Studies describing tumor as a hierarchically-organized cell population have changed the classical oncogenesis view and proposes new therapeutic strategies. Cancer stem cells (CSC) are thought to sustain tumor initiation/maintenance, therapy resistance, and systemic metastases. Targeting this tumor cell population is crucial to achieve a true cure. A large research effort is now aiming atdeveloping drugs targeting CSCs based either on a priori understanding of key pathways regulating CSC biology or high-throughput screening to identify novel targets and compounds.