Safety and Effectiveness of Satralizumab in Japanese Patients with Neuromyelitis Optica Spectrum Disorder: A 30‑Month Interim Analysis of Post‑marketing Surveillance

A large-scale post-marketing surveillance (PMS) study is ongoing to evaluate the safety and effectiveness of satralizumab over 6 years in Japanese patients with neuromyelitis optica spectrum disorder (NMOSD) in real-world settings. We present the results of a 30-month interim analysis of the study. This PMS is being conducted across 234 sites in Japan. In this 30-month interim analysis, the end of the observation period was defined as either the date of data lock for the 30-month case report form for all patients or the last observation date for patients with satralizumab discontinuation. Primary outcomes include proportion of patients experiencing adverse drug reactions (ADRs), event rate, and oral glucocorticoid use. Secondary outcomes include time to relapse and relapse rate. Of 571 patients included (mean age: 52.4 years), 91.76% were female. At baseline, 85.98% of patients received oral glucocorticoids. ADRs were reported in 28.72% of patients (event rate: 27.69 events/100 person-years), with infections being most common (11.73%; 8.97 events/100 person-years). Univariate analysis showed that at 30 months, serious infections occurred in 6.83% of patients (5.00 events/100 person-years vs 8.13 events/100 person-years during 0-6 months) and were more frequent in patients aged ≥ 75 years, with diagnosis-to-treatment initiation duration ≥ 10 years, ≥ 3 relapses within 2 years, and Expanded Disability Status Scale score ≥ 6. Mean glucocorticoid dose decreased from 12.27 mg/day (baseline) to 3.48 mg/day (30 months). Kaplan-Meier cumulative relapse-free rate was 85.86% at 30 months. The annualized relapse rate was 0.08/person-year. Overall, 9.63% and 3.50% of patients discontinued treatment because of adverse events and relapses, respectively. Serious infections were more common during the satralizumab treatment period, occurring most frequently within the first 6 months, highlighting the need for continuous monitoring of infections throughout satralizumab treatment. Satralizumab was found to be safe, without new safety concerns over 30 months. A reduction in concomitant immunosuppressive therapy usage was observed. The study demonstrated the effectiveness of satralizumab in preventing relapses in Japanese patients with NMOSD. UMIN Clinical Trials Registry, UMIN000041047.