Studies in Treatment-Experienced Subjects
The safety profile of SELZENTRY is primarily based on 840 HIV-infected subjects who received at least one dose of SELZENTRY during two Phase 3 trials. A total of 426 of these subjects received the indicated twice daily dosing regimen.
Assessment of treatment-emergent adverse events is based on the pooled data from two studies in subjects with CCR5-tropic HIV-1 (A4001027 and A4001028). The median duration of maraviroc therapy for subjects in these studies was 48 weeks, with the total exposure on SELZENTRY twice daily at 309 patient-years versus 111 patient-years on placebo + OBT. The population was 89% male and 84% white, with mean age of 46 years (range 17–75 years). Subjects received dose equivalents of 300 mg maraviroc once or twice daily.
The most common adverse events reported with SELZENTRY twice daily therapy with frequency rates higher than placebo, regardless of causality, were upper respiratory tract infections, cough, pyrexia, rash, and dizziness. Additional adverse events that occurred with once daily dosing at a higher rate than both placebo and twice daily dosing were diarrhea, edema, influenza, esophageal candidiasis, sleep disorders, rhinitis, parasomnias, and urinary abnormalities. In these two studies, the rate of discontinuation due to adverse events was 5% for subjects who received SELZENTRY twice daily + optimized background therapy (OBT) as well as those who received placebo + OBT. Most of the adverse events reported were judged to be mild to moderate in severity. The data described below occurred with SELZENTRY twice daily dosing.
The total number of subjects reporting infections were 233 (55%) and 84 (40%) in the SELZENTRY twice daily and placebo groups, respectively. Correcting for the longer duration of exposure on SELZENTRY compared to placebo, the exposure-adjusted frequency (rate per 100 subject-years) of these events was 133 for both SELZENTRY twice daily and placebo.
Dizziness or postural dizziness occurred in 8% of subjects on either SELZENTRY or placebo, with 2 subjects (0.5%) on SELZENTRY permanently discontinuing therapy (1 due to syncope, 1 due to orthostatic hypotension) versus 1 subject on placebo (0.5%) permanently discontinuing therapy due to dizziness.
Treatment-emergent adverse events, regardless of causality, from A4001027 and A4001028 are summarized in Table 3. Selected events occurring at ≥2% of subjects and at a numerically higher rate in subjects treated with SELZENTRY are included; events that occurred at the same or higher rate on placebo are not displayed.
Table 3 Percentage of Subjects with Selected Treatment-Emergent Adverse Events (All Causality) (≥2% on SELZENTRY and at a higher rate compared to placebo) Studies A4001027 and A4001028 (Pooled Analysis, 48 Weeks) | SELZENTRY Twice Daily300 mg dose equivalent | Exposure-adjusted rate (per 100 pt-yrs) PYE=309PYE = patient years of exposure | Placebo | Exposure-adjusted rate (per 100 pt-yrs) PYE=111 |
|---|
| N=426 (%) | | N=209 (%) | |
|---|
| | | | | |
| EYE DISORDERS | | | | |
| Conjunctivitis | 2 | 3 | 1 | 3 |
| Ocular infections, inflammations and associated manifestations | 2 | 3 | 1 | 2 |
| | | | | |
| GASTROINTESTINAL DISORDERS | | | | |
| Constipation | 6 | 9 | 3 | 6 |
| | | | | |
| GENERAL DISORDERS AND ADMINISTRATION SITE CONDITIONS | | | | |
| Pyrexia | 13 | 20 | 9 | 17 |
| Pain and discomfort | 4 | 5 | 3 | 5 |
| | | | | |
