Efficacy and Safety of Taitacept in Treatment of Refractory or Recurrent Anti-NMDAR/anti-LGI1 Encephalitis

Inclusion Criteria: 1. Age ≥14 years old, male or female; 2. Symptoms of autoimmune encephalitis (AE) ≤ 9 months prior to enrollment; 3. Diagnosed as autoimmune encephalitis, diagnostic criteria as follows: 1. Rapid onset (\<3 months) of at least four of the following six major symptoms: * Abnormal (mental) behavior or cognitive dysfunction * Speech dysfunction (verbal urgency, hypospeech, mutism) * Seizures * Movement disorders, dyskinesias, or postural rigidity/abnormalities * Decreased level of consciousness * Autonomic dysfunction or central hypoventilation in the presence of one or more of the six major symptoms; 2. Positive anti-NMDAR (GluN1) IgG antibody detected in CSF or positive serum and/or cerebrospinal fluid LGI1 antibody; c．Reasonable exclusion of other etiologies and other well-defined encephalitis syndromes (e.g., Bickerstaff brainstem encephalitis, acute disseminated encephalomyelitis, Hashimoto encephalopathy, primary CNS vasculitis, Rasmussen encephalitis); 4. Refractory AE: ineffective treatment with steroids and rituximab or other immunosuppressants, post-treatment mRS score≥2 (stable for at least 24 hours）;Recurrent AE: at least 2 months after 1st or 2nd line treatment, new symptoms or worsening of existing symptoms (mRS increase\>1); 5）Doses of steroids and other immunosuppressants (e.g. azathioprine, mycophenolate mofetil, cyclophosphamide) should be stabilised for 4 weeks prior to enrolment; 6）Ability to obtain patient or proxy consent; 7）Women of childbearing potential should use effective contraception during treatment or avoid heterosexual intercourse for at least 3 months after the last dose of talitacicept; Exclusion Criteria: 1. History of other autoimmunity such as SLE, RA, SS. Patients with hyperthyroidism and hypothyroidism cannot be excluded; 2. Abnormal laboratory indicators, including but not limited to the following indicators: White blood cell count\<3×10\^9 /L Neutrophil count\<1.5×10\^9 /L Hemoglobin\<85g/L Blood platelet count\<80×10\^9 /L Serum creatinine\>1.5×ULN TBil(total bilirubin) \>1.5×ULN ALT\>3× ULN AST\>3× ULN Alkaline phosphatase\>2× ULN Creatine kinase\>5× ULN 3. Evidence of active infection such as shingles, HIV or active tuberculosis, etc. 4. Currently have active hepatitis or have severe liver disease and a history of it. * Patiens with abnormal Hepatitis B test as follows should be excluded: HbsAg positive; HbsAg negative but HbcAb positive, and HBV-DNA positive. Whereas patients with HbsAg negative but HbcAb positive, and HBV-DNA negative can be included. * Exclude patients who are positive for hepatitis C antibodies ; 5. Uncontrolled diabetes mellitus: Glycosylated hemoglobin\>9.0% or fasting blood glucose≥11.1mmol/L; 6. Received any live vaccine within 3 months prior to enrollment or planned to receive any vaccine during the study; 7. Received rituximab or other biological therapies within 1 month prior to enrollment; 8. Malignancy; 9. Allergic to human biological products; 10. Participated in any clinical trial within 28 days prior to enrollment or within 5 times the half-life of the investigational drug participating in the clinical trial 11. Patients who plan to have children during the trial, or who are pregnant or breastfeeding; 12. Alcohol or drug abuse/addiction is known to have an impact on compliance with trial requirements; 13. Patients who are deemed unsuitable for the trial by the investigator (e.g., those with severe mental disorders).