Immunotherapy uses the body’s own defense mechanisms and immune system to fight cancer at the cellular level. This treatment is rapidly growing with many research studies and new treatment options in progress. These treatments enhance the immune system’s response to fight cancer cells.
How Immunotherapy Works
The immune system normally fights against infection and disease. Biologic agents that mimic the body’s signals to control cell growth or issue an immune response can be grown in a laboratory and given to patients to stimulate a response to cancer cells. Immunotherapy, depending on the type, boosts the immune system’s ability to fight cancer cells or helps mark cancer cells to make them easier for the immune system to target. Immunotherapy harnesses the immune system to attack cancer cells, to stop or slow cancer cell growth by aiding the immune system in destroying cancerous cells, or limiting the cancer’s ability to spread.
Types of Immunotherapies
Most immunotherapy treatments fall into five primary categories.
Monoclonal antibodies
- Cancer cells have proteins on the surface of the cell called antigens. In the lab, an antibody can be created which attaches directly to that protein which may be specific for that tumor. This attachment can do many things to disrupt the ability of the cell to grow or spread, or it may make the cell more vulnerable to attack by the immune system.
- Immune check point inhibitors are a type of monoclonal antibody that disrupts the cancer cell defense against the immune system and, in many cases, allows the immune system to destroy these cancer cells
Adoptive cell therapy
- Adoptive cell therapy differs from monoclonal antibodies in that the lymphocytes are directly harvested from the patient and multiplied in a lab. These cells can be modified, augmented, and then administered to the patient as a form of immune cellular therapy against the cancer.
- Chimeric antigen cell therapy (CAR-T) is a personalized therapy in which a patient’s own immune cells are removed from the patient’s body, genetically reprogrammed, then infused back into the patient to identify and attack their cancer as a one-time treatment.
Cancer vaccines
- Most vaccines are given to prevent a disease (including some viruses that can cause cancer), but cancer treatment vaccines are given after a person has been diagnosed with cancer to help increase the body’s ability to fight tumor growth, limit the spread of cancer cells, and reduce the risk of recurrence.
- Vaccines are another form of immunotherapy, and many are in development. Peptide vaccines are based on stimulating an immune response against a protein commonly present on certain cancer cells. Dendritic cell vaccines are a type of cell-based therapy and require removal of the cells that present proteins to the immune system (called dendritic cells). These extracted dendritic cells can then be activated and programmed to recognize cancer cells based on common cancer proteins.
- Vaccines may be personalized, using tissue from a person’s individual cancer and combined with substances in a lab to develop a vaccine tailored to their immune system.
Non-specific immunotherapies (cytokines)
- Some immunotherapy drugs and proteins don’t target cancer cells specifically, but instead boost the immune system, leading it to a better response to cancer cells. The cytokines (interleukins and interferons) are capable of activating a broad array of immune cells with the potential benefit of fighting infections or cancer.
- Cytokines are given most often in combination with other treatments such as chemotherapy or radiation therapy, but they can be administered as the primary treatment.
T-cell promoters
- Some immunotherapy drugs restore or promote T-cell activity by blocking the defenses of tumor cells. These include PD-1 and PD-L1 type inhibitors and ipilimumab, which uses a different mechanism, but enhances tumor killing activity of T-cells.
Treatment with Immunotherapy
Immunotherapy is used for many types of cancer. It may be used alone or in combination with other types of cancer treatments such as chemotherapy, radiation therapy, or surgery. It can be given as an IV, oral, topical, or intravesical (directly into the bladder) application
Sources: American Cancer Society, American Society for Clinical Oncology, and National Cancer Institute