Comparative Pharmacokinetic/Pharmacodynamic Profiles in Japanese and Caucasian Patients with Transfusional Hemosiderosis Receiving Treatment with Deferasirox (Exjade®, ICL670).

Introduction: In Japan, myelodysplastic syndromes (MDS) and aplastic anemia (AA) are the most common transfusion-dependent anemias. Deferasirox (Exjade^®, ICL670) is a once-daily, oral iron chelator for the treatment of transfusional iron overload; its efficacy and tolerability have been established in adults and children with a range of transfusion-dependent anemias, including MDS. Here, deferasirox has been evaluated in Japanese patients and the pharmacokinetics (PK) and pharmacodynamics (PD) compared with those seen in a US study.

Methods: The tolerability, PK and PD of deferasirox have been assessed in a Phase I, open-label, unblinded, dose-escalation trial (1101) in Japanese patients with MDS and AA in 9 centers. Deferasirox was administered as a single dose of 5 (n=6), 10 (n=7), 20 (n=6) or 30 mg/kg (n=7). After a 7-day break, daily doses were administered (same doses/same patients) for 7 consecutive days. Data were compared with a study (0104) in 24 Caucasian β-thalassemia patients (age range 18–39 years) who were administered doses of deferasirox of 10, 20 or 40 mg/kg/day for 12 days. Throughout the study, iron intake and excretion were rigorously measured.

Results: A total of 26 Japanese patients (8 male, 18 female; mean age 65.6 years; 8 aged <65 years) completed single- and multiple-dosing periods (16 MDS; 6 AA; 4 other anemias). After a single dose and also at steady state, linear PK (C_max and AUC) were observed at all doses. The figures show C_max and AUC at steady state for both the Japanese patients (closed circles, solid lines) and the Caucasian patients (open squares, dotted lines), and demonstrate that PK were similar.

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Dose-dependent iron excretion (range 0.07–0.61 mg iron/kg/day) was observed, similar to that in the Caucasian patients (range 0.12–0.45 mg iron/kg/day). A linear relationship (PK/PD) was noted between AUC and iron excretion. Deferasirox was well tolerated, with generally infrequent and mild adverse events (AEs). The most common AEs related to deferasirox were diarrhea (n=2 each after single and multiple doses of 30 mg/kg/day) and nausea (n=1 each after multiple doses at 10 and 30 mg/kg/day). One patient had two serious AEs, pyrexia and duodenal ulcer, both suspected to be related to study drug, after multiple doses of 30 mg/kg/day.

Conclusions: Deferasirox is well tolerated both after single and multiple doses in Japanese MDS/AA patients, with similar PK/PD parameters to those in the Caucasian β-thalassemia cohort. Exposure to deferasirox in the Japanese patient cohort was dose dependent with a linear PK/PD relationship resulting in dose-dependent iron excretion. These data suggest that deferasirox is effective and well tolerated regardless of underlying disease, race or age.