IMMUNOTHERAPY

Immunotherapy is a treatment that uses the body's own natural defenses to fight cancer. White blood cells (T cells) that make up the immune system can be stimulated in several ways by specially designed drugs that allow them to recognize and kill cancer cells.

Early immunotherapy drugs worked in a general way by boosting the body’s immune system to fight cancer cells. However, recent research has discovered several proteins on the surface of T cells that act like a brake, or checkpoint, preventing them from attacking cancer cells.

Another checkpoint is PD-1, discovered in 2000. Several drugs have been developed to turn off PD-1 in many types of cancer, allowing existing T cells near the tumor to attack.  

Other immunotherapies fall into two general categories.

Targeted immunotherapies attack specific proteins on the surface of cells that help identify cancer and stimulate an immune response. Common types include:

• Monoclonal antibodies are designed to identify specific abnormalities on the surface of cancer cells. Monoclonal antibodies        attach themselves to these abnormalities, marking them as a target for the immune system.
• Cancer vaccines help the body recognize cancer cells and stimulate the immune system to destroy them. Some vaccines          contain cancer cells harvested from the patient’s tumor. Others contain proteins designed to attach themselves to cancer          cells.
  

General immunotherapies are non-specific treatments that do not affect the cancer itself. They work on proteins called cytokines that send signals to stimulate the body’s immune system to fight cancer cells. Common types include:

• Interleukins control the growth and activity of T cells. More than a dozen interleukins have been identified. Interleukin-2 (IL-      2) is used to treat kidney cancers and melanomas that have spread to other regions of the body. Other interleukins are being    studied as possible treatments for other types of cancer.
• Interferons are a group of three proteins released by T cells in reaction to invading organisms. Interferons increase the            immune system's reaction to cancer cells. Interferon alpha (IFN-alfa) is currently being used to treat melanoma, kidney              cancer and certain types of leukemia and lymphoma.
  
• Colony Stimulating Factors (CSF) strengthen the immune system by stimulating the production of white blood cells in the      bone marrow. CSF therapies are used to help elevate low white blood cell counts after chemotherapy.