Inclusion Criteria:
1. Age 18-65 years (inclusive), any gender.
2. Subjects diagnosed with the following autoimmune disease: moderate/severe refractory Systemic Lupus Erythematosus, elapsed/refractory Systemic Sclerosis, relapsed/refractory ANCA-Associated Vasculitis, refractory Idiopathic Inflammatory Myopathy, active Sjögren's Syndrome, chronic/refractory Immune Thrombocytopenia, refractory Antiphospholipid Syndrome, relapsed/refractory pemphigus, relapsed/refractory IgG4-Related Disease.
3. Having adequate organ function as required by the protocol.:
4. Voluntarily adhere to the contraception requirements as specified in the protocol.
5. Willing to comply with all study procedures and voluntarily participate in this study and sign the informed consent form (ICF).
Exclusion Criteria:
1. Previous or current active malignancy, including patients with cancer-associated polymyositis/dermatomyositis. Exceptions are cured or relapse-free for at least 3 years: cervical carcinoma in situ, non-invasive basal cell or squamous cell skin cancer, locally advanced prostate cancer after radical treatment, or ductal carcinoma in situ after radical surgery.
2. Severe pulmonary disease within the past 1 year, such as moderate/severe pulmonary arterial hypertension (pulmonary artery systolic pressure \>50 mmHg on echocardiography), requirement for oxygen therapy via reservoir mask or non-invasive/invasive ventilator support at screening.
3. Use of any of the protocol specified drugs or treatments within the specified timeframes.
4. History or current symptoms of severe central nervous system (CNS) disease within the past 6 months.
5. Known severe allergy to the study drug or any of its components.
6. Presence of uncontrolled fungal, bacterial, or viral infection, or other infections considered by the investigator to make the subject unsuitable for participation.
7. History of major organ transplant or hematopoietic stem cell/bone marrow transplantation.
8. History of other autoimmune diseases requiring systemic treatment, other than the target indication.
9. History of non-IIM conditions such as drug induced myopathy, HIV associated myopathy, thyroid myopathy, or family history of myopathy.
10. Pregnant or breastfeeding women.
11. Use of any live vaccines within 6 weeks before enrollment.
12. Participation in another interventional clinical study and receipt of an active investigational drug within 3 months prior to signing the ICF, or intention to participate in another clinical trial or receive treatment for autoimmune diseases outside the protocol during the entire study period.
13. Psychiatric disorders with depression or suicidal tendencies.
14. Any other factors considered by the investigator to make the subject unsuitable for enrollment or to affect the subject's participation or completion of the study.
