In the field of CAR-cell-based therapies, recent preclinical and clinical studies have shown that primary NK cells can be genetically modified to express a CAR in a feeder-free condition [22] and that CAR-NK cells are safe and potentially very effective against r/r CD19-positive cancers (including non-Hodgkin’s lymphoma and chronic lymphocytic leukaemia) [25]. Here, CD19 is linked to cancer.