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Research in immunotherapy
Immunotherapy uses the immune system to help destroy cancer cells. It is sometimes called biological therapy. Some types of immunotherapy are already in use. Immune checkpoint inhibitors (types of monoclonal antibodies), interferon and interleukin are types of immunotherapy being used to treat cancer.
Researchers continue to study other ways of using the immune system to destroy cancer cells. They are also looking at combining different immunotherapies, using immunotherapy with chemotherapy or radiation therapy, giving immunotherapy after surgery and treating earlier stage cancers with immunotherapy.
Monoclonal antibodies are made in the lab. Monoclonal antibodies find and bind to a specific antigen (such as a protein) on a cancer cell or other cells in the body or both. This binding can “flag” a cancer cell to be recognized and destroyed by the immune system or can alter signals that block the immune response, allowing the immune system to attack and destroy cancer cells. Monoclonal antibodies are both an immunotherapy and a targeted therapy.
Researchers are developing new monoclonal antibodies to treat many different types of cancer. One type of monoclonal antibody that researchers are studying is called an immune checkpoint inhibitor. The immune system normally stops itself from attacking healthy cells in the body by having some cells make specific proteins that prevent immune cells from becoming fully active. These are known as checkpoint proteins. Cancer cells sometimes use these checkpoints to avoid being attacked by the immune system. Immune checkpoint inhibitors block checkpoint proteins so that immune system cells can attack and kill the cancer cells.
Researchers are studying ways to make monoclonal antibodies more powerful by attaching them to chemotherapy drugs or other substances. Research is also looking at ways to make them safer and work better.
Cancer treatment vaccines
Most people think of vaccines as something that prevents you from getting a disease or infection. And they’re right – the HPV vaccine, which is already in use, prevents cervical and other HPV-related cancers. But researchers are also developing vaccines to treat cancer. Therapeutic cancer vaccines help the immune system to fight cancer by:
- training the immune system to recognize cancer cells
- increasing the number of immune cells that recognize cancer cells
- stimulating immune cells to kill cancer cells
- preventing the cancer from coming back
Cancer vaccines can be made from different starting materials, depending on the type of cancer being treated.
Tumour cell vaccines can be made from modified or killed cancer cells. The cancer cells are collected from the person with cancer who is being treated or from another person with a similar type of cancer. They are modified (changed) in a lab to make it easier for the immune system to recognize and attack them. These cancer cells are then given radiation to make sure they are all killed and then the killed cancer cells are injected into the person. The injected cancer cells stimulate an immune response so the immune system destroys them and the similar types of cancer cells still in the body.
Antigen vaccines use proteins or parts of proteins (called antigens) that are unique to specific cancers or that are found in higher than normal amounts on cancer cells. When the antigen vaccine is injected into the person, the vaccine causes an immune response that helps the body to attack cancer cells.
Dendritic cell vaccines are made from a person’s white blood cells (immune cells that help fight infection and disease). In the lab, the white blood cells are treated with chemicals that turn them into a specialized type of white blood cell called a dendritic cell. They are then exposed to killed cancer cells or purified antigens found on the cancer cells. The dendritic cells are then injected back into the person, where they help other immune cells in the body become activated to find and attack cancer cells.
Vector-based vaccines are made from viruses, bacteria or yeast cells that have been modified in the lab to deliver antigens found on cancer cells. But the modified viruses, bacteria or yeast won’t cause disease or infection. Vector-based vaccines deliver more than one type of antigen, those from cancer cells and those found on the virus, bacteria or yeast cell. This helps increase the chance that the immune system will mount an attack against the cancer cells in the body. Some research is studying the human immunodeficiency virus (HIV) to treat leukemia.
Oncolytic virus therapy
Oncolytic virus therapy uses a genetically modified virus (a virus that has its genetic information changed) to infect and destroy cancer cells. The virus can be injected directly into the tumour where it goes into cancer cells and makes copies of itself. This causes the cancer cells to burst and die. As the cells die they release antigens and other chemicals that trigger the immune system to start attacking the other cancer cells, including those that haven’t been infected with the virus.
CAR T-cell therapy and adoptive T-cell transfer therapy
Adoptive T-cell transfer therapy uses a person’s own T cells to fight cancer. A T cell is a type of white blood cell and an important part of the immune system. They help fight infection and destroy abnormal cells, including cancer cells.
CAR T-cell therapy takes millions of T cells from a person with cancer. In the lab, they are changed so they have chimeric antigen receptors (CARs) on their surface. These receptors recognize a specific antigen (protein) found on the type of cancer being treated. The T cells are then given back to the person where they multiply, attack and destroy the cancer cells.
CAR T-cell therapy has been approved in the United States for some types of advanced non-Hodgkin lymphoma and for children and young adults with acute lymphocytic leukemia. But at this time in Canada, CAR T-cell therapy is only available through clinical trials.
Another adoptive T-cell therapy uses T cells from a person’s tumour that are able to find cancer, known as tumour infiltrating lymphocytes (TILs). These T cells are grown in large numbers in the lab and then injected back into the person. The goal of this approach is that the large number of T cells given to the person will find, attack and destroy the remaining cancer cells in the body.
Predicting who is likely to benefit from immunotherapy
Predicting which people with cancer are most likely to benefit from immunotherapy is an important area of research.
The immunoscore is a measure of T-cell markers detected inside a tumour. T cells are an important part of the immune system. They are often found in the area that surrounds cancer cells within a tumour (called the tumour microenvironment). Researchers are trying to find out if the immunoscore can help doctors predict which people with cancer are most likely to benefit or unlikely to benefit from immunotherapy.
Biomarkers are substances, such as proteins, genes or pieces of genetic material like DNA and RNA, that are found naturally in the body. They can be measured in body fluids like blood and urine or tissue that has been removed from the body.
PD-1 and PD-L1 are examples of biomarkers that may help predict which people with cancer are most likely to benefit or unlikely to benefit from immunotherapy. PD-1 is an immune checkpoint protein that stops T cells from attacking other cells in the body. It does this by attaching to PD-L1, a protein found on some normal cells and some cancer cells. Some cancer cells have a lot of PD-L1, which helps protect them from being attacked by T cells. Research suggests that the cancers with higher PD-L1 may respond better to PD-1 checkpoint blockade immunotherapy.
A foreign substance that stimulates the immune system to produce antibodies against it.
A foreign substance that stimulates the immune system to produce antibodies against it.
A type of cancer that starts in immune cells of the lymphatic system.
Lymphomas are classified as Hodgkin lymphoma and non-Hodgkin lymphoma.
A type of cancer that starts in the blood-forming tissue in the bone marrow. It causes large numbers of abnormal white blood cells to be produced and enter the bloodstream. These abnormal cells crowd out normal white blood cells, red blood cells and platelets so they can’t work properly.
Leukemias are classified as lymphocytic leukemia or myelogenous leukemia.
The complex group of cells and organs that defend the body against infection, disease and foreign substances.
A treatment that uses and strengthens the immune system to fight disease including cancer.
Immunotherapy is a type of biological therapy.
Making progress in the cancer fight
The 5-year cancer survival rate has increased from 25% in the 1940s to 60% today.