Bladder cancer is very common and is one of the most common types of cancer. Men are more likely to get bladder cancer than women. The risk is also high, especially for the elderly aged 75-84. It is vital to understand that bladder cancer can affect both women and men, regardless of age. It is quite manageable if detected in the early stages but things get tricky if found at advanced stages. Also, this type of cancer is infamous for its recurrence. It has the highest rate of recurrence compared to other cancers.
Very recently, a comparatively new approach to treating this disease has gained attention from many urologists and oncologists all over the world. This treatment uses our very own immune system to battle cancer. As its name suggests, it is known as immunotherapy. Other approaches or their combination have been successful in treating the low grade or in the early stages. But immunotherapy has shown to be effective for advanced stages of bladder cancer which is quite harder to treat. Extensive research is going on to find how to utilise this newer approach both standalone and in combination with other treatment approaches.
A bit about bladder cancer
Any abnormal growth of cells present in the bladder can lead to bladder cancer. Cancer cells usually begin to grow in the inner layer of the bladder, the urinary or transitional epithelium. However, the tumour can grow out of the bladder and spread to the surrounding area. It can spread not only to the lymph nodes but also to other organs such as the lungs and liver (known as metastasis).
So, bladder cancer can occur in the inner linings (non-muscle invasive), in the muscle (muscle-invasive), in local areas (locally advanced), or could spread to other organs (metastatic).
What is immunotherapy?
Described in layman’s terms, immunotherapy is a treatment that bolsters and preps your immune system to combat cancer. It enhances the immune system to locate and attack cancer cells. So, it relies on your immune system and how it interacts with cancer cells. You may find it a bit similar to chemotherapy where we kill cancer cells. But the way of destroying the cancer cells is different. Here, we don’t use the chemo drugs involved in chemotherapy. Also, cells are killed by blocking signals or checkpoints and activating the immune cells.
Treating bladder cancer with immunotherapy
Bladder cancer has many types of mutations. Immunotherapy drugs rely on these mutations to do their jobs. So, it can be helpful to treat patients diagnosed with this type of cancer. As said earlier, it is often used to treat advanced cancer because of its known effectiveness for the later stages. Several immunotherapy drugs have been already approved and are being used in the clinical tests now.
BCG and bladder cancer
BCG stands for Bacillus Calmette-Guérin. It is widely used in immunotherapy of bladder cancer. It has been used for more than 40 years now. It works so well for some while it doesn’t for others. It is a weakened tuberculosis bacteria that is used for preparing tuberculosis vaccines. It is administered in the bladder using a catheter. This can be repeated for several cycles spaced after a specific number of days. It has been quite effective for non-muscle invasive bladder cancer but not for muscle-invasive cancer.
Checkpoint inhibitor drugs
Checkpoints are the signals that stop the immune cells from attacking the normal cells. Healthy cells take the advantage of these signals to stop being attacked by the immune system. Cancer cells also use these signals to hide from the immune cells. Checkpoint inhibitor drugs block these signals on the surface of cancer cells and hence make them susceptible to attacks of the immune cells. Now, T-cells, soldiers of the immune system, can find and attack cancer cells readily. PD-1/PD-L1 and CTLA-4 are some of the checkpoints proteins found on T-cells and cancer cells.
Checkpoint inhibitors for bladder cancer
Some of the checkpoint inhibitor drugs used for bladder cancer that works on the PD-L1 checkpoint protein on the cancer cells are Atezsomeolizumab (Tecentriq), durvalumab (Imfinzi), and avelumab (Bavencio). They help our immune system to find cancer cells posing as normal cells. These also boost our immune response in the process so that the tumour can shrink or cannot grow fast.
Some inhibitor drugs focus on another checkpoint protein ie, PD-1 to help the immune system stay active and detect the cancer cells. These are Nivolumab (Opdivo) and pembrolizumab (Keytruda). So when administered with this drug, our immune cells attack the cancer cells which causes tumours to shrink or at least grow very slowly.
Benefits of immunotherapy
Treatments like chemotherapy have huge side effects on the patients. While immunotherapy does not have adverse effects on the patients like chemo. So, if the person is unable to cope with the side effects of chemo or the chemo is not giving desired results, then immunotherapy can be a great alternative. This treatment has shown to be effective in the advanced stages too. BCG can be used for non-muscle invasive bladder cancer while checkpoint inhibitors work well for muscle-invasive bladder cancer and also for the patients in the later stages(stage 3/4) and also when metastasis has occurred. Sometimes patients cannot undergo surgery due to some complications. Such patients can benefit from this treatment. Often patients respond well to immunotherapy and the risks involved are also very less.
Immunotherapy has revolutionised and brought new hope for better ways of treating bladder cancer. Not only bladder cancer, but immunotherapy also promises to transform the treatment of all types of cancer. Clinical trials are being carried out to explore and develop this way of treating bladder cancer more effectively.