A RANDOMIZED CLINICAL-TRIAL COMPARING INTERFERON-ALPHA AND INTRAVENOUS IMMUNOGLOBULIN IN POLYNEUROPATHY ASSOCIATED WITH MONOCLONAL IGM

Objectives-The polyneuropathy associated with a monoclonal IgM directe d to the myelin associated glycoprotein (MAG) is a specific entity wit h a putative causal link between the IgM and the neuropathy. The small benefit offered by alkylating agents or plasma exchanges in these pat ients justifies the search for alternative treatments. Methods-A 12 mo nth multicentre, prospective, randomised, open clinical trial was carr ied out comparing intravenous immunoglobulin (IVIg; 2g/kg and then 1g/ kg every three weeks) and recombinant interferon-alpha (IFN-alpha; 3 M U/m(2) subcutaneously three times weekly). The main end point was a cl inical neuropathy disability score (CNDS) after six months of treatmen t. Twenty patients were enrolled; 10 were assigned to IVIg and 10 to I FN-alpha. Results-At six months, one out of 10 patients treated with I VIg had a CNDS improvement of more than 20% whereas eight out of 10 pa tients treated with IFN-alpha. had such an improvement (P=0.005). The mean CNDS worsened by 2.3 (SD 7.6) (8%) in the IVIg group whereas it i mproved by 7.5 (SD 11.1) (31%) in the IFN-alpha group (P=0.02). This i mprovement persisted after 12 months and was mainly related to an impr ovement of the sensory component (P=0.02) whereas the motor component was unchanged (P=0.39). Electrophysiological data did not show improve ment of motor nerve conduction velocities whereas sensory nerve conduc tion velocities improved in the upper Limbs. A decrease in the level o f the monoclonal IgM was seen in two patients treated with IFN-alpha. At the end of the treatment, antibody activity to MAG was still detect ed in the serum of all patients. Conclusion-IVIg, as used in this stud y, did not improve patients with polyneuropathy and monoclonal IgM. By contrast, although its mechanism of action remains to be fully elucid ed, IFN-alpha was effective in eight out of 10 patients at six months.