TP53 and diffuse midline glioma: To do so, we tested whether the brain-penetrant ATM inhibitor AZD1390 (18), combined with focal brain irradiation, could similarly improve the survival of a patient-derived xenograft model of the H3.3K27M-mutant and p53-mutant diffuse midline glioma SF8628 (29–32), which lacks a functional ATM mutation (Supplemental Figure 10 and Supplemental Table 6).