Monoclonal antibody is the laboratory made antibody which is used for the research purposes. It reacts with only one foreign protein or antigen and is mainly used for the diagnosis of cancer.

Scientists have developed drugs using monoclonal antibodies to treat the patients of caner. Though these drugs are very new for the cancer treatment but scientists are hopeful that they will be a better in curing the disease.

Mode of action of antibody drug:-

Increase visibility of cancer cells:-
When the monoclonal antibody drug enters the body, it binds to the surface of the cancerous cells. Due to this binding, the cells become visible to the immune system of the body. Though immune system attacks the foreign objects in the body which cause harmful effects in the body but usually it happens that the immune system does not consider cancerous cells as enemies that is why it does not attack them. But when a monoclonal attaches to the cell surface, it can be easily recognized by the immune system and can be destroyed.

Rituximab, a monoclonal antibody drug which attaches to the specific protein present in the white blood cells. When the drug attaches to the protein present in the B cells or white blood cells, it makes the cancerous cells more visible to the immune system and it can attack them easily.

Blockage of growth signals:-
There are certain growth factors or chemicals in the body which are attached to the receptors of the cells which are normal in function. They are also attached on the cancer cells, but cancer cells make multiple copies of these growth factors due to which they reproduce rapidly than the normal cells. The function of monoclonal antibody drug is that it blocks the receptors and growth signals are blocked.

Scientists have developed a monoclonal antibody drug, Cetuximab which is used for treating the colon, head and neck cancer. This drug attacks the receptors by blocking the growth signals to reach to the receptors. When the signals block, it will be difficult for the cancer cells to grow. So the growth of the cells will slow down or will completely stop.

Cancer cells and delivery of radiation:-
If the monoclonal antibody is attached with a radioactive particle, it will be easy for the doctors to detect cancer cells as this radiation will deliver directly to the cells. in this method, the healthy cells of the body remain undamaged and only the cancer cells will be destroyed. The level of radiation attached with monoclonal antibody is very low but affect remains for a long period of time.

For this purpose a drug has been developed named Ibritumomab which performs the same function. This drug attaches the radioactive particle with the monoclonal antibody and attacks the cancerous cells by blocking the receptors receiving the growth signals.

Transfer of powerful cells into the cancer cells:-
In this way, the drugs having powerful effects can be attached to the monoclonal antibody; it does not show its effects until it reaches into the target cancer cell. To perform this function, Gemtuzumab, a monoclonal antibody drug has been developed which acts against the leukemia. The drug attaches to the antibody and enters the target cell blocking its activity.

Doctors administer these drugs through a vein. Sometimes, these drugs can be used along with the other treatments of cancer disease. When these drugs were developed they were only used for the advanced level cancers which could not be cured with chemotherapy or radiation therapy but now these drugs can be used at any level of the disease.

Side effects of monoclonal antibody drugs:-
Though monoclonal antibodies are very effective in treating the cancer but they also have some side effects which can be very serious. Patient can have itching or flue like symptoms. Other symptoms are fever, muscle aches, nausea and diarrhea. Some of the rare but very serious side effects may be the low blood counts. The patient's body may not produce enough red blood cells or white blood cells which can be dangerous. There is a risk of heart failure or minor heart attack while using monoclonal antibodies. Some of the drugs may cause bleeding because new blood vessels do not form during the use of these drugs.

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