Biological therapies (targeted therapies) for colon cancer

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 colon cancer are monoclonal antibodies and include bevacizumab (Avastin®)|, cetuximab (Erbitux®)| and panitumumab (Vectibix®)|.

They can be used to treat some cases of colon cancer that have spread outside the bowel (stage 4, advanced or metastatic cancer).

Research trials are trying to find out whether, for stage 3 colon cancer, giving monoclonal antibodies, as well as chemotherapy, after surgery can further reduce the chance of the cancer coming back.

How monoclonal antibodies work Back to top

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.

Not all colon 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 changed (mutated) can help the doctors to decide whether cetuximab or panitumumab will be appropriate for you.

Bevacizumab (Avastin®) 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.

How the drugs are given Back to top

Cetuximab is usually given in combination with chemotherapy|, although it can be used on its own. It’s given as a drip (infusion) into a vein. Panitumumab is usually given on its own as an infusion into a vein.

Bevacizumab is given as an infusion through a small tube (cannula) inserted into a vein. It may be given in combination with chemotherapy drugs.

The National Institute for Health and Clinical Excellence (NICE), which advises doctors about treatment, have recommended the use of cetuximab in combination with chemotherapy for some people who have advanced (metastatic) colon 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. Your cancer specialist can discuss with you whether cetuximab is recommended for you. Currently, panitumumab is not recommended by NICE.

Bevacizumab can also be used to treat advanced cancers of the colon that have not been controlled by other chemotherapy combinations. Bevacizumab is currently not recommended by NICE and as a result it may not be possible to get it on the NHS.

Side effects Back to top

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.