IDH2 and glioblastoma: Together with a few prior case reports of POLE mutant and mismatch repair deficient IDH-wildtype glioblastomas with favorable clinical course and response to immune checkpoint blockade [7, 20, 24], our patient cohort further suggests that de novo RRD glioblastomas may have better clinical outcomes than conventional glioblastoma overall and potentially benefit from immune checkpoint blockade.