CDK4 and glioblastoma: For instance, temozolomide, a DNA methylation agent for adult GBM treatment, and PD-0332991, a CDK4/6 inhibitor were reported effective in murine brainstem models using adult GBM cell lines [60,61,71], however, clinical trials using TMZ and CDK4/6 inhibitor did not markedly extend survival for children with DIPG [72,73].