Hydroxytyrosol is potent against CSC phenotypes. Mechanisms: -Blocks EMT, reducing transition into CSC-like states -Inhibits Notch signaling -Reduces CD44+ / CD24– CSC markers -Inhibits hypoxia-driven stemness (HIF-1α suppression) Hydroxytyrosol is especially active in: -Breast CSCs -Melanoma CSC-like cells -Gastric CSC models