Glioblastoma is a highly malignant and almost always fatal brain cancer. Neuro-oncologist Justin Lathia of the Cleveland Clinic shares his knowledge and research discoveries on what makes glioblastomas so nasty. The cancer cells within the tumor vary greatly in their genetic abnormalities and sensitivities to chemotherapy and radiation Particularly resistant to treatment are glioblastoma stem cells. These cancer cells interact with other cells in the brain in ways that enable them to flourish and to evade the immune system. Knowledge of these mechanisms is providing new avenues for developing effective treatments.