Monoclonal antibodies are a more specific therapy than chemotherapy, meaning that they are directed at a target that is primarily located on tumour cells, as opposed to normal body cells. Monoclonal antibody drugs are treatments that enlist natural immune system functions to fight cancers. These drugs may be used in combination with other treatments. Not only does this make for very effective lymphoma treatment, it also greatly reduces the side effects, as normal cells are minimally affected.
How do monoclonal antibodies work?
Tne way the immune system attacks foreign substances in the body is by making large numbers of antibodies. An antibody is a protein that sticks to a specific protein called an antigen. Antibodies circulate throughout the body until they find and attach to the antigen. Once attached, they can recruit other parts of the immune system to destroy the cells containing the antigen.
Researchers can design antibodies that specifically target a certain antigen, such as one found on cancer cells. They can then make many copies of that antibody in the lab. These are known as monoclonal antibodies (mAbs).
Several monoclonal antibodies are available for the treatment of NHL and many more are under clinical investigation. The most commonly used monoclonal antibody in the treatment of lymphoma is MabThera® (rituximab).
How does MabThera work?
- MabThera is a monoclonal antibody that tightly attaches itself to the CD20 antigen on the surface of B-cells, the cancerous cell in many types of NHL. The CD20 antigen is also present on the surface of healthy, non-cancerous B-cells, which means that MabThera will also attach to and facilitate the destruction of these cells. However, normal B-cells, like all blood cells, are made from stem cells in the bone marrow, and these stem cells do not have the CD20 antigen. This means that they are not affected by MabThera and so are not destroyed.
- Stem cells can then replenish the store of healthy B-cells in the body. So although during treatment with MabThera the number of mature, normal B-cells is temporarily reduced, their levels return to normal once the treatment is completed. MabThera is a commonly used treatment for patients with either indolent or aggressive NHL. It is used on its own or in combination with chemotherapy and has been shown to increase the length of remission in indolent (slow growing) NHL. It can also increase a person’s chance of cure in aggressive (fast-growing) NHL.
How is MabThera given?
- MabThera is given intravenously and can be given alone or in combination with chemotherapy, often increasing the effectiveness of chemotherapy treatments. Medications are given prior to MabThera to prevent side effects occurring during the intravenous infusion. If side effects do occur, the treatment can be given at a slower infusion rate or stopped until the side effects pass. When given on its own MabThera is usually given as four weekly treatments over a 22-day period (cycle).
- When given in combination with chemotherapy, one dose of MabThera is administered with each cycle of chemotherapy treatment. Prolonged treatment with MabThera, called “MabThera maintenance” therapy, may also be given for the treatment of people with follicular NHL who have responded to their initial MabThera treatment.
- The MabThera maintenance therapy is generally given once every three months for a period of two years. This ongoing MabThera treatment has been shown to sustain the response obtained from the initial therapy and may improve survival for people with follicular lymphoma.
Are there side effects from MabThera monoclonal antibody therapy?
- Unlike the side effects associated with chemotherapy and radiation, most of the side effects from MabThera treatment are minor and short-lived, lasting only during the actual infusion and for a few hours afterwards. The chances of experiencing side effects also decrease with each treatment received because the person adjusts to the treatment and, as treatment continues, there are fewer lymphoma cells to kill.
- The most common side effects are flu-like symptoms including fever, chills and sweating. Less common side effects include nausea, vomiting, rashes, fatigue, headache, wheezing, infection, and a sensation of tongue or throat swelling. People are monitored throughout their treatment infusion session for signs of allergic reactions including itching, rashes, wheezing and swelling.
- If these symptoms occur, the treatment is slowed down or stopped for a short time until the symptoms subside. An antihistamine (e.g. Benadryl) and paracetamol are commonly given before treatment to avoid allergic reactions.
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