Tumor microenvironment and immunotherapy: from bench to bedside.

The tumor microenvironment (TME) is a multifaceted and ever-changing assemblage of cells and extracellular constituents. These components are closely linked to the onset and progression of malignancies, as well as their treatment. The TME is characterized by aberrant vasculature, altered extracellular matrix, immune cells, secreted factors, and cancer-associated fibroblasts and macrophages. The importance of the tumor microenvironment (TME) in understanding the course of cancer and resistance to treatment has been highlighted. The TME can suppress immune responses and promote tumor survival by inducing immunosuppressive mechanisms, such as regulatory T cells, myeloid-derived suppressor cells (MDSCs), and checkpoint molecule expression (e.g., PD-L1). Recent research has focused on understanding the interactions between immune cells within the TME to develop strategies that can remodel this environment and increase the effectiveness of immunotherapy. However, the efficacy of immunotherapeutic strategies is frequently hindered by the immunosuppressive nature of the TME. This abstract explores how these dynamics have led to the development of novel immunotherapeutic strategies aimed at reprogramming the TME to enhance antitumor immune responses. Novel approaches targeting TME therapy, such as immune checkpoint blockade (ICB), metabolic inhibitors, and key enzymes of immune metabolism, have been used to treat of cancer immunotherapy. Additionally, new and promising treatments including CAR-T cell therapy, oncolytic viruses, and cytokine-mediated TME modulation have shown promising results. This review provides a general overview of the TME, its components, its impact on immunotherapy outcomes, and emerging approaches to enhance therapeutic efficacy by remodeling the TME.