There are a lot of cancer management modalities available across many areas of medical technology these days. Some work by removing the tumor mass, the others focus on destroying their DNA and shrinking it, yet others work by looking for a possible molecular target and hitting it with specific drugs and the list goes on.
Human blood contains three major components, namely, red blood cells, white blood cells, and platelets. White blood cells make up the human immune system and help fight infections. Among them, lymphocytes play a major role in fighting chronic insults like cancer or viral infections. These are further classified into T cells and B cells with their extremely significant and defined roles in fighting pathogens. T cells are particularly involved in immunity against cancer.
As the name wonderfully describes, immunotherapy helps strengthen an individual’s immune system to fight cancer cells. You might be aware of the basis of vaccines, where a small portion of microbe is deliberately introduced into the child to develop antibodies of his/her own, in case the disease strikes. Immunotherapy works in a similar fashion.
The mechanism of action:
Normally body’s defense mechanism acts against all pathogens and invaders including cancer growth. The T cells present inside the tumor mass are called tumor-infiltrating lymphocytes. Generally, with the help of proteins on its surface, a T cell should be able to identify the cancer cells and kill it. Ironically, during its growth, cancer accumulates certain properties that the body‘s defense is unable to identify tumor cells.
Commonly used immunotherapy drugs are called immune checkpoint inhibitors. These are monoclonal antibodies that act via binding the inhibitory molecules on the cancerous cell or the lymphocyte, enabling the lymphocyte to identify the cancer cell. Chimeric antigen receptor (CAR) T cell therapy is another higher form of immunotherapy against blood cancers and lymphomas, in which a sample of a patient’s fighter T cells is collected and reformed to create special structures called chimeric antigen receptors (CARs). Now when these CAR-T cells are infused back into the patient, the fresh receptors are able to latch onto a specific antigen on the tumor cells and kill them. Success has been achieved in treating highly refractory blood cancers with this therapy. Similarly, adoptive T cell therapy is now being translated to the treatment of solid malignancies. In this therapy, T cells of the patient are exposed to cancer antigens outside the body and once they are able to identify the cancerous cells, they are infused back into the patient’s circulation.
Advantages of Immunotherapy:
- Malignant melanoma was the first cancer where immunotherapy has proven its beneficial role in survival, even in cases where no other treatment was available.
- Recently, the role of immunotherapy has been proven in conjugation with other cancer treatment modalities like chemotherapy.
- There are lesser toxic effects compared to chemotherapy.
- It is also postulated that it may develop immune memory where the body can keep on fighting the cancer cells even when it is stopped.
- Unlike chemotherapy, immunotherapy can be a given safely for a longer period, without sustaining serious toxicities.
- Being less toxic, it can be used in relatively weak or unstable patients with due precautions.
Risks of Immunotherapy:
- Increased or decreased weight
- Skin rash
- Hormonal changes, most commonly thyroid function and adrenal function problems
- Liver of kidney function abnormalities
- Infusion or allergic reaction in the form of itching, redness
- Autoimmune reactions against organs of your own body, e.g. heart, brain, pancreas, etc.
- Immunotherapy produces variable responses in various individuals with cancer, in some it may not work as expected
- As compared to chemotherapy, it is more costly at present, as all immunotherapy drugs are imported from other countries in India
How and when is it used:
Immunotherapy drugs are administered intravenously, on a two, three, or four weekly intervals, depending upon the patient’s age, type, and stage of tumor and other similar factors. It is mainly a daycare procedure. Mostly it is used in stage 4 cases to control increasing cancer. However, recently, its role has been proven in the early stages too, before and after surgery or radiotherapy in curative settings.
In case of immunotherapy does not work, it is not affordable or stops working after some time, then the patient can be offered other modalities like surgery, radiation therapy, chemotherapy, targeted therapy, or hormonal therapy depending upon, disease and patient condition. To conclude, immunotherapy is a revolutionary advancement in cancer therapy. When used tactfully, it can produce encouraging benefits in patients’ quality of life and survival.