Rituximab for polyneuropathy with IgM monoclonal gammopathy.

BACKGROUND: Polyneuropathy with IgM monoclonal gammopathy can be a disabling disorder necessitating treatment.

METHODS: In a prospective open label trial, 17 patients with disabling IgM MGUS polyneuropathy were treated with rituximab, a chimeric anti-CD-20 monoclonal antibody.

RESULTS: Rituximab induced an improvement of >or=1 point on the Overall Disability Sum Score in 2/17 patients, an improvement of >or=5% of the distal MRC sum score in 4/17 and the sensory sum score in 9/17 patients. Bone marrow investigations showed CD 20 B cell depletion in all patients. There were no serious adverse events. Compared with treatment with intermittent cyclophosphamide with prednisone or treatment with fludarabine, it shows a comparable response percentages but fewer side effects. The presence of anti-MAG and a disease duration shorter than 10 years may predict treatment response.

CONCLUSION: Rituximab is a candidate for treatment of IgM MGUS polyneuropathy and should be further investigated in a double-blind randomised trial.