October 12, 2021
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Early rituximab therapy effective for autoimmune encephalitis

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Early and short-term rituximab may be an option to treat patients with certain forms of autoimmune encephalitis, according to study results published in Neurology: Neuroimmunology & Neuroinflammation.

“Rituximab is a B cell-depleting monoclonal [antibody] directed against CD20 with established efficacy in many neurologic autoimmune diseases, including MS, and neuromyelitis optica spectrum disorders,” Franziska S. Thaler, MD, of the Institute of Clinical Neuroimmunology, Ludwig-Maximilians-Universität, Munich, Germany, and colleagues wrote. “Rituximab was shown to be effective in [autoimmune encephalitis] associated with different auto-[antibodies].”

However, rituximab did not show efficacy among patients with stiff-person syndrome in a randomized placebo-controlled trial. Thaler and colleagues highlighted the lack of detailed and comparative assessments of rituximab use and the long-term outcome between subtypes of autoimmune encephalitis in a real-world setting.

The current retrospective study included patients in the German Network for Research on Autoimmune Encephalitis who had received at least one dose of rituximab and a control cohort that did not receive rituximab. Forms of autoimmune encephalitis included NMDA receptor (NMDAR), leucine-rich glioma-inactivated-1 (LGI1), contactin-associated protein-like-2 (CASPR2) and glutamic acid decarboxylase 65 (GAD65). On hundred sixty-three patients received rituximab.

Rituximab was initiated significantly earlier among those with NMDAR and LGI1 autoimmune encephalitis, at a median of 54 days and 155 days from disease onset, respectively, compared with CASPR2 autoimmune encephalitis and GAD65 disease, which had initiation at a median of 632 days and 1,209 days from disease onset, respectively.

Patients with NMDAR autoimmune encephalitis who were or were not treated with rituximab had significant improvements in modified Rankin Scale (mRS) scores. Patients with NMDAR autoimmune encephalitis who were treated with rituximab were more severely affected at baseline but more often reached independent living. Rituximab-treated and nontreated patients with LGI1 autoimmune encephalitis improved; however, only rituximab-treated patients with CASPR2 autoimmune encephalitis improved significantly. The researchers observed no improvement in patients with GAD65 disease. Further, they noted rituximab-treated patients had a significant reduction in relapse rate.

There was a significant association between detection of NMDAR antibodies and mRS score improvement. Early treatment initiation also correlated with a favorable outcome.

“Our results support the efficacy of early rituximab treatment in NMDAR, LGI1 and CASPR2 [autoimmune encephalitis] and suggest that short-term therapy could be a treatment option,” the researchers wrote. “They also suggest that patients with long-standing GAD65 disease are less likely to benefit from B-cell depletion than the other [autoimmune encephalitis] subgroups. Nevertheless, future controlled, randomized and prospective studies in addition to national and supranational registries with collaborative research efforts are in dire need in the field of [autoimmune encephalitis].”