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
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