Today, world is witnessing remarkable advancements in the field of anti-cancer treatment. Latest in the list is “immunotherapy”. The concept of immunotherapy is based on boosting body’s own immune cells to kill or control growth of cancer cells. Unlike chemotherapy, where chemotherapy drugs kill cancer cells, immunotherapy drugs have no direct effect over 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 check point inhibitors are the ones who are most promising. Out of these, immune check point inhibitors have gained maximum popularity. Currently, there is hardly a 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 body’s own defence mechanism can kill cancer cells. Immune check point 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 agent and then killing them. Now there are technologies available- where these antibodies can be produced outside body. These antibodies attach to protein expressed on the cancer cells.
Anti PDL1/PD1 : Nivolumab (opdyta/opdivo), atezolizumab, durvalumab, pembrolizumab (keyturda), avelumab.
Anti CTLA-4 antibody : Ipilumab
Issues with these medications are listed below:
1) Different kind of side-effect profile: Since these drugs mediate anticancer activity via stimulation of immune mechanisms- there is always a possibility of causing hyper stimulation. This can result in immune cells to release 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 diarrhoea and pain abdomen. Also, joint pain, endocrine problems, fatigue, can occur. Mild cases can be managed with over the counter medications. However with rising degree of severity-addition of immunosuppressant drugs such as steroids and in many cases, temporary withholding of immunotherapy drug is required.
2) Cost: These drugs are new in market and they come at substantial cost. To conclude, immunotherapy in cancer treatment has ushered 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.