Trastuzumab (Herceptin)

Trastuzumab is a monoclonal antibody – a type of targeted treatment. It has the brand name Herceptin. It can control the growth of cancer cells that produce too much of a protein called HER2 (human epidermal growth factor receptor 2). Some breast cancers and stomach cancers have large amounts of HER2 and they are called HER2 positive cancers. HER2 makes the cancer cells grow and divide. When Herceptin attaches to HER2 it can make the cells stop growing and die. 

Your doctor may prescribe Herceptin for you if you have

• HER2 positive early breast cancer – you can find out about this treatment in our biological therapy for breast cancer section
• HER2 positive breast cancer that has spread – depending on your situation you may also have the chemotherapy drugs paclitaxel (Taxol) or docetaxel (Taxotere) or hormone therapies called aromatase inhibitors
• A type of stomach cancer called adenocarcinoma of the stomach that is HER2 positive and has spread – you also have chemotherapy with the drug capecitabine (Xeloda) or a combination of fluorouracil and cisplatin 
• Advanced HER2 positive cancer of the area where where the food pipe meets the stomach (gastro oesophageal cancer)

You have trastuzumab into your bloodstream by drip (infusion). You may have it through a thin, short tube (a cannula) put into a vein in your arm each time you have treatment. Or you may have it through a central line, a portacath or a PICC line. These are long, plastic tubes that give the drug directly into a large vein in your chest. You have the tube put in just before your course of treatment starts and it stays in place as long as you need it.

For breast cancer, you usually have the infusion once a week or 3 weekly. For stomach cancer you have it every 3 weeks. Treatment takes about 30 to 90 minutes each time.

For early breast cancer you have the treatment for a year. For breast cancer or stomach cancer that has spread you have it for as long as it is controlling the cancer.

The side effects associated with trastuzumab are listed below. You can use the links (underlined) to find out more about each side effect or look in the cancer drug side effects section. If you are having other drugs in combination with trastuzumab you may also have side effects related to those drugs. 

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

• A reaction while the drug is given causing chills, fever, swelling of the face and lips, and possibly an itchy rash, feeling sick, breathlessness, wheezing, a headache, flushes, dizziness and faintness – this happens to about half of patients with the first treatment but less often with further treatments. More rarely, it is possible to have a more severe reaction to your first infusion, but your nurse will be watching for this
• Tiredness (fatigue) during and after treatment – most people find their energy levels are back to normal from 6 months to a year after their treatment finishes
• Weakness
• Skin rashes
• Diarrhoea – this affects about 1 in 3 people. It is usually mild but do tell your doctor or nurse as you can be given medicines to stop it
• Heart problems such as an irregular heartbeat or palpitations – this should get better once treatment is stopped. Your heart function will be tested before you start treatment and monitored regularly throughout your treatment. You cannot have this drug for early breast cancer if you already have particular heart conditions such as congestive heart failure or angina that needs treatment
• Pain – this may affect the abdomen, chest, joints or muscles
• Low or high blood pressure
• Sore eyes
• Watery eyes
• A runny nose 
• Shaking
• Hot flushes
• Dizziness

Between 1 and 10 in every 100 people have one or more of these effects.

A temporary drop in the number of blood cells made by the bone marrow, causing

• An 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 more 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. Contact your doctor or nurse 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 effects include

• Long term weakening of the heart muscle leading to chest pain, breathlessness, a cough, swelling in the arms or legs and heart fluttering
• Indigestion (heartburn)
• Constipation – drink plenty of fluids. Your doctor or specialist nurse can give you laxatives so let them know if you are constipated for more than 3 days
• Shingles – pain and a rash in an area of skin. Let your doctor or nurse know if you have this
• Kidney changes – you will have regular blood tests to check how well your kidneys are working
• Numbness or tingling in the fingers and toes – you may have trouble with fiddly tasks such as doing up buttons. This can start a few days or weeks after treatment and usually goes away within a few months of the treatment finishing
• Changes in your nails
• Hair thinning
• Sleep problems
• Itching – let your doctor or nurse know as they may be able to prescribe medicines to help
• A dry mouth
• Dry skin
• Sweating
• Anxiety or depression
• Loss of appetite
• Taste changes

Fewer than 1 in 100 people have these.

• Long term lung changes leading to difficulty breathing and a cough
• Liver problems – you may have regular blood tests to check this
• Women may stop having periods (amenorrhoea) – this may only be temporary
• Loss of fertility – you may not be able to become pregnant or father a child after treatment with this drug. It is important to talk with your doctor before starting treatment if you plan to have a baby in the future

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 they can help you manage them. They can give you advice or reassure you. Your nurse will give you a contact number to ring if you have any questions or problems. If in doubt, call them.

Tell your doctor about any other medicines you are taking, including vitamins, herbal supplements and over the counter remedies – some drugs can react together. It can take up to 6 months for Herceptin to be removed from the body so tell your doctor that you have had Herceptin before starting any new medicines during this time. 

Trastuzumab can have harmful effects on a baby developing in the womb. You should not become pregnant while taking trastuzumab or for 6 months afterwards. Talk about contraception to your doctor or nurse before having the treatment if there is any chance you could become pregnant. 

Breastfeeding is not advisable during this treatment because the drug may come through in the breast milk.

This page does not list all the very rare side effects of this treatment that are very unlikely to affect you. For further information look at the Electronic Medicines Compendium website at www.medicines.org.uk.

If you have a side effect not mentioned here that you think may be due to this treatment you can report it to the Medicines Health and Regulatory Authority (MHRA) at www.mhra.gov.uk.