Siltuximab for Cytokine Release Syndrome Prophylaxis Prior to tx w/ Teclistamab in RRMM

The purpose of this study is to examine the safety, efficacy and feasibility of the use of one standard dose of siltuximab prior to teclistamab infusion. Siltuximab is an investigational (experimental) drug that works by binding directly to human interleukin-6 (IL-6). IL-6 is a cytokine; these are products that are secreted by certain cells of the immune system and effect other cells in participant's body. IL-6 regulates immune, inflammatory and metabolic processes. Siltuximab has already been tested and approved for use by the FDA in participants with a condition called multicentric Castleman's disease, which is a lymphoproliferative disorder. This study is being conducted to investigate if administration of a single dose of siltuximab will reduce the rates of and severity of Cytokine Release Syndrome (CRS) and Immune effector Cell-Associated Neurotoxicity Syndrome (ICANS) in participants prior to teclistamab administration. CRS and ICANS are adverse effects commonly experienced by participants being treated with teclistamab that are related to inflammation in the body. Siltuximab is experimental because it is not approved by the Food and Drug Administration (FDA) for prophylactic use prior to administration of teclistamab infusion.