The Hopes of Countless Millions
TYPES OF IMMUNOTHERAPY
Monoclonal Antibodies
The immune system requires antibodies to protect the body from foreign cells.
Researchers have the capability of producing antibodies. Therefore, these antibodies can be inserted into the body intravenously to help fight against cancer cells.
These are the different types of monoclonal antibodies, including, naked monoclonal antibodies, conjugated monoclonal antibodies, and bispecific monoclonal antibodies.
Naked Monoclonal Antibodies
They are called “naked” due to the fact that there is no other drug connected to them. These antibodies do not actually destroy cancer cells, but they guide the immune system in attacking them. Some binds to cancer cells in order to spark an immune response. This will notify the immune system that the cells antibodies are binded to are cancerous. Afterward, the immune system will be able to eliminate the cancer cells.
Other antibodies prevent cancer cells from growing or spreading by blocking antigens that help cancer cells do so. This will decrease the amount of cancer cells in the body.
This infographic describes how a monoclonal antibody can bind to an antigen, which sparks an immune response. 1
Conjugated Monoclonal Antibodies
These antibodies carry with them a “chemotherapy drug or radioactive particle” because they will find and attach to cancer cells to transport the drugs to the required locations where it will help eliminate cancer cells. This decreases the amount of side effects and lessens the damage of healthy cells.
Bispecific Monoclonal Antibodies
This type of immunotherapy has the ability to help the immune system fight cancer cells because they can attach to two distinct proteins simultaneously, such as cancer and immune cells.
Immune Checkpoint Inhibitors
It is crucial that the immune system can recognize foreign cells and attack them. In addition, it is essential that it identifies normal cells and understands not to attack them, and the immune system uses checkpoints to do so.
PD-1/PD-L1 Inhibitors
This immunotherapy allows the immune
system to effectively attack cancer cells
because they prevent the binding of PD-1
and PD-L1. PD-1 is a “checkpoint protein”
that is located on T cells. When it binds
to PD-L1, which is a protein that can be
found on normal or cancer cells, it
prevents T cells from attacking normal,
healthy cells. Unfortunately, a variety of
cancer cells have PD-L1 to help them
from being eliminated by immune cells.
Therefore, when PD-1 can be prevented
from binding to PD-L1, it increases
the immune system’s ability in
fighting against cancer cells because it
will not misunderstand cancer cells as “normal.”
The picture illustrates how PD-1 and PD-L1 inhibitors are important in cancer immunotherapy to fight against cancer cells. 2
CTLA-4 Inhibitors
This immunotherapy turns off a type of protein called CTLA-4. CTLA-4 is located on T cells that can prevent the immune system from performing its functions. Therefore, when these proteins are turned off, the immune system can attack cancer cells better.
Adoptive Cell Transfer
Car T-Cell Therapy
T cells are necessary in the elimination of foreign substances in the body. They have receptors, which are proteins that bind to a specific antigen to help the immune system identify and defeat any foreign cells.
In this immunotherapy, a patient undergoes leukapheresis, which is a process where a doctor takes blood from a cancer patient to obtain T cells. The T cells will then be genetically modified, since a type of receptor called chimeric antigen receptor (CAR) will be added, making them CAR T-cells. These receptors aid the T cells in identifying and attaching to a cancer cells’ antigen. After, CAR T-cells will be grown in a lab until it produces a large amount of CAR T-cells. To reduce the amount of immune cells in order for CAR T-cells to have a higher chance of being effective, chemotherapy will be given to a patient before CAR T-cells are inserted back into the body. The CAR T-cells will further expand to produce more CAR T-cells in the body, which increases the amount of cancer cells destroyed.
The diagram briefly explains the CAR T-cell therapy and how it works in the body. 3
Non-specific Immunotherapies
The body’s cells can produce cytokines, which plays a role in ensuring that the immune cells are doing what it is supposed to, such as growing.
Interleukins
A type of interleukin that was made in a lab is called Interleukin-2 (IL-2). Their job is to guide the immune system in dividing and growing their cells.
Interferons
They help the body defend itself from infections.
A type of interferon is IFN-alfa, which was created in a lab. It is capable of decreasing the rate of cancer cells’ growth and helping the immune system in fighting against the cancer cells.
Cancer Vaccines
When a certain antigen is destroyed, the
immune system has the ability to recognize it.
When the same antigen exists in the future,
the immune response is quicker the second
time and helps the immune system attacks it
before the antigen causes harm to the body.
Therefore, vaccines help prevent
infections/diseases in the body that have
already occurred.
Cancer vaccines are a type of immunotherapy
that work the same way as well; however, they
specifically identify and eliminate cancer cells.
In some cases, they include healthy cells from a patient. In a lab, the cells will be contaminated with substances, such as antigens, so an immune response will occur when the vaccine is inserted intravenously. Adjuvants, which are substances that enhance the immune response, will also be added to vaccines to increase the effectiveness of the treatment.
The infographic provides a brief explanation of how cancer vaccines are produced. 4
Up to this point, the FDA has only approved one type of cancer vaccine to treat prostate cancer:
Sipuleucel-T (Provenge®)
This is a cancer immunotherapy that is utilized when the hormone therapy used to treat advanced prostate cancer is not effective. The first step in the creation of this cancer vaccine is to obtain a patient’s “immune system cells.” Dendritic cells will be produced when the normal cells were contaminated by chemicals in a lab. In addition to chemicals, prostatic acid phosphatase (PAP), a protein, will guide the immune system in the elimination of prostate cancer cells by creating an immune response. After, the dendritic cells will be inserted into a patient through a vein.
The image describes an overview of how Sipuleucel-T (Provenge®) is produced, delivered into the patient, and the number of cycles needed. 5
Even though this immunotherapy can prevent cancer, there are still factors that decrease the effectiveness of cancer vaccines:
1) Cancer cells has the ability to prevent the immune system from doing what it is supposed to, which explains the growth/development of cancer cells, since T cells can not eliminate the cancer cells.
2) The immune system has difficulties with recognizing a cancer cell as a foreign cell due to the fact that they evolve from the body’s normal, healthy cells. This will prevent the immune system from attacking the cancer cells.
3) When patients are in their end stages of cancer, the tumors can increase in size, which makes it hard for vaccines to be effective in fighting against cancer.
4) A patient can lack a strong immune response due to old age or an unhealthy immune system. This increases the chance of the cancer vaccine not being able to work.