Panitumumab (Vectibix®)

Panitumumab is a type of medication called a monoclonal antibody. Monoclonal antibodies are created in a lab to attach to the targets found on specific types of cancer cells. The antibody “calls” the immune system to attack the cell it is attached to, causing your immune system to kill the cell. These antibodies can work in different ways, including stimulating the immune system to kill the cell, blocking cell growth, or other things needed for cell growth. Panitumumab binds to the epidermal growth factor receptor (EGFR).

This medication only works in cancers with a normal RAS gene (called wild type) and your provider will test for this before starting therapy with panitumumab.

How to Take Panitumumab

Panitumumab is given as an intravenous (IV, into a vein) infusion. The actual dose (based on your body size) and how often you receive this medication will be determined by your healthcare provider.

Possible Side Effects of Panitumumab

There are a number of things you can do to manage the side effects of panitumumab. Talk to your care team about these recommendations. They can help you decide what will work best for you. These are some of the most common or important side effects:

Nail and Skin Changes

Panitumumab can cause some unique nail and skin side effects. You may develop a rash. This rash can be serious. Be sure to tell your provider of any skin changes you notice, as these can become severe. While this rash may look like acne, it is not, and should not be treated with acne medications. The rash may appear red, swollen, crusty, dry, and feel sore. You may also develop very dry skin, which may crack, itch, or become flaky or scaly. The rash often starts in the first week of treatment but can happen at any time during treatment. Tips for nail and skin care include:

• Use a thick, alcohol-free emollient lotion or cream on your skin at least twice a day, including right after bathing.
• Avoid sun exposure, as it can worsen the rash or cause a severe burn. Use sunscreen with an SPF of 30 or higher and wear a hat and sunglasses to protect your head and face from the sun.
• Bathe/shower in cool or lukewarm (not hot) water and pat your skin dry.
• Use soaps, lotions, and laundry detergents without alcohol, perfumes, or dyes.
• Wear gloves to wash dishes or do housework or gardening.
• Drink plenty of water and try not to scratch or rub your skin.
• Call your healthcare team if you notice a rash, as they can give suggestions to manage the rash and/or prescribe medication to apply to the rash or medication you can take by mouth.
• If you develop peeling or blistering of the skin, notify your healthcare team right away.

While receiving panitumumab, you may develop an inflammation of the skin around the nail bed/cuticle areas of toes or fingers, which is called paronychia. It can look red, swollen, or pus-filled. Nails may develop "ridges" in them or fall off. You may also develop cuts or cracks that look like small paper cuts in the skin on your toes, fingers, or knuckles. These side effects may appear several months after starting treatment but can last for many months after treatment stops.

• Follow the same recommendations for your skin (above).
• Don't bite your nails or cuticles. Don't cut the cuticles.
• Keep your fingernails and toenails clean and dry.
• You may use nail polish, but do not wear fake nails (gels, acrylics, overlay).
• Notify your healthcare provider if any nails fall off or you develop any of these side effects or other skin abnormalities.

Fatigue

Fatigue is very common during cancer treatment and is an overwhelming feeling of exhaustion that is not usually relieved by rest. While on cancer treatment, and for a period after, you may need to adjust your schedule to manage fatigue. Plan times to rest during the day and conserve energy for more important activities. Exercise can help combat fatigue; a simple daily walk with a friend can help. Talk to your healthcare team for helpful tips on dealing with this side effect.

Nausea and/or Vomiting

Talk to your oncology care team so they can prescribe medications to help you manage nausea and vomiting. In addition, dietary changes may help. Avoid things that may worsen the symptoms, such as heavy or greasy/fatty, spicy or acidic foods (lemons, tomatoes, oranges). Try saltines, or ginger ale to lessen symptoms.

Call your oncology care team if you are unable to keep fluids down for more than 12 hours or if you feel lightheaded or dizzy at any time.

Diarrhea

Your oncology care team can recommend medications to relieve diarrhea. Also, try eating low-fiber, bland foods, such as white rice and boiled or baked chicken. Avoid raw fruits, vegetables, whole-grain breads, cereals, and seeds. Soluble fiber is found in some foods and absorbs fluid, which can help relieve diarrhea. Foods high in soluble fiber include applesauce, bananas (ripe), canned fruit, orange sections, boiled potatoes, white rice, products made with white flour, oatmeal, cream of rice, cream of wheat, and farina. 

Important but Less Common Side Effects

• Eye Concerns: While receiving panitumumab, some patients may have irritation or damage to the cornea (clear part that covers the eyeball) or changes in their eyesight. Tell your healthcare team if you develop any eye pain, swelling, redness, or any vision changes, including blurriness and sensitivity to light.
• Infusion-Related Side Effects: The infusion can cause a reaction that may lead to chills, fever, or difficulty breathing. Reactions are most common during the first week of therapy, including the evening after the infusion. Your care team will tell you what to do if this happens.
• Lung Problems: Patients can develop inflammation or scarring of the lungs (called pneumonitis or fibrosis), or interstitial lung disease while taking this medication. Tell your healthcare provider right away if you develop any new or worsening symptoms, including shortness of breath, trouble breathing, cough, or fever.
• Electrolyte Abnormalities: This medication can affect the normal levels of electrolytes (potassium, magnesium, calcium, etc.) in your body. Your levels will be monitored using blood tests. If your levels become too low, your care team may prescribe specific electrolytes to be given by IV or taken by mouth. Do not take any supplements without first consulting with your care team.
• Kidney Problems: This medication can cause severe diarrhea and dehydration which can affect your kidney function. Your healthcare team will monitor your kidney function using blood tests.

Sexual and Reproductive Concerns

This medication may affect the reproductive system, resulting in the menstrual cycle becoming irregular or stopping permanently. You may experience menopausal effects including hot flashes and vaginal dryness. In addition, the desire for sex may decrease during treatment. You may want to consider sperm banking or egg harvesting if you may wish to have a child in the future. Discuss these options with your oncology team.

Exposure of an unborn child to this medication could cause birth defects, so you should not become pregnant or father a child while on this medication. For women, effective birth control is necessary during treatment and for at least 2 months after treatment, even if your menstrual cycle stops. For men, effective birth control is necessary during treatment. You should not breastfeed while receiving this medication and for at least 2 months after your last dose.