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Trade/other name(s): Vectibix

Why would this drug be used?

This drug is used to treat colorectal cancers that have that have certain genetic markers (see “How does this drug work?”). It is being studied for use against other cancers as well.

How does this drug work?

Panitumumab is a type of immunotherapy known as a monoclonal antibody. A monoclonal antibody is a man-made version of an immune system protein that fits like a lock and key with one certain protein.

Panitumumab is designed to seek out and lock onto a protein called epidermal growth factor receptor (EGFR), which is found on certain cells in the body. Some cancer cells have more than the usual number of these proteins on their surfaces, which helps them grow and survive. Panitumumab attaches to these proteins and stops their activity, which helps stop cancer cells from growing and dividing. It may also help by tagging the cancer cells to be destroyed by the body’s immune system.

In colorectal cancer, this drug does not work if the cancer cells have certain gene changes. Your doctor will test your cancer cells to be sure the cells do not have these gene changes before starting treatment with this drug.

Before taking this medicine

Tell your doctor…

  • If you are allergic to anything, including medicines, dyes, additives, or foods.
  • If you have ever had any type of lung disease. In rare cases, this drug may damage the lungs, which could make lung function worse.
  • If you have any other medical conditions such as kidney disease, liver disease (including hepatitis), heart disease, congestive heart failure, diabetes, gout, or infections. You may need to be watched more closely while being treated, or the drug dose, regimen, or timing may need to be changed.
  • If you are pregnant, trying to get pregnant, or if there is any chance of pregnancy. This drug may cause problems if it is given at the time of conception or if a woman gets it during pregnancy (see “Precautions”).
  • If you are breast-feeding. While no studies have been done, this drug may pass into breast milk and affect the baby. Women should avoid breast-feeding during treatment and for 2 months after receiving the last does of panitumumab.
  • If you think you might want to have children in the future. This drug has been shown to reduce fertility in some animals and may affect humans as well. Talk with your doctor about the possible risk with this drug and options that may preserve your ability to have children.
  • About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs. In fact, keeping a written list of each of these medicines (including the doses of each and when you take them) with you in case of emergency may help prevent complications if you get sick.

Interactions with other drugs

The use of panitumumab along with chemotherapy and bevacizumab (Avastin) might raise the risk of side effects, some of which might be serious or even life-threatening.

No other serious interactions are known at this time, but this does not necessarily mean that none exist. Check with your doctor, nurse, or pharmacist about your other medicines, herbs, and supplements, and whether alcohol can cause problems with this medicine.

Interactions with foods

No serious interactions with food are known at this time. Check with your doctor, nurse, or pharmacist about whether some foods may be a problem.

Tell all the doctors, dentists, nurses, and pharmacists you visit that you are taking this drug.

How is this drug taken or given?

Panitumumab is given by infusion into a vein (IV), usually once every 2 weeks. The dose is usually given over 60 minutes, although larger doses are given over 90 minutes. The total dose depends on your weight.

You will be watched closely during the infusion for possible signs of an infusion reaction. If you have a mild infusion reaction, your doctor or nurse will likely slow the rate at which the drug is given. If you have a more serious reaction, treatment may need to be stopped entirely.

Further treatments may need to be delayed if you develop a serious skin or lung problem. If the symptoms improve, treatment may be started back at a lower dose. Your doctor may stop the drug if the symptoms are severe or last for more than a month.


About 9 out of 10 people have problems with the skin, mouth, nails, or eyes. This is most often seen as redness or an acne-like rash on the face, neck, and trunk that starts during the first few weeks of treatment and goes away a few months after treatment is stopped. It may become severe in about 1 out of 10 people, with problems such as infections (redness, swelling, tenderness, or pus) or cracking skin. To help reduce skin effects, use sunscreen and hats, and limit time in the sun. Tell your doctor right away if you have rash, sores, signs of skin infection, or other skin, mouth, eye or vision problems. Treatment with this drug may need to be delayed or stopped completely.

