What is Immunotherapy and how has it changed the landscape of cancer treatment?

What is Immunotherapy?

Immunotherapy is a type of cancer treatment that boosts your immune system to fight cancer. The immune system is made up of white blood cells and organs and tissues of the lymph system.

What is the rationale for Immunotherapy?

Normally our immune systems detect and destroys any abnormal cells in the body. They also fight against and destroy cancer cells. However, the cancer cells eventually find a way to avoid destruction by the immune system. They do this by becoming less visible to the immune system by turning off proteins on their surface which help in their detection. They also manipulate the defensive T cells around them which interferes in normal immune response to cancer cells. They ultimately create an environment which helps them thrive unchecked.

What does Immunotherapy do?

Immunotherapy helps lift the brakes applied by the Cancer cells on the fighter T cells and thus unleashes a robust immune response. This eventually helps to kill cancer cells and improves survival.

What are the different forms of Immunotherapy?

  1. Immune check point inhibitors - These include PD1, PD L1 & CTLA inhibitors which are essentially drugs which block the inhibitory targets found either on the T cell or the tumor cell so as to produce a robust immune response.
  2. Vaccines – There is only one approved vaccine-based therapy for advanced cancer which is sipuleucel-T, which is an dendritic-cell preparation engineered to target the patient’s own tumor. This has been used in castrate-resistant prostate cancer.
  3. Cytokines – are molecules which effect the inflammatory response to cancer cells. These include drugs like:

a. Interferon Alpha which is used in Melanoma

b. Bacillus Calmette-Guerin (BCG), which is prepared from attenuated bacteria mycobacterium bovis, and is injected directly in the bladder for the treatment and secondary prevention of superficial bladder cancer

What are the different Indications where immunotherapy is used?

Use has been approved in a number of indications including advanced cases of Melanoma, renal cell carcinoma, non-small cell lung cancer, head and neck cancer, urothelial carcinoma, Hodgkin lymphoma, Merkel cell carcinoma

How is Immunotherapy different from Chemotherapy?

Immunotherapy has a much slower onset of action as compared to chemotherapy and patients may even experience transient worsening of condition before tumor stabilizes and regresses. Immunotherapy is better tolerated than chemotherapy with lesser side effects.

What are the side effects of Immunotherapy?

Immunotherapy can lead to inflammation in eyes, liver, kidney, lung, thyroid to name a few. Patients may suffer from breathlessness, diarrhea, dizziness and faintness. The risk of serious side effects is less.

Conclusion: Immunotherapy has helped improve outcomes in many advanced cancers. Future research will help determine the role in other advanced cancers and whether it has a role in early stages of cancer.