Immunotherapy is also known as biologic therapy. It is a type of cancer treatment which boosts the body's natural defenses to fight against cancer. The human body’s immune system helps our body fight infections and other diseases. It sis made up of white blood cells and organs and tissues of lymph system. Immunotherapy uses substances produced by the body or produced in a laboratory to improve or restore immune system function. Immunotherapy works in many ways. It may:
· Stop or slow the growth of cancer cells
· Stop cancer from spreading to other parts of the body
· Help the immune system work better to destroy cancer cells
Immunotherapy can be active, passive or hybrid (both active and passive). Cancer cells have molecules on their surface that can be detected by the immune system. These molecules are known as tumour-associated antigens (TAAs). The TAAs are mostly proteins or other molecules like carbohydrates. Active immunotherapy works by targeting the immune system to attack tumor cells by attacking TAAs. Passive immunotherapy on the other hand improves the already existing anti-cancerous responses of the body. It does so by the use of monoclonal antibodies, lymphocytes and cytokines.
Types of Immunotherapy
There are several types of immunotherapy methods that are being used to treat cancer. These methods of treatments either help the immune system to attack the cancer directly or it may stimulate the immune mechanism.
Types of immunotherapies which help the immune system to act directly against the cancer include:
· Checkpoint inhibitors: These are drugs which help the immune system to respond more strongly to cancer cells. These drugs work by releasing substances that act as “brakes” that keep T cells which is a type of white blood cell and form a part of the immune system, from killing cancer cells. These inhibitor drugs do not target the tumor cells directly. But they interfere with the ability of tumor cells to avoid immune system attack.
· Adoptive cell transfer is a method of treatment in immunotherapy that attempts to boost the natural ability of T cells of the body to fight against cancer. In this method, T cells are taken from the tumor itself. Then those T cells that are most active against the cancerous cells are grown in large batches in the laboratory.
The procedure of growing body’s T cells in the laboratory can take 2 to 8 week’s time. During this time, the patient may undergo treatment such as chemotherapy or radiation therapy. After these treatments are done, the T cells that were grown in the laboratory are injected back in the body through a needle in your vein.
· Monoclonal antibodies which are also known as therapeutic antibodies, are immune system proteins that are created in the lab. These monoclonal antibodies are designed in a way to attach to specific targets that are found on the cancer cells. Some monoclonal antibodies work by marking cancer cells in such a manner so that they will be recognised and destroyed by the body’s immune system. Some monoclonal antibodies directly stop tumor cells from growing or cause their self-destruction. There are some others which work by carrying toxins to cancer cells. As therapeutic monoclonal antibodies work by recognizing specific proteins present on cancer cells, they are also known as targeted therapies.
· Another method is by use of Treatment vaccines, which work against cancerous cells by boosting the immune system response to tumor cells. These Treatment vaccines are very different from the ones those help prevent disease.
Some methods of immunotherapy which help to increase our body’s immune response to fight against the cancer cells include:
· Cytokines are proteins which are made by our own body cells. These play important role in our body’s normal immune responses and also in the immune system’s ability to respond to cancer. The two main types of cytokines used in the treatment of cancer are known as interferons and interleukins.
· BCG, which is also known as Bacillus Calmette-Guérin, is an immunotherapy method which is used to treat urinary bladder cancer. It is a much weakened form of the bacteria which causes tuberculosis. When it is injected directly into the bladder by using a catheter, it produces an immune response against tumor cells. It is also being studied in treatment of other types of cancer.
Immunotherapy is used as widely as surgery, chemotherapy, and radiation therapy. But, immunotherapies have been proved to treat people with many other types of cancer.