What Is Immunotherapy, How Does It Work? How Effective Is It?

The immune system is the body’s natural defense system. It provides protection against diseases, and recognizes and destroys invasive microorganisms and tumor cells formed in tissues. The field of science that studies the immune system is called immunology.

The purpose of cancer immunotherapy is to stimulate the patient’s own immune system against the tumor. Cancer cells differ from normal body cells. They can therefore be recognized and destroyed by the immune system. However, cancer cells that have the potential to manifest as normal cells can escape the immune system’s notice, or the response may not be sufficient to destroy the cancer cells completely. In such cases, immunotherapy activates the immune system and ensures that cancer cells are recognized and destroyed. This can be achieved by administration of antigens, as well as vaccines or oncolytic viruses.

Immunotherapies have been among the most important developments in cancer treatment in the last 10 years. It is noteworthy that there are fewer side effects compared to chemotherapy and it delivers positive results in some patients who no longer respond to chemotherapy. Traditionally immunotherapies were monoclonal antibodies, which are a kind of defensive protein.

Later, checkpoint inhibitors, gene treatments and vaccines entered the picture. Immunotherapies are personalized treatments, and both the drugs used and response to treatment vary from one type of cancer to another and from person to person.

Immunotherapy is most commonly used in the treatment of lung cancer and malignant melanoma, a type of skin cancer. However, it also yields promising results for prostate, bladder, kidney and breast tumors, head and neck cancer, brain tumors, a type of skin cancer called Merkel cell carcinoma, and stomach tumors. Studies are still underway. Another question to be answered is whether it is possible to increase the success rate of the treatment if immunotherapy is used in combination with radiotherapy or chemotherapy. However, it should be remembered that most studies on immunotherapy are intended for metastatic diseases. Studies are still being conducted to find answers to these questions. It seems possible that more radiotherapy and immunotherapy will be used in clinics once these studies are finalized.