This correlated with the generally lower proliferation index of IDHm xenografts (e.g., MIB index based on Ki67 staining was 21.8 ± 3% for E478 and 54.7 ± 2% for P3 PDX) and the slower tumor development in mice (Table 1), which is also in agreement with the better prognosis of IDHm glioma patients observed in the clinic. Here, MKI67 is linked to glioma.