For example, regulatory T cells, myeloid-derived suppressor cells, and tumor-associated macrophages have been found to constitute up to 30% of glioblastoma tumor mass.19 Indeed, O’Rourke et al. also showed that there was “recruitment of IL-10–secreting, FoxP3-expressing regulatory T cells.”12 Overall, this shows that current CAR-T therapy is limited by the multiple resistance mechanisms that may be raised in response to 1 arm of treatment. This evidence concerns the gene FOXP3 and glioblastoma.