Cancer immunotherapy harnesses the body’s own immune system to recognize and destroy cancer cells. Tumors often evade immune attack by hiding their abnormal features or actively suppressing immune responses. Modern immunotherapies work by lifting these brakes, boosting immune activity, or redirecting immune cells toward cancer.

Checkpoint inhibitors are a central approach. Drugs targeting proteins such as PD 1, PD L1 and CTLA 4 prevent cancer cells from shutting down T cells. This can lead to durable responses in melanoma, lung cancer, kidney cancer and others, though not all patients benefit and immune related side effects can occur.

Another strategy is adoptive cell therapy, where immune cells are collected from a patient, strengthened or genetically engineered, then reinfused. CAR T cell therapy modifies T cells to express synthetic receptors that recognize specific molecules on cancer cells. This has produced remarkable results in some leukemias and lymphomas, but challenges include toxicity, limited success in solid tumors and high cost.

Cancer vaccines aim to train the immune system using tumor associated or patient specific neoantigens. Personalized vaccines are being explored, particularly in melanoma and other cancers with many mutations.

Cytokine therapies, such as interleukin 2 and interferons, globally stimulate immune responses but can cause substantial toxicity. Newer cytokine designs seek more targeted activation.

Ongoing research focuses on combinations of immunotherapies with each other and with chemotherapy, radiotherapy or targeted drugs. Scientists are also developing biomarkers to predict who will respond and are investigating ways to overcome the immunosuppressive tumor microenvironment. Overall, cancer immunotherapy is transforming oncology, but optimizing safety, broadening effectiveness and reducing cost remain key goals.