| INFECTIONS AND INFESTATIONS | | | | |
| Upper respiratory tract infection | 23 | 37 | 13 | 27 |
| Herpes infection | 8 | 11 | 4 | 8 |
| Sinusitis | 7 | 10 | 3 | 6 |
| Bronchitis | 7 | 9 | 5 | 9 |
| Folliculitis | 4 | 5 | 2 | 4 |
| Pneumonia | 2 | 3 | 5 | 10 |
| Anogenital warts | 2 | 3 | 1 | 3 |
| Influenza | 2 | 3 | 0.5 | 1 |
| Otitis media | 2 | 3 | 0.5 | 1 |
| | | | | |
| METABOLISM AND NUTRITION DISORDERS | | | | |
| Appetite disorders | 8 | 11 | 7 | 13 |
| | | | | |
| MUSCULOSKELETAL AND CONNECTIVE TISSUE DISORDERS | | | | |
| Joint related signs and symptoms | 7 | 10 | 3 | 5 |
| Muscle pains | 3 | 4 | 0.5 | 1 |
| | | | | |
| NEOPLASMS BENIGN, MALIGNANT AND UNSPECIFIED | | | | |
| Skin neoplasms benign | 3 | 4 | 1 | 3 |
| | | | | |
| NERVOUS SYSTEM DISORDERS | | | | |
| Dizziness/postural dizziness | 9 | 13 | 8 | 17
|
| Paresthesias and dysesthesias | 5 | 7 | 3 | 6 |
| Sensory abnormalities | 4 | 6 | 1 | 3 |
| Disturbances in consciousness | 4 | 5 | 3 | 6 |
| Peripheral neuropathies | 4 | 5 | 3 | 6 |
| | | | | |
| PSYCHIATRIC DISORDERS | | | | |
| Disturbances in initiating and maintaining sleep | 8 | 11 | 5 | 10 |
| Depressive disorders | 4 | 6 | 3 | 5 |
| Anxiety symptoms | 4 | 5 | 3 | 7 |
| | | | | |
| RENAL AND URINARY DISORDERS | | | | |
| Bladder and urethral symptoms | 5 | 7 | 1 | 3 |
| Urinary tract signs and symptoms | 3 | 4 | 1 | 3 |
| | | | | |
| RESPIRATORY, THORACIC AND MEDIASTINAL DISORDERS | | | | |
| Coughing and associated symptoms | 14 | 21 | 5 | 10 |
| Upper respiratory tract signs and symptoms | 6 | 9 | 3 | 6 |
| Nasal congestion and inflammations | 4 | 6 | 3 | 5 |
| Breathing abnormalities | 4 | 5 | 2 | 5 |
| Paranasal sinus disorders | 3 | 4 | 0.5 | 1 |
| | | | | |
| SKIN AND SUBCUTANEOUS TISSUE DISORDERS | | | | |
| Rash | 11 | 16 | 5 | 11 |
| Apocrine and eccrine gland disorders | 5 | 7 | 4 | 7.5 |
| Pruritus | 4 | 5 | 2 | 4 |
| Lipodystrophies | 3 | 5 | 0.5 | 1 |
| Erythemas | 2 | 3 | 1 | 2 |
| | | | | |
| VASCULAR DISORDERS | | | | |
| Vascular hypertensive disorders | 3 | 4 | 2 | 4 |
Laboratory Abnormalities
Table 4 shows the treatment-emergent Grade 3–4 laboratory abnormalities that occurred in >2% of subjects receiving SELZENTRY.
Table 4 Maximum Shift in Laboratory Test Values (Without Regard to Baseline) Incidence ≥2% of Grade 3–4 Abnormalities (ACTG Criteria) Studies A4001027 and A4001028 (Pooled Analysis, 48 Weeks)| Laboratory Parameter Preferred Term | Limit | SELZENTRY Twice daily + OBT | Placebo + OBT |
|---|
| | N =421 Percentages based on total subjects evaluated for each laboratory parameter % | N =207 % |
|---|
| Aspartate aminotransferase | >5.0× ULN | 4.8 | 2.9 |
Alanine aminotransferase | >5.0× ULN | 2.6 | 3.4 |
| Total bilirubin | >5.0× ULN | 5.5 | 5.3 |
| Amylase | >2.0× ULN | 5.7 | 5.8 |
| Lipase | >2.0× ULN | 4.9 | 6.3 |
| Absolute neutrophil count | <750/mm3 | 4.3 | 2.4 |
Study in Treatment-Naïve Subjects
Treatment-Emergent Adverse Events
Treatment-emergent adverse events, regardless of causality, from Study A4001026, a double-blind comparative controlled study in which 721 treatment-naïve subjects received SELZENTRY 300 mg BID (N=360) or efavirenz (N=361) in combination with zidovudine/lamivudine for 96 weeks, are summarized in Table 5. Selected events occurring at ≥ 2% of subjects and at a numerically higher rate in subjects treated with SELZENTRY are included; events that occurred at the same or higher rate on efavirenz are not displayed.
