Monoclonal antibody therapy offers patients of certain types of cancer an extra option as part of overall cancer treatment. However, because it is a relatively new therapy it’s important for patients to research this option thoroughly, understanding how they work and what the risks are.
What are monoclonal antibodies and how do they work? Monoclonal antibodies are molecules created in a lab that attach to the defects in a cancer cell. They mimic natural antibodies found in the immune system created to fight germs and other invaders. Monoclonal antibodies serve four purposes once they attach to the cancer cells: (a) ‘Highlights’ the cancer cell. A well-functioning immune system attacks and gets rid of invaders but doesn’t always recognize cancer cells as invaders, which is why it often continues to spread. The Monoclonal antibody helps to make the cancer cells more visible; (b) Stop the rapid growth of cancer cells. On the surface of normal and cancer cells, chemicals called ‘growth factors’ signal the cell to grow. Cancer cells make extra copies of these growth signals which is why they grow and spread faster than regular cells. The antibodies help to block the growth signals from getting through; (c) New blood vessels are prevented from developing. Another thing the growth signals do is attract blood vessels to the cancer cell providing them with oxygen and nutrients to thrive. The monoclonal antibodies blocking the growth signals also ‘starve’ the tumor by blocking a needed blood supply; and (d) Helps direct radiation. Doctors can combine the monoclonal antibody with a radioactive particle so radiation can be sent right to a cancer cell. This procedure helps reduce damage to surrounding healthy cells. The key here is that this form of radiation/monoclonal antibodies send low levels of radiation for longer periods of time and seems to be just as effective as the higher doses of radiation.
How are the monoclonal antibodies administered? The therapy is done intravenously. The length of treatment depends on the type of cancer being treated and the sorts of drugs the patient is on. The antibodies can be used alone or in conjunction with other treatments. Because many of these therapies are still considered experimental, they are usually used for cancers that are in the advanced stages and not responding to regular treatments.
What are the side effects of monoclonal antibody therapies? There are both common and serious side effects reported:
Common: hives or itching, flu-like symptoms (eg: chills, fatigue, fever and/or muscle aches), nausea, diarrhea and skin rashes.
Serious: infusion reactions, dangerously low blood cell counts, heart problems, skin problems and bleeding.
What are the various types of monoclonal antibodies? The following is a list of reported FDA-approved monoclonal antibodies used in cancer treatment and the forms of cancer each is used for:
Alemtuzumab (Campath) – chronic lymphocytic leukemia
Bevacizumab (Avastin) – brain, breast, colon, kidney and lung
Cetuximab (Erbitux) – colon, head and neck
Ibritumomab (Zevalin) – non-Hodgkin’s lymphoma
Ofatumumab (Arzerra) – Chronic lymphocytic leukemia
Panitumumab (Vectibix) – Colon
Rituximab (Rituxan) – chronic lymphocytic leukemia and non-Hodgkin’s lymphoma
Tositumomab (Bexxar) – non-Hodgkin’s lymphoma
Trastuzumab (Herceptin) – breast and stomach
Monoclonal antibody therapy is used in treating many forms of cancer. However, because it is still considered experimental, it’s important to discuss this form of cancer therapy in detail with your doctor before deciding whether it’s right for you.
MayoClinic.com: Monoclonal antibody drugs for cancer treatment: How they work (January 22, 2011)