MECHANISMS OF TUMOR IMMUNE EV ASION AND STRATEGIES TO ENHANCE ANTITUMOR IMMUNITY

Abstract

Tumor immune evasion is a fundamental biological process that enables malignant cells to survive immune surveillance, establish progressive disease, and develop resistance to anticancer therapies. Although the immune system can recognize and eliminate transformed cells, tumor evolution selects cellular populations capable of avoiding immune recognition, suppressing effector responses, modifying the tumor microenvironment, and surviving immune -mediated cytotoxicity. Contemporary evidence indicates that immune escape is a multifactorial process involving impaired antigen presentation, loss or alteration of tumor -associated antigens, activation of immune checkpoint pathways, recruitment of immunosuppressive cell populations, secretion of inhibitory cytokines, metabolic competition, hypoxia, abnormal tumor vasculature, and genetic and epigenetic remodeling. Intratumoral heterogeneity further contributes to immune escape by enabling selection of resistant subclones and limiting the effectiveness of therapies directed against individual antigens or pathways. The development of immune checkpoint inhibitors, adoptive cellular therapies, cancer vaccines, bispecific antibodies, cytokine- based approaches, and strategies targeting the tumor microenvironment has substantially expanded the therapeutic potential of antitumor immunity. Nevertheless, primary and acquired resistance remains a major clinical challenge. Current approaches increasingly focus on combination strategies designed to simul taneously restore antigen presentation, improve immune -cell trafficking, overcome immunosuppression, reverse T -cell dysfunction, and increase tumor immunogenicity. A deeper understanding of the mechanisms underlying immune evasion is therefore essential fo r the development of personalized and durable immunotherapeutic approaches.