Malignant gliomas are the most common subtype of primary brain tumor – and one of the deadliest. Even as doctors make steady progress treating other types of solid tumor cancers, from breast to prostate, the most aggressive form of malignant glioma, called a glioblastoma multiforme or GBM, has steadfastly defied advances in neurosurgery, radiation therapy and various conventional or novel drugs. But scientists have discovered a new signaling pathway between GBM cells – one that, if ultimately blocked or disrupted, could significantly slow or reduce tumor growth and malignancy.