Today, the world is witnessing remarkable advancements in the field of anti-cancer treatment. The latest on the list is “immunotherapy”. The concept of immunotherapy is based on boosting the body’s own immune cells to kill or control the growth of cancer cells. Unlike chemotherapy, where chemotherapy drugs kill cancer cells, immunotherapy drugs have no direct effect on the cancer cells. There are many types of anticancer immunotherapy drugs being tried in the trials. Cancer vaccines, oncolytic viral therapy, T cells, and immune checkpoint inhibitors are the ones that are most promising. Out of these, immune checkpoint inhibitors have gained maximum popularity. Currently, there is hardly any cancer where these drugs are not being tried in a clinical trial.
Cancers cells have certain molecules expressed on their surface. These molecules inhibit immune cells and cause cancer-specific immunosuppression. There are two main class of such molecules: PDL1/ CTLA-4
If by some mechanism if it becomes possible to get rid of these molecules then the body’s own defense mechanism can kill cancer cells. Immune checkpoint inhibitors work in this manner.
These inhibitors come in form of antibodies which are kind of proteins. Antibodies are produced by our body in order to fight infection. They attach to different kinds of proteins expressed on infectious agents and then killing them. Now there are technologies available- where these antibodies can be produced outside the body. These antibodies attach to proteins expressed on the cancer cells.
Anti PDL1/PD1 : Nivolumab (opdyta/opdivo), atezolizumab, durvalumab, pembrolizumab (keyturda), avelumab.
Anti CTLA-4 antibody: Ipilimumab
Issues with these medications are listed below:
- Different kind of side-effect profile:
Since these drugs mediate anticancer activity via stimulation of immune mechanisms- there is always a possibility of causing hyperstimulation. This can result in immune cells releasing metabolites causing damage to normal cells of the body. This can manifest in many ways depending upon which organ is affected most. Gastrointestinal adverse events are most common- manifesting with diarrhea and pain abdomen. Also, joint pain, endocrine problems, fatigue, can occur. Mild cases can be managed with over-the-counter medications. However, with a rising degree of severity-addition of immunosuppressant drugs such as steroids and in many cases, temporary withholding of immunotherapy drugs is required.
These drugs are new in the market and they come at a substantial cost. To conclude, immunotherapy in cancer treatment has ushered in a new era. They have not only added one more line of treatments in many cancers but also offer options to patients where chemotherapy does not work like kidney cancer or melanoma.