In ongoing trials of CAR-modified T cell therapy for patients with hematological malignancies, some patients with B cell acute lymphoblastic leukemia (B-ALL) who received modified T cells with a different construct (19-28z, which targets the CD19 antigen found on B cells) developed severe cytokine release syndrome (sCRS), which is characterized by persistent fever, elevation of serum cytokines, and clinical toxicities [28]. This evidence concerns the gene CD19 and acute lymphoblastic leukemia.