To assess the long-term response of patients treated with rituximab and describe the characteristics of those with favorable outcomes. 

Anti-myelin associated glycoprotein (MAG) neuropathy is a debilitating paraproteinemic demyelinating neuropathy. Efficacy of immunotherapy has been inconsistent across multiple studies; however, rituximab—a B-cell depleting agent—has been shown to be beneficial in a subset of patients.  

Case-series of 7 patients with anti-MAG neuropathy on rituximab. Records reviewed for demographic, serological, and electrodiagnostic features. Outcomes to assess efficacy include modified Rankin scale (mRS) and inflammatory neuropathy cause and treatment (INCAT) scale. 

86% of patients were white men. At diagnosis, the mean age was 57 years and the average anti-MAG titer was 1:40,000 in responders and 1:513,600 in non-responders (p=0.04). Disease-duration prior to therapy initiation was 4±3 years in responders, compared to 11±7 years in non-responders (p=0.05). Titers decreased by 7.5±4.7 folds after treatment. At 12 months post-treatment, 4/7 patients reported symptomatic improvement of paresthesia, allodynia, tremor and gait. Neurologic examination demonstrated recovery of distal strength, vibration and proprioception with resolution of Romberg’s sign, and re-emergence of reflexes in the lower extremities. INCAT (mRS) score improved by 1.8±1.0, (p=0.01) (1.3±0.5, p=0.004) points from a baseline of 3.0±1.6 (2.3±0.5). Terminal latency index (TLI) of the median nerve was 0.30±0.05. The remaining patients did not have further deterioration in their symptoms, exam or scores.  One patient had lambda light-chains, unlike the others with kappa light-chains, and did not improve. Another elderly patient with TLI of 0.18 did not respond either despite a 9-fold reduction in anti-MAG titer.

Features of rituximab responders include shorter disease-duration, lower anti-MAG titers and TLI>0.25. Non-responders did not deteriorate further and remained stable. This retrospective case-series supports rituximab as a viable option in a subset of patients for management of anti-MAG neuropathy, with improvements in symptoms, neurological exam and functional neuropathy scales.