Cytokine release syndrome and neurotoxicity following CAR T-cell therapy for hematologic malignancies

Chimeric antigen receptor T cells are a new and exciting immunotherapeutic approach to managing cancer, with impressive efficacy but potentially life-threatening inflammatory toxicities such as cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). Patients with severe CRS may develop capillary leak syndrome and disseminated intravascular coagulation, with a cytokine signature similar to that of macrophage activation syndrome/hemophagocytic lymphohistiocytosis. Moderate-to-severe CRS is managed with the IL-6 receptor antagonist tocilizumab with or without corticosteroids, with questions remaining regarding the optimal management of nonresponders. ICANS is an inflammatory neurotoxicity typically occurring after CRS and characterized by impaired blood-brain barrier integrity. Symptoms of encephalopathy range from mild confusion and aphasia to somnolence, obtundation, and in some cases seizures and cerebral edema. ICANS is currently managed with corticosteroids; however, the optimal dose and duration remain to be determined. Little information is available to guide the management of patients with steroid-refractory ICANS. Numerous cytokine-targeted therapies have been proposed to manage these inflammatory toxicities, but few clinical data are available. Management of inflammatory toxicities of chimeric antigen receptor T cells often requires multidisciplinary management and intensive care, during which allergists and immunologists may encounter patients with these unique toxicities.