Killing time for cancer stem cells (CSC): discovery and development of selective CSC inhibitors.

Can cancer be cured or will it have to be controlled as a chronic disease? Despite a better understanding of the biology of tumour cells, the treatment of most cancers has not significantly changed for the past three decades. Are current cancer drugs targeted at the wrong kind of cells? Accumulating evidence has implicated that cancer is a disease of stem cells. In this context, a small fraction of cancer cells adopt the properties of stem cells. In some cases, the cancer stem cells (CSC) could be the close derivative of normal tissue stem cells. In either situation, the net result will be the same, in that CSC are the cells to be used as targets in the development of molecular and pharmaceutical therapies to treat and prevent human cancer. This could be a paradigm shift in the treatment of cancer, away from targeting the blast cells and towards the targeting of the CSC. A challenge to this approach will be to find a way to specifically target CSC without toxicity to normal cells. In this article, we propose how CSC can be used in therapy programs (target identification, drug discovery, etc.). Therefore, in the future, it might be possible to rid a patient of all his/her cancer cells, including the cancer stem cells.