[Alpha interferon in the therapy of polycythemia vera]

In previous researches recombinant interferon alpha (IFN-alpha) has been demonstrated to significantly control red cell mass and thrombocytemia in patients with polycythemia vera (PV). Further evaluation of drug effectiveness and of modalities of maintenance therapy is warranted. We treated four patients with PV according to PVSG criteria with IFN-alpha (3 MU subcutaneously three times a week) for five months. Thereafter the starting dose was reduced to 1.5 MU three times a week. Treatment with IFN-alpha at the higher dosage induced regression in sizes of the spleen and a return to normal levels of peripheral blood platelets and leukocytes. Phlebotomies, previously performed to keep under control hematocrit values, were no more needed. During maintenance treatment with IFN-alpha reduced dose platelet level remained in the normal range, spleen size did not show further variation but hematocrit slowly rose and phlebotomies had to be resumed. These results confirm IFN-alpha effectiveness in PV, but suggest the need of relatively high dosages of the drug and difficulties in switching to a maintenance treatment.