Influence of mild and moderate hepatic impairment on axitinib pharmacokinetics

Objective: To evaluate the effects of hepatic impairment on the pharmacokinetics and safety of a single, oral axitinib dose in subjects with mild or moderate hepatic impairment. Methods: In this phase I, open-label, parallel-group study, a total of 24 subjects with either normal hepatic function (n = 8) or with mild (n = 8) or moderate (n = 8) hepatic impairment were administered a single, oral dose of axitinib (5 mg). Blood samples were collected at intervals up to 144 h following dosing, and plasma pharmacokinetics and safety were assessed. Changes in axitinib plasma exposures in subjects with mild or moderate hepatic impairment were predicted using computer simulations and used to guide initial dosing in the clinical study. Results: Axitinib exposure was similar in subjects with normal hepatic function and those with mild hepatic impairment, but approximately twofold higher in subjects with moderate hepatic impairment. Axitinib exposure weakly correlated with measures of hepatic function but was not affected by smoking status. Axitinib protein binding was similar in the three treatment groups. No significant treatment-related adverse events were reported. Conclusions: Compared with subjects with normal hepatic function, moderate hepatic impairment increased axitinib exposure, suggesting that the oral clearance of axitinib is altered in these subjects. In addition, these data indicate a possible need for a dose reduction in subjects who develop moderate or worse hepatic impairment during axitinib treatment. A single 5-mg dose of axitinib was well tolerated in subjects with mild or moderate hepatic impairment

Effect of ketoconazole on the pharmacokinetics of axitinib in healthy volunteers

Objective Axitinib (AG-013736), an oral, potent, and selective inhibitor of vascular endothelial growth factor receptors 1, 2, and 3, is metabolized primarily by cytochrome P450 (CYP) 3A with minor contributions from CYP1A2, CYP2C19, and glucuronidation. Co-administration with CYP inhibitors may increase systemic exposure to axitinib and alter its safety profile. This study evaluated changes in axitinib plasma pharmacokinetic parameters and assessed safety and tolerability in healthy subjects, following axitinib co-administration with the potent CYP3A inhibitor ketoconazole. Methods In this randomized, single-blind, two-way crossover study, 32 healthy volunteers received placebo, followed by a single 5-mg oral dose of axitinib, administered either alone or on the fourth day of dosing with oral ketoconazole (400 mg/day for 7 days). Results Axitinib exposure was significantly increased in the presence of ketoconazole, with a geometric mean ratio for area under the plasma concentration–time curve from time zero to infinity of 2.06 (90% confidence interval [CI]: 1.84–2.30) and a geometric mean ratio for maximum plasma concentration (Cmax) of 1.50 (90% CI: 1.33–1.70). For axitinib alone or with ketoconazole, Cmax occurred 1.5 and 2.0 h after dosing, respectively. Adverse events were predominantly mild; the most commonly reported treatment-related adverse events were headache and nausea. Conclusions Axitinib plasma exposures and peak concentrations were increased following concurrent administration of axitinib and ketoconazole in healthy volunteers. Axitinib alone and in combination with ketoconazole was well tolerated. These findings provide an upper exposure for expected axitinib plasma concentrations in the presence of potent metabolic inhibition

A Population Pharmacokinetic Analysis of Nelfinavir Mesylate in Human Immunodeficiency Virus-Infected Patients Enrolled in a Phase III Clinical Trial

A population pharmacokinetic analysis was conducted on nelfinavir in patients infected with human immunodeficiency virus (HIV) who were enrolled in a phase III clinical trial. The data consisted of 509 plasma concentrations from 174 patients who received nelfinavir at a dose of 500 or 750 mg three times a day. The analysis was performed using nonlinear mixed-effect modeling as implemented in NONMEM (version 4.0; double precision). A one-compartment model with first-order absorption best described the data. The timing and small number of early postdose blood levels did not allow accurate estimation of volume of distribution (V/F) and the absorption rate constant (k(a)). As a result, two models were used to analyze the data: model 1, in which oral clearance (CL/F), V/F, and k(a) were estimated, and model 2, in which V/F and k(a) were fixed to known values and only CL/F was estimated. Estimates of CL/F ranged from 41.9 to 45.1 liters/h, values in close agreement with previous studies. Neither body weight, age, sex, race, dose level, baseline viral load, metabolite-to-parent drug plasma concentration ratio, history of liver disease, nor elevated results of liver function tests appeared to be significant covariates for clearance. The only significant covariate-parameter relationship was concomitant use of fluconazole on CL/F, which was associated with a modest reduction in interindividual variability of CL/F. Patients who received concomitant therapy with fluconazole had a statistically significant reduction in nelfinavir CL/F of 26 to 30%. Since serious dose-limiting toxicity and concentration-related toxicities are not apparent for nelfinavir, this effect of fluconazole is unlikely to be of clinical significance

Treatment of advanced thyroid cancer with axitinib: Phase 2 study with pharmacokinetic/pharmacodynamic and quality-of-life assessments

BACKGROUND: In a previous phase 2 trial, axitinib was active and well tolerated in patients with advanced thyroid cancer. In this second phase 2 trial, the efficacy and safety of axitinib were evaluated further in this population, and pharmacokinetic/pharmacodynamic relationships and patient-reported outcomes were assessed. METHODS: Patients (N = 52) with metastatic or unresectable, locally advanced medullary or differentiated thyroid cancer that was refractory or not amenable to iodine-131 received a starting dose of axitinib 5 mg twice daily. The primary endpoint was the objective response rate (ORR). Secondary endpoints included progression-free survival (PFS), overall survival (OS), safety, pharmacokinetic parameters, and patient-reported outcomes assessed with the MD Anderson Symptom Inventory questionnaire. RESULTS: The overall ORR was 35% (18 partial responses), and 18 patients had stable disease for ≥16 weeks. The median PFS was 16.1 months, and the median OS was 27.2 months. All-causality, grade ≥3 adverse events (>5%) were fatigue, dyspnea, diarrhea, decreased weight, pain in extremity, hypertension, decreased appetite, palmar-plantar erythrodysesthesia, hypocalcemia, and myalgia. Patients who had greater axitinib exposure had a longer median PFS. Quality of life was maintained during treatment with axitinib, and no significant deterioration in symptoms or interference in daily life caused by symptoms, assessed on MD Anderson Symptom Inventory subscales, were observed. CONCLUSIONS: Axitinib has activity and a manageable safety profile while maintaining quality of life, and it represents an additional treatment option for patients with advanced thyroid cancer