Table 5 Percentage of Subjects with Selected Treatment-Emergent Adverse Events (All Causality) (≥2% on SELZENTRY and at a higher rate compared to efavirenz) Study A4001026 (96 Weeks) | SELZENTRY + zidovudine/lamivudine 300 mg BID N = 360 (%) | EFAVIRENZ + zidovudine/lamivudine 600 mg QD N = 361 (%) |
|---|
| | | |
| BLOOD AND LYMPHATIC SYSTEM DISORDERS | | |
| Anemias NEC | 8 | 5 |
| Neutropenias | 4 | 3 |
| | | |
| EAR AND LABYRINTH DISORDERS | | |
| Ear disorders NEC | 3 | 2 |
| GASTROINTESTINAL DISORDERS | | |
| Flatulence, bloating and distention | 10 | 7 |
| Gastrointestinal atonic and hypomotility disorders NEC | 9 | 5 |
| Gastrointestinal signs and symptoms NEC | 3 | 2 |
| | | |
| GENERAL DISORDERS AND ADMINISTRATION SITE CONDITIONS | | |
| Body Temperature perception | 3 | 1 |
| | | |
| INFECTIONS AND INFESTATIONS | | |
| Bronchitis | 13 | 9 |
| Herpes Infection | 7 | 6 |
| Upper Respiratory Tract Infection | 32 | 30 |
| Bacterial infections NEC | 6 | 3 |
| Herpes zoster/varicella | 5 | 4 |
| Lower respiratory tract and lung infections | 3 | 2 |
| Neisseria infections | 3 | 0 |
| Tinea infections | 4 | 3 |
| Viral infections NEC | 3 | 2 |
| | | |
| MUSCULOSKELETAL AND CONNECTIVE TISSUE DISORDERS | | |
| Joint related signs and symptoms | 6 | 5 |
| | | |
| NERVOUS SYSTEM DISORDERS | | |
| Memory loss (excluding dementia) | 3 | 1 |
| Parasthesias and Dyesthesias | 4 | 3 |
| | | |
| RENAL AND URINARY DISORDERS | | |
| Bladder and urethral symptoms | 4 | 3 |
| | | |
| REPRODUCTIVE SYSTEM AND BREAST DISORDERS | | |
| Erection and ejaculation conditions and disorders | 3 | 2 |
| | | |
| RESPIRATORY, THORACIC AND MEDIASTINAL DISORDERS | | |
| Upper respiratory tract signs and symptoms | 9 | 5 |
| | | |
| SKIN AND SUBCUTANEOUS TISSUE DISORDERS | | |
| Acnes | 3 | 2 |
| Alopecias | 2 | 1 |
| Lipodystrophies | 4 | 3 |
| Nail and nail bed conditions (excluding infections and infestations) | 6 | 2 |
Laboratory Abnormalities
Table 6 Maximum Shift in Laboratory Test Values (Without Regard to Baseline) Incidence ≥2% of Grade 3–4 Abnormalities (ACTG Criteria) Study A4001026 (96 Weeks)| Laboratory Parameter Preferred Term | Limit | SELZENTRY 300 Twice daily + zidovudine/lamivudine N =353N = total number of subjects evaluable for laboratory abnormalities. % | Efavirenz 600 mg QD + zidovudine/lamivudine N =350 % |
|---|
| Percentages based on total subjects evaluated for each laboratory parameter. If the same subject in a given treatment group had >1 occurrence of the same abnormality, only the most severe is counted. |
| Aspartate aminotransferase | >5.0× ULN | 4.0 | 4.0 |
| Alanine aminotransferase | >5.0× ULN | 3.9 | 4.0 |
| Creatine kinase | | 3.9 | 4.8 |
| Amylase | >2.0× ULN | 4.3 | 6.0 |
| Absolute neutrophil count | <750/mm3 | 5.7 | 4.9 |
| Hemoglobin | <7.0 g/dL | 2.9 | 2.3 |
Less Common Adverse Events in Clinical Trials
The following adverse events occurred in <2% of SELZENTRY-treated subjects. These events have been included because of their seriousness and either increased frequency on SELZENTRY or are potential risks due to the mechanism of action. Events attributed to the patient's underlying HIV infection are not listed.
Blood and Lymphatic System: marrow depression and hypoplastic anemia
Cardiac Disorders: unstable angina, acute cardiac failure, coronary artery disease, coronary artery occlusion, myocardial infarction, myocardial ischemia
Hepatobiliary Disorders: hepatic cirrhosis, hepatic failure, cholestatic jaundice, portal vein thrombosis, hypertransaminasemia, jaundice
Infections and Infestations: endocarditis, infective myositis, viral meningitis, pneumonia, treponema infections, septic shock, Clostridium difficile colitis, meningitis
Musculoskeletal and Connective Tissue Disorders: myositis, osteonecrosis, rhabdomyolysis, blood CK increased
Neoplasms benign, Malignant and Unspecified (including Cysts and Polyps): abdominal neoplasm, anal cancer, basal cell carcinoma, Bowen's disease, cholangiocarcinoma, diffuse large B-cell lymphoma, lymphoma, metastases to liver, esophageal carcinoma, nasopharyngeal carcinoma, squamous cell carcinoma, squamous cell carcinoma of skin, tongue neoplasm (malignant stage unspecified), anaplastic large cell lymphomas T- and null-cell types, bile duct neoplasms malignant, endocrine neoplasms malignant and unspecified
Nervous System Disorders: cerebrovascular accident, convulsions and epilepsy, tremor (excluding congenital), facial palsy, hemianopia, loss of consciousness, visual field defect
Antiretroviral Pregnancy Registry
To monitor maternal-fetal outcomes of pregnant women exposed to SELZENTRY and other antiretroviral agents, an Antiretroviral Pregnancy Registry has been established. Physicians are encouraged to register patients by calling 1-800-258-4263.
