Recombinant interferon-alpha,but not interferon-gamma is effective therapie for essential thrombocythemia

Summary Recombinant interferon-gamma with a starting dose of 0.5 mg 3×/week subcutaneously, was administered to 6 patients with essential thrombocythemia (median platelet count 1172×10⁹/1, range 602–1564). Four of the patients had received alkylating agents previously. Hematological remission, defined as a decrease in platelet counts to 350×10⁹/l, was observed in none of these patients. Subsequently 4 of these 6 patients, supplemented by 2 others were treated with interferonalpha_2c at a dose of 5×10⁶ U daily subcutaneously. Five patients showed hematological remission. In case of hematological remission the interferonalpha dosis was reduced to 5× an thereafter to 3× weekly 5×10⁶ U. During an observation period ranging from 12–41 weeks platelet counts remained normal in all patients. Side-effects were mild and consisted of fever, myalgias, malaise and itching occurring mainly during the first month of treatment. No dose adaptation was required. The patients treated previously with interferon-gamma experienced the side effects from this drug less tolerably than those from the alpha-compound. These observations suggest that recombinant interferonalpha may be an effective drug in treating essential thrombocythemia resulting in a sustained response.