Biologic therapies are anti-cancer drugs that work disrupt the processes that take place within cancer cells. These interfere with the cancer cells' capacity to grow.

Biologic therapies are sometimes used to treat colon cancer that has spread to other parts of the body. They can be given alone or in combination with chemotherapy

The targeted therapies that may be used include:

• cetuximab
• panitumumab
• bevacizumab
• aflibercept
• regorafenib

All these drugs are through a vein as an infusion (intravenously) with the exception of regorafenib, which taken in tablet form.

Cetuximab and panitumumab are types of targeted therapy called EGFR inhibitors. These prevent the activation of tumor cells caused by a factor stimulating cell proliferation called epidermal growth factor (EGF).

Not all intestinal cancers respond to cetuximab or panitumumab. Doctors will test the cancer cells for genes called KRAS and NRAS, to know if they have a normal sequence or are mutated, as this information will help them decide if these treatments are appropriate. Cetuximab and panitumumab are often given in combination with chemotherapy.

Bevacizumab, aflibercept, and regorafenib inhibits cancer growth and cuts off blood supply, thus depriving the cancer of oxygen and nutrients.

Drugs that interfere with the growth of blood vessels are called angiogenesis inhibitors or anti-angiogenics.

Side effects

Some targeted therapies can cause allergic reactions. This may happen while you are receiving the medication or shortly thereafter. The signs of an allergic reaction may include flu-like symptoms, a drop in blood pressure, or feeling unwell (nausea). Allergic reactions happen more often with the first dose of the drug. To lower this risk, the first dose is given slowly over a number of hours, and drugs are given to make allergic reactions less likely.

The most common side effect of cetuximab and panitumumab is skin rash. Other possible effects include diarrhea, changes to the hair, and soreness in the eyes.

The most common side effect of bevacizumab, aflibercept, and regorafenib is high blood pressure. There is also a slight risk of intestinal perforation, though this is rare.