Ofatumumab (Arzerra)

Ofatumumab (pronounced off-ah-too-moo-mab) is a type of monoclonal antibody. Monoclonal antibodies are a type of biological therapy. Ofatumumab is also known by its brand name Arzerra. It is a treatment used for chronic lymphocytic leukaemia when the cancer drugs fludarabine and alemtuzumab are no longer working.

You may also have it in research trials for other types of cancer.

Monoclonal antibodies are copies of a single antibody. They are made in the laboratory and used for targeted cancer treatment. They recognise and find specific proteins on the outside of cancer cells.

Ofatumumab targets part of a protein called CD20 on the surface of the chronic lymphocytic leukaemic cells. The ofatumumab sticks to all the CD20 proteins it finds. Then the cells of the immune system pick out the marked cells and kill them.

You have ofatumumab through a drip into a vein (infusion) through a pump. Your first treatment is a small test dose and takes around 6 hours. If this goes well the second treatment is the full dose and again takes around 6 hours. If this treatment also goes well and you don’t have any problems you may be able to have further treatments over less than 6 hours.

You usually have the treatment once a week for 8 weeks. Then you have a break with no treatment for 4 or 5 weeks. You then have treatment once every 4 weeks for 4 months.

Between 30 minutes and 2 hours before you have each treatment you have an injection of corticosteroids. You will also have paracetamol and an antihistamine (either as tablets or into your bloodstream). These reduce the chance of having an allergic reaction to ofatumumab.

The side effects associated with ofatumumab are listed below. You can click on the underlined links for information about coping with each side effect. Where there is no link you can go to our cancer drug side effects section or use the search box at the top of the page. The side effects may be different if you are having ofatumumab with other drugs.

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

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

• 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. You should contact your treatment centre if you have any of these effects. Your doctor will check your blood counts regularly to see how well your bone marrow is working.

• An allergic reaction while you have the treatment, causing fever, chills, shivering (rigors), a headache and feeling sick – in trials 4 out of 10 people had a reaction during the first treatment and around 3 out of 10 with the second treatment. Rarely, people have a more severe reaction with wheezing, an itchy rash and a drop in blood pressure. Your nurse will stop or slow your drip if you have a reaction
• Infections – more than 1 in 10 people develop a chest infection or a bladder infection. If you develop a temperature, feel short of breath, or have pain when passing urine, tell your doctor or nurse straight away
• Tiredness affects about 1 in 10 people during and after treatment – most people find their energy levels are back to normal within 6 months to a year
• A rash, which may be itchy
• Loss of fertility – we don’t know exactly how this drug affects fertility so do talk with your doctor before starting treatment if having a baby is important to you
• A change in blood pressure
• A faster heart rate
• Diarrhoea – drink plenty of fluids and tell your doctor or nurse if it becomes severe or continues for more than 3 days
• Feeling sick – this is usually well controlled with anti sickness medicines
• Back pain

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

• A cough and shortness of breath affects about a quarter of people (25%) – tell your doctor or nurse if it continues
• High uric acid levels in the blood due to the breakdown of tumour cells (tumour lysis syndrome) – you will have regular blood tests to check your uric acid levels and may have a tablet called allopurinol to take. Drinking plenty of fluids helps to flush out the extra uric acid

Ofatumumab can cause a severe reaction in people who have Hepatitis B infection or who have had it in the past. You will have a blood test to check for hepatitis B.

You won’t get all these side effects and some may be very mild. A side effect may get worse through your course of treatment. Or you may have more side effects as the course goes on. This depends on

• How many times you've had a drug before
• Your general health
• How much 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.

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

You should not have immunisations with live vaccines while you are having this treatment or for at least 6 months afterwards. In the UK, live vaccines 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.