Grundlagen der Tumorimmunologie und T-Zell-Erkennung [Principles of tumor immunology and T-cell recognition]

Progress in tumor immunology has significantly advanced our understanding of cancer. Tumors are no longer regarded merely as collections of genetically altered cells, but rather as dynamic tissues that closely interact with the immune system. This perspective received little attention for a long time, as cancer usually becomes clinically apparent only when mechanisms of immune control fail. T cells play a central role in the recognition and elimination of malignant cells and are therefore becoming increasingly important as therapeutic agents. A prerequisite is that tumor antigens are processed and presented by major histocompatibility complex molecules. In addition to newly arising tumor-specific antigens, known as neoantigens, tumor-associated self-antigens and cancer-testis antigens are a major focus of modern immunotherapies. At the same time, tumors develop mechanisms to escape the immune response, including antigen loss, reduced antigen presentation, inhibitory checkpoints, and an immunosuppressive tumor microenvironment. Distinguishing between immune-hot and immune-cold tumors helps characterize different immunological states and guide their therapeutic classification . These biological principles are clinically relevant because checkpoint inhibitors, chimeric antigen receptor (CAR) T cells, tumor-specific T‑cell receptor (TCR) T cells, and neoantigen-based cancer vaccines specifically target these processes. At the same time, new challenges arise, particularly with regard to patient selection, the development of resistance, and off-target and on-target, off-tumor toxicity.