A chimeric, human-murine, monoclonal antibody targeting the pro-inflammatory cytokine interleukin 6 (IL-6), with antitumor and anti-inflammatory activities. Upon intravenous administration of siltuximab, this agent targets and binds to IL-6. This inhibits the binding of IL-6 to the IL-6 receptor (IL-6R), which results in the blockade of the IL-6/IL-6R-mediated signal transduction pathway. This inhibits cancer cell growth in tumors overexpressing IL-6. or A drug used to treat a rare condition called Castleman disease in patients who do not have HIV or human herpesvirus 8. It is also being studied in the treatment of multiple myeloma. Siltuximab binds to a protein called interleukin-6 (IL-6), which is made by some white blood cells and other cells in the body. Siltuximab may help reduce inflammation and stop the growth of cancer cells or abnormal blood cells. It is a type of monoclonal antibody. Also called anti-IL-6 chimeric monoclonal antibody, cCLB8, CNTO 328, and Sylvant.