GDF15 and neoplasm: 54. TAAs can secrete TNF-α, TGF-β, IL-6, IGF-1, GDF-15, VEGF, FGF, HGF, and EGF to enhance the proliferation of GBM cells 11, 51. Moreover, TAAs might also participate in the adaptation of GBM cells to a hypoxic microenvironment through CCL20/CCR6 signaling, thus promoting angiogenesis and tumor cell invasion 11. In addition, astrocytes have been shown to be involved in resistance to radiotherapy or chemotherapy 55. Multiple factors, such as tenascin-C, IL-10, IFN-γ, IL-6, STAT-3, GDF-15 and PD-L1, secreted by TAAs protect GBM cells against anticancer immune reactions 51.