Emerging as the 4th modality of cancer, immunotherapy has shown considerable promise when it comes to treating a wide range of cancers. Immunotherapy primarily focuses on strengthening the immune system and its responses to identify and attack the cancer cells in the body.
The main function of the immune system is to identify any aberrant cells and eliminate them from the body. However, the immune system usually fails to identify cancerous cells due to the fact that they possess genetic alterations that obscure their appearance to the immune system and its responses.
They also display proteins on their surface that inhibit immune system activity. Immunotherapy as a line of treatment ensures that the body can identify these cancerous cells and inhibit their tumor growth or eradicate cancer completely.
There are various different types of immunotherapies available today and each have their own advantages. Oncologists consider various factors such as the histology of cancer, the stage, previous lines of treatments used and the overall health of a patient before deciding which type of immunotherapy to follow.
Also Read: What Is Immunotherapy ?
Types Of Immunotherapy
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Checkpoint Inhibitors
Checkpoint Inhibitors have emerged as a reliable form of treatment over the past decade. These drugs prevent a person from turning off if cancer cells are identified in the body. In simple words, they block the checkpoint proteins and give permission to the healthy cells of the body to continue fighting cancer.
One of the key functions of the immune system is to differentiate between the healthy cells of the body and any foreign agents that may bring us harm. This ensures that the immune responses of the body can get rid of any foreign substances while sparing the healthy cells of the body.
In order to separate between the healthy cells and the harmful cells of the body, the immune system uses checkpoint proteins that are found on the surface of the cells. These checkpoints can be understood as something similar to a switch that needs to be turned ‘on’ or ‘off’ to trigger an immune response.
However, the immune system fails to take notice of these checkpoints when it comes to cancerous cells because cancer cells are healthy cells of the body that have attained mutation. This makes it difficult for the immune system to recognize these cells as foreign entities. The cancer cells in the body use these very checkpoints to avoid being attacked by the immune responses in the body.
Along with this, these cancer cells also send deceptive signals at the checkpoints that tell the T-cells of the body that they are not harmful. This is where checkpoint inhibitors come into play as these drugs are curated in a way that enables them to target checkpoint proteins.
Since checkpoint inhibitors are a subset of immunotherapy, they don’t directly kill the cancer cells but instead boost the immune system to find and locate these cancer cells, in order to ensure the immune responses can attack them comprehensively.
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Monoclonal Antibodies
Monoclonal Antibodies are a type of immunotherapy that works by triggering the immune system and its responses and recognizing and attacking the cancer cells in the body. Monoclonal antibodies are immunoglobulins that are derived from a monoclonal cell line and have a very defined specificity.
They trigger immunological activities by binding to a specific ligand or antigen. Monoclonal antibodies essentially represent a large group of therapeutic medications that have had a massive impact in the treatment of cancer and in modern medicine as a whole.
Monoclonal antibodies are man made proteins that operate like the natural human antibodies in the immune system. There are typically 4 ways using which monoclonal antibodies are made and their names are attributed to the content using which they are made of.
These include murine monoclonal antibodies, chimeric monoclonal antibodies, humanized monoclonal antibodies and human antibodies.
Types of Monoclonal Antibodies Used To Treat Cancer
Naked Monoclonal Antibodies – Naked monoclonal antibodies have no drugs or radioactive material bound to them and work in the body all by themselves. These are the most common types of mAbs used to treat cancer.
While most naked antibodies attach themselves to the antigens on the cancer cells, some operate by binding to the other non cancerous cells or other free floating proteins. Some naked monoclonal antibodies work by working as a marker for the immune system to attack the cancer cells in the body.
Some drugs such as rituximab which is used to treat some types of Non-Hodgkin Lymphoma and other similar cancers, bind with the CD antigen which is found on the B lymphocyte. Once they are attached the antibody attacks immune cells to destroy the cancerous cells in the body.
Some naked antibodies also work by targeting the immune system checkpoints while some others work by binding and blocking the proteins on the cancer cells. Trastuzumab is a drug that works against the HER2 protein, which is a major protein found in breast cancer. Breast and stomach have large amounts of these proteins on their surface which helps them to grow. Trastuzumab binds to these proteins and helps them to grow.
Cancer Vaccines
Cancer vaccines, which are a type of immunotherapy can also be used in the treatment of small cell lung cancer. Cancer vaccines target proteins that are present on cancer cells. Sometimes, these vaccines specifically target proteins that are unique to a patient’s cancer.
An antigen is a substance that kick-starts the immune response of the body to start acting against that cancer cell. Cancer vaccines help the immune system to identify these antigens and ultimately attack the cancer cells in the body. The Denvax Clinics, located all over India utilizes dendritic cells to curate cancer vaccines for their patients.
The procedure uses a patient’s own mononuclear cells which are then cultured in cytokines and other nutritional media. Once these immature dendritic cells attain maturity, they are then administered to the patient via IV infusion. Some possible side effects of cancer vaccines include –
- Anorexia
- Back pains
- Chills
- Headache
- Jointache
CAR T-Cell Therapy
CAR T-Cell Therapy is a type of personalized cancer treatment in which a patient’s T-cells (a type of immune cell) are modified in the laboratory to attack the cancer cells. The immune system of the body operates by keeping a close eye on all the substances that are found in the body. CAR T-Cell therapy is aimed at boosting the immune responses of the body so that they can proactively target and kill cancer cells. In CAR T-Cell Therapy, T- Cells are taken from a patient’s blood and are treated in the lab. A gene for a receptor known as the Chimeric Antigen Receptor aka CAR enables the T cells to attach themselves to a particular cancer antigen. Due to the fact that each cancer has different antigens, CAR T-cell therapy is a personalized form of cancer treatment.
The initial development of CAT T-Cell Therapy primarily focussed on the most commonly diagnosed cancer in children – acute lymphoblastic leukemia (ALL). Chemotherapy has been the commonly used line of treatment for such cancers however, effective treatment options have been limited for patients with a possibility of a relapse. CAR T-Cell therapy has shown positive results for such patients.
As beneficial CAR T-Cell therapy may prove to be for various kinds of cancers, it can result in some side effects. Due to this, it becomes necessary that such a kind of therapy is administered under close supervision. Along with this, a patient should be closely monitored and examined if they are showing signs of some side effects. As CAR T cells multiply, this then leads to the immune system being ramped up. Some of the serious side effects of such a type of therapy include –
- Difficulty in breathing.
- High fever and chills.
- Nausea.
- Feeling dizzy.
- Headaches.
- Rapid heartbeat
In rare cases a patient may also experience a serious side effect referred to as Cytokine-Release Syndrome (CRS). Cytokines are chemical messengers that aid the T cells carry out their operations. Cytokines are produced in the body when the CAR T-Cells proliferate and kill cancer cells. The symptoms of this syndrome can be mild such as nausea, headache, chills and fever. Along with this a patient may also experience some serious symptoms such as low blood pressure, tachycardia (medical term for an increased heart rate of over 100 beats a minute) and cardiac complications.
Final Note
Immunotherapy when used in combination with the three modalities of cancer can show positive outcomes in patients with cancer. Checkpoint inhibitors, monoclonal antibodies, cancer vaccines and CAR T-Cell therapy have proven effective against a wide range of cancers and can be highly effective when used in conjunction with chemotherapy, radiation therapy and surgery.
