Cetuximab is primarily used to treat cancers of the large intestine (colon and rectum) or head and neck cancers. It can also be used to treat other types of cancer as part of a research trial.

WHAT IS CETUXIMAB?

Cetuximab belongs to a group of cancer drugs known as monoclonal antibodies. Monoclonal antibodies are sometimes called targeted therapies because they work with specific proteins (receptors) located on the surface of cells.

HOW DOES CETUXIMAB 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.

Cetuximab blocks EGFRs. This stops them from stimulating the cancer cells to divide and grow. It can also make the cancer cells more sensitive to the effects of chemotherapy and radiotherapy. Cetuximab is more likely to work in cancers that have a large number of EGFRs on their surface.

Cetuximab only works for intestinal cancers that have a normal RAS gene. So before cetuximab is used to treat the colon cancer, the cancer cells are subjected to a test to see if there are changes (mutations) in the RAS gene. This helps doctors decide if treatment with cetuximab is appropriate. The tests can be performed using cells from previous biopsies or surgery. This test is not necessary for cancers of the head and neck.

WHEN IS CETUXIMAB USED?

Cetuximab is used as a treatment for advanced (metastatic) cancer of the large intestine and for head and neck cancers. It is also being tested in clinical trials as a possilbe treatment for other types of cancer.

Cetuximab for colon cancer

Cetuximab is used to treat advanced colon cancer:

• in combination with chemotherapy
• as a stand-alone treatment for people who have already been treated with oxaliplatin and irinotecan.

Cetuximab for head and neck cancer

Cetuximab is used to treat:

Head and neck cancer that has begun to spread toward nearby tissues (locally advanced head and neck cancer). It is administered in combination with radiotherapy.

Head and neck cancer that has returned after being treated (recurrent) or has spread (advanced or metastatic). It is given in combination with a chemotherapy regimen that includes a platinum-containing drug (such as cisplatin).

APPEARANCE OF CETUXIMAB

Cetuximab is a colorless liquid.

HOW IS CETUXIMAB ADMINISTERED?

Cetuximab is given as a drip into a vein (intravenous infusion). The first treatment is a larger dose of cetuximab given slowly, over approximately two hours. After this, you will have to stay in the clinic for about an hour to ensure that you do not have a reaction to the infusion.

After the first infusion, subsequent treatments are given weekly and take about an hour.

POSSIBLE SIDE EFFECTS OF CETUXIMAB

Each person reacts differently to a given drug. 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 cetuximab.

Here we outline the most common 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 nurse.

The side effects of cetuximab are normally mild, and some of them can be relieved with drugs. The side effects of chemotherapy and radiotherapy can also be worsened by having cetuximab.

The side effects of cetuximab are divided into two groups:

• infusion-related side effects, which are produced during the infusion itself (while you are receiving treatment) or up to one hour afterward (or, rarely, up to several hours later)
• subsequent side effects, which can occur days or even weeks after the treatment
• Infusion-related side effects

These tend to be mild or moderate, although in rare cases they can be more severe. You can receive drugs before the infusion to reduce the likelihood of having a reaction.

If you have a reaction, the drip is usually stopped until the reaction has gone away. 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 headaches, feeling flushed, fever, chills, or dizziness
• red, warm, and itchy bumps on the skin (such as urticaria)
• a feeling of swelling in the lips, tongue, or throat
• difficulty breathing, wheezing, and cough
• 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 the aforementioned symptoms or feel unwell after you get home, get in touch with your hospital immediately for advice.

Later side effects

SKIN CHANGES

One very common effect of cetuximab is a rash that looks like acne on the face, neck, and body. These initially appear during the first three weeks of treatment and normally go away completely when the treatment ends. Some people develop more severe skin changes, which may include reddening of the skin, acne, and red spots on the skin. The skin on your face may also turn scaly. Some people have skin resembling eczema on their fingertips, elbows, and limbs. This may be painful or produce a burning sensation. If you have any of these changes to your skin, tell your doctor immediately.

If you develop very severe skin problems, the time between treatments can be extended or your dose can be lowered.

To help reduce skin itchiness, try to avoid things that dry out the skin such as central heating and soap. Your doctor can prescribe creams to moisturize your skin.

Some skin reactions can worsen with sun exposure. You can still go out in the sun, though you need to use high-SPF sunscreen and cover yourself with clothing and a hat.

NAUSEA AND VOMITING

Your doctor can prescribe antiemetic drugs, which can prevent or substantially reduce your nausea and vomiting.

If your nausea remains uncontrolled or continues, tell your doctor, as they can prescribe other drugs that could work better. Some antiemetic drugs can constipation. Tell your doctor or nurse if this is a problem.

HEADACHES

Tell your doctor if you have headaches, as he or she can advise you on what could help you.

DIARRHEA

Cetuximab 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.

CHANGES IN THE LIVER

Treatment with cetuximab can cause changes in the way your liver works, although this will return to normal once your treatment is over. It is very unlikely you will notice any problems, though your doctor will take periodic blood samples to check whether your liver is working properly.

TIREDNESS (FATIGUE)

Tiredness is a common side effect of cetuximab, especially toward the end of treatment and for a few months 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 your hair is 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.

REDUCED LEVELS OF MAGNESIUM IN THE BLOOD

You will have regular blood tests done, and you may be given magnesium supplements if your levels are too low.

EYE SORENESS

Cetuximab can make the mucosa of your eyelids swollen, causing your eyes to become sore and red. Tell your doctor so he or she can prescribe eyedrops if necessary.

BREATHLESSNESS

Some people may feel short of breath. 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.

ADDITIONAL INFORMATION ON CETUXIMAB

OTHER MEDICINES

Some drugs, including those bought over the counter in a store or pharmacy, may be harmful to you while you are taking cetuximab. Tell your doctor if you are taking any medicines, including over-the-counter drugs, complementary therapies, and herbal remedies.

FERTILITY

This treatment may effect your ability to conceive or give birth. It is important that you talk to your doctor before beginning treatment.

CONTRACEPTION

Little is known about the effects of cetuximab on developing babies. Therefore, it is not recommendable to become pregnant while taking this drug.

It is unknown whether cetuximab 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.

BREASTFEEDING

There is a potential risk that cetuximab may be present in breast milk, and therefore women are recommended not to breast feed during the treatment and for a few months afterward.