Panitumumab (Vectibix®) is a targeted therapy drug used to treat bowel cancer that has spread to other parts of the body.
How panitumumab works
Panitumumab is a type of drug called a monoclonal antibody. These drugs are sometimes called targeted therapies. They work by ‘targeting’ specific proteins (receptors) on the surface of cells.
Certain cancers have receptors on their surface called epidermal growth factor receptors (EGFRs). A protein called epidermal growth factor activates them, causing the cancer cells to grow. Panitumumab locks on to the EGFRs and stops this happening.
When treating bowel cancer, panitumumab only works on bowel cancers that have a normal RAS gene. The RAS gene helps control cell growth. Before panitumumab is used, doctors test the bowel cancer cells for changes (mutations) in this gene.
Panitumumab can be used to treat people with bowel cancer that has spread to other areas of the body (advanced or metastatic). It can be given with chemotherapy. Or it can be given on its own after chemotherapy treatments have been tried.
Panitumumab may only be available in some situations. Your cancer doctor can tell you if it is suitable for you. Some people may be given it as part of a clinical trial. If a drug is not available on the NHS, there may be different ways you are still able to have it. Your cancer doctor can give you advice.
How panitumumab is given
A nurse gives you panitumumab as a drip into a vein (intravenous infusion). You have the first infusion slowly, usually over about 60 minutes.
If you do not have any problems, you can have your next treatment over 30 to 60 minutes.
Some people are given higher doses of panitumumab. These infusions are given over about 90 minutes. You usually have panitumumab once every two weeks.
We have included the most common side effects of panitumumab here. We have not included all the less common and rarer side effects. You may get some of the side effects we mention, but you will not get them all. Always tell your doctor or nurse about any side effects you have.
If you have chemotherapy with panitumumab, some side effects may be worse. You may also have side effects not listed here. We have more information about chemotherapy.
Your doctor can give you drugs to help control some side effects. It is important to take them exactly as your nurse or pharmacist has explained. This will help the drugs work as well as possible for you.
Your nurse will give you advice about managing side effects. After your treatment is over, the side effects will start to improve.
Serious and life-threatening side effects
Some cancer treatments can cause severe side effects. Rarely, these may be life-threatening. Your cancer doctor or nurse can explain the risk of these side effects to you.
Contact the hospital
Your nurse will give you telephone numbers for the hospital. If you feel unwell or need advice, you can call them at any time of the day or night. Save these numbers in your phone or keep them somewhere safe.
We cannot list every side effect for this treatment. There are some rare side effects that are not listed. You can visit the electronic Medicines Compendium (eMC) for more detailed information.
Side effects during the infusion
About 1 in 20 people (5%) have an allergic reaction to panitumumab. It is most likely to happen when the drug is being given or for up to an hour afterwards. You may be given drugs before the infusion to reduce the chance of a reaction.
If you have a reaction, the nurses usually treat this by slowing the infusion. You will have the rest of your treatments at a slower rate. A reaction is usually mild, but rarely it can be more severe.
You will be monitored closely during treatment. But tell your nurse or doctor if you feel unwell or have any of the following symptoms:
- flu-like symptoms, such as a headache, feeling flushed, or having a fever, chills or dizziness
- red, warm and itchy bumps on the skin (like nettle rash)
- a feeling of swelling in the lips, tongue or throat
- breathlessness, wheezing, a cough or sudden difficulty breathing
- a tight chest or chest pain.
Rarely, people may get a reaction up to 24 hours or more after treatment. If you have any of these symptoms or feel unwell after you get home, contact the hospital straight away.
Skin and nail changes
Most people having panitumumab will have skin changes during treatment.
The most common side effect is an acne-like rash on the face, neck and body. This usually begins during the first 2 or 3 weeks of treatment and goes away a few weeks after treatment ends.
Your skin may also become dry, itchy or scaly, and it may feel tender. The skin around your nails may become red and sore. Your nails may become brittle and break.
Very rarely, people may have a severe skin reaction. The symptoms can include large blisters, peeling skin or sores in the mouth. You may also have a fever (high temperature). Contact the hospital straight away if this happens.
Always tell your doctor or nurse about any skin changes. They can give you advice and prescribe creams or medicines to help. If you have severe skin problems, your doctor may suggest a longer time between treatments or a lower dose of panitumumab.
Your eyelashes may grow longer and curlier. You may notice that your head and body hair is finer, curlier or more brittle. Men may notice less beard growth. Some people may lose their hair. This may happen slowly over several months. These changes usually improve when treatment is over. We have more information about coping with hair loss.
