Cetuximab (Erbitux)

Cetuximab (pronounced see-tux-ee-mab) is a type of monoclonal antibody. Monoclonal antibodies are a type of biological therapy. Cetuximab is also known by its brand name, Erbitux. It is a treatment for advanced bowel cancer and cancer of the head and neck. You may also have it as part of trials for other types of cancer.

Some cancer cells have receptors called epidermal growth factor receptors (EGFR) on their surface. A protein produced naturally in the body called epidermal growth factor (EGF) attaches to the receptors. This triggers the cell to grow and divide into more cells. Cetuximab works by attaching itself to the EGF receptors. This blocks the EGF protein from reaching the cancer cells and stops them from growing. It also helps the immune system to recognise the cancer cells so that it can attack them.

Studies have shown that cetuximab does not work in people whose bowel cancer has a genetic change called a k-ras mutation. Around 4 out of 10 people (40%) with bowel cancer have a k-ras mutation. So doctors will test your tumour sample to see if you have a normal k-ras gene before starting treatment.

You have cetuximab through a drip into a vein (infusion). You have the first treatment over 2 hours. If this goes well you can have the next treatments over an hour. You have the treatment once a week. You are likely to have cetuximab alongside other treatments, such as chemotherapy drugs.

The side effects associated with cetuximab are listed below. The effects may be different if you are having it with other drugs.

More than 10 in every 100 people have one or more of these.

• Tiredness during and after treatment – most people find their energy levels are back to normal within 6 months to a year
• Some kind of skin reaction in more than 8 out of 10 people (80%) – this may be a rash similar to acne on your face, neck and trunk or your skin may be dry and itchy. More than 1 in 6 people (15%) have a severe skin rash
• Mild effect on the liver – you are unlikely to notice any symptoms and your liver function will almost certainly go back to normal when treatment is finished. To be on the safe side, you will have regular blood tests to check how well your liver is working
• Flu like symptoms in 3 out of 20 people treated (15%), including fever and chills – taking paracetamol can help
• Breathlessness – 1 in 4 people (25%) have this side effect
• A sore mouth
• Infection of the skin around your nails
• Low magnesium levels in your blood – you will have regular blood tests to check the levels
• Loss of fertility – we don’t know exactly how this drug may affect fertility, so it is important to talk to your doctor before starting treatment if having a baby is important to you
• We don’t yet know whether cetuximab can have a harmful effect on a developing baby, so it is important to talk about contraception with your doctor or nurse before having the treatment
• Cetuximab may be present in breast milk so it is not advisable for women to breastfeed during treatment or for 2 months after the last dose

With this drug, usually when given in combination with chemotherapy, some people have a temporary drop in the number of blood cells made by the bone marrow. Between 1 and 10 in every 100 people have one or more of the side effects listed below.

• Increased risk of getting an infection from a drop in white blood cells – it is harder to fight infections and you can become very ill. You may have headaches, aching muscles, a cough, sore throat, pain passing urine or feel cold and shivery
• Tiredness and breathlessness due to a drop in red blood cells (anaemia) – you may need a blood transfusion
• Bruising easily due to a drop in platelets – you may have nosebleeds, bleeding gums after brushing your teeth, or lots of tiny red spots or bruises on your arms or legs (known as petechia)

Some of these side effects can be life threatening, particularly infections. You should contact your doctor if you have any of these effects. Your doctor will check your blood counts regularly to see how well your bone marrow is working.

Other occasional side effects include

• A reaction to cetuximab during infusion, causing flu like symptoms such as a fever, chills and shivering (rigors), a headache and feeling sick. 1 in 50 people (2%) have a more severe allergic reaction, with wheezing, an itchy rash and a drop in blood pressure. Your doctor will give you medicines beforehand to try to prevent a reaction. If you have a reaction, your nurse will slow your drip down or stop it for a while
• Watery, itchy eyes in 1 in 20 people (5%)
• Diarrhoea – you should drink plenty of fluids. If your diarrhoea is severe or continues you could become dehydrated so let your doctor or nurse know
• Loss of appetite
• Feeling sick – this is usually well controlled with anti sickness medicines

The side effects above may be mild or more severe. A side effect may get better or worse through your course of treatment, or more side effects may develop as the course goes on. This depends on

• How many times you've had the drug before
• Your general health
• The amount of the drug you have (the dose)
• Other drugs you are having

Talk to your doctor, pharmacist or nurse about all your side effects so that they can help you manage them. Your specialist, clinic or ward nurse should give you a contact number. You can ring if you have any questions or problems. They can give you advice or reassure you. If in doubt, call them.

Tell your doctor about any other medicines you are taking, including vitamins, herbal supplements and other over the counter remedies – some drugs can react together.

If you are having chemotherapy or radiotherapy alongside cetuximab, you should not have immunisations with live vaccines while you are having this treatment or for at least 6 months afterwards. In the UK, these include rubella, mumps, measles (usually given together as MMR), BCG and yellow fever. You can have other vaccines, but they may not give you as much protection as usual until your immune system has fully recovered.

It is safe for you to be in contact with other people who've had live vaccines as injections. There can be problems with oral vaccines, but not many people in the UK have oral vaccines now. So there is usually no problem in being with any baby or child who has recently had any vaccination in the UK. You might need to make sure that you aren't in contact with anyone who has had oral polio, cholera or typhoid vaccination recently, particularly if you live abroad.