IDH1 and glioblastoma: In addition to IDH1 wild‐type proneural patients, IGS‐18 patients (as defined by Gravendeel) also benefited from BEV treatment.26 A retrospective study of the BELOB trial using gene expression profiling and RNA‐seq found that combined BEV and lomustine (CCNU) treatment significantly improved the PFS (the median PFS was 1.4, 2.9 and 4.2 months in the CCNU, BEV and BEV/CCNU arms, respectively, P = 0.0004) and improved the OS (the mOS was 7.9, 8.3 and 11.9 months in the CCNU, BEV and BEV/CCNU arms, respectively, P = 0.09) of IGS‐18 (ie, classical GBM) patients.