Exposure Response Relationship in Treatment-Experienced Subjects
The relationship between maraviroc, modeled plasma trough concentration (Cmin) (1–9 samples per patient taken on up to 7 visits), and virologic response was evaluated in 973 treatment-experienced HIV-1-infected subjects with varied optimized background antiretroviral regimens in studies A4001027 and A4001028. The Cmin, baseline viral load, baseline CD4+ cell count and overall sensitivity score (OSS) were found to be important predictors of virologic success (defined as viral load < 400 copies/mL at 24 weeks). Table 7 illustrates the proportion of subjects with virologic success (%) within each Cmin quartile for 150 mg twice daily and 300 mg twice daily groups.
Table 7 Treatment-Experienced Subjects with Virologic Success by Cmin Quartile (Q1–Q4)) | 150 mg BID (with CYP3A inhibitors) | 300 mg BID (without CYP3A inhibitors) |
|---|
| n | Median Cmin | % subjects with virologic success | n | Median Cmin | % subjects with virologic success |
|---|
| Placebo | 160 | - | 30.6 | 35 | - | 28.6 |
| Q1 | 78 | 33 | 52.6 | 22 | 13 | 50.0 |
| Q2 | 77 | 87 | 63.6 | 22 | 29 | 68.2 |
| Q3 | 78 | 166 | 78.2 | 22 | 46 | 63.6 |
| Q4 | 78 | 279 | 74.4 | 22 | 97 | 68.2 |
Exposure Response Relationship in Treatment-Naive Subjects
The relationship between maraviroc, modeled plasma trough concentration (Cmin) (1–12 samples per patient taken on up to 8 visits), and virologic response was evaluated in 294 treatment-naive HIV-1-infected subjects receiving maraviroc 300 mg twice daily in combination with zidovudine/lamivudine in study A4001026. Table 8 illustrates the proportion (%) of subjects with virologic success < 50 copies/mL at 48 weeks within each Cmin quartile for the 300 mg twice daily dose.
Table 8 Treatment-Naïve Subjects with Virologic Success by Cmin Quartile (Q1–Q4) | 300 mg BID |
|---|
| n | Median Cmin | % subjects with virologic success |
|---|
| Eighteen of 75 (24%) subjects in Q1 had no measurable maraviroc concentration on at least one occasion vs. 1 of 73 and 1 of 74 in quartiles 3 and 4 respectively. |
| Q1 | 75 | 23 | 57.3 |
| Q2 | 72 | 39 | 72.2 |
| Q3 | 73 | 56 | 74.0 |
| Q4 | 74 | 81 | 83.8 |
Effects on Electrocardiogram
A placebo-controlled, randomized, crossover study to evaluate the effect on the QT interval of healthy male and female volunteers was conducted with three single oral doses of maraviroc and moxifloxacin. The placebo-adjusted mean maximum (upper 1-sided 95% CI) increases in QTc from baseline after 100, 300 and 900 mg of maraviroc were –2 (0), -1 (1), and 1 (3) msec, respectively, and 13 (15) msec for moxifloxacin 400 mg. No subject in any group had an increase in QTc of ≥60 msec from baseline. No subject experienced an interval exceeding the potentially clinically relevant threshold of 500 msec.
Absorption
Peak maraviroc plasma concentrations are attained 0.5–4h following single oral doses of 1–1200 mg administered to uninfected volunteers. The pharmacokinetics of oral maraviroc are not dose-proportional over the dose range.
The absolute bioavailability of a 100 mg dose is 23% and is predicted to be 33% at 300 mg. Maraviroc is a substrate for the efflux transporter P-glycoprotein.
Effect of Food on Oral Absorption
Coadministration of a 300mg tablet with a high fat breakfast reduced maraviroc Cmax and AUC by 33% in healthy volunteers. There were no food restrictions in the studies that demonstrated the efficacy and safety of maraviroc [see Clinical Studies (14)]. Therefore, maraviroc can be taken with or without food at the recommended dose [see Dosage and Administration (2)].
Distribution
Maraviroc is bound (approximately 76%) to human plasma proteins, and shows moderate affinity for albumin and alpha-1 acid glycoprotein. The volume of distribution of maraviroc is approximately 194L.
Metabolism
Studies in humans and in vitro studies using human liver microsomes and expressed enzymes have demonstrated that maraviroc is principally metabolized by the cytochrome P450 system to metabolites that are essentially inactive against HIV-1. In vitro studies indicate that CYP3A is the major enzyme responsible for maraviroc metabolism. In vitro studies also indicate that polymorphic enzymes CYP2C9, CYP2D6 and CYP2C19 do not contribute significantly to the metabolism of maraviroc.
