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Neuromyelitis optica (NMO) has been shown to be a relapsing disease with a high risk of disability that benefits from long-term immunosuppression (NEJM JW Neurol May 29 2012). However, phase III therapeutic trials are lacking for this rare disease. Common options include azathioprine with at least 6 months of prednisone, mycophenolate mofetile with at least 6 months of prednisone, and rituximab. The present study is a retrospective comparison of these three regimens at two academic centers with large NMO populations.
Of 90 patients with NMO, 32 were treated with azathioprine, 28 with mycophenolate, and 30 with rituximab. Comparing pretreatment with post-treatment relapses, azathioprine reduced the annualized relapse rate by 72% (from 2.26 to 0.63), mycophenolate by 87% (from 2.61 to 0.33), and rituximab by 89% (from 2.89 to 0.33). Efficacy improved when each agent was dosed optimally. Freedom from relapses was achieved in 47% of patients with azathioprine, 64% with mycophenolate, and 67% with rituximab.
Mealy MA et al. Comparison of relapse and treatment failure rates among patients with neuromyelitis optica: Multicenter study of treatment efficacy. JAMA Neurol 2014 Jan 20; [e-pub ahead of print]. (http://dx.doi.org/10.1001/jamaneurol.2013.5699)
Comment
This study is valuable because it provides head-to-head comparative data among the neuromyelitis optica treatments. The findings emphasize that each of the treatments works and must be dosed optimally. Optimal means following lymphocyte counts with azathioprine and mycophenolate, using prednisone for at least the first 6 months with azathioprine and mycophenolate, and retreating on schedule with rituximab to maintain B-cell depletion (NEJM JW Neurol Sep 13 2011). Many patients have a favorable treatment response to azathioprine, but there are clear nonresponders as well. Mycophenolate may have an edge over azathioprine in efficacy, relative ease of use (i.e., no need for thiopurine methyltransferase gene determination), and dosing, but mycophenolate has significant teratogenicity, a concern in treating women of childbearing potential. Rituximab has advantages for efficacy, infrequent dosing, and relatively rapid onset. Rituximab may be preferential for severe, rapidly relapsing NMO, whereas the two oral agents can be considered based on clinician familiarity and family planning considerations.