Cancer immune therapy
Immunotherapy is treatment that uses your body’s own immune system to help fight cancer. Get information about the different types of immunotherapy and the types of cancer they are used to treat. Immune system is a collection of organs, special cells, and substances that help protect you from infections and some other diseases. Immune cells and the substances they make travel through your body to protect it from germs that cause infections. They also help protect you from cancer in some ways.
What is cancer immunotherapy ?
Immunotherapy is treatment that uses certain parts of a person’s immune system to fight diseases such as cancer. This can be done in a couple of ways.
- Stimulating your own immune system to work harder or smarter to attack cancer cells
- Giving you immune system components, such as man-made immune system proteins
Some types of immunotherapy are also sometimes called biologic therapy or biotherapy.
For a long time doctors suspected that the immune system could affect certain cancers. Even before the immune system was well understood, William Coley, MD, a New York surgeon, first noted that getting an infection after surgery seemed to help some cancer patients. In the late 1800s, he began treating cancer patients by infecting them with certain kinds of bacteria, which came to be known as Coley toxins. Although he had some success, his technique was overshadowed when other forms of cancer treatment, such as radiation therapy, came into use.
Since then, doctors have learned a great deal about the immune system and how it might be used to treat cancer. In the last few decades immunotherapy has become an important part of treating some types of cancer. Newer types of immune treatments are now being studied for many other types, and they’ll impact how we treat cancer in the future.
Immunotherapy includes treatments that work in different ways. Some boost the body’s immune system in a very general way. Others help train the immune system to attack cancer cells specifically.
What the immune system does ?
Your immune system is a collection of organs, special cells, and substances that help protect you from infections and some other diseases. Immune cells and the substances they make travel through your body to protect it from germs that cause infections. They also help protect you from cancer in some ways.
It may help to think of your body as a castle. Germs like viruses, bacteria, and parasites are like hostile, foreign armies that are not normally found in your body. They try to invade your body to use its resources, and they can hurt you in the process. Your immune system is your body’s defense force. It helps keep invading germs out, or kills them if they do get into your body.
The immune system keeps track of all of the substances normally found in the body. Any new substance in the body that the immune system doesn’t recognize raises an alarm, causing the immune system to attack it. Substances that cause an immune response are called antigens. The immune response can destroy anything containing the antigen, such as germs or cancer cells.
Germs have substances on their outer surfaces, such as certain proteins, that are not normally found in the human body. The immune system sees these foreign substances as antigens and attacks them.
Cancer cells are also different from normal cells in the body. They sometimes have unusual substances on their outer surfaces that can act as antigens. But germs are very different from normal human cells and are often easily seen as foreign, whereas cancer cells and normal cells have fewer clear differences. Because of this, the immune system doesn’t always recognize cancer cells as foreign. Cancer cells are less like soldiers of an invading army and more like traitors within the ranks of the human cell population.
Clearly there are limits on the immune system’s ability to fight cancer on its own, because many people with healthy immune systems still develop cancer. Sometimes the immune system doesn’t see the cancer cells as foreign because the cells are not different enough from normal cells. Sometimes the immune system recognizes the cancer cells, but the response might not be strong enough to destroy the cancer. Cancer cells themselves can also give off substances that keep the immune system in check.
To overcome this, researchers have found ways to help the immune system recognize cancer cells and strengthen its response so that it will destroy them.
Most of us know about vaccines given to healthy people to help prevent infections, such as measles and chicken pox. These vaccines use weakened or killed germs like viruses or bacteria to start an immune response in the body. Getting the immune system ready to defend against these germs helps keep people from getting infections.
Most cancer vaccines work the same way, but they make the person’s immune system attack cancer cells. The goal is to help treat cancer or to help prevent it from coming back after other treatments. But there are some vaccines that may actually help prevent certain cancers.
Vaccines to help prevent cancer
Many people might not realize it, but some cancers are caused by viruses. Vaccines that help protect against infections with these viruses might also help prevent some of these cancers.
Some strains of the human papilloma virus (HPV) have been linked to cervical, anal, throat, and some other cancers. Vaccines against HPV may help protect against some of these cancers.
People who have chronic (long-term) infections with the hepatitis B virus (HBV) are at higher risk for liver cancer. Getting the vaccine to help prevent HBV infection may therefore lower some people’s risk of getting liver cancer.
These are traditional vaccines in that they target the viruses that can cause certain cancers. They may help protect against some cancers, but they don’t target cancer cells directly. These types of vaccines are only useful for cancers known to be caused by infections.
But most cancers, such as colorectal, lung, prostate, and breast cancers, are not thought to be caused by infections. Doctors are not yet sure if it’s possible to make vaccines to prevent these other cancers. Some researchers are now trying, but this research is still in very early stages. Even if such vaccines prove to be possible, it will be many years before they become available.
Vaccines to help treat cancer
Cancer treatment vaccines are different from the vaccines that work against viruses. These vaccines try to get the immune system to mount an attack against cancer cells in the body. Instead of preventing disease, they are meant to get the immune system to attack a disease that already exists.
Some cancer treatment vaccines are made up of cancer cells, parts of cells, or pure antigens. Sometimes a patient’s own immune cells are removed and exposed to these substances in the lab to create the vaccine. Once the vaccine is ready, it’s injected into the body to increase the immune response against cancer cells.
Vaccines are often combined with other substances or cells called adjuvants that help boost the immune response even further.
Cancer vaccines cause the immune system to attack cells with one or more specific antigens. Because the immune system has special cells for memory, it’s hoped that the vaccine might continue to work long after it’s given.
Sipuleucel-T (Provenge ®)
This is the only vaccine approved so far by the US Food and Drug Administration (FDA) to treat cancer. It is used to treat advanced prostate cancer that is no longer being helped by hormone therapy.
For this vaccine, immune system cells are removed from the patient’s blood and sent to a lab. There they are exposed to chemicals that turn them into special immune cells called dendritic cells. They are also exposed to a protein called prostatic acid phosphatase (PAP), which should produce an immune response against prostate cancer.
The dendritic cells are then given back to the patient by infusion into a vein (IV). This process is repeated twice more, 2 weeks apart, so that the patient gets 3 doses of cells. Back in the body, the dendritic cells help other immune system cells attack the prostate cancer.
Although the vaccine doesn’t cure prostate cancer, it has been shown to help extend patient’s lives by several months on average. Studies to see if this vaccine can help men with less advanced prostate cancer are now being done.
Side effects are usually mild and can include fever, chills, fatigue, back and joint pain, nausea, and headache. A few men may have more severe symptoms, including problems breathing and high blood pressure.
Japanese immune vaccine Picibanil (OK-432)
Japan was one of the world’s first countries to resume research on cancer vaccines. After 30 years of research scientists created Picibanil, a streptococcal vaccine. It was approved in Japan as an anticancer agent in 1975. In the ensuing 30 years, since then, a significant amount of data, including clinical as well as experimental studies, has been accumulated. OK-432 has been reported to induce various cytokines, activate immunological cells and thus promote anticancer immunity. It is effectively used to treat lung cancer, breat cancer, thyroid gland cancer, stomach cancer, and, especially effectively, lymphangioma.
The positive effect of Picibanil is based on two-way mechanism of action: direct inhibition of RNA synthesis in tumor cells, as wells as stimulation of host immunity, by inducing many types of cytokines. The cytokine family is responsible for hematopoiesis , and increases the leukocyte and platelet counts by acting on bone marrow cells. These cytokines are also involved in the radiation-protective effect of Picibanil and its promotion of liver regeneration.
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