Cancer initiating / stem cells (CSCs) represent a minority of the tumor cell population and are difficult to eradicate through conventional cancer therapeutic treatments. The ability to destroy CSCs by priming immune intervention represents a novel approach in personalized medicine. Similar to other stem cells, these cells possess self-renewing and differentiation potential. They are characterized by their ability to form tumorspheres in suspension cultures. As part of the PRIME-XV brand of validated cell therapy media, Irvine Scientific provides a serum-free medium designed for maximal enrichment of CSCs from solid tumors.