Rituximab treatment for autoimmune limbic encephalitis in an institutional cohort

Abstract

Objective: To determine efficacy and safety of rituximab treatment as a second-line immunotherapy treatment for autoimmune limbic encephalitis (ALE) and to determine factors associated with functional improvement and favorable outcome following rituximab treatment. Methods: We recruited 80 patients with ALE who were treated with rituximab as a second-line immunotherapy from the Korea Autoimmune Synaptic and Paraneoplastic Encephalitis Registry and reviewed 81 patients without rituximab as a control. We grouped patients according to the detection or type of antibodies; in addition, we evaluated clinical, laboratory, first-line immunotherapy, and rituximab treatment profiles and defined main outcomes as improvements on the modified Rankin Scale (mRS) score and a favorable mRS score (0-2) at the last follow-up. Results: Functional improvement occurred more frequently in the rituximab group compared to the control group. In the rituximab group, 30 (37.5%) patients had synaptic autoantibodies, 15 (18.8%) in the paraneoplastic autoantibodies, and 35 (43.8%) were antibody-negative. The effect of rituximab was the same regardless of autoantibody status. Additional monthly rituximab therapy and partial response to first-line immunotherapies were associated with mRS score improvements, as well as favorable mRS scores. mRS scores of 4-6 as the worst neurologic status predicted an unfavorable mRS score. There were no reported serious infusion-related or infectious adverse effects of rituximab. Conclusions: Rituximab is effective and safe as a second-line immunotherapy for ALE, regardless of autoantibody status. Additional monthly rituximab therapy might potentiate the efficacy of rituximab. Classification of evidence: This study provides Class IV evidence that rituximab improves mRS scores for patients with autoimmune limbic encephalitis who fail first-line therapy.