What is Gemtuzumab ozogamicin (Mylotarg®)?

Gemtuzumab ozogamicin (Mylotarg®) is used to treat acute myeloid leukaemia (AML). It is best to read this information with our general information about AML.

Gemtuzumab ozogamicin has two parts:

Gemtuzumab targets a protein called CD33. CD33 is found on the surface of some leukaemia cells and some types of developing white blood cells. Gemtuzumab locks on to the CD33 protein. It releases ozogamicin into the leukaemia cells to damage and kill them.

We use the term gemtuzumab in this information to mean gemtuzumab ozogamicin.

Your doctor will talk to you about this treatment and its possible side effects before you agree (consent) to have treatment.

How gemtuzumab is given

You may have gemtuzumab as part of your first treatment for AML. You will usually be given gemtuzumab during a stay in hospital. It is given in combination with other cancer drugs.

During treatment you see a doctor who treats AML (haematologist), a cancer nurse or specialist nurse, and a specialist pharmacist. This is who we mean when we mention doctor, nurse or pharmacist in this information.

Your doctor, nurse or pharmacist will discuss your treatment plan with you. They will explain when and how often you get gemtuzumab. They may give you a copy of the treatment plan to keep.

Gemtuzumab is given as a drip into a vein (intravenous infusion). The drip will usually run through a pump. This will give you the treatment over 2 hours.

About side effects

We explain the most common side effects of this treatment here. We also include some less common side effects.

You may get some of the side effects we mention, but you are unlikely to get all of them. If you are also having treatment with other cancer drugs, you may have some side effects that we have not listed here. Always tell your doctor, nurse or pharmacist about any side effects you have.

Your doctor can give you drugs to help control some side effects. It is important to take them exactly as your nurse or pharmacist explains. This means they will be more likely to work for you. Your nurse will give you advice about managing your side effects. After your treatment is over, most side effects start to improve.

Serious and life-threatening side effects

Some cancer treatments can cause severe side effects. Rarely, these may be life-threatening. Your cancer doctor or nurse can explain the risk of these side effects to you.

Contact the hospital

Your nurse will give you telephone numbers for the hospital. If you feel unwell or need advice, you can call them at any time of the day or night. Save these numbers in your phone or keep them somewhere safe.

More information

We cannot list every side effect for this treatment. There are some rare side effects that are not listed. You can visit the electronic Medicines Compendium (eMC) for more detailed information.

Side effects while treatment is being given

Allergic reaction

Some people have an allergic reaction while having this treatment. Before treatment, you will be given medicines to help prevent or reduce any reaction.

Signs of a reaction can include:

  • feeling hot or flushed
  • a skin rash
  • itching
  • shivering
  • feeling dizzy
  • a headache
  • feeling breathless
  • swelling of your face or lips
  • pain in your back, tummy or chest.

Your nurse will check you for signs of a reaction during your treatment. If you feel unwell or have any of these signs, tell them straight away. If you do have a reaction, it can be treated quickly.

Sometimes a reaction can happen up to 24 hours after treatment. If you develop any signs or feel unwell after you get home, contact the hospital straight away.

Low blood pressure

Gemtuzumab may cause low blood pressure. The nurse will check your blood pressure regularly during treatment. Let them know if you feel dizzy.

If you usually take medicine to lower your blood pressure, your doctor may ask you not to take it for 12 hours before having gemtuzumab.

Common side effects

Risk of infection

This treatment can reduce the number of white blood cells in your blood. These cells fight infection.

If the number of white blood cells is low, you are more likely to get an infection. A low white blood cell count is called neutropenia.

If you have an infection, it is important to treat it as soon as possible. Contact the hospital straight away on the 24-hour contact number you have if:

  • your temperature goes over 37.5°C (99.5°F)
  • you suddenly feel unwell, even with a normal temperature
  • you have symptoms of an infection.

Symptoms of an infection include:

  • feeling shivery
  • a sore throat
  • a cough
  • diarrhoea
  • needing to pass urine often.

It is important to follow any specific advice your cancer treatment team gives you.

The number of white blood cells will usually return to normal before your next treatment. You will have a blood test before having more treatment. If your white blood cell count is low, your doctor may delay your treatment for a short time.

Bruising and bleeding

This treatment can reduce the number of platelets in your blood. Platelets are cells that help the blood to clot. 

Tell your doctor if you have any bruising or bleeding that you cannot explain. This includes:

  • nosebleeds
  • bleeding gums
  • tiny red or purple spots on the skin that may look like a rash.

Some people may need a drip to give them extra platelets. This is called a platelet transfusion.

