INTERMITTENT CYCLOPHOSPHAMIDE AND PREDNISONE TREATMENT OF POLYNEUROPATHY ASSOCIATED WITH MONOCLONAL GAMMOPATHY OF UNDETERMINED SIGNIFICANCE

In an open prospective study, we analyzed the effect of cyclophosphami de (300 mg/m(2) body surface daily for 4 days) combined with prednison e (40 mg/m(2) body surface daily for 5 days) at 4-week intervals durin g 6 months in 16 patients with polyneuropathy associated with monoclon al gammopathy of undetermined significance (MGUS). Eleven patients had an IgM-MGUS and five an IgG-MGUS. During a follow-up period of 3 year s, eight patients had improvement and six patients stabilized, based o n quantitative neurologic examination, the Rankin disability scale, an d electrophysiologic studies. These 14 patients had neuropathy with de myelinating and axonal features. One patient with a purely axonal neur opathy had deterioration despite therapy. One other patient developed severe leukopenia as side effect of cyclophosphamide, necessitating wi thdrawal of treatment. A difference in response was not present in pat ients with IgM- or IgG-MGUS, nor in patients with or without autoantib odies against myelin-associated glycoprotein. Nine patients had a bone marrow biopsy before and 1 year after treatment. In eight patients, t he monoclonal lymphoid IgM or plasma cell IgG infiltration decreased, while in four the monoclonality disappeared after treatment. In the pa tient who had neurologic deterioration, repeated bone marrow biopsy sh owed deposits of amyloid. In conclusion, short-term treatment with int ermittent cyclophosphamide and prednisone may have a long-term favorab le effect in patients with demyelinating polyneuropathy associated wit h MGUS.