Alemtuzumab (MabCampath) | Cancer Research UK
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What alemtuzumab is

Alemtuzumab (pronounced al-em-too-zoo-mab) is a type of monoclonal antibody. Monoclonal antibodies are a type of biological therapy. It is also called Campath or Mabcampath. 

Alemtuzumab is a treatment for chronic lymphocytic leukaemia (CLL). You may also have it as part of some clinical trials for CLL or lymphoma. Or you may have it as part of a stem cell transplant.


How alemtuzumab works

Alemtuzumab targets a protein called CD52 on the surface of a type of white blood cell called mature B lymphocytes. In CLL, the B lymphocytes are abnormal. The alemtuzumab sticks to all the CD52 proteins it finds on the leukaemic B cells. Then the immune system picks out the marked cells and kills them.

B cells in an early stage of development don’t have the CD52 protein and so they aren’t killed. This means they can then produce healthy B cells. So the number of healthy B cells in the body is back to normal within a few months of treatment.


How you have alemtuzumab

You have alemtuzumab into your bloodstream (intravenously). You can 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 drugs directly into a large vein in your chest. You have the tube put in before or during your course of treatment and it stays in place as long as you need it.

You can read our information about having cancer drugs.

You have the alemtuzumab as a drip (an infusion) over 2 hours. 

You start on a low dose and the doctor gradually increases the dose until you are having the recommended amount. This is called dose escalation. Doctors do this because some people react to the treatment. By gradually increasing the dose you are less likely to react. While you are having dose escalation you have treatment daily. It takes between 3 days and a week to reach the right dose. Then you have treatment 3 times a week, for between 4 and 12 weeks.

Research is also looking at giving alemtuzumab as an injection under the skin (subcutaneously).


Tests during treatment

You have blood tests before starting treatment and regularly during your treatment. The tests check your levels of blood cells and other substances in the blood. They also check how well your liver and kidneys are working.


About side effects

We've listed the side effects associated with alemtuzumab. You can use the links to find out more about each side effect. Where there is no link, please go to our information about cancer drug side effects or use the search box at the top of the page.

You may have a few side effects. They 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)

The side effects may be different if you are having alemtuzumab with other medicines.

Tell your doctor, nurse or pharmacist straight away if any of the side effects get severe.


Common side effects

More than 10 in every 100 people have one or more of the side effects listed below.

  • 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, a sore throat, pain passing urine, or you may feel cold and shivery. If you have a severe infection this can be life threatening. Contact your treatment centre straight away if you have any of these effects or if your temperature goes above 38°C. Your doctor may prescribe antibiotics and antiviral medicines to take alongside alemtuzumab
  • Tiredness and breathlessness due to a drop in red blood cells (anaemia) – you may need a blood transfusion. You should only have blood products that have been irradiated
  • Bruising more easily due to a drop in platelets – you may have nosebleeds, or bleeding gums after brushing your teeth. Or you may have lots of tiny red spots or bruises on your arms or legs (known as petechiae)
  • A reaction to alemtuzumab happens in 4 out of 5 people (80%), usually in the first week of treatment. It causes flu like symptoms such as a fever, chills and shivering (rigors), a headache, breathlessness, feeling sick and itching. Your nurse will give you medicines before the treatment to try to prevent a reaction. If you have a reaction, your nurse will slow down or stop your drip for a while
  • Feeling sick or being sick affects 1 out of 2 people (50%) but is usually well controlled with anti sickness medicines
  • Diarrhoea affects 1 in 5 people (20%) – drink plenty of fluids and tell your doctor or nurse if diarrhoea becomes severe or continues for more than 3 days
  • A sore mouth and mouth ulcers
  • Changes to your blood pressure – it may be raised or lowered
  • Tiredness and weakness (fatigue) during and after treatment – most people find their energy levels are back to normal within 6 months to a year
  • A skin reaction affects 1 in 5 people (20%), causing dryness and itching and reddening
  • Sweating
  • Breathlessness affects 1 in 4 people (25%) and you may also have a cough – tell your doctor or nurse if you have difficulty breathing
  • Loss of fertility – you may not be able to become pregnant or father a child after this treatment. Talk to your doctor before starting treatment if you think you may want to have a baby in the future. Men may be able to store sperm before starting treatment
  • Headaches
  • Difficulty sleeping
  • Anxiety
  • A fast heart rate

Occasional side effects

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

  • Abdominal (tummy) pain and pain in other parts of your body such as muscles, bones, or joints
  • Indigestion
  • Constipation – your nurse may give you laxatives to help prevent this but tell them if you are constipated for more than 3 days
  • Watery, itchy eyes
  • Loss of appetite
  • Liver changes that are very mild and unlikely to cause symptoms – the liver will almost certainly go back to normal when treatment is finished

Rare side effects

Fewer than 1 in 100 people have these.

  • A severe allergic reaction, with wheezing, an itchy rash and a drop in blood pressure. Tell your nurse straight away if you have difficulty breathing, a sudden rash or feel dizzy
  • A chest infection – pneumonia
  • A heart attack
  • Kidney problems – you will have regular blood tests to check how well your kidneys are working
  • Bleeding into your stomach from a stomach ulcer – let your doctor or nurse know straight away if you have sudden pain in your tummy (abdomen) or if you vomit blood

Important points to remember

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.

Other medicines

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

Pregnancy and contraception

This drug may harm a baby developing in the womb. It is important not to become pregnant or father a child while you are having treatment and for at least 6 months afterwards. Talk to your doctor or nurse about effective contraception before starting treatment.


Don't breastfeed during this treatment and for several months afterwards because the drug may come through in the breast milk.


Immunisations and alemtuzumab

You shouldn't have immunisations with live vaccines while you are having treatment or for at least 6 months afterwards. In the UK, these include rubella, mumps, measles (usually given together as MMR), BCG, yellow fever and Zostavax (shingles vaccine).

You can have other vaccines, but they may not give you as much protection as usual until your immune system has fully recovered from your treatment. It is safe to have the flu vaccine.

It is safe for you to be in contact with other people who've had live vaccines as injections. There can be problems with vaccines you take by mouth (oral vaccines), but not many people in the UK have these 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.


More information about alemtuzumab

This page doesn't 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

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

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Updated: 17 December 2015