What is immunotherapy for cancer? Different that treatment such as chemotherapy that is toxic to cancer, immunotherapy uses medications to cause the immune system to attack cancer. Some block receptors that allow the immune system to see the cancer. Others may stimulate the anti cancer immune response. The immune system is dynamic and once it is effectively taught how to attack cancer the responses can be more durable.
To have the best chance at generating an immune response, combination immunotherapy is usually needed. This is because cancer is adaptive and cancer generally evade a single pronged approach to treatment.
There are several types of immunotherapy treatments:
- Monoclonal antibodies
- Therapeutic Antibodies
- Oncolytic virus therapy
- T-cell therapy
- Cancer vaccines
Combining several of these together is more effective. However to use more combinations the medications work better when injected into the tumor, called intratumoral immunotherapy. This allows for more extensive combinations and a better chance at an immune response. In addition it often has less side effects. This is a systemic treatment and once the immune cells are taught in one location they will attack cancer in other areas of the body.
Antibodies are proteins that fight infection, and when the body’s immune system detects something harmful, it produces these antibodies.
Monoclonal antibodies are a laboratory made specific type of therapy. They may be used in a variety of ways such as a targeted therapy to block an abnormal protein in a cancer cell. The immune system has a difficult time targeting cancer cells already. This is because cancer starts when cells become altered and start to grow out of control. The immune system doesn’t always recognize cancer cells as foreign so when monoclonal antibodies are used as an immunotherapy, some of these attach to specific proteins on cancer cells. This will flag the cells so the immune system can find and destroy them.
Therapeutic antibodies are antibodies made in the laboratory that are designed to cause the destruction of cancer cells. One class of therapeutic antibodies, called antibody drug conjugates (ADCs), has proven to be very effective. Several have been approved by the Food and Drug Administration (FDA) for the treatment of different cancers.
ADCs are created by chemically connecting antibodies, or fragments of antibodies, to a toxic substance. The antibody portion of the ADC allows it to connect to a target molecule that is on the surface of cancer cells. The toxic substance can be a bacterial toxin, a small-molecule drug or a radioactive compound. Once an ADC binds to a cancer cell, it is taken up by the cell and the toxic substance kills it.
Several FDA approved ADC drugs have been used to treat various cancerous diseases. The ADC drug known as Kadcyla® has been used to fight breast cancer while others such as Adcetris® has been used in the treatment of Hodgkin lymphoma and a type of non-Hodgkin T-cell lymphoma. Zevalin®, another FDA approved ADC, has been used for the treatment of non-Hodgkin B-cell lymphoma.
Oncolytic virus therapy
Oncolytic virus therapy uses genetically modified viruses to kill cancer cells. A medical professional will inject a virus into the tumor which will then enter the cancer cells and makes copies of itself. As a result, the cells burst and die. Specific substances called antigens are then released as the cells die. This triggers the patient’s immune system to target all the cancer cells in the body that have those same antigens.
T-cells are immune cells that fight infection. In T-cell therapy, some T-cells are removed from a patient’s blood then the cells are changed in a laboratory so they have specific proteins called receptors. The receptors allow those T-cells to recognize the cancer cells. The changed T-cells are grown in large numbers in a lab and returned to the patient’s body. Once in the body, they seek out and destroy cancer cells.
A vaccine is another method used to help the body fight cancer. The vaccine works by exposing the immune system to an antigen which triggers the immune system to recognize and destroy that antigen. The two types of cancer vaccines are prevention vaccines and treatment vaccines. Doctors will give prevention vaccines to healthy children and adults to protect the body from viruses that can lead to cancer or other diseases, but the patient must receive it before the virus is contracted. The two types of cancer prevention vaccines approved by the FDA are the HPV vaccine and Hepatitis B vaccine. Many health articles on cancer try to stress the importance of getting vaccinated for these viruses that can lead to cancer.
The hepatitis B vaccine prevents the hepatitis B virus (HBV) infection which can cause liver cancer after a long lasting-infection. The HPV vaccine protects against human papillomavirus (HPV). If the virus is long-lasting, it can cause several different types of cancer such as anal cancer, genital warts and cervical, vaginal, and vulvar cancers. It is important to remember that immunotherapy treatments for cancer work better for some than it does for others.
Treatment vaccines are different from the vaccines that work against viruses. These vaccines try to get the immune system to fight 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. The treatment vaccine Sipuleucel-T (Provenge®) is used to treat prostate cancer. It is the only vaccine approved in the United States to treat cancer so far.
For additional help on understanding immunotherapy as a treatment for cancer, please visit williamscancerinstitute.com