By Anne McLeod, MD
2009-12-05
At last year’s annual meeting, platelets were center stage, with a Plenary Session presentation on the use of rituximab in idiopathic thrombocytopenic purpura (ITP), and the introduction of new drugs for treating thrombocytopenia and myeloproliferative disorders. So, one year later, an Education Program Session to help us sort through all of these new developments is welcome news. Today at 9:30 a.m. in the La Nouvelle Ballroom C of the Ernest N. Morial Convention Center (and again at 2:00 p.m. today), the session, Platelets: Too Many, Too Few, will give attendees a better understanding of the molecular basis of platelet disorders, and will describe new approaches to management of thrombocytopenia and thrombocytosis.
Past ASH President Dr. Ken Kaushansky, whose group was the first to clone thrombopoietin in the early 1990s, will discuss how our understanding of the complex interactions between growth factors, transcription factors, and the hematopoietic microenvironment has exploded over the last two decades. The discovery of thrombopoietin and of its role in almost all aspects of platelet production has led to the development of thrombopoietin receptor agonists now in clinical use. This session will provide an overview of what has been learned about the regulation of thrombopoiesis to date and the many questions that remain unanswered.
Determining the cause of thrombocytopenia is often difficult, and the lengthy differential diagnosis usually has drugs at the top of the list. Dr. James George of The Oklahoma Health Sciences Centre will tackle this frequent and challenging cause of thrombocytopenia and its management. All too often we suspect a drug is the cause of a patient’s thrombocytopenia, but we lack the ability to confirm the diagnosis. This puts patients at risk for a recurrent event, as drug-dependent antibodies can persist for many years. In this session, Dr. George will describe our current understanding of the pathogenesis of drug-induced thrombocytopenia and will arm us with a series of questions to help us better evaluate and manage this disorder. Dr. George is the creator of the Web site “Platelets on the Web,” which can be found at www.ouhsc.edu/platelets. This extremely useful Web site is a comprehensive database of 1,301 published reports on 317 drugs and provides hematology consultants with information on the level of evidence for a causal relation of the drug to the development of thrombocytopenia. It also contains very helpful information on ITP and TTP-HUS for patients and consulting hematologists alike and is sure to impress the house staff!
Our understanding of thrombocytosis has been changing rapidly, and in the final presentation, Dr. Radek Skoda of Basel, Switzerland, one of the first investigators to publish on the high prevalence of the JAK2V617F mutation in MPDs and past presenter of the Ham-Wasserman Lecture, will conclude the session with a discussion of our current understanding of inherited and acquired disorders that lead to thrombocytosis. Mutations in the thrombopoietin receptor MPL and in JAK2 have been found in only 50 percent to 60 percent of patients with thrombocytosis. This has forced us to accept that the pathways controlling platelet production are complex, and additional research will be needed to discover other molecular causes of thrombocytosis.
Be sure to attend Platelets: Too Many, Too Few today at 9:30 a.m. or 2:00 p.m., where these three giants in platelet research will help us get the management of platelet disorders just right.
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