Immunotherapy: New weapon to fight Cancer
Immunotherapy is a novel frontier for cancer treatment. It has a unique mechanism of action by which it harnesses the body’s own immunity to fight cancers.
Conceptually chemotherapy and targeted therapy target cancer cells. Chemotherapy kills the rapidly dividing cells especially cancer cells. Targeted therapy is designed to target cancer cells with specific molecular abnormality. Contrary to this immunotherapy guides our immune cells to identify and kill cancer cells. Thus immunotherapy is completely different from chemotherapy or targeted therapy.
How is it given?
Immunotherapy is generally administered as an injection via intravenous drips.
Checkpoint inhibitors and CAR T cell have revolutionized the field of immuno oncology. Checkpoint inhibitors are used in advanced solid malignancies while CAR T cells are used in some hematological malignancies.
Physiologically immune cells don’t destroy one own’s cell as physiologically some brakes are kept from activating immune cells. This is how self-destruction of our own cells is prevented. But cancer cells take advantage of this mechanism by deactivating our immune cells and thus hiding their identity to immune cells. Checkpoint inhibitors prevent this deactivation and thus helps the immune system to identify cancer cells. Checkpoint inhibitors are either CTLA4 inhibitors or PD1 inhibitor or PDL1 inhibitor.
Checkpoint inhibitors are generally used in following advanced cancers.
- Lung Cancer
- Skin cancer
- Head and Neck Cancer
- Urinary Bladder cancer
- Kidney cancer
- Hodgkin Lymphoma
- Breast cancer
- Gastrointestinal Cancers
The beauty of checkpoint inhibitor is that it can have sustained response even in advanced cases which is largely unusual for these tumors.
Toxicity profile of checkpoint inhibitor is completely different from traditional chemotherapy. Early identification and prompt management of toxicity is a must. This requires expert multidisciplinary management.
CAR T cells
CAR T cell therapy is the one in which T cells are genetically engineered to identify cancer cells eg CD19 CAR for ALL and CLL. CAR T cells have been successfully tried in some blood cancers. It is also being actively researched in other cancers.
As of now majorly Immunotherapy is to control the disease. Cost implications are huge for immunotherapy. A fraction of a patient can have long term survival. It is almost impossible to identify that fraction. So decided to take immunotherapy should always be taken after discussing with your treating oncologists.