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. MABs are made in a laboratory.
How monoclonal antibodies work
Monoclonal antibodies recognise and attach to specific proteins produced by 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.
Different monoclonal antibodies cause different side effects.
It can take a long time to develop this type of treatment because making monoclonal antibodies can be very complicated.
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.
Monoclonal antibodies which trigger the immune system to treat cancer
Injected monoclonal antibodies seek out cancer cell proteins.
The monoclonal antibodies bind to the proteins
The antibodies signal to immune cells.
The immune cells arrive and punch holes in the cancer cell. The cancer cell dies.
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).
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.
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
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.
Below is a video showing how monoclonal antibodies work when they carry cancer drugs or radiotherapy to cells.
Monoclonal antibodies which carry radiotherapy or cancer drugs
Radiolabelled monoclonal antibodies seek out cancer cell proteins.
The monoclonal antibody attaches to the protein.
Radiotherapy is delivered to the cancer cell. The cancer cell dies.
All monoclonal antibodies have names that include 'mab' at the end of their generic name, for example:
- trastuzumab (Herceptin)
- bevacizumab (Avastin)
- rituximab (Mabthera)
We haven't listed them all here but you can find more information about these and other individual monoclonal antibody treatments 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 information about these in the specific research pages for each type of cancer.
How you have monoclonal antibodies
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
General side effects of monoclonal treatment
All treatments have side effects. Some side effects depend on the type of cell the MAB is targeting. They may also depend on 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:
- an itchy rash
- feeling sick
- flushes and faintness
- changes in blood pressure