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Immunotherapy is a promising form of cancer treatment that uses the body’s immune system to fight cancer. Some immunotherapies are already available for specific groups of patients, but at the same time, researchers are still working on understanding the precise biological processes that these treatments use to fight cancer.
A research team in Texas recently published a new study that provides insight into how one form of immunotherapy works. These results may help to make the treatment more effective for more people with cancer.
Checkpoint inhibitors promote immune response to cancer
One form of immunotherapy is called a checkpoint inhibitor. Proteins on immune cells and on cancer cells may interact with each other in a way that prevents the immune system from attacking the cancer cells. Checkpoint inhibitors block this interaction, activating the immune system to produce effective cancer-fighting cells.
Checkpoint inhibitors currently target 2 different immune cell proteins. One protein is called PD-1 and is targeted by therapies currently approved for the skin cancer melanoma and for non-small cell lung cancer. The other protein is called CTLA-4 and is targeted by a treatment approved for melanoma.
The lead scientist on the new study, Dr James Allison, was a pioneer in immunotherapy research whose work resulted in the development of ipilimumab, the CTLA-4 checkpoint inhibitor. In the current research, his team set out to gain a detailed understanding of how the different checkpoint inhibitors work and whether they activate the same or different immune system processes to fight cancer cells.
Different checkpoint inhibitors activate different immune cells
The researchers studied how the immune system responded when melanoma tumours were exposed to the checkpoint inhibitors targeting either the PD-1 or CTLA-4 proteins.
They treated the tumours with the different checkpoint inhibitors and looked at the specific types of immune cells that were activated after each treatment. They wanted to understand whether these therapies activated the same types of immune cells, which would indicate whether they use the same biological processes.
The researchers found that there were some similarities in the types of immune cells produced after each treatment, but for the most part, treatment with different checkpoint inhibitors resulted in activation of different, specific groups of immune cells. This finding demonstrates that each checkpoint inhibitor uses a different biological pathway to attack cancer cells.
Checkpoint inhibitors could be used in combination
Immunotherapy for cancer treatment holds a lot of promise, but currently only a small fraction of people with cancer actually benefit from it. In order to unlock its full potential, researchers need a better understanding of exactly how these treatments work so they can improve the current versions.
This research shows that checkpoint inhibitors that appear to act in similar ways actually work using distinct biological processes, involving different types of immune cells. There may even be potential to use these checkpoint inhibitors together, since activating 2 separate immune pathways could be more effective in attacking cancer cells.
More research is needed to confirm these results in more people, but it is an important step forward for researchers in understanding exactly how these new treatments work and how they can make them better.
Eileen Hoftyzer, BSc, and Carolyn Goard, PhD