Cytokine release syndrome with novel therapeutics for acute lymphoblastic leukemia

T-cell-engaging immunotherapies are exciting new approaches to treat patients with acute lymphoblastic leukemia (ALL). These unique agents, which include blinatumomab, a CD3/CD19 bispecific antibody, and chimeric antigen receptor (CAR) modified T cells targeted to CD19 have shown unprecedented remission rates in the relapsed, refractory ALL setting. Cytokine release syndrome (CRS), resulting from the high magnitude of immune activation by these therapies, is the most significant treatment-related toxicity. CRS manifests with fever and malaise and can progress to life-threatening capillary leak with hypoxia and hypotension. The clinical signs of CRS correlate with T-cell activation and high levels of cytokines, including interleukin 6 (IL-6). Tocilizumab, an anti-IL-6 receptor antagonist, is usually effective in the management of severe CRS induced by CAR T cells and has been adopted by most clinical trial programs. With blinatumomab administration, the goal has been to prevent CRS with corticosteroid premedication, disease cytoreduction, and dose adjustments. Collaborative efforts are underway to harmonize the definition and grading system of CRS to allow for better interpretation of toxicities across trials and allow for informed management algorithms.