Maraviroc is the major circulating component (~42% drug-related radioactivity) following a single oral dose of 300 mg[14C]-maraviroc. The most significant circulating metabolite in humans is a secondary amine (~22% radioactivity) formed by N-dealkylation. This polar metabolite has no significant pharmacological activity. Other metabolites are products of mono-oxidation and are only minor components of plasma drug-related radioactivity.
Excretion
The terminal half-life of maraviroc following oral dosing to steady state in healthy subjects was 14–18 hours. A mass balance/excretion study was conducted using a single 300mg dose of 14C-labeled maraviroc. Approximately 20% of the radiolabel was recovered in the urine and 76% was recovered in the feces over 168 hours. Maraviroc was the major component present in urine (mean of 8% dose) and feces (mean of 25% dose). The remainder was excreted as metabolites.
Hepatic Impairment
Maraviroc is primarily metabolized and eliminated by the liver. A study compared the pharmacokinetics of a single 300 mg dose of SELZENTRY in subjects with mild (Child-Pugh Class A, n=8), and moderate (Child-Pugh Class B, n=8) hepatic impairment to pharmacokinetics in healthy subjects (n=8). The mean Cmax and AUC were 11% and 25% higher, respectively, for subjects with mild hepatic impairment, and 32% and 46% higher, respectively, for subjects with moderate hepatic impairment compared to subjects with normal hepatic function. These changes do not warrant a dose adjustment. Maraviroc concentrations are higher when SELZENTRY 150 mg is administered with a potent CYP3A inhibitor compared to following administration of 300 mg without a CYP3A inhibitor, so patients with moderate hepatic impairment who receive SELZENTRY 150 mg with a potent CYP3A inhibitor should be monitored closely for maraviroc-associated adverse events. The pharmacokinetics of maraviroc have not been studied in subjects with severe hepatic impairment [see Warnings and Precautions (5.1)].
Effect of Concomitant Drugs on the Pharmacokinetics of Maraviroc
Maraviroc is a substrate of CYP3A and Pgp and hence its pharmacokinetics are likely to be modulated by inhibitors and inducers of these enzymes/transporters. The CYP3A/Pgp inhibitors ketoconazole, lopinavir/ritonavir, ritonavir, darunavir/ritonavir, saquinavir/ritonavir and atazanavir ± ritonavir all increased the Cmax and AUC of maraviroc [see Table 10]. The CYP3A inducers rifampin, etravirine and efavirenz decreased the Cmax and AUC of maraviroc [see Table 10].
Tipranavir/ritonavir (net CYP3A inhibitor/Pgp inducer) did not affect the steady state pharmacokinetics of maraviroc (see Table 10). Co-trimoxazole and tenofovir did not affect the pharmacokinetics of maraviroc.
Table 10 Effect of Coadministered Agents on the Pharmacokinetics of Maraviroc| Coadministered drug and dose | N | Maraviroc Dose | Ratio (90% CI) of maraviroc pharmacokinetic parameters with/without coadministered drug (no effect = 1.00) |
|---|
| Cmin | AUCtau | Cmax |
|---|
| CYP3A and/or P-gp Inhibitors |
Ketoconazole 400 mg QD | 12 | 100 mg BID | 3.75 (3.01, 4.69) | 5.00 (3.98, 6.29) | 3.38 (2.38, 4.78) |
Ritonavir 100 mg BID | 8 | 100 mg BID | 4.55 (3.37, 6.13) | 2.61 (1.92, 3.56) | 1.28 (0.79, 2.09) |
| | | | | | |
Saquinavir (soft gel capsules) /ritonavir 1000 mg/100 mg BID | 11 | 100 mg BID | 11.3 (8.96, 14.1) | 9.77 (7.87, 12.14) | 4.78 (3.41, 6.71) |
| | | | | | |
Lopinavir/ritonavir 400 mg/100 mg BID | 11 | 300 mg BID | 9.24 (7.98, 10.7) | 3.95 (3.43, 4.56) | 1.97 (1.66, 2.34) |
Atazanavir 400 mg QD | 12 | 300 mg BID | 4.19 (3.65, 4.80) | 3.57 (3.30, 3.87) | 2.09 (1.72, 2.55) |
