Long-term safety and effectiveness of eculizumab in patients with aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder: a 2-year interim analysis of post-marketing surveillance in Japan.

Background: The terminal complement C5 inhibitor eculizumab is approved in Japan for relapse prevention in aquaporin-4 antibody-positive (AQP4+) neuromyelitis optica spectrum disorder (NMOSD) and is undergoing mandatory post-marketing surveillance (PMS) of clinical use. Objectives: The objective of the study is to assess the real-world, long-term safety and effectiveness of eculizumab in Japanese patients with AQP4+ NMOSD. Design: Regulatory-mandated PMS analysis implemented as an all-case surveillance of all patients with AQP4+ NMOSD who have been treated with eculizumab in Japan since its approval in November 2019. Methods: This PMS interim analysis assessed the safety and effectiveness of eculizumab in Japanese patients with AQP4+ NMOSD from November 2019 to April 2022. Results: Of 147 patients treated with eculizumab who consented to publication, 71 had at least one case report form collected and locked at the interim analysis data cut-off, constituting the safety analysis set; three patients from PREVENT (NCT01892345) were excluded from the effectiveness analysis set. Twelve and 10 patients in the safety and effectiveness analysis sets discontinued, respectively. In the safety analysis set, 67/71 patients (94.4%) were female, mean illness duration was 6.8 [standard deviation (SD): 6.2] years, mean age at eculizumab initiation was 50.7 (SD: 13.3) years, and mean eculizumab treatment duration was 44.6 (SD: 23.7) weeks. At diagnosis of NMOSD, 34/71 patients (47.9%) and 35/71 patients (49.3%) in the safety analysis set had symptoms of optic neuritis and transverse myelitis, respectively. In the safety analysis set, 19/71 patients (26.8%) reported adverse events, 10/71 (14.1%) reported adverse drug reactions (ADRs), and 7/71 (9.9%) reported serious ADRs; no meningococcal infections were observed. In the effectiveness analysis set, 64/68 patients (94.1%) were female, mean disease duration was 6.9 (SD: 6.3) years, mean age at eculizumab initiation was 50.6 (SD: 13.2) years, and 27/68 (39.7%) were tested for C5 genetic polymorphism (all negative). In the 2 years before eculizumab, 51/68 patients (75.0%) experienced relapse. Relapse rate was 0.02/patient-year after eculizumab initiation versus 0.74/patient-year in the 2 years before eculizumab. Overall, 37/68 patients (54.4%) were prescribed immunosuppressants in the 6 months before and 19/40 (47.5%) in the 6-12 months after starting eculizumab treatment. The proportion of patients taking >10 mg/day of prednisolone decreased from 45.6% at 24-20 weeks before to 23.1% and 0% at 48-52 and 100-104 weeks after eculizumab, respectively. Conclusion: This article reports interim PMS data for Japanese patients and provides updated real-world evidence for the safety of eculizumab and its effectiveness at preventing relapses in patients with AQP4+ NMOSD. Safety and effectiveness results are consistent with those from PREVENT.