Researchers have discovered a key reason why chronic myeloid leukemia progresses from its more-treatable chronic phase to a life-threatening phase called blast crisis. The study indicates that CML progresses when immature white blood cells lose a molecule called miR-328 and this traps the cells in a rapidly growing, immature state. The research should provide a better understanding of the blast-crisis stage of CML, and it suggests a possible new treatment strategy for the disease.