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. The gene discussed is IDH1; the disease is central nervous system cancer.