Atazanavir/ritonavir 300 mg/100 mg QD | 12 | 300 mg BID | 6.67 (5.78, 7.70) | 4.88 (4.40, 5.41) | 2.67 (2.32, 3.08) |
Darunavir/ritonavir 600 mg/100 mg BID | 12 | 150 mg BID | 8.00 (6.35, 10.1) | 4.05 2.94, 5.59 | 2.29 (1.46, 3.59) |
| CYP3A and/or P-gp Inducers |
Efavirenz 600 mg QD | 12 | 100 mg BID | 0.55 (0.43, 0.72) | 0.552 (0.492, 0.620) | 0.486 (0.377, 0.626) |
Efavirenz 600 mg QD | 12 | 200 mg BID (+efavirenz): 100 mg BID (alone) | 1.09 (0.89, 1.35) | 1.15 (0.98, 1.35) | 1.16 (0.87, 1.55) |
Rifampicin 600 mg QD | 12 | 100 mg BID | 0.22 (0.17, 0.28) | 0.368 (0.328, 0.413) | 0.335 (0.260, 0.431) |
Rifampicin 600 mg QD | 12 | 200 mg BID (+rifampicin): 100 mg BID (alone) | 0.66 (0.54, 0.82) | 1.04 (0.89, 1.22) | 0.97 (0.72, 1.29) |
Etravirine 200 mg BID | 14 | 300 mg BID | 0.609 (0.525, 0.707) | 0.468 (0.381, 0.576) | 0.400 (0.282, 0.566) |
| Nevirapine Compared to historical data 200 mg BID (+ lamivudine 150 mg BID, tenofovir 300 mg QD) | 8 | 300 mg SD | - | 1.01 (0.65, 1.55) | 1.54 (0.94, 2.51) |
| CYP3A and/or P-gp Inhibitors and Inducers |
Lopinavir/ritonavir + efavirenz 400 mg/100 mg BID + 600 mg QD | 11 | 300 mg BID | 6.29 (4.72, 8.39) | 2.53 (2.24, 2.87) | 1.25 (1.01, 1.55) |
Saquinavir(soft gel capsules) /ritonavir + efavirenz 1000 mg/100 mg BID + 600 mg QD | 11 | 100 mg BID | 8.42 (6.46, 10.97) | 5.00 (4.26, 5.87) | 2.26 (1.64, 3.11) |
Darunavir/ritonavir + etravirine 600 mg/100 mg BID + 200 mg BID | 10 | 150 mg BID | 5.27 (4.51, 6.15) | 3.10 (2.57, 3.74) | 1.77 (1.20, 2.60) |
Tipranavir/ritonavir 500 mg/200 mg BID | 12 | 150 mg BID | 1.80 (1.55, 2.09) | 1.02 (0.850, 1.23) | 0.86 (0.61, 1.21) |
| Other | | | | | |
Raltegravir 400 mg BID | 17 | 300 mg BID | 0.90 (0.85, 0.96) | 0.86 (0.80, 0.92) | 0.79 (0.67, 0.94) |
Effect of Maraviroc on the Pharmacokinetics of Concomitant Drugs
Maraviroc is unlikely to inhibit the metabolism of coadministered drugs metabolized by the following cytochrome P enzymes (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, and CYP3A) because maraviroc did not inhibit activity of those enzymes at clinically relevant concentrations in vitro. Maraviroc does not induce CYP1A2 in vitro.
In vitro results indicate that maraviroc could inhibit P-glycoprotein in the gut and may thus affect bioavailability of certain drugs.
Drug interaction studies were performed with maraviroc and other drugs likely to be coadministered or commonly used as probes for pharmacokinetic interactions [see Table 6]. Maraviroc had no effect on the pharmacokinetics of zidovudine or lamivudine. Maraviroc decreased the Cmin and AUC of raltegravir by 27% and 37%, respectively, which is not clinically significant. Maraviroc had no clinically relevant effect on the pharmacokinetics of midazolam, the oral contraceptives ethinylestradiol and levonorgestrel, no effect on the urinary 6β-hydroxycortisol/cortisol ratio, suggesting no induction of CYP3A in vivo. Maraviroc had no effect on the debrisoquine metabolic ratio (MR) at 300 mg twice daily or less in vivo and did not cause inhibition of CYP2D6 in vitro until concentrations >100µM. However, there was 234% increase in debrisoquine MR on treatment compared to baseline at 600 mg once daily, suggesting potential inhibition of CYP2D6 at higher dose.
Antiviral Activity in Cell Culture
Maraviroc inhibits the replication of CCR5-tropic laboratory strains and primary isolates of HIV-1 in models of acute peripheral blood leukocyte infection. The mean EC50 value (50% effective concentration) for maraviroc against HIV-1 group M isolates (subtypes A to J and circulating recombinant form AE) and group O isolates ranged from 0.1 to 4.5 nM (0.05 to 2.3 ng/mL) in cell culture.
