About monoclonal antibodies

MABs are a type of biological therapy. Monoclonal just means all one type. So each MAB is a lot of copies of one type of antibody. It is now possible to make MABs in a laboratory.

There is information about antibodies and the immune system in our section about your body.

Monoclonal antibodies are designed to recognise and find specific proteins on cancer cells. Each monoclonal antibody recognises one particular protein. Different types of cancer have different proteins. So different antibodies have to be made to target different types of cancer.

Many different monoclonal antibodies are already available to treat cancer. Some are licensed to treat particular types of cancer. Some newer types are still in clinical trials. Different monoclonal antibodies cause different side effects. It can take a long time to develop this type of treatment because some monoclonal antibodies are very complicated.

There are 3 main types of monoclonal antibodies and they work in slightly different ways. They may

• Trigger the immune system to attack cancer cells
• Stop cancer cells from taking up proteins
• Carry cancer drugs or radiation to cancer cells

Trigger the immune system

Some monoclonal antibodies trigger the immune system to attack and kill cancer cells. Although cancer cells are abnormal, they develop from normal cells so they can be difficult for the immune system to spot. Some monoclonal antibodies simply attach themselves to cancer cells, making them easier for the cells of the immune system to find them. These include

• Rituximab (Mabthera) for non Hodgkin’s lymphoma (NHL) and some types of leukaemia
• Alemtuzumab (MabCampath) for chronic lymphocytic leukaemia (CLL)

Below is a short video showing how monoclonal antibodies work when they trigger the immune system. Click on the arrow to watch it.

Stop cancer cells from taking up proteins

Some monoclonal antibodies work by seeking out cancer cells that have too many growth factor receptors. The MABs then block the receptors so the cancer cell can’t receive the signal to grow. This type of MAB includes

• Trastuzumab (Herceptin) for breast cancer and stomach cancer
• Bevacizumab (Avastin) for advanced bowel cancer, breast cancer and some other cancers
• Cetuximab (Erbitux) for advanced bowel cancer or in trials for other cancers
• Panitumumab (Vectibix) for advanced bowel cancer

Another monoclonal antibody researchers are looking at is pertuzumab (Omnitarg). The growth factor receptor HER2 is found on some breast cancer and prostate cancer cells. Pertuzumab blocks (inhibits) this receptor. 

Below is a video showing how monoclonal antibodies work when they stop cancer cells making proteins. Click on the arrow to watch it. 

Carry cancer drugs or radiation to cancer cells

Some monoclonal antibodies have drugs or radiation attached to them. The MAB finds the cancer cells and delivers the drug or radiation directly to them. These are called conjugated MABs.

MABs that have a radioactive substance attached are still in clinical trials. They include

• Ibritumomab (Zevalin) – in trials for non Hodgkin’s lymphoma (NHL) and some other cancers
• Tositumomab (Bexxar) – in trials for non Hodgkin’s lymphoma (NHL)

MABs that have a drug attached are still in clinical trials. They include

• Gemtuzumab ozogamicin (Mylotarg) – for acute leukaemia
• ADEPT – for bowel cancer

Another monoclonal antibody researchers are looking into is brentuximab. Brentuximab targets a receptor called CD30 that is found on most Hodgkin's lymphoma cells. This monoclonal antibody has a chemotherapy drug attached to it called vedotin. Brentuximab attaches to the CD30 receptor delivering the chemotherapy directly to the cell. 

Below is a video showing how monoclonal antibodies work when they carry cancer drugs or radiotherapy to cells. Click on the arrow to watch it. 

There is more information about individual monoclonal antibodies in the cancer drug section and in the treatment sections for each type of cancer. Because some of these treatments are very new, you may find this information in the specific research pages for each type of cancer.

You have monoclonal antibody treatment through a drip (infusion) into a vein. How often you have treatment and how many treatments you need will depend on

• Which monoclonal antibody you have
• The type of cancer you have

All treatments have side effects. Some side effects depend on the type of cell the MAB is targeting. And whether the MAB has a drug or radioactive substance attached to it.

The most common side effect of all monoclonal antibodies is an allergic reaction to the drug. This reaction is most likely to happen when you first have the treatment. You will have paracetamol and an antihistamine drug before you have the treatment to prevent a reaction. If you have a reaction, your doctor or nurse can usually control it by slowing down or stopping the drip for a while.

An allergic reaction can include these symptoms, though you may not have all of them

• Chills
• Fever
• An itchy rash
• Feeling sick
• Breathlessness
• Wheezing
• Headaches
• Flushes and faintness
• Changes in blood pressure

You can find more information about the side effects of individual biological therapy drugs in the cancer drugs section.