In this phase 3 trial, investigators evaluated the efficacy and safety of satralizumab as adjunct therapy for patients with neuromyelitis optica spectrum disorder (NMOSD).
Study design
The multicenter randomized, double-masked, placebo-controlled trial included 83 patients with NMOSD who were randomized in a 1:1 ratio to receive either subcutaneous satralizumab, an interleukin-6 (IL-6) inhibitor or placebo. The primary endpoint was the time to first relapse.
Outcomes
Patients who were randomized to satralizumab were less likely to relapse compared with placebo (20% vs. 43%), with a hazard ratio (HR) of 0.38. Fifty-five NMOSD patients were seropositive for aquaporin-4 antibody (AQP4-IgG). Of these, 3 of 27 (11%) receiving satralizumab had a relapse, which was significantly lower than placebo where 12 of 28 (43%) patients had a relapse (HR 0.21).
Among the 28 NMOSD patients who were seronegative for AQP4-IgG, there was no difference in relapses between the satralizumab and placebo groups (36% vs. 43%, respectively; HR 0.66). Rates of serious adverse events and infections did not differ between groups.
Limitations
Patients received concomitant immunosuppressive therapy and therefore it is unclear if satralizumab would be effective as monotherapy. Although satralizumab appeared to be less effective for AQP4-IgG negative NMOSD, there were fewer of these patients and therefore a larger number of patients will be required to confirm this. In addition, myelin oligodendrocyte glycoprotein (MOG) antibody status was not reported in this cohort.
Clinical significance
This randomized clinical trial demonstrated that adjunctive satralizumab leads to a reduction of relapses in patients with AQP4-IgG seropositive NMOSD. However, the drug may not be effective for AQP4-IgG seronegative NMOSD. These findings also support a role for IL-6 in the pathophysiology of AQP4-IgG NMOSD.
The year of 2019 has proven to be an important one for NMOSD with satralizumab joining eculizumab and inebilizumab as another possible effective treatment for NMOSD. These therapies will undoubtedly change the treatment landscape for this debilitating disease.