Effect of Telitacicept on Antibody Titers in Primary APS Patients

Inclusion Criteria: * Age ≥18 years; * Diagnosis of primary APS, meet 2006 Sydney classification criteria or continuously positive for antiphospholipid antibodies within the first 12 months of inclusion (tested at least every 12 weeks), classified as high-risk antiphospholipid antibody spectrum based on the risk of antibody levels, in order to meet at least one of the following conditions: 1. Positive lupus anticoagulant (LAC) (tested according to ISTH guidelines); 2. Two or three types of aPL positivity (lupus anticoagulant, anticardiolipin antibody, and anti-β2 any two or all three types of glycoprotein I antibodies; 3. Or persistent high titer aPL; * There are no other autoimmune diseases occurring simultaneously; * According to EULAR recommendations for antiphospholipid syndrome, a stable APS treatment regimen should be adopted; * Female patients who are not pregnant, breastfeeding, have no fertility potential, or have not undergone contraception. Exclusion Criteria: * Patients with a history of malignant tumor in the past 5 years, except for basal cell carcinoma or squamous cell carcinoma of skin or cervical carcinoma in situ treated locally, and there is no evidence of metastasis within 3 years; * Patients with a history of primary immunodeficiency; * Serious lack of IgG (IgG level \< 400 mg/dL); * IgA deficiency (IgA level \< 10 mg/dL); * Patients with a current history of infection; * Patients with a current history of drug or alcohol abuse or dependence, or …