How the Immune System is Transforming Cancer Treatment

Dr SUSHANTKUMAR IKHAR, Senior Medical Oncologist & Hematologist HCG Hospital Nagpur

Immunotherapy is a drug used in the treatment of cancer. It is a new modality of treatment. immunotherapy is given intravenously (injection) usually at 2 or 3 weeks interval. Ipilimumab is the first immunotherapy approved for cancer treatment. there are several others drugs in this category for example Pembrolizumab, Nivolumab , Atezolizumab and Avelumab.

Immunotherapy has been approved in various types of cancer. But it is particularly useful in head and a cancer, skin cancer (melanoma), lung cancer, kidney cancer, breast cancer (triple negative type of breast cancer), food pipe (esophagus) and stomach cancer, and also in large intestine (i.e colon and rectum) cancer.

It is usually used in advance stages of cancer, i.e stage 4; usually it means cancer has spread to other organs of body or when cancer can't be cured with surgery or radiation.

There is general misconception among general population that immunotherapy drug can cure each and every type of cancer. However it's not like that, the response to immunotherapy varies from person to person and from one cancer to another. The response to immunotherapy depends mainly upon the tumor biology also called as tumor micro-environment. This means even if two persons have same kind of cancer and receive same type of immunotherapy , one may response wonderfully while other may not .

Immunotherapy--it is named so because it acts by enhancing or boosting or our immune system. Every person has immune system , it acts by identifying , attacking and then killing foreign cells (cells not belonging to our body`s natural system) like bacteria , virus and other infectious agents. Similarly cancer cells are foreign cells for our immune system- so it tries to kill them , but when cancer evolves or spread , it adapts strategies to evade / stop immune system from working normally. One of the mechanism is to secrete proteins like PD L1 which block our immune system. Immunotherapy acts on these proteins and prevents them from inhibiting by cancer cells leading to enhanced activation and killing of cancer cells by immune cells (Killer T cells).

As Immunotherapy acts indirectly it is devoid of conventional side effects of chemotherapy -like hair loss, weakness, nausea , vomiting , decreased oral intake (anorexia) , fatigue , anemia (decreased RBC) , fever due to infection (due to low white blood cell count) etc. As opposite to this chemotherapy kills cancer cell directly by blocking its cells division . Chemotherapy drugs in process of killing cancerous cells also affect some of our normal body cells hence it has above mentioned side effects. Due to better tolerance immunotherapy (as compared to chemotherapy) can be used in old age

patients or those with comorbidities like uncontrolled diabetes , deranged kidney function , deranged liver function or poor performance status (patient's who are not fit for chemotherapy due to poor functioning level). Most chemotherapies cannot be given in above conditions or are associated with significant toxicities.

It should be noted that most Immunotherapy drug are very costly as compared to conventional chemotherapy drugs. Most health insurance don't cover immunotherapy drugs. However Immunotherapy is not a magic drug which will work in all patients. Physician (Medical oncologist) is best person to determine which drug to be used , depending upon type & stage of cancer, tumor biology , comorbidities , affordability , performance status of patient and affordability. There are certain markers (test done on tumor tissue) like which can be used to predict whether immunotherapy will work or not in a particular cancer.

By - Dr SUSHANTKUMAR IKHAR, Senior Medical Oncologist & Hematologist HCG Hospital Nagpur