UAB Comprehensive Cancer Center Magazine Spring 2017 - Page 5

The second layer is the adaptive immune system, which There are many types of immunotherapy research and allows for a stronger immune response by remembering treatments, but two particular research advances have had a each pathogen by a signature antigen. Vaccines are designed major impact on the field. The first is checkpoint inhibitor to trigger this type of adaptive response. When a specific therapy. Immune checkpoint proteins normally keep antigen is introduced via vaccine, the body crafts a specific immune responses in check by preventing overly intense immune response and will remember that response if and immune responses that might damage normal cells as well when that antigen reappears in the body. as abnormal cells. Tumors, however, can take over these Both the innate and adaptive immune systems depend proteins and use them to suppress immune response. When on the ability to distinguish between self molecules (those an antibody is administered to inhibit that checkpoint, the naturally found in the body) and non-self molecules (those binding between the tumor cell receptor and the receptor on foreign to the body). There are many types of cells within the T cells is blocked, thus allowing the T cells to become the immune system that identify and eliminate pathogens. activated and destroy the tumor cell. Most commonly known are white blood cells, or leukocytes, The first checkpoint inhibitor antibodies were approved which includes cells known as Natural Killer Cells that by the U.S. Food and Drug Administration for melanoma specifically destroy compromised host cells, such as patients in 2011 and have demonstrated a remarkable tumor cells. response rate. Since that time, there have been at least Adaptive immune system cells are seven checkpoint inhibitor antibodies special types of leukocytes known approved by the FDA, which are Immunotherapy is a rapidly as lymphocytes, the major types of being used to treat non-small cell growing area in cancer which are B cells and T cells. T lung cancer, bladder cancer, and head cells recognize non-self pathogens and neck cancer, among others. research and treatment. In after antigens have been processed and Checkpoint inhibitors are also its most basic definition, it is presented with a self receptor known being studied in combination with simply the process of using as a major histocompatibility complex other forms of cancer therapy, (MHC) molecule. There are two such as chemotherapy or radiation the body’s immune system major subtypes of T cells, which each therapy. When treating a tumor with to fight cancer. recognize different antigens within chemotherapy or radiation therapy, the body. tumor cells can release new antigens The immune system’s natural ability to detect and that could potentially stimulate an immune response that, destroy abnormal cells prevents many cancers. Cancer when paired with checkpoint inhibitors, could be even more cells, however, are able to avoid detection in myriad ways, effective for cancer patients. including reducing the expression of tumor antigens The second major advance is the use of adoptive cell on their surface or inducing cells in the surrounding transfer, specifically CAR T cell therapy. In this approach, environment to suppress the immune response. By the a patient’s T cells are collected from the blood and time the cancer is large enough to be detected, the genetically modified in the laboratory to express a protein immune system can be overwhelmed and unable to mount known as chimeric antigen receptor (CAR). The modified an adequate response, which allows the cancer to grow cells then attach to specific proteins on the surface of cancer unchecked and metastasize to other organs. Thus, the cells, allowing them to become activated and induce cell importance of understanding these responses and processes death. This type of therapy has shown promise in leukemia is a key component in the emerging field of immunotherapy. patients and is being studied in patients with solid tumors as well. Immunotherapy 101 Immunotherapy is a rapidly growing area in cancer research and treatment. In its most basic definition, it is simply the process of using the body’s immune system to fight cancer. Immunotherapy either stimulates specific components of the immune system or counteracts signals produced by cancer cells that suppress immune response. Immunotherapy Research at UAB The UAB Comprehensive Cancer Center is currently conducting multiple research studies involving immunotherapy, particularly checkpoint inhibitor antibodies, says Donald Buchsbaum, Ph.D., professor and director of the UAB Division of Radiation Biology # K N O W U A B C C C • U A B . E D U / C A N C E R 3