title: Platelet Dysfunction in Patients with Chronic Myeloid Leukemia: Does Imatinib Mesylate Improve It?
abstract: OBJECTIVE
  The aim of this study was to investigate the effects of imatinib mesylate on platelet aggregation and adenosine triphosphate (ATP) release in chronic myeloid leukemia patients.
  
  
  METHODS
  Platelet aggregation and ATP release induced by 5.0 mM adenosine diphosphate, 0.5 mM arachidonic acid, 1.0 mg/mL ristocetin, and 2 µg/mL collagen were studied by whole blood platelet lumi-aggregometer in 20 newly diagnosed chronic myeloid leukemia patients before and after imatinib mesylate treatment.
  
  
  RESULTS
  At the time of diagnosis, 17/20 patients had abnormal platelet aggregation results; 8 (40%) had hypoactivity, 6 (30%) had hyperactivity, and 3 (15%) had mixed hypo- and hyperactivity. Repeat platelet aggregation studies were performed after a mean of 19 months (min: 5 months-max: 35 months) in all patients who received imatinib mesylate during this period. After therapy, 18/20 (90%) patients had abnormal laboratory results; 12 (60%) had hypoactive platelets, 4 (20%) had mixed hypo- and hyperactive platelets, and 2 (10%) had hyperactive platelets. Three of the 8 patients with initial hypoactivity remained hypoactive, while 2 developed a mixed picture, 2 became hyperactive, and 1 normalized. Of the 6 patients with initial hyperactivity, 4 became hypoactive and 2 developed a mixed pattern. All of the 3 patients with initial hypo- and hyperactivity became hypoactive. Finally, 2 of the 3 patients with initial normal platelets became hypoactive while 1 remained normal. There was a significant decrease in ristocetin-induced platelet aggregation after therapy (p<0.001), while platelet aggregation and secretion induced by other agonists showed no difference after treatment (p>0.05).
  
  
  CONCLUSIONS
  These findings indicate that a significant proportion of chronic myeloid leukemia patients have different patterns of platelet function abnormalities and imatinib mesylate has no effect on these abnormalities, with a significant impairment in ristocetin-induced platelet aggregation.
authors.affiliation: Osmangazi University Faculty of Medicine, Department of Hematology, Eskişehir, Turkey, E-mail : olga.akay@hotmail.com.
authors.forename: Olga Meltem
authors.initials: OM
authors.lastname: Akay
authors.forename: Fezan
authors.initials: F
authors.lastname: Mutlu
authors.forename: Zafer
authors.initials: Z
authors.lastname: Gülbaş
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use; D015415:Biomarkers; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D006801:Humans; D000068877:Imatinib Mesylate / Q000494:pharmacology / Q000627:therapeutic use; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000097:blood* / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects; D010979:Platelet Function Tests; D047428:Protein Kinase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents; D015415:Biomarkers; D047428:Protein Kinase Inhibitors; D000068877:Imatinib Mesylate; D000255:Adenosine Triphosphate