Immune system ↗Cells acquire altered biology
Mutation, chromosomal change, viral proteins, epigenetic state, stress, and abnormal expression can create growth advantage and immune visibility.
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Recognize abnormal.
Survive evasion.
Immune cells can detect and destroy abnormal cells, but cancers evolve under selection. Antigen visibility, dendritic priming, T-cell access, NK signals, checkpoints, stroma, metabolism, and treatment all shape the outcome.
Some changes create recognizable peptides
Neoantigens, viral antigens, differentiation antigens, and overexpressed proteins can be processed and displayed by MHC molecules.
Cell stress supplies activating context
Damage signals, innate sensors, cytokines, and dying-cell material can recruit and activate antigen-presenting cells.
Tumor antigen is cross-presented
Dendritic cells can carry tumor-derived antigen to lymph nodes and prime CD8 and helper T-cell responses when costimulation is adequate.
Matching targets can be killed
Cytotoxic T cells enter tissue, recognize peptide–MHC I, form an immune synapse, and induce tumor-cell death.
Missing-self and stress signals add surveillance
NK cells can attack cells with reduced MHC I or increased activating ligands while inhibitory signals protect many healthy cells.
Some abnormal cells are removed
Innate and adaptive immunity may destroy nascent transformed cells before a clinically detectable tumor develops.
Immune pressure constrains survivors
Persistent immune attack can hold selected clones in check while creating evolutionary pressure for less visible or more resistant variants.
Visible targets disappear
Tumor clones can stop expressing antigens, lose MHC components, alter processing, or resist death signaling.
Inhibitory ligands switch off T cells
PD-L1 and other signals engage immune checkpoints that normally protect tissue but can suppress antitumor activity.
Stroma becomes suppressive
Regulatory cells, suppressive macrophages, fibroblasts, abnormal vessels, hypoxia, adenosine, nutrient depletion, and metabolites restrict immunity.
Effector cells may not reach the tumor
Vascular adhesion, chemokines, dense matrix, spatial architecture, and local survival cues determine whether lymphocytes enter and persist.
Inhibitory signaling is interrupted
Antibodies against PD-1, PD-L1, CTLA-4, or other checkpoints can restore selected T-cell activity in approved cancer contexts.
Antitumor lymphocytes are expanded or engineered
TIL, TCR-engineered, and CAR T-cell approaches use different recognition strategies, manufacturing processes, and disease settings.
Tumor targets can be marked or engaged
Therapeutic antibodies may block growth signals, recruit immune killing, deliver payloads, or connect T cells to tumor targets.
Immune priming can be therapeutic
Cancer-treatment vaccines and immune modulators aim to generate or strengthen antitumor responses and differ from preventive infection vaccines.
Only selected patients benefit
Cancer type, antigen, biomarker, tumor burden, prior treatment, microenvironment, host factors, and resistance mechanisms change response.
Healthy organs can become targets
Checkpoint activation can inflame skin, gut, liver, lung, endocrine glands, heart, nerves, kidneys, joints, or other tissues, sometimes after treatment ends.