Treatment of children with anagrelide for thrombocythemia

Essential thrombocythemia (ET) is a rare myeloproliferative disease characterized by hyperproliferation of megakaryocytes and persistent elevation of platelets. Major complications are thrombosis, bleeding, and microvascular occlusive symptoms, sometimes resulting in serious morbidity. In patients with platelet counts > 1000 x 10(9)/l, cytoreduction is important to reduce the risk for thrombotic or hemorrhagic events. However, the frequent side effects and the carcinogenic potential of many cytoreductive agents limit their use, especially in younger patients. Anagrelide, a noncarcinogenic agent with moderate toxicity, has been successfully used in adult patients with ET, but experience with anagrelide in pediatric patients with ET is limited.

Three children who received anagrelide (Induction dose 1 mg/day, maintenance dose 1 to 2.5 mg/day) as therapy for ET are described.

All children had a rapid and marked decline of their platelet counts, and only one child developed mild and transient abdominal side effects.

Treatment with anagrelide seems to be a promising approach for children with ET. It should be considered as first-line therapy because of its selective activity against platelet production, tolerable toxicity, suspected negligible cancerigenic effect, and the possibility of oral administration.