Within a few years, the CAR field has progressed from reports of anecdotal responses in patients with non-Hodgkin lymphoma (NHL) or chronic lymphocytic leukemia (CLL) to achieving reproducible outcomes in hundreds of patients with B cell malignancies, most strikingly in B cell acute lymphoblastic leukemia (B-ALL), including patients with chemotherapy-refractory disease.48 Indeed, the antitumor activity of anti-CD19 CAR was first reported in a case of advanced follicular NHL, in which anti-CD19 CAR therapy resulted in dramatic regression. Here, CD19 is linked to acute lymphoblastic leukemia.