pharmacokinetics of maraviroc (300 mg b.i.d.). All subjects received maraviroc on days 1-14 of both study periods. Subjects also received ATZ on days 1-7 and ATZ/r on days 8-14 of one treatment period, and placebo on days 1-14 of the other treatment period. Study 4 was a two-way crossover study investigating the effects of ritonavir-boosted tipranavir (TPV/r; 500 mg/200 mg b.i.d.) on the pharmacokinetics of maraviroc (150 mg b.i.d.). Subjects received maraviroc plus TPV/r or placebo on days 1-8. RESULTS All of the drugs/drug combinations tested (except for TPV/r) increased maraviroc exposure, albeit to different degrees of magnitude. SQV/r caused the largest increase in maraviroc exposure (8.3-fold increase in AUC(tau)), whereas RTV caused the smallest increase in maraviroc exposure (2.6-fold increase in AUC(tau)). Downward adjustment of the maraviroc dose in study 2 during co-administration of HIV protease inhibitors was able to compensate for the interactions. TPV/r had no clinically relevant effect on maraviroc exposure at steady state. There were no treatment-related serious adverse events or discontinuations due to adverse events in any of the studies, and most adverse events were mild or moderate in severity and resolved without intervention. CONCLUSIONS Potent CYP3A4 inhibitors, including ketoconazole and protease inhibitors (except TPV/r), increase maraviroc exposure. Downward adjustment of the maraviroc dose during co-administration with protease inhibitors can compensate for the interaction. TPV/r does not affect the steady-state pharmacokinetics of maraviroc, and hence no dose adjustment would be warranted.

Effects of CYP3A4 inducers with and without CYP3A4 inhibitors on the pharmacokinetics of maraviroc in healthy volunteers

AIMS To assess the potential of known CYP3A4 inducers, with and without CYP3A4 inhibitors, to alter the pharmacokinetic profile of maraviroc. METHODS Two separate, open, randomized, placebo-controlled studies were conducted in healthy subjects. Study 1 was a 28-day parallel-group study with three treatment groups of 12 subjects each. On days 1-7, all subjects received maraviroc 100 mg b.i.d.; on days 8-21, subjects received maraviroc 100 mg b.i.d. plus either rifampicin 600 mg q.d., efavirenz (EFV) 600 mg q.d., or placebo q.d. as assigned; on days 22-28, the maraviroc dose was increased to 200 mg b.i.d. for patients receiving either rifampicin or EFV. Study 2 was a 21-day, two-way crossover study with three cohorts (12 subjects per cohort). On days 1-21, subjects received maraviroc 300 mg b.i.d. and boosted lopinavir (LPV/r, lopinavir 400 mg + ritonavir 100 mg) or placebo b.i.d. in cohort 1, maraviroc 100 mg b.i.d. and boosted saquinavir (SQV/r, saquinavir 1000 mg + ritonavir 100 mg) or placebo b.i.d. in cohort 2, and maraviroc 100 mg b.i.d. and 1000 mg saquinavir + LPV/r (400 mg/100 mg) or placebo b.i.d. in cohort 3. On days 8-21, subjects in all three cohorts also received EFV 600 mg or placebo q.d. RESULTS Maraviroc (100 mg b.i.d.) exposure (AUC(12) and C(max)) was reduced in the presence of rifampicin and EFV by approximately 70% and 50%, respectively. Maraviroc AUC(12) and C(max) approached preinduction values when the maraviroc dose was increased to 200 mg b.i.d. for both the rifampicin-treated and EFV-treated groups. Co-administration of LPV/r with maraviroc (300 mg b.i.d.) resulted in geometric mean ratios (GMRs) of 395% and 197% for maraviroc AUC(12) and C(max), respectively, compared with placebo; addition of EFV resulted in GMRs of 253% and 125% for AUC(12) and C(max), respectively. Co-administration of SQV/r with maraviroc (100 mg b.i.d.) resulted in GMRs of 977% and 478% for maraviroc AUC(12) and C(max), respectively, compared with placebo; addition of EFV resulted in GMRs of 500% and 226% for AUC(12) and C(max), respectively. No pharmacokinetic data are reported for cohort 3 because all subjects were discontinued during period 1 due to poor toleration of the drug regimen. There were no serious adverse events reported in either study, and most adverse events were mild or moderate in severity and resolved without intervention. CONCLUSION As expected with a CYP3A4 substrate, maraviroc exposure (C(max) and AUC(12)) was significantly reduced by the known CYP3A4 inducers, rifampicin and EFV, by approximately 70% and 50%, respectively. Upward adjustment of the maraviroc dose during co-administration with rifampicin or EFV appears to compensate for this reduction. Protease inhibitors (PIs) significantly increased maraviroc exposure; however, the addition of EFV to the maraviroc + PI regimens reduced the magnitude of PI-mediated increase in maraviroc exposure (by approximately 50%), but the net effect was still CYP3A4 inhibition.

