Long-term treatment with interferon-alpha 2b for severe pruritus in patients with polycythaemia vera.

Pruritus is a major clinical problem in patients with polycythaemia vera (PV). Conventional symptomatic treatment is unsatisfactory. Recently, a favourable effect of interferon-alpha on pruritus in patients with PV has been reported. Also, interferon-alpha suppresses the increased haemopoiesis in PV. However, long-term treatment with interferon-alpha may be hampered by side-effects and the inconvenience of chronic subcutaneous injection therapy. We conducted a long-term study (median follow-up 13 months) of the efficacy and tolerability of interferon-alpha in 15 patients (mean age 68 years) with PV and severe pruritus. Six patients were evaluable after 1 year. Pruritus significantly improved in 12/15 patients. Haematological control improved, as evidenced by a decreased number of phlebotomies from a mean of 4.3 in the year before the study to 1.8 while on interferon-alpha. Leucocyte and platelet numbers also decreased significantly. Five patients (33%) did not tolerate interferon-alpha. The effects of interferon-alpha could not be ascribed to an inhibitive effect on histamine production or to the disappearance of the abnormal erythroid progenitor clone, because erythropoietin-independent erythroid colony formation persisted during interferon-alpha treatment. We conclude that long-term interferon-alpha treatment is feasible and effectively relieves pruritus in patients with PV, but side-effects are an important concern. The optimal dose regimen that is well tolerated, relieves pruritus, and offers satisfactory haematological control at the same time remains to be established.