Panitumumab is a biological therapy that can be sued to treat people with cancer of the large intestine (colon and rectum) that has spread to other parts of the body. Panitumumab can also be used to treat other types of cancer as part of a research trial.
WHAT IS PANITUMUMAB?
Panitumumab belongs to a group of cancer drugs known as monoclonal antibodies. Monoclonal antibodies are sometimes called targeted therapies.
HOW DOES PANITUMUMAB WORK?
Some types of cancer have a large number of receptors on their surface called epidermal growth factor receptors (EGFR). When the receptors that activate the cancer cells are activated, they divide and grow.
Panitumumab blocks EGFRs. This stops them from stimulating the cancer cells to divide and grow. Panitumumab is more likely to work in cancers that have a large number of EGFRs on their surface.
Panitumumab only works for intestinal cancers that have a normal KRAS gene. So before cetuximab is used to treat the colon cancer, the cancer cells are tested to see if there are changes (mutations) in the KRAS gene. This helps doctors decide if the treatment is appropriate. Tests can be done using samples of the cancer cells at the same time the patient is diagnosed; alternatively, from previous biopsies or surgery can also be used.
WHEN IS PANITUMUMAB USED?
Panitumumab is used to treat people with colon cancer that has spread to other parts of the body (advanced or metastatic cancer). It can be used as:
- first treatment in combination with the chemotherapy regimen FOLFOX
- as second-line treatment in combination with the chemotherapy regimen FOLFIRI
- on its own (known as monotherapy) after other chemotherapy treatments such as 5FU (fluorouracil), irinotecan, or oxaliplatin have been tried.
WHAT DOES PANITUMUMAB LOOK LIKE?
Panitumumab is a colorless liquid.
Panitumumab is given as a drip into a vein (called intravenous infusion). The treatment is usually given once every two weeks. The first infusion is given slowly over 60-90 minutes. If you don't have a reaction to the infusion, the subsequent infusions will be given over 30 to 60 minutes.
POSSIBLE SIDE EFFECTS OF PANITUMUMAB
Each person reacts differently to cancer treatment. Some people have very few side effects, while others may develop more. The side effects described here will not affect everyone who is treated with the drug.
We outline the most commonly side effects, though we have left out the rarer ones. If you notice you develop any side effects that are not listed here, talk to your doctor or specialist nurse.
The side effects of panitumumab are normally mild, and some can be relieved with drugs. These side effects fall into two groups:
- Infusion-related reactions, which can occur during the infusion or over a maximum of about 24 hours thereafter.
- Other side effects that can happen days or even weeks later.
These are uncommon and affect fewer than 5 out of every 100 given the infusion. If reactions do happen, they are normally mild, though in rare cases they can be severe. You can take drugs before the infusion to reduce the likelihood of having a reaction. If you have a reaction, the drip is usually lowered or stopped until you feel better. Future infusions will be given at a slower pace.
You will be closely monitored during your treatment, though you should tell your nurse or doctor if you feel unwell or have any of the following symptoms:
- flu-like symptoms, such as feeling flushed or having a fever, shivering, or nausea
- red, warm, and itchy bumps on the skin (such as urticaria)
- a feeling of swelling in the lips, tongue, or throat
- breathlessness, wheezing, cough, or sudden difficulty breathing
- back or stomach pain
- chest pain or pressure in your chest.
Rarely, a reaction related to the infusion can happen a couple of hours after the treatment. If you develop these symptoms or feel unwell after you get home, get in touch with your hospital immediately for advice.
OTHER POSSIBLE SIDE EFFECTS OF PANITUMUMAB
The most common side effect of panitumumab is an acne-like rash that normally appears on the head, chest, and back. This usually develops in the first 2-3 weeks of treatment and goes away a few weeks later, once the treatment has concluded.
Your skin may become dry and itchy. Some people find that their nails hurt, become red, and break easily.
These steps may help reduce the effects on your skin, although they won't prevent them entirely:
- When bathing and washing, use tepid water and gentle, unscented soap.
- Avoid using skin products that contain alcohol.
- Do not use anti-acne products, as these can dry out your skin and make your symptoms worse.
- Sunlight can worsen skin symptoms. Apply sunscreen with a minimum SPF of 30 and UVA protection before going outside. If you are taking radiotherapy, ask your cancer specialist whether applying cream or lotion to this area will help.
- Moisturize your skin regularly and after bathing. Your doctor or nurse specialist can recommend skin moisturizers.
- If you wish to weak makeup to hide the rash, choose one that is hypoallergenic.
- Wear rubber gloves when doing household chores and when gardening.
Tell your doctor as soon as possible if you experience changes to your skin or nails. They may prescribe a treatment to help you with this. If your skin problems are severe, the time between treatments can be extended or the dose you take may be lowered.
NAUSEA AND VOMITING
Your doctor can prescribe antiemetic drugs to prevent or greatly reduce your nausea or vomiting. If your nausea remains uncontrolled or continues, tell your doctor.
Some of these drugs can cause constipation. Tell your doctor or nurse if this is a problem.
Panitumumab can cause diarrhea. Normally, this can be easily controlled with drugs, so tell your doctor if your diarrhea is severe or ongoing. It's important to drink lots of fluids if you have diarrhea.
Tiredness is a common side effect, especially toward the end of treatment and for a few weeks after the treatment has finished. It is important that you try to pace yourself and rest as much as you need to. Try to balance this with light exercise, such as taking short walks. If you feel drowsy, don't drive or operate heavy machinery.
CHANGES TO YOUR HAIR
Changes to the hair happen less often than changes to the skin, though they sometimes develop after three months or more.
Your eyelashes may grow longer and become curlier than usual. Men may notice that their beard does not grow as much. You may notice that the hair on your head becomes more fine, curly, or fragile.
Few people have hair loss. If this happens, it normally happens gradually over several months.
These changes are normally temporary and get better little by little once the treatment is over.
RESPIRATORY PROBLEMS OR COUGHING
This is more likely if you have an existing problem with your lungs. Tell your doctor if you notice any increase in your feeling of breathlessness.
SORENESS OF THE MOUTH AND MOUTH ULCERS
Your mouth may become sore or dry or you may develop small ulcers during your treatment. Some find that sucking on ice can help. Drinking lots of fluids and regularly brushing your teeth gently using a soft-bristled toothbrush can help lower the risk of this happening. Tell your doctor or nurse if you have any of these problems, as they can prescribe a mouthwash and drugs to prevent infection in the mouth.
Some people find that panitumumab gives them headaches. Let your doctor or nurse know if this is the case, as they can give you painkillers to help with this.
Tell your doctor if you notice any changes in your vision or if you have any eye pain, reddening, or itchiness. They can prescribe eye drops to help this.
ADDITIONAL INFORMATION ON PANITUMUMAB
Some drugs, including those bought over the counter in a store or pharmacy, may be harmful to you while you are taking panitumumab. Tell your doctor if you are taking any medicines, including over-the-counter medications, complementary therapies, and herbal medicines.
This treatment may affect your ability to conceive. It is important that you talk to your doctor before beginning treatment.
Little is known about the effects of panitumumab on developing babies. Therefore, it is not recommendable to become pregnant while taking this drug.
It is unknown whether panitumumab is present in semen or vaginal fluid. In order to protect your partner, it is safest to avoid having sex or use a barrier contraceptive device for about 48 hours after the chemotherapy.
There is a potential risk that panitumumab may be present in breast milk, and therefore women are recommended not to breast feed during the treatment and for a few months afterward.
If you are admitted to the hospital for any reason not related to cancer, it is important that you tell your doctors and nurses caring for you that you are receiving treatment with panitumumab.