Monoclonal antibody immunotherapy uses antibodies prepared in the lab. Once the monoclonal antibodies are administered in to the body, they activate other cells involved in immune system to destroy or kill the cancer cells. Monoclonal antibodies are most widely used form of immunotherapy to treat cancer.
The first monoclonal antibodies are produced by fusing mouse myeloma cell with B cell, which produces the specific type of antibody. The cells which are produced from fusing are called as hybrydoma. These hybridoma cells produced as a result of combining B cell producing a specific antibody and a immortal myeloma cell makes hybridoma cell a antibody producing factory. Because the antibodies produced from this hybridoma cell are identical, so the name monoclonal antibody (Mab).
Now researchers or scientists can replace parts of mouse monoclonal antibodies with human parts. They are called as chimeric or humanized monoclional antibodies.
Many monoclonal antibodies are approved by FDA (Food and Drug Administration) as safe and effective form of cancer therapy.
Types of Monoclonal Antibodies used in cancer treatment:
Naked Monoclonal Antibodies:
Naked monoclonal antibodies are used as it is without attaching them to a radioactive material or toxin or drugs. This is the most commonly used form of immunotherapy to treat cancer. Some examples are
It is used to treat patient with B-cell non-Hodgkinn lymphoma. Rituximab produced against B cell CD20 antigen.
Ofatumumab is used to treat patient with chronic lymphocytic leukemia. This is also a monoclonal antibody produced against CD20 antigen.
Alemtuzumab is used to treat patient with B-cell chronic lymphocytic leukemia. These monoclonal antibodies are produced against CD52 antigens, which are present in both B cell and T cell. Hence they activate the host immune system against the cancer.
Trastuzumab is used to treat patient with HER2/neu positive breast cancer. It is a monoclonal antibody stops the activation of HER/neu protein there by stoping the cancer cell growth.
Cetuximab is used to treat patient with advanced colorectal cancer and head and neck cancer. These antibodies are produced against EGFR protein, which play a very important role in tumor cell growth and cell division. When EGFR protein activation is blocked by monoclonal antibody Cetuximab it stops the cancer cell growth and division.
Conjugated Monoclonal Antibody:
Monoclonal antibodies that are attached with drug or toxins or radioactive substances are known as conjugated monoclonal antibody. Here monoclonal antibodies used as vehicles to deliver drug or toxins specifically to cancer cells.
Monoclonal antibodies tagged with radioactive substances are known as radiolabeled and therapy is called as radioimmunotherapy. Monoclonal antibodies labelled with drugs are known as chemolabeled. Monoclonal antibodies attached with toxins are known as immunotoxins.
Two radiolabelled monoclonal antibodies are used to treat cancer they are
1. Ibritumomab tiuxetan used to treat patient with B-cell non-Hodgkin lymphoma. These antibodies directly deliver radioactive substance to cancerous B lymphocytes.
2. Tositumomab are used to treat patient with rituximab resistant non-Hodgkin lymphoma.
Compared to other forms of therapy monoclonal antibody therapy induce mild side effect in cancer patients. Side effects like fever, weakness, low blood pressure or vomiting may be seen in some patients.
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