Colorectal Cancer

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Treating Colon/Rectum Cancer TOPICS

Targeted therapies for colorectal cancer

As researchers have learned more about the gene and protein changes in cells that cause cancer, they have been able to develop newer drugs that specifically target these changes. These targeted drugs work differently from standard chemotherapy (chemo) drugs. They often have different (and less severe) side effects. They can be used either along with chemo or by themselves if chemo is no longer working.

VEGF targeted drugs

Bevacizumab (Avastin®), ramucirumab (Cyramza®), and ziv-aflibercept (Zaltrap®) are drugs used for colon cancer that target vascular endothelial growth factor (VEGF). VEGF is a protein that helps tumors form new blood vessels to get nutrients (a process known as angiogenesis).

Bevacizumab and ramucirumab are monoclonal antibodies, which are man-made versions of immune system proteins. These drugs are typically combined with chemo to treat advanced colon cancer.

Ziv-aflibercept is a different kind of protein that targets VEGF. It can also be combined with chemo to treat advanced colon cancer, although it was approved to be combined only with a certain chemo combination.

These drugs are given as infusions into a vein (IV) every 2 or 3 weeks.

When combined with chemo, these drugs can help patients with advanced colon or rectal cancers live longer, but they do come with some side effects.

Common side effects include high blood pressure, tiredness, bleeding, low white blood cell counts, headaches, mouth sores, loss of appetite, and diarrhea.

Rare but possibly serious side effects include blood clots, severe bleeding, holes forming in the colon (called perforations), heart problems, and slow wound healing. If a hole forms in the colon it can lead to severe infection and may require surgery to correct.

EGFR targeted drugs

Cetuximab (Erbitux®) and panitumumab (Vectibix®) are both monoclonal antibodies that specifically attack the epidermal growth factor receptor (EGFR), a molecule that often appears in high amounts on the surface of cancer cells and helps them grow.

Cetuximab is used in metastatic colorectal cancer, either as part of first-line treatment or after other treatments have been tried. Most often it is used either with irinotecan or by itself in those who can't take irinotecan or whose cancer is no longer responding to it.

Panitumumab is used to treat metastatic colorectal cancer, usually after other treatments have been tried.

About 4 out of 10 colorectal cancers have mutations (defects) in the KRAS gene, which make these drugs ineffective. Doctors now commonly test the tumor for this gene change and only use these drugs in people who do not have the mutation. Doctors may also test for a mutation in the BRAF gene, which would also indicate that these drugs would not work.

Both of these drugs are given by IV infusion, either once a week or every other week.

The most common side effects are skin problems such as an acne-like rash on the face and chest during treatment, which in some cases can lead to infections. The skin problems with panitumumab can be more serious and lead to the skin peeling off. Other side effects may include headache, tiredness, fever, and diarrhea.

A rare but serious side effect of these drugs is an allergic reaction during the infusion, which could cause problems with breathing and low blood pressure. You may be given medicine before treatment to help prevent this.

Other targeted drugs

Regorafenib (Stivarga®) is another targeted drug for advanced colorectal cancer. It is a type of targeted therapy known as a kinase inhibitor. Kinases are proteins on or near the surface of a cell that transmit important signals to the cell's control center. Regorafenib blocks several kinase proteins that either prompt tumor cells to grow or help form new blood vessels to feed the tumor. Blocking these proteins can help stop the growth of cancer cells.

In a study of patients who had already been treated with most of the other drugs used to treat colorectal cancer, regorafenib helped these patients live on average about 6 weeks longer.

This drug is given in pill form. Common side effects include fatigue, decreased appetite, hand-foot syndrome (redness and irritation of the hands and feet), diarrhea, sores in the mouth and throat, weight loss, voice change, infections, and high blood pressure. Some serious side effects that can occur include liver damage, severe bleeding, and perforations in the stomach or intestines.

You can learn more about targeted drugs in our document Targeted Therapy.

Last Medical Review: 10/15/2014
Last Revised: 08/13/2015