What is it?
Our immune system protects our body from diseases or potentially damaging foreign threats such as bacteria, viruses, fungi and toxins. It detects and responds to a wide variety of pathogens from viruses to parasitic worms, as well as cancer cells and objects, distinguishing them from our healthy tissue. Immunotherapy which is also called biological therapy is the treatment that uses our immune system to fight a disease by activating or suppressing it as the case may be.
In recent years, because of its promising results in treating various forms of cancer, immunotherapy has become of great interest to researchers, clinicians and pharmaceutical companies.
How does it work?
The theory behind immunotherapy is that our immune system already knows how to distinguish between the cells that belong to our body and those that do not. Those which do not appear to be part of our body are fought against. However, since the cancer cells come from our cells, they sometimes can disguise themselves and our immune system fails to recognize them as threats. As these grow, they can change, or mutate, and can further evade our immune system, or can even slow our immune system down.
Immunotherapy includes various treatment strategies that help the immune system find and target cancer cells once and for all. They include:
- Helping the immune system recognize cancer cells
- Activating and amplifying immune cells
- Interfering with a cancer cell’s ability to hide
- Interfering with the microenvironment of cancer cells by altering cancer cell signals
- Using the principles of the immune system as a template for designing cancer drugs
Types
Various immunotherapies that are currently being used can be classified as below:
- Adoptive cell therapy also known as cellular immunotherapy, in which the immune cells are used to eliminate cancer. Some of these approaches involve directly isolating our immune cells and simply expanding their numbers, whereas others involve genetically engineering our immune cells to enhance their cancer-fighting capabilities.
- Cancer vaccines which are known as the treatment or therapeutic vaccines which boost the body’s immune system to treat existing cancer. These vaccines work in different ways including
- Immunomodulators are medications used to help regulate or normalize the immune system which stimulates its ability to find and kill cancer cells. Treatments include checkpoint inhibitors, cytokines, interferon and interleukins.
- Prevent the recurrence of cancer.
- Destroy any cancer cells in the body after treatments.
- Prevent a tumor from growing or spreading.
- Monoclonal antibodies are laboratory-made proteins that attack specific parts of a cancer cell. They can also deliver drugs, toxins or radioactive material directly to tumors.
- Oncolytic viruses are genetically engineered or naturally existing viruses that can selectively replicate in cancer cells and then kill them without damaging the healthy cells.
Why is it promising?
Immunotherapy has created more treatment possibilities beyond traditional cancer treatments like chemotherapy, surgery or radiation. Considering the different types of immunotherapies available today, they provide a more targeted treatment option depending upon the type of cancer being treated. It’s been considered an effective treatment for patients with certain types of cancer that have been resistant to chemotherapy and radiation treatment and immunotherapies can also be used alongside other forms of treatment to enhance performance.
Immunotherapy can train the immune system to remember cancer cells and this ‘immune memory’ may result in longer-lasting remissions. The studies on long-term overall survival have shown that the beneficial responses to cancer immunotherapy treatment are durable which means that these beneficial responses may be maintained even after treatment is completed. Also, the immunotherapies may not cause the same side effects as the conventional cancer treatments since these conventional treatments have a direct effect of a chemical or radiological therapy on cancer and healthy tissues resulting in common side effects such as hair loss and nausea.
Risks
Although the immunotherapies are not free from side effects, such side effects are considered to be fewer compared to the conventional cancer treatments. These side effects vary depending upon the patient and the type of cancer being treated.
Commonly reported mild side effects include fatigue, fever, pain, soreness and muscle aches, swelling, rash and blisters, nausea, vomiting and/or diarrhea, fluctuating weight and appetite, shortness of breath, difficulty sleeping, heart palpitations etc. Some immunotherapies can also cause serious potentially life-threatening side effects like monoclonal antibodies, which are known to cause high blood pressure, bleeding, blood clots, kidney damage, severe rashes and other serious risks. Similarly, the CAR T-cell therapy can cause cytokine release syndrome (CRS) which results in dangerously high fevers and low blood pressure. Other reported serious side effects include seizures, confusion, serious infections, low blood cell counts and severe headaches.
Future
The breakthroughs made in the field of immunotherapy in recent years has given hope in the form of better survival and quality of life to many advanced-stage cancers where there was previously little or no hope. Although, despite the progress, a lot more remains to be done since many cancer patients still don’t respond to immunotherapies, the clinical enthusiasm for immunotherapy is high mainly because of its potential as a sustainable and durable cancer cure. Researchers believe that in the future, more targeted immunotherapy will replace the conventional therapies essentially for all cancer types.
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