Immunotherapy is treatment that is designed to harness the ability of the body’s immune system to combat infection or disease. Immunotherapy might produce an immune response to disease or enhance the immune system’s resistance to active diseases such as cancer. Sometimes referred to as biological therapy, immunotherapy often uses substances referred to as biological response modifiers (BRMs). The body usually only produces small amounts of these BRMS in response to infection or disease, but in the laboratory, large amounts of these BRMs can be generated in order to provide a therapy for cancer, rheumatoid arthritis and other illnesses.
Examples of immunotherapies include monoclonal antibodies, interferon, interleukin-2 (IL-2), and colony-stimulating factors CSF, GM-CSF and G-CSF. Interferon is currently being used to treat hepatitis C and is also being tested, along with IL-2 as a treatment for advanced malignant melanoma. Immunotherapy is being investigated as a means of blocking the inflammation seen in conditions such as Chron’s disease and rheumatoid arthritis.
Immunotherapy, also called biologic therapy, is a type of cancer treatment that boosts the body’s natural defenses to fight the cancer. It uses substances made by the body or in a laboratory to improve or restore immune system function. Immunotherapy may work in these ways:
There are several types of immunotherapy, including:
When the body’s immune system detects something harmful, it produces antibodies. Antibodies are proteins that fight infection.
Monoclonal antibodies are a specific type of therapy made in a laboratory. They may be used in a variety of ways. For example, monoclonal antibodies can be used as a targeted therapy to block an abnormal protein in a cancer cell.
Monoclonal antibodies can also be used as an immunotherapy. For example, some monoclonal antibodies attach to specific proteins on cancer cells. This flags the cells so the immune system can find and destroy those cells.
Other types of antibodies work by releasing the brakes on the immune system so it can destroy cancer cells. PD-1/PD-L1 and CTLA-4 pathways are critical to the immune system’s ability to control cancer growth. These pathways are often called “immune checkpoints.” Many cancers use these pathways to escape the immune system. The immune system responds to the cancer by blocking these pathways with specific antibodies called immune checkpoint inhibitors. Once the immune system is able to find and respond to the cancer, it can stop or slow cancer growth.
The following are examples of immune checkpoint inhibitors:
Clinical trials of monoclonal antibodies are ongoing for several types of cancers.
The side effects of monoclonal antibody treatment depends on the purpose of the drug. For example, the side effects of monoclonal antibodies used for targeted therapy are different than those used for immunotherapy. The side effects of immune checkpoint inhibitors may include side effects similar to an allergic reaction.
Like monoclonal antibodies, non-specific immunotherapies also help the immune system destroy cancer cells. Most non-specific immunotherapies are given after or at the same time as another cancer treatment, such as chemotherapy or radiation therapy. However, some non-specific immunotherapies are given as the main cancer treatment.
Two common non-specific immunotherapies are:
Oncolytic virus therapy uses genetically modified viruses to kill cancer cells. First, the doctor injects a virus into the tumor. The virus enters the cancer cells and makes copies of itself. As a result, the cells burst and die. As the cells die, they release specific substances called antigens. This triggers the patient’s immune system to target all the cancer cells in the body that have those same antigens. The virus does not enter healthy cells.
In October 2015, the U.S. Food and Drug Administration approved the first oncolytic virus therapy to treat melanoma. The virus used in the treatment is called talimogene laherparepvec (Imlygic), or T-VEC. The virus is a genetically modified version of the herpes simplex virus that causes cold sores. The doctor can inject T-VEC directly into areas of melanoma that a surgeon cannot remove. Patients receive a series of injections until there are no areas of melanoma left. Side effects can include:
Researchers are testing other oncolytic viruses for different types of cancer in clinical trials. They are also testing the viruses in combination with other treatments, such as chemotherapy.
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 the laboratory and returned to the patient’s body. Once there, they seek out and destroy cancer cells. This type of therapy is called chimeric antigen receptor (CAR) T-cell therapy.
Known commercially as Provenge, sipuleucel-T is the only vaccine that has received FDA approval as a cancer therapy. The agent is used to treat advanced prostate cancer in cases where hormonal therapy is no longer helping. The process involves removing immune cells from a patient’s blood and sending them to a laboratory where they are exposed to substances that turn them into specialized immune cells referred to as dendritic cells. In addition, they are exposed to the protein prostatic acid phosphatase (PAP) which is intended to initiate an immune attack against prostate cancer cells. These altered cells are then infused back into the patient. The cells are infused again on two more occasions, separated by two weeks, meaning the patient receives three doses of the dendritic cells. The dendritic cells then help other immune cells to destroy the prostate cancer. This has been shown to improve patient survival by several months and the vaccine is currently being investigated to see whether it can be used to treat men with less advanced prostate cancer.
There is currently no treatment that can cure Chron’s disease, but advances in mucosal immunology have led to the discovery of a wide range of new targets for resolving the inflammation seen in this condition. Research suggests that the intestinal inflammation starts because of an aberrant response by the innate immune system that is eventually driven by T cells. Current therapies are focused on inhibiting, altering or suppressing T-cell differentiation and in the UK, the medications azathioprine or mercaptopurine are the most frequently used.
In cases of severe Chron’s disease that is not helped by these drugs, two biological therapies are available that may be used to treat the condition. These powerful immunosuppressants are called infliximab and adalimumab and both work by targeting a protein called tumor-necrosis factor-alpha (TNF-α). TNF- α is a cell signalling protein (cytokine) secreted by T-helper-1 cells that has been shown to play a critical role in the inflammation process seen in Chron’s disease.
Infliximab is administered via intravenous infusion in hospital and adalimumab can be administered via an injection, which the patient or a family member may be able to learn to do themselves.
Rheumatoid arthritis can be treated with disease-modifying antirheumatic drugs (DMARDS) to slow progression of the disease and prevent permanent damage in the joints and other tissues. Examples of these DMARDs include methotrexate, hydroxychloroquine and sulfasalazine. However, in cases where methotrexate or other DMARDs fail to ease symptoms and inflammation, a biological therapy may be recommended to block certain parts of the immune system that contribute to inflammation in this condition. Biological treatments such as etanercept, infliximab or certolizumab are usually taken in combination with a DMARD. They are administered via injection and stop chemicals in the blood from activating an immune response that attacks the joints.
There are two common ways allergists test kids to zero in on the offending allergen(s):