When used with other antiretroviral agents in cell culture, the combination of maraviroc was not antagonistic with NNRTIs (delavirdine, efavirenz and nevirapine), NRTIs (abacavir, didanosine, emtricitabine, lamivudine, stavudine, tenofovir, zalcitabine and zidovudine), or protease inhibitors (amprenavir, atazanavir, darunavir, indinavir, lopinavir, nelfinavir, ritonavir, saquinavir and tipranavir). Maraviroc was additive/synergistic with the HIV fusion inhibitor enfuvirtide. Maraviroc was not active against CXCR4-tropic and dual-tropic viruses (EC50 value >10 µM). The antiviral activity of maraviroc against HIV-2 has not been evaluated.
Resistance in Cell Culture
HIV-1 variants with reduced susceptibility to maraviroc have been selected in cell culture, following serial passage of two CCR5-tropic viruses (CC1/85 and RU570). The maraviroc-resistant viruses remained CCR5-tropic with no evidence of a change from a CCR5-tropic virus to a CXCR4-using virus. Two amino acid residue substitutions in the V3-loop region of the HIV-1 envelope glycoprotein (gp160), A316T and I323V (HXB2 numbering), were shown to be necessary for the maraviroc-resistant phenotype in the HIV-1 isolate CC1/85. In the RU570 isolate a 3-amino acid residue deletion in the V3 loop, ΔQAI (HXB2 positions 315–317), was associated with maraviroc resistance. The relevance of the specific gp120 mutations observed in maraviroc-resistant isolates selected in cell culture to clinical maraviroc resistance is not known. Maraviroc-resistant viruses were characterized phenotypically by concentration response curves that did not reach 100% inhibition in phenotypic drug assays, rather than increases in EC50 values.
Cross-resistance in Cell Culture
Maraviroc had antiviral activity against HIV-1 clinical isolates resistant to NNRTIs, NRTIs, PIs and the fusion inhibitor enfuvirtide in cell culture (EC50 values ranged from 0.7 to 8.9 nM (0.36 to 4.57 ng/mL)). Maraviroc-resistant viruses that emerged in cell culture remained susceptible to the enfuvirtide and the protease inhibitor saquinavir.
Clinical Resistance
Virologic failure on maraviroc can result from genotypic and phenotypic resistance to maraviroc, through outgrowth of undetected CXCR4-using virus present before maraviroc treatment (see Tropism below), through resistance to background therapy drugs (Table 11), or due to low exposure to maraviroc [see Clinical Pharmacology (12.2)].
Antiretroviral treatment-experienced subjects (Studies A4001027 and A4001028)
Week 48 data from treatment-experienced subjects failing maraviroc-containing regimens with CCR5-tropic virus (n=58) have identified 22 viruses that had decreased susceptibility to maraviroc characterized in phenotypic drug assays by concentration response curves that did not reach 100% inhibition. Additionally, CCR5-tropic virus from 2 of these treatment failure subjects had ≥3-fold shifts in EC50 values for maraviroc at the time of failure.
Fifteen of these viruses were sequenced in the gp120 encoding region and multiple amino acid substitutions with unique patterns in the heterogeneous V3 loop region were detected. Changes at either amino acid position 308 or 323 (HXB2 numbering) were seen in the V3 loop in 7 of the subjects with decreased maraviroc susceptibility. Substitutions outside the V3 loop of gp120 may also contribute to reduced susceptibility to maraviroc.
Antiretroviral treatment-naïve subjects (Study A4001026)
Treatment-naïve subjects receiving SELZENTRY had more virologic failures and more treatment emergent resistance to the background regimen drugs compared to those receiving efavirenz (Table 11).
Table 11 Development of Resistance to MVC or EFV and Background Drugs in Antiretroviral Treatment-Naïve Trial A4001026 for Patients with CCR5-tropic Virus at Screening using Enhanced Sensitivity Trofile® Assay | MVC | EFV |
|---|
Total N in Dataset (As-Treated) | 273 | 241 |
| Total Virologic Failures (As-Treated) | 85(31%) | 56 (23%) |
| Evaluable Virologic Failures with Post Baseline Genotypic and Phenotypic Data | 73 | 43 |
| • Lamivudine Resistance | 39 (53%) | 13 (30%) |
| • Zidovudine Resistance | 2 (3%) | 0 |
| • Efavirenz Resistance | -- | 23 (53%) |
| • Phenotypic Resistance to MVC Includes subjects failing with CXCR4- or dual/mixed-tropism because these viruses are not intrinsically susceptible to maraviroc. | 19 (26 % ) | |
In an as-treated analysis of treatment-naïve subjects at 96 weeks, 32 subjects failed a maraviroc-containing regimen with CCR5-tropic virus and had a tropism result at failure; 7 of these subjects had evidence of maraviroc phenotypic resistance defined as concentration response curves that did not reach 95% inhibition. One additional subject had a ≥3-fold shift in the EC50 value for maraviroc at the time of failure. A clonal analysis of the V3 loop amino acid envelope sequences was performed from 6 of the 7 subjects. Changes in V3 loop amino acid sequence differed between each of these different subjects, even for those infected with the same virus clade suggesting that that there are multiple diverse pathways to maraviroc resistance. The subjects who failed with CCR5-tropic virus and without a detectable maraviroc shift in susceptibility were not evaluated for genotypic resistance.
