Several clinical studies have reported dramatic response rates in relapsed or refractory (r/r) hematological malignancies, showcasing the unparalleled therapeutic potential of anti-CD19-CAR T cells to treat diseases such as acute lymphoblastic leukemia (ALL) [14], diffuse large B cell lymphoma (DLBCL) [15] and, to a lesser extent, chronic lymphocytic leukemia (CLL) [16]. The gene discussed is CD19; the disease is B-cell chronic lymphocytic leukemia.