Lymphodepletion chemotherapy followed by infusion of T cells that are genetically modified to express a chimeric antigen receptor (CAR) targeted to CD19 is a novel therapy for patients with relapsed and/or refractory B cell acute lymphoblastic leukemia, non-Hodgkin lymphoma, and chronic lymphocytic leukemia. Using data from a large phase I/II clinical trial of CD19 CAR-T cell immunotherapy (NCT01865617) we will discuss factors associated with outcomes of CAR-T cell therapy in adult B cell malignancies. The impact of lymphodepletion chemotherapy on CAR-T cell engraftment and immune rejection, mechanisms of failure of CAR-T cell immunotherapy, and ex vivo leukapheresis T cell and manufactured product characteristics associated with outcomes will be presented.