In clinical studies, promising results have been achieved so that the regulatory authorities U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA) approved two second-generation CD19-directed CAR-T cell products in 2018, i.e., axicabtagene ciloleucel (Yescarta®, Kite/Gilead) for the treatment of adult diffuse large B cell lymphoma (DLBCL), transformed follicular lymphoma (tFL) and primary mediastinal B cell lymphoma (PMBCL) as well as tisagenlecleucel (Kymriah®, Novartis) for the treatment of pediatric and adolescent acute lymphoblastic leukemia (ALL) and adult DLBCL. This evidence concerns the gene CD19 and acute lymphoblastic leukemia.