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Monoclonal antibodies (MABs)

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. They are made in a laboratory.

How they work

Monoclonal antibodies work by recognising and finding specific proteins on cancer cells.

Each monoclonal antibody recognises one particular protein. They work in different ways depending on the protein they are targeting. So different monoclonal 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.

Diagram showing a monoclonal antibody attached to a cancer cell

Types of monoclonal antibody

Monoclonal antibodies work in different ways and some work in more than one way. They may do one of the following:

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.

Below is a short video showing how monoclonal antibodies work when they trigger the immune system.

Block molecules that stop the immune system working (checkpoint inhibitors)

The immune system uses particular molecules to stop it being overactivated and damaging healthy cells. These are known as checkpoints.

Some cancer cells make high levels of checkpoint molecules to switch off immune system cells called T cells. T cells would normally attack the cancer cells. Drugs that block checkpoint molecules are called checkpoint inhibitors.

They are a type of immunotherapy and include drugs that block CTLA-4, PD-1 and PD-L1 (programmed death ligand 1). 

Checkpoint inhibitors include:

  • nivolumab (Opdivo)
  • iIpilimumab (Yervoy)
  • pembrolizumab (Keytruda)

Block signals telling cancer cells to divide

Cancer cells often make large amounts of molecules called growth factor receptors. These sit on the cell surface and send signals to help the cell survive and divide.

Some monoclonal antibodies stop growth factor receptors from working properly. Either by blocking the signal or the receptor itself. So the cancer cell no longer receives the signals it needs.

Below is a video showing how monoclonal antibodies work when they stop cancer cells making proteins. 

Carry cancer drugs or radiation to cancer cells

Some monoclonal antibodies have drugs or radioactive substances attached to them.

The MAB finds the cancer cells and delivers the drug or radioactive substance directly to them. These are called conjugated MABs.

Below is a video showing how monoclonal antibodies work when they carry cancer drugs or radioactive substances to cells.

How you have them

You have monoclonal antibody treatment as an injection under the skin (subcutaneous injection), or through a drip (infusion) into a vein. For some drugs, you have your first treatment into your vein, then further treatments as an injection under your skin. 

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

Examples of monoclonal antibodies

All monoclonal antibodies have names that include 'mab' at the end of their generic name, for example:

  • trastuzumab (Herceptin)
  • pertuzumab (Perjeta)
  • bevacizumab (Avastin)
  • rituximab (Mabthera)
  • nivolumab (Opdivo)
  • ipilimumab (Yervoy)

We haven't listed them all here but you can find more information about these and other monoclonal antibody treatments in our list of cancer drugs. 

Ask your doctor or specialist nurse if targeted drugs are used to treat your type of cancer and if they are suitable for you.

Side effects

All treatments have side effects. These can vary depending on the type of MAB you have. They also depend on whether the MAB has a drug or radioactive substance attached to it.

Allergic reaction during treatment

A common side effect of some monoclonal antibody treatment is an allergic reaction to the drug. This reaction is most likely to happen during treatment and when you first have the treatment. 

If this is possible with your drug, you might have paracetamol and an antihistamine drug before treatment to prevent a reaction.

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

  • breathlessness
  • fever and chills
  • an itchy rash
  • flushes and faintness

Your nurse will monitor you and treat any symptoms if they happen.

General side effects

Side effects might include:

  • skin changes such as red and sore skin or an itchy rash
  • diarrhoea
  • tiredness
  • flu like symptoms such as chills, fever, dizziness
  • feeling or being sick
Contact you doctor or nurse if you have these symptoms, particularly if you have diarrhoea, a rash or flu like symptoms. They can decide whether you need treatment.

For more information about the side effects of your treatment, go to the individual drug pages. 

Last reviewed: 
27 Nov 2014
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  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. If you need additional references for this information please contact patientinformation@cancer.org.uk with details of the particular issue you are interested in.

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