Essential thrombocythemia and fibroblast growth factor-2: role of anagrelide

Evolution into myelofibrosis is part of the natural history of the essential thrombocythemia (ET). The myelosuppressive therapy in ET may itself increase the risk of transformation to myelofibrosis. The challenge in treating ET is to prevent this risk. It is reported that activated thrombocythemic platelets release fibroblast growth factor-2 (FGF-2). Anagrelide (ANA) is a myelosuppressive agent that inhibits the platelet function. The major concern regarding ANA is whether it do not increase the putative risk of transformation to myelofibrosis. In this study we report the results of a randomized group of patients with ET in treatment with ANA that after a follow-up of 5 years showed a reduction in the myelofibrosis. A likely explanation for this finding is the broader activity of ANA which also affects the platelet function.