IDH1 and glioma: Beyond that, locoregional delivery such as intraventricular (i.c.v.), intracavitary (i.c.), or intratumor (i.t.)immunotherapy application has to be investigated in the context of IDH-mutant low-grade glioma in the future, as it has been demonstrated in several human phase I HGG trials to be a potential alternative to overcome the natural barriers [86,87,88].