To explore the effectiveness and safety of bortezomib, cyclophosphamide and dexamethasone (BCD regimen) in newly diagnosed idiopathic Multicentric Castleman's disease (iMCD) patients.

This will be a single center, open-labeled, single arm, phase-II pilot study. The treatment and the response evaluation phase will last from the time of enrollment up to 21 months (evaluation will be carried out every 3 months in the first 9 months and every 6 months from Month 9 to Month 21). The maintenance and follow-up phase to assess for progression of disease will last from 21 months to 45 months after enrollment (evaluation will be carried out every 12 months). The total study duration will be 4 years after the last patient starts study medication.

Inclusion Criteria:

1. Demography: ≥18 years, all race/ethnic groups in China;
2. Newly diagnosed and previously untreated (patients are allowed to have received oral prednisone for up to 1 week before enrollment) symptomatic iMCD patients (symptomatic disease is defined by the presence of clinical symptoms with the NCI-CTCAE grading ≥1 that are attributable to the disease, and for which treatment is indicated; iMCD diagnosis is based on the international consensus diagnostic criteria);
3. Clinical laboratory values meeting these criteria at screening: absolute neutrophil count ≥ 1·0 x 109/L, Platelets ≥ 50 x 109/L, Alanine aminotransferase (ALT) within 2·5 x upper limit of normal (ULN); total bilirubin within 2·5 x ULN; estimated glomerular filtration rate (according to MDRD formula) <15ml/min;
4. Women of childbearing potential must agree to use birth control measures during the study and for at least 3 months after receiving the last dose of study agent, and must have a negative pregnancy test at screening period. Men must agree to use birth control measures during the study and for at least 3 months after receiving the last dose of study agent;
5. Informed consent must be signed.

Exclusion Criteria:

1. age under 18 years;
2. Immunosuppressive or anti-neoplastic drugs within the last 3 months;
3. serious diseases including malignancy;
4. Plan to have babies within 1 year after enrollment (for women and men), or pregnancy / breast-feeding (for women);
5. Known hypersensitivity to study agents;
6. Active infection requiring systemic treatment;
7. Other severe concurrent disease (eg. uncontrolled diabetes, symptomatic coronary heart disease) that is likely to interfere with study procedures or results, or that in the opinion of the investigator would constitute a hazard for participating in this study;
8. Unwilling or unable to provide informed consent;
9. Unwilling to return for follow-up at PUMCH.