GZMB and cancer: Autophagy is a lysosomal degradation process in cells, which has been shown to be aberrantly upregulated in BC cells, especially BCSCs.[4] Of note, autophagy in cancer cells can degrade NK cell‐derived granzyme B (GZMB), consequently limiting NK cell effector function.[22] Consistently, in this study, we also found that the combination of SAHA and the autophagy inhibitor 3‐methyl adenine (3MA) performed much better in enhancing NK cell cytotoxicity to BCSCs than single exposure to SAHA or 3MA.