Of the 32 maraviroc virologic failures failing with CCR5-tropic virus, 20(63%) also had genotypic and/or phenotypic resistance to background drugs in the regimen (lamivudine, zidovudine).
Tropism
In both treatment-experienced and treatment-naive subjects, detection of CXCR4-using virus prior to initiation of therapy has been associated with a reduced virologic response to maraviroc.
Antiretroviral treatment-experienced subjects
In the majority of cases, treatment failure on maraviroc was associated with detection of CXCR4-using virus (i.e., CXCR4-or dual/mixed-tropic) which was not detected by the tropism assay prior to treatment. CXCR4-using virus was detected at failure in approximately 55% of subjects who failed treatment on maraviroc by week 48, as compared to 9% of subjects who experienced treatment failure in the placebo arm. To investigate the likely origin of the on-treatment CXCR4-using virus, a detailed clonal analysis was conducted on virus from 20 representative subjects (16 subjects from the maraviroc arms and 4 subjects from the placebo arm) in whom CXCR4-using virus was detected at treatment failure. From analysis of amino acid sequence differences and phylogenetic data, it was determined that CXCR4-using virus in these subjects emerged from a low level of pre-existing CXCR4-using virus not detected by the tropism assay (which is population-based) prior to treatment rather than from a co-receptor switch from CCR5-tropic virus to CXCR4-using virus resulting from mutation in the virus.
Detection of CXCR4-using virus prior to initiation of therapy has been associated with a reduced virological response to maraviroc. Furthermore, subjects failing maraviroc BID at week 48 with CXCR4-using virus had a lower median increase in CD4+ cell counts from baseline (+41 cells/mm3) than those subjects failing with CCR5-tropic virus (+162 cells/mm3). The median increase in CD4+ cell count in subjects failing in the placebo arm was +7 cells/mm3.
Antiretroviral treatment-naïve subjects
In a 96-week study of antiretroviral treatment-naïve subjects, 14% (12/85) who had CCR5-tropic virus at screening with an enhanced sensitivity tropism assay (Trofile®) and failed therapy on maraviroc had CXCR4-using virus at the time of treatment failure. A detailed clonal analysis was conducted in two previously antiretroviral treatment-naïve subjects enrolled in a Phase 2a monotherapy study who had CXCR4-using virus detected after 10 days treatment with maraviroc. Consistent with the detailed clonal analysis conducted in treatment-experienced subjects, the CXCR4-using variants appear to emerge from outgrowth of a pre-existing undetected CXCR4-using virus. Screening with an enhanced sensitivity tropism assay reduced the number of maraviroc virologic failures with CXCR4- or dual/mixed-tropic virus at failure to 12 compared to 24 when screening with the original tropism assay. All but one (11/12; 92%) of the maraviroc failures failing with CXCR4 or dual/mixed-tropic virus also had genotypic and phenotypic resistance to the background drug lamivudine at failure and 33% (4 /12) developed zidovudine-associated resistance substitutions.
Subjects who had CCR5-tropic virus at baseline and failed maraviroc therapy with CXCR4-using virus had a median increase in CD4+ cell counts from baseline of +113 cells/mm3 while those subjects failing with CCR5-tropic virus had an increase of +135 cells/mm3. The median increase in CD4+ cell count in subjects failing in the efavirenz arm was + 95 cells/mm3.
Carcinogenesis
Long-term oral carcinogenicity studies of maraviroc were carried out in rasH2 transgenic mice (6 months) and in rats for up to 96 weeks (females) and 104 weeks (males). No drug-related increases in tumor incidence were found in mice at 1500 mg/kg/day and in male and female rats at 900 mg/kg/day. The highest exposures in rats were approximately 11 times those observed in humans at the therapeutic dose of 300 mg twice daily for the treatment of HIV-1 infection.
Mutagenesis
Maraviroc was not genotoxic in the reverse mutation bacterial test (Ames test in Salmonella and E. coli), a chromosome aberration test in human lymphocytes and rat bone marrow micronucleus test.
Impairment of Fertility
Maraviroc did not impair mating or fertility of male or female rats and did not affect sperm of treated male rats at approximately 20-fold higher exposures (AUC) than in humans given the recommended 300 mg twice daily dose.
Trofile® is a registered trademark of Monogram Biosciences, Inc.
Pfizer Logo (Selzentry 02)
LAB-0357-5.0
Additional barcode labeling by:
Physicians Total Care, Inc.
Tulsa, Oklahoma 74146