What is alemtuzumab?
Alemtuzumab is one of a new group of cancer drugs known as monoclonal antibodies. It is mainly used to treat people with B-cell chronic lymphocytic leukaemia (CLL). It is sometimes used as part of research trials to treat other types of leukaemia. Currently alemtuzumab is usually given to people whose CLL has come back after previous treatment or if it is not responding to chemotherapy.
When a drug is being developed it has to go through various stages of research, called clinical trials or studies. These are intended to establish a safe dosage, the side effects the drug may cause and which cancers it may be used to treat. The trials also find out how effective the drug is, and whether it is better than the existing treatments or has extra benefit when given with these drugs.
What is a monoclonal antibody?
Monoclonal antibodies are used to try to destroy some types of cancer cells while causing little harm to normal cells. They recognise certain proteins that are found on the surface of some types of cancer cells. The monoclonal antibody recognises the protein and locks on to it (like a key in a lock). This may then trigger the body’s immune system to attack the cancer cells and cause the cells to destroy themselves.
Alemtuzumab locks on to a protein called CD52. This is found on the surface of certain white blood cells (lymphocytes), including those affected by the leukaemia. The leukaemic lymphocytes are known as malignant lymphocytes. Alemtuzumab attacks both malignant and normal lymphocytes. However the body quickly replaces any normal white blood cells that are damaged, so the risk of side effects from the treatment is small.
What it looks like
Alemtuzumab is a clear fluid after being diluted.
How is it given
Alemtuzumab is given as a drip (infusion) through a fine tube (cannula) inserted into a vein in the arm or back of the hand. Each drip takes approximately two hours.
Some people have an allergic reaction to alemtuzumab. To reduce the risk of a reaction the first few doses are given slowly. You may also be given some antihistamines, paracetamol and sometimes a small dose of steroids before the infusion. These will help to reduce the risk of reactions. If you do have a reaction, the infusion can be stopped and started again once the symptoms are over.
You will be asked to stay in hospital for a few hours after the infusion, or possibly overnight, to be monitored. The dose of alemtuzumab is increased over a few days until the recommended dose is achieved. This usually takes 3–7 days and is known as dose escalation. Once the recommended dose is achieved the treatment is given three times a week (e.g. on Monday, Wednesday and Friday). Most people have treatment for 4–12 weeks.
Each person’s reaction to a cancer drug is unique. Some people have very few side effects, while others may experience more. We have outlined the commonest side effects, so that you can be aware of them if they occur. However, we have not included those which are very rare and therefore extremely unlikely to affect you. If you notice any effects which you think may be due to the drug, but which are not listed here, please discuss them with your doctor or nurse.
Most side effects of alemtuzumab fall into two groups:
- early side effects – those which occur during or immediately after the drug has been given (which include allergic-type reactions)
- later side effects – tthose which occur after a few weeks of treatment, of which the main one is infection.
Early side effects
Allergic reactions It is common to have a slight allergic reaction to alemtuzumab, although some people have a more severe reaction. Signs of a reaction include skin rashes and itching, a feeling of swelling in the tongue or throat, irritation of the nasal passages, wheezing, a cough and breathlessness. You will be monitored closely during your treatment but it is very important to tell your nurse or doctor if you have any of these symptoms.
To reduce the chance of developing an allergic reaction certain drugs (antihistamines) are given before the infusion. The infusion can also be slowed down or stopped until the reaction is over. Generally the reaction gets better within a few hours, once the treatment has ended, and is almost always more severe with the first few doses of alemtuzumab.
Flu-like symptoms This can include a high temperature and chills, weakness, sweating, muscle aches, tiredness, dizziness and headaches. These effects can occur while the drug is being given, but do not usually last long.
Feeling sick (nausea) and occasional vomiting There are now very effective anti-sickness drugs to prevent or substantially reduce this. If the sickness is not controlled, or continues, let your doctor know so that he or she can prescribe other anti-sickness drugs which may be more effective.
Low blood pressure This may happen during the infusion, so your blood pressure will be regularly checked. People who normally take medicines to lower their blood pressure need to discuss with their doctor whether any adjustments should be made to their usual medicines during this time.
Later side effects
After a few weeks of treatment the following effects may occur.
Reduction in white blood cells Healthy white cells fight off infection and so alemtuzumab may increase your risk of developing infections. This risk is usually at its highest whilst you are having the treatment and for about two months afterwards. It is recommended that antibiotic and antiviral medication is taken during alemtuzumab treatment and for at least two months afterwards. In some people the production of white blood cells by the bone marrow may be reduced for up to a year following treatment.
Problems with blood clotting This is caused by a reduction in the production of platelets by the bone marrow. It may lead to an increased risk of bleeding, although this usually only lasts a short time. You will have your blood checked regularly to monitor this.
Less common side effects
You may also have diarrhoea, abdominal pains, skin rashes, breathlessness or a cough. Let your doctor or nurse know if you have any of these so that effective treatment can be prescribed.
Alemtuzumab may worsen heart problems in people who already have them. For this reason it will be used with caution if you have had heart disease.
It is unknown what effect alemtuzumab may have on an unborn baby. It is recommended that women able to become pregnant, and men who are sexually active, use effective birth control whilst having alemtuzumab and for at least one year after the treatment has ended. It is recommended that women should not breastfeed during the treatment and for at least four weeks afterwards.
This section has been compiled using information from a number of reliable sources including:
- Martindale: The Complete Drug Reference (33rd edition). Sweetman et al. Pharmaceutical Press, 2002.
- British National Formulary (46th edition). British Medical Association and Royal Pharmaceutical Society of Great Britain, September 2003.
For further references, please see the general bibliography.