Monoclonal antibodies (MABs) are a type of targeted drug therapy. These drugs recognise and find specific proteins on cancer cells.
There are many different MABs to treat cancer. They work in different ways to kill the cancer cell or stop it from growing. They all have names that include 'mab' at the end of their generic name. For example, trastuzumab (Herceptin) and rituximab (Mabthera).
Some MABS help the immune system to attack and kill cancer cells. These MABs are also a type of immunotherapy.
What are monoclonal antibodies (MABs)?
Antibodies are found naturally in our blood and help us to fight infection. MAB therapies mimic natural antibodies but are made in a laboratory. Monoclonal means all one type. So each MAB therapy is a lot of copies of one type of antibody.
Many different MABs are available to treat cancer. They work in different ways and some work in more than one way.
How they work
MABs work by recognising and finding specific proteins on cancer cells.
Each MAB recognises one particular protein. So different MABs have to be made to target different types of cancer. Depending on the protein they are targeting, they work in different ways to kill the cancer cell. Or to stop it from growing.
Many different MABs are already available to treat cancer. Some are licensed to treat a particular type of cancer. And others can be effective against several types of cancer. Some newer types are still in clinical trials.
Ask your doctor or specialist nurse if MABs are used to treat your type of cancer and if they are suitable for you.
Types of monoclonal antibody
MABs work in different ways and some work in more than one way. They may do one of the following:
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 MABs 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 MABs work when they stop cancer cells making proteins.
Monoclonal antibodies that stop cancer cells taking up proteins
For a normal cell to grow and divide proteins bind to receptors setting off a signal telling the cell to divide.
The cell divides into two.
In cancer cells, treatment with monoclonal antibodies can block the signal.
When no signal is sent the cancer cell doesn’t divide
Carry cancer drugs or radiation to cancer cells
Carry cancer drugs or radiation to cancer cells
Some MABs 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 MABs work when they carry cancer drugs or radioactive substances to cells.
MABs which carry radiotherapy or cancer drugs
Radiolabelled MABs seek out cancer cell proteins.
The MAB attaches to the protein.
Radiotherapy is delivered to the cancer cell. The cancer cell dies.
Help your immune system find and kill cancer cells
Some MABS have an effect on the immune system. The immune system is then in a better position to kill cancer cells. Because MABs work in different ways, some of these drugs are also a type of immunotherapy. Examples of how they do this include:
- blocking proteins that stop the immune system working (checkpoint inhibitors)
- attaching to cancer cells, making it easier for the cells of the immune system to find them (a process called antibody-dependent cell-mediated cytotoxicity, or ADCC)
Block signals telling cancer cells to develop a blood supply (anti angiogenic drugs)
Some cancer cells make a protein called vascular endothelial growth factor (VEGF). The VEGF protein attaches to receptors on cells that line the walls of blood vessels within the tumour. This triggers the blood vessels to grow so the cancer can then grow.
Some MABs block vascular endothelial growth factor (VEGF) from attaching to the receptors on the cells that line the blood vessels. These MABs are called anti angiogenic drugs.
How you have them
You usually have MAB treatment through a drip (infusion) into a vein. There are a few MABs you have as an injection under the skin (subcutaneous injection).
How often you have treatment and how many treatments you need will depend on:
- which MAB you have
- the type of cancer you have
Before you have some types of MAB you might need to have tests using some of your cancer cells or a blood sample to find out whether the treatment is likely to work. These tests look for changes in certain proteins or genes.
You cancer specialist can tell you if this applies to your treatment. This is not the case for all MABs and you don’t always need this test.
To test your cancer cells, your specialist needs a sample (biopsy) of your cancer. They might be able to test some tissue from a biopsy or operation you have already had.
Examples of MABS
All MABs have names that include 'mab' at the end of their generic name, for example:
- trastuzumab (Herceptin)
- pertuzumab (Perjeta)
- bevacizumab (Avastin)
- rituximab (Mabthera)
We haven't listed them all here but you can find more information about these and other MABs in our list of cancer drugs.
All treatments have side effects. These can vary depending on the type of MAB you have.
Allergic reaction during treatment
A common side effect of some MABs 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, a steroid 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:
- 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
- flu-like symptoms such as chills, fever, dizziness
- feeling or being sick
Specific side effects
Some MABS have specific side effects which can sometimes be serious. For example, some MABs can cause heart problems or increase your risk of bleeding. Your team will tell you about this before your start treatment.
For more information about the side effects of your treatment, go to the individual drug pages.