Acute treatment
When it comes to acute treatment of NMOSD, the goal is to suppress the inflammatory attack but also to minimize long-term damage and optimize long-term neurological function. “The potential for irreversible injury with an attack is very high, and cumulative disabilities in NMOSD can result directly from attacks,” E. Ann Yeh, MD, director of the Pediatric MS and Neuroinflammatory Disorders Program at the Hospital for Sick Children at the University of Toronto, said during her talk.
IV steroids are generally the first choice, with a preference for methylprednisolone. Pediatric patients that are MOG antibody positive usually respond better and more quickly than do adults, with rapid daily improvements in mobility, vomiting, and eyesight. Dr. Yeh recommends weaning good responders off steroids because AQP-4 positive patients are likely to relapse without a steroid wean, and antibody testing may be unavailable or results may be delayed. The wean can range from 4 weeks to 4-6 months, depending on antibody status, likelihood of AQP-4 positivity, and clinical parameters.
Inadequate responses are usually pretty evident. If there is only light perception by day 4 or 5, or paralyzed patients are nonambulatory and achieve only twitchy movements by that time, second-line therapies should be considered, including therapeutic plasma exchange (TPE) with 5-7 exchanges or intravenous immunoglobulins (IVIg).
Dr. Yeh called for quick treatment. Whatever you do, “please do it sooner rather than later if you think there’s no response [to steroids],” Dr. Yeh said.
TPE is the first choice, according to Dr. Yeh. “There seems to be a fair amount of information that suggests that if you’re having difficulty getting a response to steroids, TPE can make a difference in these patients,” she said. But in some cases TPE may not be available, and IVIg can be attempted first. If it achieves no or only marginal improvement, TPE can be attempted later, but it must be kept in mind that TPE conducted too soon could wash out IVIg. Patients who get much better on IVIg can undergo a steroid wean, and then be evaluated for prophylactic therapy, said Dr. Yeh.
The evidence for IVIg is limited, reflecting the difficulty of studying treatments in rare populations. Still, when TPE is not available and the patient is quite impaired, IVIg makes sense to try. “Absence of evidence does not mean that the therapy doesn’t work, and I don’t think we should throw out the baby with the bath water,” said Dr. Yeh.
Although IVIg treatment is generally well tolerated, there have been a few serious adverse events, such as anaphylactic shock and aseptic meningitis, according to Andrea Savransky, MD, a pediatrician at National Pediatric Hospital in Buenos Aires, who also spoke at the session. “I think it is important to weigh the benefits against the risk,” Dr. Savransky said. She noted that TPE should not be taken lightly. One study showed more complications in pediatric patients than in adult patients, and it must be performed in specialized centers.
Emerging treaments
Tanuja Chitnis, MD, director of the Partners Pediatric MS Center at Massachusetts General Hospital, Boston, discussed some of the emerging treatments for pediatric NMOSD. Rituximab has been associated with success in some retrospective studies, but dosing should be personalized. Dr. Chitnis reported that B cells can return before 6 months, so she monitors B cells beginning 2 months after induction, redosing after 4 or 5 months rather than 6 if B cells return.
Nevertheless, relapses can still occur after rituximab therapy. “There is room for additional therapies to address this gap,” said Dr. Chitnis. Three new antibodies have received approval for treatment of NMOSD in adults. These include the complement inhibitor eculizumab, the IL-6 receptor antibody satralizumab, and the anti-CD19 antibody inebilizumab. Phase 3 clinical trials in children have been conducted for eculizumab and are in the planning stage for inebilizumab, and pediatric patients were included in pivotal trials for satralizumab.
Eculizumab treatment resulted in a 94.2% reduction in relapse risk in AQP4-positive adults. Satralizumab showed a 79% reduction in relapse risk among AQP-4 positive subjects with NMOSD or neuromyelitis optica and a 34% reduction in those who were AQP-4 negative. The pediatric subgroup had similar levels of response to adults, though the numbers were too small for a subgroup analysis.
In AQP-4 positive patients, inebilizumab treatment yielded a 77% reduction in relapse rate. In all patients, there was a 73% reduction.
For MOG antibody-positive patients with AQP-4 negative disease, novel therapies are at earlier stages of development. Typical MS therapies such as interferon beta and glatiramer acetate don’t seem to be effective. Some that have shown signs of efficacy include azathioprine, mycophenylate mofetil, rituximab, and IVIg infusion, but the state of the field is not encouraging. “This is an observation now being studied in larger cohorts, but in general I have not found that there’s a very strong response to any of these therapies, possibly with the exception of IVIg,” said Dr. Chitnis.
Dr. Tenembaum has no relevant financial disclosures. Dr. Armangue has received speaking honoraria from Novartis and travel expenses for scientific meetings from Merck, Biogen, and Roche. Dr. Yeh is on the scientific advisory board of Juno Therapeutics and has received research support from Biogen. Dr. Chitnis advises Biogen-Idec, Novartis, and Alexion, serves on clinical trial advisory boards for Novartis and Sanofi Aventis, and has received research support from Verily, EMD Serono, and Novartis. Dr. Savransky has received honoraria from Genzyme de Argentina SA.