Targeted Therapy Drugs for Colorectal Cancer
As researchers have learned more about the gene and protein changes in cells that cause cancer, they have developed newer drugs to specifically target these changes. Targeted drugs work differently from standard chemotherapy (chemo) drugs. They sometimes work when standard chemo drugs don’t, and 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.
Drugs that target blood vessel formation (VEGF)
Vascular endothelial growth factor (VEGF) is a protein that helps tumors form new blood vessels to get nutrients (a process known as angiogenesis). Drugs that stop VEGF from working can be used to treat some colon or rectal cancers. These include:
- Bevacizumab (Avastin)
- Ramucirumab (Cyramza)
- Ziv-aflibercept (Zaltrap)
These drugs are given as infusions into your vein (IV) every 2 or 3 weeks, typically along with chemotherapy. When combined with chemo, these drugs can often help patients with advanced colon or rectal cancers live longer.
Possible side effects of drugs that target VEGF
Common side effects of these drugs include high blood pressure, tiredness, bleeding, low white blood cell counts (with increased risk of infections), 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.
Another 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.
Drugs that target cells with EGFR changes
Epidermal growth factor receptor (EGFR) is a protein that often appears in high amounts on the surface of cancer cells and helps them grow. Drugs that target EGFR can be used to treat some advanced colon or rectal cancers. These include:
- Cetuximab (Erbitux)
- Panitumumab (Vectibix)
Both of these drugs are given by IV infusion, either once a week or every other week.
About 4 out of 10 colorectal cancers have mutations (defects) in the KRAS or NRAS gene, which make these drugs ineffective. Doctors now commonly test the tumor for these gene changes before treatment, and only use these drugs in people who do not have these mutations. Doctors may also test for a mutation in the BRAF gene, which would also indicate that these drugs would not work.
Possible side effects of drugs that target EGFR
The most common side effects of these drugs are skin problems such as an acne-like rash on the face and chest during treatment, which can sometimes lead to infections. The skin problems with panitumumab can be more serious and might lead to the skin peeling off. Other side effects can 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 therapy drugs
Regorafenib (Stivarga) 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 help tumor cells grow or help form new blood vessels to feed the tumor. Blocking these proteins can help stop the growth of cancer cells.
This drug is used to treat advanced colorectal cancer, typically when other drugs are no longer helpful. It is taken in pill form.
Common side effects include:
- Loss of appetite
- Hand-foot syndrome (redness and irritation of the hands and feet)
- Sores in the mouth and throat
- Weight loss
- Voice change
- High blood pressure
Less common but more serious side effects can include
- Liver damage
- Severe bleeding
- Perforations in the stomach or intestines
To learn more about targeted drugs, see Targeted Therapy.
Last Medical Review: October 15, 2015 Last Revised: January 20, 2016