A promising stem cell-based immunotherapy against melanomas has been fast-tracked by the U.S. Food and Drug Administration (FDA), based on previous clinical trials showing that it may double 5-year survival rates to about 50%. The upcoming phase III clinical trial will accept 250 people with melanomas that have spread; enrollment is expected to begin in early 2014. This experimental immunotherapy uses a mixture of a person’s own cells: cancer stem cells from his or her tumor, which are thought to be behind the spread of tumors, and immune system cells from the blood, which learn to recognize the cancer stem cells. These cancer stem cells are inactivated to keep them from forming new tumors, then the mixture is injected back into the patient. The reintroduced immune system cells then focus an attack on the cancer stem cells that remain in the tumor, which helps keep them from spreading.