Genetically Modified Haploidentical Natural Killer Cell Infusions for B-Lineage Acute Lymphoblastic Leukemia

NK cell cytotoxicity is most powerful against acute myeloid leukemia (AML) cells, whereas their capacity to lyse ALL cells is generally low and difficult to predict. A novel method has been developed to redirect NK cells towards CD19, a molecule highly expressed on the surface of B-lineage ALL cells, but not expressed on normal cells other than B-lymphocytes. In this method, donor NK cells are first expanded by co-culture with irradiated K562 cell line modified to express membrane bound IL-15 and 41BB ligand (K562-mb15-41BBL). Overexpansion of these proteins promotes selective growth of NK cells. Then, the expanded NK cells are transduced with a signaling receptor that binds to CD19 (anti-CD19-BB-zeta). NK cells expressing these receptors showed powerful anti-leukemic activity against CD19+ ALL cells in vitro and in an animal model of leukemia. This study represents the translation of laboratory findings into clinical application. It will allow us to assess the safety of infusing genetically modified NK cells into research participants who have chemotherapy refractory or relapse B-lineage ALL. In this same cohort, we also intend to study the in vivo lifespan and phenotype of genetically modified NK cells and explore the efficacy of NK cells in patients with B-lineage ALL.