Effect on blood cells
Risk of infection
If your number of white blood cells is low, you are more likely to get an infection.
Contact the hospital straight away if:
- your temperature goes over 37.5°C (99.5°F)
- you suddenly feel unwell, even if your temperature is normal
- you have symptoms of an infection.
Symptoms of an infection include:
- feeling shivery
- a sore throat
- a cough
- needing to pass urine often.
Anaemia (low number of red blood cells)
This treatment can reduce the number of red blood cells in your blood. These cells carry oxygen around the body. If the number of red blood cells is low, you may be tired and breathless. Tell your doctor or nurse if you feel like this.
If you are very anaemic, you may need a drip to give you extra blood cells. This is called a blood transfusion.
Your doctor can give you anti-sickness drugs to help prevent or control sickness. If you still feel sick, tell your doctor. They can prescribe other anti-sickness drugs that may work better for you.
Diarrhoea or constipation
You may have diarrhoea or tummy pain. Some people become constipated, but this is less common. Your doctor can give you drugs to help. If you are also having chemotherapy, diarrhoea may be more severe. Follow any instructions the hospital give you. If you have diarrhoea or constipation, make sure you drink at least two litres (three and a half pints) of fluids every day.
Sore mouth and ulcers
Your mouth may become sore or dry and you may get small ulcers. This can make you more likely to get an infection in your mouth. Gently clean your teeth or dentures morning and night and after meals. Use a soft-bristled or children’s toothbrush. Your nurse might advise you to use mouthwashes. It is important to follow any advice you are given and to drink plenty of fluids.
Tell your nurse or doctor if you have any problems with your mouth. They can prescribe medicines to prevent or treat mouth infections and reduce soreness.
Effects on the eyes
Indigestion or loss of appetite
Some people have indigestion or acid reflux. Acid reflux is when acid comes up from the stomach into the gullet (oesophagus). Tell your doctor if this happens. They can give you treatment to help.
During treatment, you may lose your appetite. Try to eat small meals regularly. If your appetite does not improve after a few days, let your nurse or dietitian know. They can give you advice on improving your appetite and keeping to a healthy weight.
Breathing problems or a cough
This is usually mild, but may be more severe if you have an existing lung problem. Let your doctor know if you have a cough or become more breathless.
Reduced levels of magnesium, potassium or calcium in the blood
Sleeplessness (insomnia) and anxiety
Some people have problems sleeping or feel anxious during treatment. Tell your doctor or nurse if you notice these symptoms.
Sore and red hands and feet
Having sore and red palms of hands and soles of feet is called palmar-plantar or hand-foot syndrome. It gets better when treatment ends. Your doctor or nurse can give you advice and prescribe creams to improve the symptoms. It can help to keep your hands and feet cool and to avoid tight-fitting socks, shoes and gloves.
Raised blood sugar levels
Sometimes this treatment may raise your blood sugar levels. This may make you
- feel very thirsty or tired
- need to pass urine more often.
Tell your doctor or nurse if you have these symptoms during treatment.
If you have diabetes, your blood sugar levels may be higher than usual. Your doctor will talk to you about how to manage this.
This treatment can increase the chances of a blood clot. A clot can cause:
- pain, redness and swelling in a leg or arm
- chest pain.
Contact your doctor straight away if you have any of these symptoms. A blood clot is serious, but your doctor can treat it with drugs that thin the blood. Your doctor or nurse can give you more information.
Changes in blood pressure
Your blood pressure may become higher or lower than normal. Tell your nurse or doctor if you have headaches or feel dizzy. These can be signs of blood pressure changes.
It is important to let your doctor know straight away if you feel unwell or have any severe side effects, even if they are not mentioned above.
Some medicines can affect this treatment or be harmful when you are having it. This includes medicines you can buy in a shop or chemist. Tell your cancer doctor about any drugs you are taking, including vitamins, herbal drugs and complementary therapies.
Your doctor will advise you not to get pregnant or make someone pregnant while having this treatment and for some time afterwards. The drugs may harm the developing baby. It is important to use effective contraception.
Women are advised not to breastfeed while having this treatment. This is because the drugs could be passed to the baby through breast milk.
Medical and dental treatment
If you need medical treatment for any reason other than cancer, always tell the doctors and nurses that you are having cancer treatment. Give them the contact details for your cancer doctor so they can ask for advice.
If you think you need dental treatment, talk to your cancer doctor or nurse. Always tell your dentist you are having this treatment.