The purpose of this study is to evaluate the efficacy and safety of Telitacicept in the treatment of patients with generalized myasthenia gravis.

This study consists of a screening period, a double-blind treatment period (part A) and an open-label treatment period (part B). After screening, eligible subjects will be randomized in a 1: 1 ratio to receive either subcutaneous Telitacicept 240 mg or placebo once a week for 24 doses (part A). Completing part A, subjects will automatically enter part B. In part B, all subjects will receive weekly subcutaneous Telitacicept 240 mg for 24 weeks.

Inclusion Criteria:

1. Written informed consent provided;
2. Male or female patients aged 18-80 years;
3. Diagnosis with generalized myasthenia gravis;
4. MGFA Class II, III, or IVa;
5. AChR-Ab or MuSK-Ab positive;
6. A total MG-ADL score of ≥ 6 with less than 50% of the total score due to ocular symptoms;
7. QMG ≥ 8, with ≥ 4 items score at least 2;
8. Have been on a stable MG SoC regimen.

Exclusion Criteria:

1. Patients with autoimmune diseases other than MG;
2. Abnormal laboratory results；
3. Use of immunosuppressants other than standard therapy within 1 month before randomization;
4. Use of biologic agents targeting therapy, such as Rituximab or complement C5 inhibitors, within 6 months before randomization;
5. Use of neonatal Fc receptor (FcRn) antagonists, intravenous immunoglobulin (IVIg), or plasmapheresis within 2 months before randomization;
6. Significant cardiovascular disease, liver, kidney, respiratory, endocrine or hematologic disease, or other medical conditions that, in the opinion of the investigator, would preclude the subject's participation in the study or require hospitalization during the study;
7. Acute or chronic infection requiring treatment;
8. Current active hepatitis;
9. HIV antibody positive;
10. Patients currently suffering from thymoma-associated immunodeficiency syndrome (Good's syndrome) or who underwent thymectomy within 6 months before screening;
11. Received or plan to receive any live vaccine within 3 months prior to randomization;
12. Patients with malignant tumors;
13. Allergy to biological products of human origin;
14. Participation in any clinical trial 28 days prior to randomization or within 5 times the half-life of an investigational drug (whichever is longer);
15. Pregnant or lactating women, and those intending to become pregnant during the trial;
16. Patients considered unsuitable by the investigator to participate in the trial (e.g., patients with severe mental disorders);

Note: Other protocol defined Inclusion/Exclusion criteria may apply.