Siltuximab for Chimeric Antigen Receptor T-Cell Therapy Related CRS and ICANS - A Multicenter Retrospective Analysis

• In this retrospective analysis, siltuximab effectively treated CRS and ICANS with an objective response rate of 75% and 60%, respectively.

• Siltuximab was effective in CRS patients previously exposed to tocilizumab with an objective response rate of 63%.

Chimeric Antigen Receptor T-Cell therapies (CAR-T) are effective in many hematologic malignancies; however, adverse events including cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) can affect a significant number of patients. Those who develop refractory CRS or ICANS have few treatment options. Siltuximab, a monoclonal antibody binding circulating IL-6, has been proposed to have clinical activity in both CRS and ICANS. We conducted a multi-center retrospective analysis of siltuximab treatment for CRS and ICANS following CAR-T cell therapy in a real-world cohort from six academic centers. Fifty-four patients were evaluated. Sixteen patients had CRS previously treated with tocilizumab and 17 patients had ICANS previously treated with steroids. Of the all the patients with CRS at the time of siltuximab, 75% had improvement in CRS grade. Of the all the patients with ICANS at the time of siltuximab, 60% had improvement in ICANS grade. To our knowledge, this is the largest cohort of patients treated with siltuximab for CRS and/or ICANS following CAR-T. Siltuximab appeared to be effective for both CRS and ICANS, including previously treated toxicities. These data support the use of siltuximab in CRS and ICANS as well as provide rationale for future prospective studies.