Notably, one patient with isocitrate dehydrogenase (IDH)-mutant GBM experienced a greater than 16-month survival, and CD4+ T cell count positively correlated with survival; however, according to the 2021 WHO classification of central nervous system tumors, the presence of an IDH mutation is not in line with the current definition of GBM. This evidence concerns the gene IDH1 and glioblastoma.