Anaemia (low number of red blood cells)

This treatment can reduce the number of red blood cells in your blood. These cells carry oxygen around the body. If the number of red blood cells is low, you may be tired and breathless. Tell your doctor or nurse if you feel like this. If you are very anaemic, you may need a drip to give you extra red blood cells. This is called a blood transfusion.

Feeling sick

You may feel sick in the first few days after this treatment. Your doctor will give you anti-sickness drugs to help prevent or control sickness. Take the drugs exactly as your nurse or pharmacist tells you. It is easier to prevent sickness than to treat it after it has started.

If you feel sick, take small sips of fluids and eat small amounts often. If you continue to feel sick, or if you vomit more than once in 24-hours, contact the hospital as soon as possible. They will give you advice and may change the anti-sickness drug to one that works better for you.

Sore mouth

You may get a sore mouth or mouth ulcers. This can make you more likely to get a mouth infection.

Use a soft toothbrush to clean your teeth or dentures in the morning, at night and after meals.

If your mouth is sore:

  • tell your nurse or doctor – they can give you a mouthwash or medicines to help
  • try to drink plenty of fluids
  • avoid alcohol, tobacco, and foods that irritate your mouth.

Loss of appetite

This treatment can affect your appetite. Do not worry if you do not eat much for a day or two. But if your appetite does not come back after a few days, tell your nurse or dietitian. They will give you advice. They may give you food or drink supplements.

Diarrhoea

This treatment may cause diarrhoea. Diarrhoea means passing more stools (poo) than is usual for you, or having watery or loose stools. If you have a stoma, it will be more active than usual.

If you have diarrhoea:

  • try to drink at least 2 litres (3½ pints) of fluids each day
  • avoid alcohol, caffeine, milk products, high-fat foods and high-fibre foods
  • contact the hospital for advice.

Constipation

This treatment can cause constipation. Here are some tips that may help:

  • Drink at least 2 litres (3½ pints) of fluids each day.
  • Eat high-fibre foods, such as fruit, vegetables and wholemeal bread.
  • Do regular gentle exercise, like going for short walks.

If you have constipation, contact the hospital for advice. Your doctor can give you drugs called laxatives to help.

Feeling tired

This treatment will make you feel very tired and you will need a lot of rest. You will get tired easily for some months after treatment too. Gentle exercise, like short walks, can give you more energy. The tiredness will gradually get better.

Headaches

This treatment may cause headaches. If this happens, tell your doctor or nurse. They can give you painkillers.

Tummy pain

This treatment may cause pain in the abdomen or tummy. Tell your doctor or nurse if you have this side effect.

Skin changes

Gemtuzumab may affect your skin. Your doctor or nurse can tell you what to expect. If your skin feels dry, try using an unperfumed moisturising cream every day. Gemtuzumab can cause a rash, which may be itchy.

Always tell your doctor or nurse about any skin changes. They can give you advice and may prescribe creams or medicines to help. Any changes to your skin are usually temporary and improve when treatment finishes.

Raised blood sugar levels

This treatment can raise your blood sugar levels. If you have a raised blood sugar level, you may:

  • feel thirsty
  • need to pass urine (pee) more often
  • feel tired.

Tell your doctor or nurse if you have these symptoms.

If you have diabetes, your blood sugar levels may be higher than usual. Your doctor will talk to you about how to manage this. You may need to change your insulin or tablet dose.

Breathlessness

This treatment can cause breathlessness. Let your doctor know if you become breathless or are more breathless than usual. Less commonly, gemtuzumab can cause a condition in which the lungs become inflamed. This can be very serious. Contact the hospital straight away if you become suddenly breathless or your breathing gets worse.

Effects on the liver

Gemtuzumab may cause changes in the way the liver works. You will have regular blood tests to check how well your liver is working.

Fluid build-up

You may gain weight, or your face, ankles and legs may swell. This improves slowly after your treatment has finished. Your doctor may give you drugs to help reduce the swelling.

Less common side effects

Tumour lysis syndrome (TLS)

Gemtuzumab may cause the leukaemia cells to break down very quickly. This releases a chemical called uric acid into the blood. The kidneys usually get rid of uric acid, but they may not be able cope with large amounts. This can cause chemical imbalances in the blood that affect the kidneys and the heart. This is called tumour lysis syndrome (TLS).

If your white blood cell count is very high before starting gemtuzumab, you may have a higher risk of TLS. Your doctor may reduce your white blood cell count before you start treatment by giving you

During treatment, your doctor may give you a drug called allopurinol or rasburicase. You will also be given fluid through your drip to help protect your kidneys.

Indigestion

Some people have indigestion or acid reflux (acid comes up from the stomach into the gullet) when taking this treatment. Tell your doctor if you are affected as they can prescribe treatment to help.

Other information

Blood clot risk

Cancer and some cancer treatments can increase the risk of a blood clot. