Histologic analysis of BM by confocal microscopy of mice treated with CD33-CAR-NK cells revealed the presence of CAR-NK cells in an intact, AML-free BM, while UTD-NK-treated or untreated mice displayed an altered, pitted BM structure together with high GFP-positive AML cell infiltration (Fig. 3G; Supplementary Fig. 3D). This evidence concerns the gene CD33 and acute myeloid leukemia.