 Precursor-B acute lymphoblastic leukemia ALL is the most common cancer in childhood. Despite major advances in ALL therapy, 20 of children and 40-50 of adults fail state-of-the art first-line treatment. But there is a strong need for alternative treatments to cure chemotherapy-refractory and relapsed B cell malignancies in pediatric patients. Relapsed and refractory B cell malignancies remain a therapeutic challenge, as these diseases are characterized by adverse survival. These cancers share a cell origin from the B-cell lineage and consequent surface expression of B-lineage markers such as CD19 and CD22. Chimeric antigen receptor CAR engineered T cell therapy has recently emerged as a new modality to target B cell malignancies. CARs couple a single-chain Fv scFv domain directed against a B-lineage-specific antigen to T-cell activating intracellular signaling domains. CAR gene-modified T cell interaction with target cells occurs in a HLA-independent fashion, so that a single vector can be used to treat all patients with cancers that express the target antigen. Miltenyi Biotec has established a semi-automated manufacturing process that can be made available to academic settings for systematic exploration of CAR strategies in advanced clinical studies. Closed-system operation, improved robustness, simplified work flows, and reduced labor intensity, while maintaining strict adherence to regulatory guidelines, allows for decentralized manufacturing. In the proposed phase II study, the investigator will explore autologous 2nd generation CD19 CAR T cell products in patients with relapsed and refractory disease incurable with standard therapies. 