Browser does not support script.
Skip to main content
search here
Macmillan and Cancerbackup merged in 2008. Together we provide free, high quality information for people affected by cancer through our publications, website and phone service. Find out more|.
Find out how we produce our information|
Biological therapies use substances that occur naturally in the body to destroy cancer cells. There are several different types of biological therapies. The main ones used to treat rectal cancer are monoclonal antibodies| called cetuximab (Erbitux®)| and panitumumab (Vectibix®)|.
These drugs can be used to treat some cases of rectal cancer that have spread outside of the bowel (stage 4, advanced or metastatic cancer).
Monoclonal antibodies are drugs that recognise and lock onto specific proteins (receptors) that are present in particular cancer cells. Because of this they are often called targeted therapies, because they ‘target’ the cancer cells.
Some cancer cells have proteins known as epidermal growth factor receptors (EGFRs). When other proteins in the body known as growth factors attach to these receptors, the cancer cell is stimulated to grow and divide.
The monoclonal antibodies cetuximab (Erbitux®) and panitumumab (Vectibix®) lock onto the EGFR, stopping growth factors from attaching, and so may prevent the cancer cell from growing and dividing.
Cetuximab is usually given in combination with the chemotherapy drug irinotecan, although it can be used on its own. It’s given as a drip (infusion) into a vein. Panitumumab is also given as an infusion into a vein and usually in combination with chemotherapy.
Not all rectal cancers respond to cetuximab or panitumumab. Before having either drug your doctors will test the cancer cells for a gene called KRAS. Knowing if the KRAS gene is normal or mutated can help the doctors decide whether cetuximab or panitumumab will be appropriate for you.
The National Institute for Health and Clinical Excellence (NICE), which advises doctors about treatment, has recommended the use of cetuximab in combination with chemotherapy for some people who have advanced (metastatic) rectal cancer that has spread to the liver. Treatment with the combination of cetuximab and chemotherapy may make it possible to remove the secondary cancers in the liver using surgery.
The NICE guidance doesn’t recommend cetuximab for everyone in this situation and your cancer specialist can discuss with you whether cetuximab is recommended for you. Currently, NICE doesn’t recommend panitumumab.
Another monoclonal antibody called bevacizumab (Avastin®)|, which works in a slightly different way, can also be used to treat advanced cancers of the rectum that have not been controlled by other chemotherapy combinations. Bevacizumab works by preventing the cancer from developing a new blood supply, and so starves the cancer of oxygen and nutrients.
Drugs that interfere with blood vessel growth in this way are called angiogenesis inhibitors or anti-angiogenics. NICE doesn’t currently recommend bevacizumab and as a result it may not be possible to get it on the NHS.
Some people can have an allergic reaction to monoclonal antibodies. This can make you have a flu-like reaction, a drop in blood pressure or feel sick|. Other possible side effects include skin rashes and tiredness|. With some monoclonal antibodies, the first dose is given slowly, over a number of hours. You may be given some other drugs first to make a reaction less likely.
For answers, support or just a chat, call the Macmillan Support Line free (Monday to Friday, 9am-8pm)
If you have any questions about cancer, need support or just want someone to talk to, ask Macmillan.