Besides the BBB, which prevents drugs from reaching their target sites, these mechanisms include various immune-suppressive mechanisms, such as secretion of immunosuppressive cytokines (IL-10, TGF-β, and IL-6)[104,105], expression of immune checkpoints[106], and recruitment of regulatory T cells (Tregs)[107], induction of M2-like phenotype of tumor-associated MΦ and microglia[106], reduced tumor antigen presentation through downregulation of MHC expression, and the ability to evade immune through soluble ligands[108,109] [Figure 2]. Here, IL6 is linked to neoplasm.