Immunotherapy for cancer is a biological therapy that boosts the body’s immune system to fight foreign substances and abnormal cells of tumors. It either uses substances from the body or from the laboratory to restore the immune system’s ability to function regularly. The immuno-oncology treatment has been used to treat different types of cancer, such as melanoma, lymphoma, kidney, lung, breast, and colon cancer. Several clinical trials of immunotherapy have proved its success. Before we plunge in, let us visit the basics.
What is the immune system?
The immune system includes the tonsils, thymus, lymph nodes, spleen, bone marrow, and white blood cells – each of which has separate functions. The two primary aspects of the immune system are:
- Innate immunity – A natural and ever-functioning defense ability of the body to protect itself from foreign particles or antigens
- Adaptive immunity – Acquired defense system that shields from specific foreign substances, which works in two ways, mediated by two major types of lymphocytes – B-cells and T-cells:
A. Cell-mediated immunity: These are carried out by T-cells
B. Humoral Immunity: These are carried out by activated B-cells and antibodies
What kinds of immuno-oncology treatments are available today?
- Monoclonal antibodies are immune system proteins produced in the lab. These antibodies are designed to attach to specific targets found on cancer cells. These monoclonal antibodies mark cancer cells so that they will be better seen and destroyed by the immune system. Sometimes these monoclonal antibodies are also called as targeted therapy as these are designed to attach to specific targets found on cancer cells.
Examples – Bevacizumab, Trastuzumab
- Immune checkpoint inhibitors– These help the immune system respond more strongly to a tumour. These drugs work by releasing “brakes” that keep T cells (a type of white blood cell and part of the immune system) from killing cancer cells. These drugs do not target the tumor directly. Instead, they interfere with the ability of cancer cells to avoid immune system attack.
Example– Nivolumab, Pembrolizumab
- Treatment vaccines– These work against cancer by boosting your immune system’s response to cancer cells. Treatment vaccines are different from the ones that help prevent disease.
Example- BCG vaccine used in bladder cancer
- Adoptive T cell transfer– Which is a treatment that attempts to boost the natural ability of your T cells to fight cancer. In this treatment, T cells are taken from your tumour. Then those that are most active against your cancer are grown in large batches in the lab. Then these will be given back to you via a needle in your vein. This type is not yet popular in India
- Non-specific Immunotherapy- This includes interferons and interleukins. Interferons help the immune system fight cancer and may slow the growth of cancer cells.
Examples- Interferon alpha and Interleukin-2
- Oncolytic virus therapy- Uses genetically modified viruses to kill cancer cells. First, the doctor injects a virus into the tumor. The virus then enters the cancer cells and makes copies of itself. As a result, the cells burst and die. As the cells die, they release specific substances called antigens. This triggers the patient’s immune system to target all the cancer cells in the body that have those same antigens. The virus does not enter healthy cells
Questions to ask your doctor
Talking with your healthcare team is crucial to making informed decisions about your treatment. Dr. AVS Suresh specializes in advanced treatment therapies like chemotherapy, immunotherapy, and targeted therapies. Watch this video to clarify, but not limiting to, some of the most frequently asked questions.