Cancer Immunology: How the Immune System Fights Cancer

Written by Georgina Davies Illustrated by Alisha Vroom Traditionally, cancer treatments have targeted tumors from the outside, but modern medicine is increasingly harnessing the body’s internal defenses to target cancer from within. Although our immune system eliminates abnormal cells every day, cancer can develop strategies to evade immune detection and destruction. By understanding how immune cells recognize, target, and sometimes fail to eliminate tumor cells, scientists are developing therapies that harness these pathways. This infographic explores the world of cancer immunology, revealing how the immune system fights cancer and highlighting the breakthroughs driving the future of immunotherapy. THE CANCER IMMUNITY CYCLE At the heart of cancer immunology is anti-tumor immunity—the process by which the immune system recognizes and eliminates cancer cells. This is not a single event, but a repeating cycle of immune recognition, T-cell activation, and tumor cell killing. How the Immune System Fights Cancer CANCER IMMUNOLOGY Antigens from dying tumor cells are taken up by antigen-presenting cells (APCs), including dendritic cells (DCs) and macrophages. 01 Release of antigens 04 T cells travel to tumor 05 T cell infiltration 04 T cellS TRAVEL TO TUMOR T cells release cytotoxins to kill the cancer cell. 07 Cancer cell death DCs present antigens to CD8 + cytotoxic T cells via MHC class I molecules. 02 Antigen presentation The T-cell receptor (TCR) recognizes a specific antigen. T-cell activation also requires adequate costimulatory signals from the APCs. 03 T-cell activation T cells detect tumor-specific antigens (TSAs) or tumor-associated antigens (TAAs), which are presented on the tumor cell surface via MHC class 1 molecules. 06 T cells recognize cancer cells Tumor cells may downregulate MHC class I molecules to avoid recognition by cytotoxic T cells. By detecting the loss of inhibitory signals from these missing molecules, natural killer (NK) cells can identify and kill tumor cells, providing a backup defense mechanism. MHCI TCR Tumors have developed multiple mechanisms to evade this immune response... TUMOR ESCAPE MECHANISMS Myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs) inhibit the anti-tumor response. 03 Regulatory immune cell recruitment MHC class I molecule downregulation, defective antigen processing machinery, or a lack of tumor peptides each result in reduced visibility to cytotoxic T cells. 01 Recognition avoidance Cytokines and metabolites suppress the immune response. Tumor-associated macrophages (TAMs) and DCs also suppress the immune response, and TAMs facilitate angiogenesis. 02 Immunosuppressive microenvironment Tumor cells exploit immune checkpoint pathways, including PD-1/PD-L1 and CTLA-4, to suppress T-cell activity and evade immune attack. 04 Using checkpoint molecules MHCI CD80/86 CD28 TCR LOSS OF MHCI TCR MHCI PD-L1 TCR PD-L1 IMMUNOTHERAPY Insights into tumor immune evasion have driven the development of immunotherapies that enhance or restore the immune system’s ability to fight cancer. VGEF TGF-ß, L-10 LACTATE, AMMONIA 01 02 03 04 05 06 Lab-made proteins bind to tumor antigens, triggering the immune response. Monoclonal antibodies Next-gen antibodies simultaneously bind tumor and immune cells, causing immune activation. Bispecific and multi-specific antibodies Monoclonal antibodies carry drugs and toxins to the tumor cells. Drug conjugates Nucleic acid, protein, cell, or vector-based therapeutic vaccines stimulate the immune system to destroy cancer cells. Cancer vaccines T or NK cells are expanded and/or genetically engineered (e.g., with chimeric antigen receptors) to target cancer. Adoptive cell therapy Prevent T cells from receiving inhibitory signals from tumor cells. Immune checkpoint inhibitors (ICIs) Infect cancer cells, killing them and releasing their antigens. Oncolytic virus therapy Enables precise delivery of ICIs or cancer vaccines, minimizing systemic toxicity. Nanotechnology -driven immunotherapies TARGET Tumor antigen ACTION Antibody binds to the tumor antigen RESULT Triggers the immune response against tumor cells TARGET Tumor antigen and immune cell antigen ACTION Brings immune cells and tumor cells into close proximity RESULT Activate immune cells to attack and eliminate tumor cells TARGET Tumor-specific antigens ACTION Antibodies deliver drugs or toxins to tumor cells RESULT Kills cancer cells while limiting damage to healthy cells TARGET Tumor-specific antigens ACTION Stimulate the immune system to attack cancer cells RESULT Activates immune cells to recognize and destroy cancer cells TARGET Tumor-specific antigens ACTION Engineered T or NK cells target cancer cells RESULT Immune cells recognize and destroy targeted cancer cells TARGET Immune checkpoints ACTION Block inhibitory signals that suppress T cells RESULT Restores T-cell activity against cancer cells TARGET Cancer cells ACTION Viruses infect and destroy cancer cells RESULT Releases tumor antigens and activates an immune response TARGET Tumor cells and immune targets ACTION Precisely delivers ICIs or cancer vaccines RESULT Enhances treatment while reducing systemic toxicity CONCLUSION The immune system’s fight against cancer is a cycle of recognition, attack, and adaptation. Immunotherapy helps tip the balance in favor of the body’s natural defenses, transforming cancer from an evasive threat into a visible, targetable opponent. MHCI PD-L1 TCR PD-L1 This is typically done ex vivo using patient or donor cells, with emerging approaches enabling in vivo engineering Sponsored by: Antigens can be presented to CD4+ helper T cells via MHC class II molecules, activating them into Th1 cells, which support the immune response. TARGETED ANTIBODIES