Effectiveness of treatments in Neuromyelitis optica to modify the course of disease in adult patients. Systematic review of literature.

Background: Neuromyelitis Optica spectrum disorder (NMOSD) is an inflammatory disease, which manifests mostly as recurrent episodes of optic neuritis or myelitis that cause important disability. Early diagnosis and prompt initiation of immunosuppressive therapy are crucial in reducing relapses, disability, and mortality. Even though, there are few prospective randomized controlled trials, several drugs have proved to be both effective and safe. Azathioprine and Rituximab represent the standard of care and are used as first-line treatment agents worldwide. However, recent studies have unveiled new therapies, such as monoclonal antibodies. To make treatment recommendations and management guidelines, it is imperative to define an appropriate standard of care.

Methods: A systematic literature review was performed in MEDLINE, EMBASE, and LILACS databases using the following terms: "(NMO OR Devic OR Neuromyelitis Optica) AND (Azathioprine OR Prednisone OR Rituximab OR Tocilizumab OR Bortezomib OR Inebilizumab OR Eculizumab OR Satralizumab)" including both, randomized clinical trials and observational studies published between January 2006 and January 2021. The inclusion criteria comprised patients aged 18 or older, NMOSD diagnosis following the Wingerchuck criteria, two or more therapies been compared, and the evaluation of both efficacy and safety outcomes. All studies comparing treatment only with placebo were excluded. Quality was assessed according with the design of the study, and results were synthesized through comparative tables for each outcome evaluated, differentiating the results of randomized and non-randomized studies.

Results: Thirteen studies with 1447 patients were included. Twelve studies evaluated the expanded disability status scale (EDSS) before and after treatment; in five of seven evaluating rituximab, it outperformed its comparators in improving the disability degree. Eleven studies assessed the annual relapse rate (ARR). Again, in six of seven evaluating rituximab, it was superior to other therapies. Time to relapse (TTR) was reported in five studies. The three studies that included Rituximab revealed a longer time to relapse in this arm of treatment. Finding were consistent in randomized and non-randomized studies. The new molecules Satralizumab, Eculizumab and Tocilizumab were evaluated in one study each, proving to be highly effective and safe. The safety profile analysis showed a higher number of adverse events for Azathioprine.

Discussion: This systematic review demonstrates a superiority tendency of Rituximab upon the other treatments strengthening the available evidence about NMOSD management. Superiority in EDSS outcomes, annual relapse rate, time to first relapse and relapses during treatment time was evidenced in the Rituximab group compared to other medications, with lower rates of adverse events. New molecules Tocilizumab, Eculizumab and Satralizumab also showed superiority in the evaluated results, especially in the relapses during treatment time outcome, although with subtle differences in EDSS and ARR outcomes.

Conclusion: Our results suggest that monoclonal antibodies are highly effective and safe for the treatment of NMOSD; Rituximab showed better performance on multiple outcomes and has more evidence available. New molecules: Eculizumab, Tocilizumab, Satralizumab are good options for treatment. Drugs like Azathioprine and Mycophenolate are effective, but with a worse risk-benefit ratio, therefore, they are useful alternatives in places that do not have access to monoclonal antibodies.