NMDAR Autoimmune Encephalitis

The purpose of this study is to assess the efficacy, safety, PK, and PD of satralizumab in participants with NMDAR and LGI1 encephalitis.

NMDA receptor antibody encephalitis is a rare autoimmune neurological disease of the central nervous system with an estimated incidence of 1.5 people per million per year. Patients with anti-NMDAR encephalitis experience an acute phase of the disease characterized by psychosis, memory loss, seizures, autonomic nervous system instability, or coma. Since the discovery of this disease 14 years ago by Prof. Dalmau, the clinical presentation of the acute phase has been well characterized, while the psychosocial impact of the disease remains largely unexplored. Currently, there are few cohort studies of patients that have identified persistent cognitive impairment as a factor impacting remission after the acute phase. Given the scarcity of information concerning the post-acute phase, it is therefore essential to determine the long-term social and psychological outcomes and their daily effects on the social and functional life of this severe disease. This is especially important as the patients are young, with a median age of 21 years, and may face lasting limitations potentially detrimental to their success in professional, educational, or social environments.

Autoimmune encephalitides are severe neurological disorders requiring urgent treatment, even though there is no standard guideline by lack of empirical evidence. Commonly used treatments are divided into so-called first-line (steroids, intravenous immunoglobulins, plasma exchanges) and second-line (rituximab, cyclophosphamide, tocilizumab, others), and may be used in association or sequentially. There is no standard practice, and initial treatment protocol may consist in first-line alone, first-line with rituximab, or first-line with dual immunosuppression (rituximab and cyclophosphamide). Absence of clear response to initial treatment in the first 4 to 6 weeks may indicate undertreatment and is generally followed by treatment escalation, mostly to dual immunosuppression. However, as the frequency of non-responders to initial treatment is unknown, it is still unclear whether dual immunosuppression should be offered to all patients from inception.