Emerging hallmark of gliomas microenvironment in evading immunity: a basic concept

Background: Over the last decade, since clinical trials examining targeted therapeutics for gliomas have failed to demonstrate a meaningful increase in survival, the emphasis has recently been switched toward innovative techniques for modulating the immune response against tumors and their microenvironments (TME). Cancerous cells have eleven hallmarks which make it distinct from normal ones, among which is immune evasion. Immune evasion in glioblastoma helps it evade various treatment modalities. Summary: Glioblastoma’s TME is composed of various array of cellular actors, ranging from peripherally derived immune cells to a variety of organ-resident specialized cell types. For example, the blood–brain barrier (BBB) serves as a selective barrier between the systemic circulation and the brain, which effectively separates it from other tissues. It is capable of blocking around 98% of molecules that transport different medications to the target tumor. Objectives: The purpose of this paper is to offer a concise overview of fundamental immunology and how ‘clever’ gliomas avoid the immune system despite the discovery of immunotherapy for glioma. Conclusions: Herein, we highlight the complex interplay of the tumor, the TME, and the nearby normal structures makes it difficult to grasp how to approach the tumor itself. Numerous researchers have found that the brain TME is a critical regulator of glioma growth and treatment efficacy.