Cancer Immunotherapy: What You Need to Know
Immunotherapy is a kind of cancer treatment that activates the immune system’s natural cancer-fighting abilities. Types include immune checkpoint drugs, cancer vaccines and personalized cell therapy.
It’s a relatively new approach to cancer treatment. It is still mostly available through clinical trials. Some therapies have been approved for use in certain types and stages of lymphoma, melanoma, lung, bladder, kidney, and head and neck cancers.
Researchers believe that immunotherapy holds a lot of promise across the cancer spectrum. They are especially optimistic about the impact of immunotherapies when used in combination with each other or with other types of cancer treatment.
What is cancer immunotherapy?
The body’s natural immune system is made up of a complex network of cells and organs that protect the body from infection. Theoretically, the immune system should be able to fight off cancer cells in the same way it fights infections from bacteria or viruses. But when the immune system isn’t strong enough to mount a defense, or when immune cells do not recognize cancer cells as “foreign,” the cancer remains unchecked and is free to grow and spread.
Cancer immunotherapy is a fast-growing field of cancer research which seeks to develop drugs, vaccines and other therapies that trigger the immune system’s natural abilities to fight cancer. As an alternative or addition to standard cancer treatments, immunotherapies have the potential to be effective on even the hardest-to-treat cancers—without many of the harsh side effects typically associated with chemotherapy or radiation therapy.
What are the types of cancer immunotherapy?
Different cancer immunotherapies work in different ways, but each type targets immune cells instead of going after the cancer cells directly. There are a variety of new and emerging types of immunotherapies, but the three that are being widely tested and have shown the most promise in patients, are:
Immune checkpoint blockers
Perhaps the most promising of all immunotherapies, immune checkpoint blockers (also called immune checkpoint inhibitors) are drugs that enable the immune system to fight off cancer by blocking a signal that typically allows cancer cells to hide from immune cells.
The reason why the immune system so often doesn’t fight off cancer, is because tumor cells can use this same checkpoint signal to protect themselves from immune cells. After all, cancer cells stem from healthy cells so they share many of the same characteristics, including the surface proteins that allow them to form the PD-1 pathway with immune cells. When tumor cells put out this signal, they are essentially disguising themselves as normal cells. Immune cells then ignore the cancer, allowing it to grow unchecked.
The body’s normal immune process is that when a virus or bacteria invades the body, immune cells are called to fight off the infection. To protect themselves from also being attacked, healthy cells use a cellular mechanism called a “checkpoint signal” that tells the immune cell not to attack. This signal is created when a protein on the surface of the healthy cell joins — or creates a “pathway” — with a protein on the immune cell called PD-1.
Immune checkpoint blocking drugs target and block the PD-1 pathway so the checkpoint signal is not sent out, and the immune cells can find and kill the cancer. Most checkpoint blockers are referred to as “anti-PD-1” drugs since they target the PD-1 pathway, but there are drugs in clinical testing that target other types of pathways.
The Food and Drug Administration has approved several immune checkpoint blocking drugs, for use in certain types of lymphoma, melanoma, lung, bladder, kidney, and head and neck cancers.
These are different from preventive vaccinations for diseases like polio or meningitis or HPV. Cancer vaccines are a form of immunotherapy which contain molecules that mimic cancer cells, but have cancer-killing antigens on the surface. Immune cells respond by flocking to the area, where they encounter the molecules. The surface antigens are then transferred to the immune cell, giving the immune cell additional cancer-fighting abilities.
A pancreatic cancer vaccine has been available for several years, and researchers continue testing new approaches for how to use it. Other cancer vaccines are being tested, including one that targets cancers that are high in mesothelin, including half of all mesotheliomas and lung, stomach and ovarian cancers.
Personalized cell therapy
Also called adoptive T cell therapy, this is another kind of immunotherapy that increases the body’s population of cancer-fighting immune cells. A type of T cell called marrow infiltrating lymphocytes (MILs) are collected from the patient, then grown and treated with antibodies in the lab. The stronger, more populous MILs are infused back into the patient’s bloodstream to attack cancer cells.
Research is ongoing, but this immunotherapy approach has been successful in some myeloma patients, and scientists have hope that it will carry over to other types of cancer.
More Information About Immunotherapy from Johns Hopkins Medicine
The Final Frontier? Immune Therapies Break Through Cancer’s Protective Barriers
Immune Therapy: A new kind of cancer therapy that empowers the body’s own natural defenses is here and, in some patients, provides unparalleled, long-lasting responses, even in the most advanced and treatment-resistant cancers.
Read more about cancer immunotherapy at Johns Hopkins.
What cancers can be treated with immunotherapy?
There is still so much left to learn, but the vast potential of immunotherapy can be seen in the ever-growing list of cancers that have responded during laboratory and clinical research.
Immunotherapy has been effective in some cancers for some patients: shrinking tumors, extending lives, and prompting drug approvals. In other cancers, immunotherapy offers hints of promise, leading scientists to explore new angles and treatment combinations.