Immunotherapy is a form of cancer treatment that harnesses the immune system to recognize and destroy tumor cells. Several major approaches are in clinical use or development, each targeting different components of immune regulation.

Checkpoint inhibitors block inhibitory signals that normally restrain T cells. Tumors often exploit molecules such as PD 1, PD L1 and CTLA 4 to shut down immune attack. Antibodies that block these checkpoints can reactivate cytotoxic T cells and have improved survival in cancers including melanoma, lung, kidney and bladder cancer. However, not all patients respond, and immune related side effects can affect organs such as skin, gut, liver and endocrine glands.

CAR T cell therapy involves engineering a patient’s T cells to express synthetic receptors that recognize specific tumor antigens. After expansion in the laboratory and reinfusion, these cells can powerfully target blood cancers such as certain leukemias and lymphomas. Toxicities such as cytokine release syndrome and neurotoxicity require careful management, and extending success to solid tumors remains challenging.

Cancer vaccines aim to stimulate immunity against tumor associated or patient specific neoantigens. Approaches include peptide, DNA or RNA vaccines and dendritic cell based methods. Personalized vaccines generated from an individual’s tumor mutations are under active study.

Adoptive cell therapies beyond CAR T cells, including tumor infiltrating lymphocytes and natural killer cell therapies, seek to boost or redirect effector cells.

Key research directions include better biomarkers to predict response, combination therapies with chemotherapy, radiotherapy or targeted agents, strategies to overcome resistance in “cold” tumors with poor immune infiltration, and reducing toxicity while maintaining durable tumor control.