IDH-1R132H mutation status in diffuse glioma patients: implications for classification

Abstract

WHO₂₀₀₇ grading of diffuse gliomas in adults is well-established. However, IDH mutations make classification of gliomas according to the WHO₂₀₀₇ edition controversial. Here, we characterized IDH-1^{R132H mut} status in a cohort of 670 adult patients with different WHO₂₀₀₇ grades of diffuse glioma. Patient characteristics, clinical data and prognoses were obtained from medical records. Patients with IDH-1^{R132H mut} were younger and had better clinical outcomes than those without mutations. Differences in age among patients with astrocytomas of different WHO₂₀₀₇ grades were eliminated after patients were grouped based on IDH-1^R132H status. IDH-1^{R132H mut} was present more often in patients with lower Ki-67 and MGMT protein levels and higher mutant p53 levels. Ki-67 was also strongly associated with WHO₂₀₀₇ grade independently of IDH-1^{R132H mut} status. Moreover, patients with Ki-67<30 survived longer than those with Ki-67≥30, regardless of IDH-1^{R132H mut} status. Patients in the IDH-1^{R132H mut} group with lower MGMT protein levels also had better clinical outcomes than those in other groups. Our results indicate that to better treat gliomas, IDH mutation status should be included when determining WHO₂₀₀₇ grade in glioma patients.