Efficacy and safety of human leucocyte interferon-alpha treatment in patients younger than 60 years of age with polycythaemia vera

Objectives. To evaluate the therapeutic activity and toxicity of human leucocyte interferon-α (lIFN-α) in patients with polycythaemia vera (PV) aged less than 60 years. Design. An open clinical study. Setting. Department of Medical Sciences, Regina Apostolorum Hospital, Albano Laziale, and Chair of Haematology, University of Rome 'Tor Vergata', S. Eugenio Hospital, Rome, Italy. Subjects. Fourteen patients with PV and aged <60 years who had active disease as indicated by the need for phlebotomy and/or cytoreductive therapy. Interventions. lIFN-α was administered subcutaneously at the starting dose of 3 MU thrice weekly. The interferon dose could be escalated to six MU thrice weekly if it was well tolerated and disease was not controlled after three months of treatment at the lower dose. Main outcome measures. Change in phlebotomy requirements, spleen size, pruritus score and haematological parameters after 6 months of treatment. Evaluation of lIFN-α side effects. Results. Complete or partial disease control was achieved in 13 patients. Six patients achieved a complete response (CR) and four a partial response (PR) after 3 months of therapy. Dose escalation in partial or nonresponders resulted in two patients switching from a status of PR to CR, and three other patients achieving a partial response after being unresponsive to the lower dosage. Human leucocyte interferon-α therapy significantly improved (P < 01) phlebotomy requirements, the degree of splenomegaly, pruritus scores, iron stores and MCV values, and platelet and leucocyte counts. A mild flu-like syndrome (lowgrade fever, nausea and myalgias) appeared during the early phase of therapy in the majority of patients, but no patient had to discontinue lIFN-α because of intolerance. Conclusions. Subcutaneous human leucocyte interferon-α appears an effective and well tolerated therapy in the management of PV-associated myeloproliferation and pruritus in patients aged less than 60 years.