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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 …
Contributors MC, AS, MR, FC and CB are the neurologists in charge of the patients at the University of Padova. LB and MG are the neurologists in charge of the patients at the University of Genova. ENO and MB are the neurologists in charge of the patients at the Humanitas Center in Rozzano, Milan. GAM and GM are the neurologists in charge of the patients at the University of Tor Vergata, Rome. NR and RF are the neurologists in charge of the patients at the San Raffaele Hospital, Milan. RZ is the haematologist in charge of most of the patients. ME is a neurologist, who did the statistical analysis. CB, MC and RZ are the persons who designed the study and wrote the draft of the manuscript.
All the authors helped in the acquisition, analysis and interpretation of data, as well as in critically revising the manuscript for important intellectual content. All the authors have read and approved the final version of the manuscript.
Competing interests None declared.
Ethics approval Local ethics committees.
Provenance and peer review Not commissioned; externally peer reviewed.
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