The Imbalance Between Tumor Immunosurveillance and Tumor Immune Escape in Glioblastoma.

Cancer immunosurveillance is the immune-mediated identification and elimination of malignant cells and is an essential mechanism to inhibit cancer growth. However, during cancer progression, tumors evolve various strategies to evade effective immune-mediated eradication, a process termed tumor immune escape. Glioblastoma (GBM) is the most common form of primary brain cancer and illustrates the delicate balance between immune escape and effective immunosurveillance, and the subsequent consequences upon acquiring various strategies of evasion. GBM exhibits several strategies that drive tumor immune escape, including downregulating antigen presentation, inhibiting immune cell function, and fostering immunosuppression. This is further amplified by the tumor-promoting effects of other tumor microenvironment constituents, such as neurons and astrocytes, and the immune system's dual role in tumor suppression and tumor persistence. Collectively, this facilitates immunologically unchecked outgrowth, manifesting as a highly aggressive, treatment-resistant disease with a universally lethal outcome for patients with GBM.