Open-label, dose-titration and continuation study to assess efficacy, safety, and pharmacokinetics of anagrelide in treatment-naïve Japanese patients with essential thrombocythemia

Shinichiro Okamoto, Yoshitaka Miyakawa, Jonathan Smith, Ian Hodgson, Brihad Abhyankar, Steven Troy, Yuzuru Kanakura

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Although anagrelide is widely used for the treatment of essential thrombocythemia (ET) in the USA and Europe, it is not licensed in Japan. Existing literature has reported differences in polymorphism and activity of CYP1A2 in Japanese and non-Japanese ethnic groups, which may alter anagrelide metabolism. We intended to identify the optimum dosage of anagrelide in treatmentnai ̈ve Japanese patients with ET and assess its long-term safety and efficacy. Twelve patients with ET and a platelet count of ≤80 × 104/μL were enrolled. Anagrelide was administered at an initial dose of 0.5 mg/day (weeks 1-4), then increased to 1.0 mg/day (weeks 5-8). During the following maintenance (weeks 9-52) and continuation periods (weeks 53-104), the dose was adjusted according to patient safety data and to maintain target platelet counts (<60 × 104/lL). Increasing the dose led to a decrease in mean platelet count, and target platelet counts were maintained in 11 patients. Adverse events were mild or moderate, and none led to discontinuation. This cohort of Japanese patients exhibited higher pharmacokinetic exposures of anagrelide and its active metabolite than those previously documented in non-Japanese patients. These differences were modest, suggesting specific dosing regimens for Japanese patients are not required.

Original languageEnglish
Pages (from-to)360-368
Number of pages9
JournalInternational journal of hematology
Issue number3
Publication statusPublished - 2013 Mar 1



  • Anagrelide
  • Elevated platelet count
  • Essential thrombocythemia
  • Japanese patients
  • Pharmacokinetic profiles

ASJC Scopus subject areas

  • Hematology

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