Targeted (biological) therapies for rectal cancer

Targeted therapies are anti-cancer medicines that work by affecting processes that happen within cancer cells. They interfere with the cells’ ability to grow. They are sometimes called biological therapies.

Targeted therapies are sometimes used to treat bowel cancers that have spread to other parts of the body. They may be given on their own or in combination with chemotherapy.

Targeted therapies that may be used include:

  • cetuximab (Erbitux®)
  • panitumumab (Vectibix®)
  • bevacizumab (Avastin®)
  • aflibercept (Zaltrap®)
  • regorafenib (Stivarga®).

All of these drugs are given into a vein as an infusion (intravenously) except for regorafenib, which is taken as tablets.

Cetuximab (Erbitux®) and panitumumab (Vectibix®) are a type of targeted therapy called EFGR inhibitors. They stop cancer cells from receiving messages that tell them to grow.

Not all bowel cancers respond to cetuximab or panitumumab. Your doctors will test the cancer cells for genes called KRAS and NRAS. Knowing if these genes are normal or changed (mutated) can help the doctors decide whether cetuximab or panitumumab will be appropriate for you.

Cetuximab and panitumumab are often given in combination with chemotherapy.

Bevacizumab (Avastin®), aflibercept (Zaltrap®) and regorafenib (Stivarga®) work by preventing the cancer from developing a blood supply. This deprives the cancer of oxygen and nutrients. Drugs that interfere with blood vessel growth are called angiogenesis inhibitors or anti-angiogenics.

If your cancer specialist thinks that a targeted therapy may be helpful, they will discuss this with you. However, these drugs are not widely available through the NHS. Your cancer specialist can apply for a drug to be funded if they believe it would benefit you. In England, this can be done through the Cancer Drugs Fund. In the other countries of the UK, your cancer specialist can apply to the Health Board (Health and Social Care Board in Northern Ireland) asking for the drug to be made available as an exception to the usual rules.

Side effects

Some targeted therapies can cause an allergic reaction. This may happen when the drug is being given or shortly after. Signs of an allergic reaction can include flu symptoms, a drop in blood pressure or feeling sick (nausea). An allergic reaction is most common with the first dose of the drug. To reduce this risk, the first dose is given slowly over a number of hours. You may also be given drugs to make an allergic reaction less likely.

The most common side effect of cetuximab and panitumumab is a skin rash. Other possible effects include diarrhoea, hair changes and sore eyes.

The most common side effect of bevacizumab, aflibercept and regorafenib is high blood pressure. There is also a small risk they may cause a hole in the bowel (perforation), but this is rare.

You should always tell your cancer specialist if you have any side effects during treatment.