Effect of maraviroc on the pharmacokinetics of midazolam, lamivudine/ zidovudine, and ethinyloestradiol/ levonorgestrel in healthy volunteers

AIMS To assess the effect of maraviroc on the pharmacokinetics of midazolam, a sensitive probe CYP3A4 substrate; lamivudine/zidovudine, a combination of nucleoside reverse transcriptase inhibitors (NRTIs); and ethinyloestradiol/levonorgestrel, a combination oral contraceptive. METHODS Three randomized, double-blind, placebo-controlled studies were conducted in healthy subjects to assess the effect of maraviroc on pharmacokinetics of other drugs. Two, two-period crossover studies were conducted to assess (i) the effect of steady-state maraviroc (300 mg b.i.d.) on pharmacokinetics of midazolam; and (ii) the effect of steady-state maraviroc (300 mg b.i.d.) on the pharmacokinetics of lamivudine/zidovudine. A third two-way crossover study was conducted to evaluate the effect of steady-state maraviroc (100 mg b.i.d.) on the pharmacokinetics of 30 microg ethinyloestradiol/150 microg levonorgestrel (Microgynon). RESULTS The geometric mean ratios for C(max) and AUC for each of the compounds tested in the presence and absence of maraviroc were between 92% and 121%. There were no notable differences in T(max), t(1/2) or CL(R) (where measured) for any of the compounds. CONCLUSIONS Maraviroc had no clinically relevant effects on the pharmacokinetics of the CYP3A4 substrate midazolam, the NRTIs zidovudine/lamivudine, or the oral contraceptive steroids ethinyloestradiol and levonorgestrel.

Pharmacokinetic Interactions of Maraviroc with Darunavir-Ritonavir, Etravirine, and Etravirine-Darunavir-Ritonavir in Healthy Volunteers: Results of Two Drug Interaction Trials

ABSTRACT The effects of darunavir-ritonavir at 600 and 100 mg twice daily (b.i.d.) alone, 200 mg of etravirine b.i.d. alone, or 600 and 100 mg of darunavir-ritonavir b.i.d. with 200 mg etravirine b.i.d. at steady state on the steady-state pharmacokinetics of maraviroc, and vice versa, in healthy volunteers were investigated in two phase I, randomized, two-period crossover studies. Safety and tolerability were also assessed. Coadministration of 150 mg maraviroc b.i.d. with darunavir-ritonavir increased the area under the plasma concentration-time curve from 0 to 12 h (AUC12) for maraviroc 4.05-fold relative to 150 mg of maraviroc b.i.d. alone. Coadministration of 300 mg maraviroc b.i.d. with etravirine decreased the maraviroc AUC12 by 53% relative to 300 mg maraviroc b.i.d. alone. Coadministration of 150 mg maraviroc b.i.d. with etravirine-darunavir-ritonavir increased the maraviroc AUC12 3.10-fold relative to 150 mg maraviroc b.i.d. alone. Maraviroc did not significantly affect the pharmacokinetics of etravirine, darunavir, or ritonavir. Short-term coadministration of maraviroc with darunavir-ritonavir, etravirine, or both was generally well tolerated, with no safety issues reported in either trial. Maraviroc can be coadministered with darunavir-ritonavir, etravirine, or etravirine-darunavir-ritonavir. Maraviroc should be dosed at 600 mg b.i.d. with etravirine in the absence of a potent inhibitor of cytochrome P450 3A (CYP3A) (i.e., a boosted protease inhibitor) or at 150 mg b.i.d. when coadministered with darunavir-ritonavir with or without etravirine.

The effects of cotrimoxazole or tenofovir co-administration on the pharmacokinetics of maraviroc in healthy volunteers

AIMS To assess the potential of cotrimoxazole and tenofovir, drugs which are inhibitors and/or substrates of renal transporters, to alter the pharmacokinetic profile of maraviroc. METHODS Two randomized, placebo-controlled, two-way crossover studies were conducted in healthy male and female subjects. In study 1, 16 subjects, aged 18-45 years, received maraviroc (300 mg b.i.d.) with and without cotrimoxazole (960 mg b.i.d.; 160 mg trimethoprim and 800 mg sulfamethoxazole). In study 2, 12 subjects, aged 21-45 years, received maraviroc (300 mg b.i.d.) with and without tenofovir (300 mg q.d.). For study 1, blood was collected predose and on days 1-7. In study 2, blood was collected predose, on day 1 and days 3-7. In both studies, blood was collected at intervals up to 12 h postdose on day 7. Urine was collected on day 7, 0-12 h post morning dose. Blood and urine were analysed for maraviroc using liquid chromatography/tandem mass spectrometry. RESULTS The geometric mean ratios for C(max) and AUC(12) were 119% and 111%, respectively, for maraviroc plus cotrimoxazole and 104% and 103%, respectively, for maraviroc plus tenofovir, compared with maraviroc plus placebo. Renal clearance of maraviroc plus placebo was 8.3 l h(-1) and 8.5 l h(-1) and was 7.8 l h(-1) for maraviroc plus cotrimoxazole and maraviroc plus tenofovir. There were no serious or severe adverse events or any clinically significant changes in laboratory tests, blood pressure, or electrocardiograms. CONCLUSIONS Neither cotrimoxazole nor tenofovir caused a clinically significant effect on the pharmacokinetics of maraviroc. Maraviroc 300 mg b.i.d. was well tolerated when co-administered with either cotrimoxazole or tenofovir.