The short-term in vivo IRT treatment study with ONC206 in combination with RT and TMZ achieves similar anti-tumor effects as evaluated by assessment of markers of cell proliferation (Ki67) and apoptosis (cleaved caspase 3) in tumor specimens collected two weeks after the start of treatment in the orthotopic U251 GBM model in vivo. Here, MKI67 is linked to glioblastoma.