Efficacy of recombinant interferon-alpha (rIFN-alpha) in polycythaemia vera: a study of 17 patients and an analysis of published data.

The efficacy and tolerability of rIFN-alpha has been evaluated in 17 selected patients with symptomatic polycythaemia vera, diagnosed according to the PRV Study Group criteria. Complete disease control (CR) was achieved, after 1-12 months, in nine patients, with partial control in a further five cases. Three patients failed to respond. Pruritus significantly improved in 83% (10/12) of cases, following 1-28 weeks of treatment. Six patients (35%), however, were unable to tolerate rIFN-alpha, on account of weight loss, myalgia and mental changes. Overall, alpha-interferon therapy significantly improved venesection requirements, MCV and PCV values, platelet counts, pruritus scores and the degree of splenomegaly. Analysis of pooled published data (100 evaluable patients, including the present study) revealed an overall CR of 60%, a PR of 27%, and a failure rate of 13%. Significant pruritus control (> 50% improvement) occurred in 77% of cases. rIFN-alpha appears to be an effective therapy for PV-associated myeloproliferation and/or pruritus, although side-effects remain a concern. Long-term studies are now indicated to determine if the natural history of the disease is altered, in particular whether the incidence of myelofibrosis and/or leukaemic transformation is reduced.