What is Immunotherapy and how it is used to treat cancer?
Cancer, if we can put it in simple words, is the way our own body cells malfunction. The beginning point of cancer is when our body starts experiencing a certain kind of cellular generation that it can not control, and from there onwards such cancerous cells rapidly grow to overtake the regular kind of cells – resulting in collapse of the system. Given that cancerous cells are not external to the body – our immune system often fails to differentiate between the ‘good cells’ and the ‘bad cells’. So how do we treat a disease that by default knows how to hide from our natural defences?
This masquerading nature of cancerous cells is where immunotherapy comes into play. Immunotherapy is one of the most preferred methods of treating cancer. It can be adopted on its own, or in combination with other forms of cancer treatments.
As the name suggests, immunotherapy has to do with our immune system – the latter is part of our very genetic make up and thus, also designed to not counter its own cells, which unfortunately makes it easy for the bad cells to hide in plain sight! Immunotherapy conditions our body’s response to cancerous cells by helping it identify them, fight against them, and at the same time – fortify the existing defences so that the body can prevent the irregular cell generation. Also known as biologic therapy, or more formally, immuno-oncology, this form of treatment is arguably the first line of attack against cancer – although it is to be noted that immunotherapy does not work the exact same way for every form of cancer.
Immunotherapy, as mentioned, helps improve our immune responses. That result can be achieved by a number of different methods. While newer forms of immunotherapy are constantly being researched and evaluated, some of the most frequently adopted therapies include-
- Checkpoint inhibitor drugs: primarily prescribed for kidney, bladder and blood cancer in advanced stages, this form of immunotherapy requires specific biomarkers to work.
- Cancer vaccines: categorized in two types – prevention and treatment, cancer vaccines aren’t vastly different from other vaccines. Depending on the type of cancer and its progress, these vaccines either help the body fight the disease or prevent it from coming back.
- Monoclonal Antibodies (mABs): These are artificially created antibodies designed to target a protein specific to the one that makes up the body of cancer cells. By targeting that protein, mABs basically signal the body’s immune system as to which cells are cancerous and should be destroyed, acting as the whistleblower. Some of the common mABs are Denosumab, Trastuzumab etc.
- T-Cell Transfer Therapy: This form of therapy engages the t-cells in our body. There are two forms, the first is where t-cells are removed from the cancerous tumour, produced outside of the body and then the patient is re-infused with the new t-cells. In a more advanced form of the same therapy, once the defective t-cells are removed – the new t-cells are chemically improved with chimeric antigen receptors that are designed to fight antigens specific to cancerous cells, thereby enhancing the body’s immune response.
- Donor Lymphocyte Therapy (DLI) : An advanced form of immunotherapy, the DLI is a complicated process that depends on infusion of lymphocytes – only if the patient has already received a bone marrow transplant, specifically from the same donor as that of the white blood cells. This therapy can also potentially cause Graft Versus Host Disease (GVHD), where the donor’s healthy immune cells adversely attack the recipient’s cells.
A much-documented adverse side of immunotherapy is the side effects it causes, given that the form of treatment is essentially a battle between our own body’s cells. The heightened immune response often attacks even healthy cells, resulting in symptoms like diarrhoea, nausea, severe body ache, fever, hair loss and rashes to list a few. There is no one method that fits all, and its impacts – both positive and negative – vary in degrees.
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