Long-term use of anagrelide in young patients with essential thrombocythemia.
Anagrelide is a novel platelet-lowering agent that has recently been approved for use in essential thrombocythemia (ET) and related disorders. Short-term drug efficacy and toxicity data have previously been presented. The purpose of this study was to obtain additional information regarding long-term anagrelide use. This is a retrospective series of 35 young patients (17 to 48 years) with ET who received anagrelide treatment before 1992. Initial drug dosage ranged between 1 and 10 mg/d, and the median maintenance dosage was 2.5 mg/d. The overall initial response rate of 94% included 74% complete remissions and 20% partial remissions. Of the 33 responding patients, 27 (82%) remained on anagrelide therapy for a median of 10.8 years (range, 7 to 15.5). Of these, 66% maintained a complete and 34% a partial remission over the study period. In general, the reporting of somatic side effects decreased over time, and anemia was the only new side effect that emerged after long-term therapy. Eight patients (24%) experienced a more than 3 g/dL decrease in hemoglobin level. Despite active therapy, 20% of the patients experienced a total of 10 thrombotic episodes, and a similar proportion experienced major hemorrhagic events. All thrombohemorrhagic complications occurred at a platelet count of more than 400 x 10(9)/L. It is concluded that long-term treatment of ET with anagrelide is associated with decreased reporting of initial side effects and the development of mild-to-moderate anemia. Complete normalization of platelet counts may be needed to minimize residual thrombohemorrhagic risk during therapy. (Blood. 2001;97:863-866)
Storen
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Division of Hematology and Internal Medicine, Mayo Clinic, Rochester, MN, USA.
Tefferi
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D000293:Adolescent; D000328:Adult; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010975:Platelet Aggregation Inhibitors / Q000009:adverse effects / Q000627:therapeutic use*; D011799:Quinazolines / Q000009:adverse effects / Q000627:therapeutic use*; D012074:Remission Induction; D012189:Retrospective Studies; D013920:Thrombocythemia, Essential / Q000150:complications / Q000188:drug therapy*; D013927:Thrombosis / Q000453:epidemiology / Q000209:etiology; D016896:Treatment Outcome
D010975:Platelet Aggregation Inhibitors; D011799:Quinazolines; C021139:anagrelide