A PHASE-II TRIAL ON ALPHA-INTERFERON (ALPHA-IFN) EFFECT IN PATIENTS WITH MONOCLONAL IGM GAMMOPATHY

Waldenstrom's macroglobulinemia (WM) is an incurable disorder of B cel ls. Following occasional reports of response to alpha interferon (IFN) and in view of its effectiveness in hairy cell leukemia, we tested th is agent in a relatively large group (n=88) of patients who had an IgM monoclonal component (MC) greater than 10 g/l. Thirty eight patients had a MC >30 g/l and were classified as Waldenstrom's macroglobulinemi a (WM), while fifty had either WM in an early stage or an IgM monoclon al gammopathy of undeterminated significance (all of them operationall y classified as IgM-MGUS). All patients received IFN 3 MU/ day for one month and then 3 times/week. Response to treatment was mainly based o n MC reduction in two consecutive determinations (>50%: major response ; 25-50%: minor response). Of 36 evaluable WM patients, 12 had a major and 6 a minor response; of 41 evaluable IgM-MGUS patients, 2 had a ma jor and 6 a minor response. In WM patients with a major response, MC r eduction was associated with disappearance of hyperviscosity symptoms, raised Hb level and reduced bone marrow lymphoplasmacytosis. At the d ose used, tolerance was excellent in the majority of patients; only 15 % withdrew from the study due to side effects. Although single cases a nd very small series have already been reported, no large study collec ting quantitative data on the effects of alpha IFN in WM has been publ ished so far. Our results suggest that IFN treatment is not indicated for patients with a low monoclonal component, while it is of clinical benefit in about 50% of patients with IgM >30 g/l.