The Safety and Efficacy of S103 in the Treatment of Refractory Generalized Myasthenia Gravis

Inclusion Criteria: 1. Age ≥18 years, ≤80 years; 2. MGFA classification type IIa-IVa; 3. Voluntary participation in the study: understanding and awareness of the study and voluntary signing of the informed consent form; 4. Meeting the diagnosis of myasthenia gravis; 5. Assessed by the investigator as meeting the diagnostic criteria for refractory MG: fulfilling one of the following 4 conditions: 1. After adequate dose and duration of at least 2 conventional immunotherapies (including steroid and non-steroid immunosuppressants), the post-intervention status (PIS) is unchanged or worsened. 2. After adequate dose and duration of at least 2 conventional immunotherapies, the PIS is improved, but the MG-ADL score remains * 6 for at least 6 months. 3. After adequate dose and duration of at least 2 conventional immunotherapies, the PIS is remission or improvement, but during regular tapering of immunotherapy, there are still ≥2 exacerbations per year (MG-ADL score ≥6). 4. The investigator considers that, despite current conventional immunotherapy, MG still imposes a significant functional burden on the patient. 6. MG-ADL score ≥6 or QMG score ≥11 at screening and baseline, with ocular muscle score less than 50% of the total score. Exclusion Criteria: 1. Any medical or psychiatric condition that the investigator deems may endanger the study participant or affect their ability to participate in the study; or any condition the investigator considers associated with poor compliance; 2. Females who are breastfeeding or pregnant, or plan to become pregnant at any time during the 12-month period after receiving CAR-T therapy, or have a history of spontaneous or induced abortion within 4 weeks prior to screening; 3. Study participants with clinically relevant active infections (e.g., sepsis, pneumonia, or abscess) or severe infections (requiring hospitalization or antibiotic treatment) within 4 weeks prior to screening; 4. Thymectomy within 6 months prior to baseline or planned thymectomy during the study period, or thymoma requiring chemotherapy and/or radiotherapy at any time; 5. Study participants who received live attenuated vaccines within 8 weeks prior to screening; or plan to receive live vaccines within 8 weeks after treatment; 6. Study participants who received prior rituximab treatment within 6 months before screening; 7. Treatment with tocilizumab, eculizumab, or efgartigimod within 3 months prior to screening; 8. Intravenous immunoglobulin, plasma exchange, or immunotherapy within 4 weeks prior to screening; 9. Known severe underlying diseases, such as liver or kidney dysfunction, hematologic disorders, prior severe cardiovascular diseases, severe hypertension, diabetes, or poorly controlled blood pressure or blood glucose; 10. Unresected thymoma; 11. Rapid symptom deterioration during the lead-in period, progressing to crisis or pre-crisis state (MGFA IVb-V); 12. Other conditions deemed by the investigator as unsuitable for study participation.