Phase III Trial of VDJ001 In Patients With Idiopathic Multicentric Castleman Disease

INTERVENTION: Intervention Group:Intravenous infusion of VDJ001 at 6 mg/kg every 3 weeks (q3w), for 10–12 administrations.;Placebo group:Intravenous infusion of placebo every 3 weeks (q3w), for 10–12 administrations.; CONDITION: IMCD PRIMARY OUTCOME: The proportion of patients achieving complete response (CR) or partial response (PR), defined as sustained comprehensive remission for at least 18 weeks, encompassing symptomatic, biochemical, and nodal global responses.; SECONDARY OUTCOME: The proportion of patients who achieved CR and PR in comprehensive remission at weeks 12/18/30;Change from baseline in immunoglobulin G (IgG) at Weeks 12/18/30;Percentage of patients discontinuing corticosteroids at Weeks 12/18/30;Time to response;Duration of response;Change from baseline in VDJ‐MCD symptom score at Weeks 12/18/30; INCLUSION CRITERIA: 1. Age >=18 years, no gender restriction. 2. Measurable, symptomatic iMCD confirmed by biopsy or central pathology review (diagnosis based on the Chinese Guidelines for the Diagnosis and Treatment of Castleman Disease (2025 Edition), requiring at least one symptom from fatigue, anorexia, fever, or weight loss). 3. Clinical laboratory values within 4 weeks prior to first dosing meeting the following criteria, (1)Absolute neutrophil count (ANC) >= 1.0 × 10^9/L, (2)Platelet count (PLT) >= 75 × 10^9/L, (3)Alanine aminotransferase (ALT) < 2.5 × ULN, (4)Total bilirubin (TBIL) < 2.5 × ULN, (5)Serum creatinine (SCr) <= 3.0 mg/dL (265 µmol/L). 4. ECOG‐PS performance status score of 0, 1, or 2. 5. When corticosteroids such as prednisone are used, the dose should not exceed 1 mg/kg/ day (or an equivalent dose of other hormones, see Appendix), and the dose should remain stable for 4 weeks before the first administration. 6. Patients of reproductive