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- myelin-associated glycoprotein (MAG)
- IgM paraprotein
- Waldenstrom’s Macroglobulinemia
- monoclonal gammopathy of undetermined significance (MGUS).
No adequate immunotherapy has so far been shown to be effective in anti-myelin-associated glycoprotein (MAG) antibody neuropathy.1 Rituximab was assessed in two randomised controlled trials, both including only patients with monoclonal gammopathy of undetermined significance (MGUS), with Waldenstrom’s macroglobulinaemia (WM) being an exclusion criterion.2
The aim of our multicentre retrospective study was to assess whether the response to rituximab in patients with anti-MAG antibody neuropathy would differ according to the associated haematological condition.
We reviewed the clinical and laboratory features of 33 patients (21 men, mean age at time of therapy: 64.6±10.3, range: 41–87, mean neuropathy duration at time of therapy: 4.67 years±4.82, range: 0.5–17) with anti-MAG antibody neuropathy who underwent therapy with rituximab single agent in five Italian neurological centres. Twenty-five (73.5%) patients had Immunoglobulin M (IgM) MGUS and 8/33 had WM, according to bone marrow biopsy. The mean age was significantly different in the two groups (62.5±10.3 years in MGUS vs 70.5±7.9 years in WM, p=0.04). The mean neuropathy duration was 4.56±4.8 years in MGUS versus 5.6±5.1 years in WM (p=0.62, Mann-Whitney U test).
Anti-MAG antibodies were assayed by ELISA (Bühlmann Laboratories AG) (28 patients) or Western blot (5 patients). The median antibodies titre was 51 200 (range: 7500–800 000) in MGUS and 56 000 (range: 11 126–600 000) in patients with WM. Patients with low (<10 000 Bühlmann Titer Units) titre were included for clinical and neurophysiological features consistent with anti-MAG neuropathy. Antibody titres were not retrievable in two patients.
Twenty patients were therapy-naive, while 13 …