Rarely, a more serious skin reaction can happen, starting with fever, sore throat, and trouble swallowing, along with redness and soreness of the eyes, mouth, throat, and other mucous membranes. On the skin it can start as a painful red rash or purple spots and evolve into blisters. This is called Stevens-Johnson syndrome or toxic epidermal necrolysis; it can become life-threatening and must be treated quickly.

Infections can happen when your skin is affected. If you notice pus or tenderness, or if you have other signs of infection such as chills or fever (100.5° or higher), call your doctor right away. Serious skin infections known as necrotizing fasciitis have been reported with this drug, as have blood infections (sepsis), which can be life-threatening.

This drug may cause diarrhea, especially if given along with certain chemotherapy drugs such as irinotecan. In some cases the diarrhea may be severe. If left unchecked, this could lead to dehydration, chemical imbalances in the body, and even kidney failure. Tell your doctor right away if you have loose stools or watery diarrhea.

This drug can cause infusion reactions in some people when the drug is given, especially with the first treatment. Mild reactions often consist of fever and chills. More serious reactions happen in about 1 out of 100 people, but can be dangerous. Symptoms can include feeling lightheaded or dizzy (due to low blood pressure), fever or chills, hives (raised itchy welts on the skin), nausea, itching, headache, coughing, shortness of breath, tightness in the throat, or swelling of the face, tongue, or eyes. Tell your doctor or nurse right away if you notice any of these symptoms during or after being given the drug. If you develop serious symptoms, treatment with this drug may need to be stopped.

In rare cases, patients have developed severe lung disease during treatment. Tell your doctor right away if you notice any changes in your breathing or any lung problems such as coughing, wheezing, or shortness of breath.

Call your doctor if you have numbness, muscle cramps, tremors, or twitching that you can’t control. This may be a sign of a low magnesium level in the blood.

Your doctor will likely test your blood throughout your treatment, looking for possible effects of the drug on blood counts or on blood chemistry levels. Based on the test results, you may be given medicines to help treat any effects. Your doctor may also need to reduce or delay your next dose of this drug, or even stop it altogether.

This drug might harm the fetus if it is given at the time of conception or during pregnancy. Women of childbearing age who are getting this drug and men taking this drug who have partners who might become pregnant should use some type of effective birth control during treatment and for 6 months after the last dose. Check with your doctor about what kinds of birth control can be used with this medicine. This drug should be used during pregnancy only if the potential benefit is thought to justify the possible risk to the fetus.

Possible side effects

You will probably not have most of the following side effects, but if you have any talk to your doctor or nurse. They can help you understand the side effects and cope with them.


  • Skin rash (redness or rash on face, neck, and trunk; acne; dryness, cracking, and itching), which may worsen with sun exposure*
  • Feeling tired
  • Diarrhea*
  • Constipation
  • Abdominal pain
  • Changes in or loss of fingernails or toenails*
  • Low blood levels of magnesium, which can cause numbness, weakness, tremors, or irregular heartbeat*

Less common

  • Nausea
  • Vomiting
  • Redness or irritation of the eyelids and the white part of the eye (conjunctivitis)
  • Mouth sores
  • Cough
  • Swelling of feet
  • Growth of eyelashes
  • Infections of the skin or around the nails, some serious*


  • Infusion reaction (may include fever, headache, dizziness, chills, itching, hives, nausea, shortness of breath)*
  • Damage to the lungs*
  • Blood clots in the lungs
  • Rash with fever, painful red or purple rash, mouth or throat redness and pain*
  • Redness or ulcerations of the eyeball (including the cornea, the clear part of the eye)
  • Deaths due to infections, lung damage, infusion reactions, serious skin reactions, or other causes

*See the “Precautions” section for more detailed information.

There are other side effects not listed above that can also occur in some patients. Tell your doctor or nurse if you develop these or any other problems.

FDA approval

Yes – first approved in 2006.

Disclaimer: This information does not cover all possible uses, actions, precautions, side effects, or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for talking with your doctor, who is familiar with your medical needs.

Last Medical Review: 11/12/2014
Last Revised: 11/12/2014