Even though CX3CR1+ CD8+ T cells might not be specific to GBM, as they are found in healthy donor and different inflammation related conditions (Böttcher et al., 2015; Gerlach et al., 2016; Yamauchi et al., 2021; Yan et al., 2018), the absence of these effector and potentially ICI therapy responsive CD8+ T cells in the glioma TME could serve as an additional explanation for the disappointing outcome of clinical trials using ICI in glioma patients. This evidence concerns the gene CX3CR1 and central nervous system cancer.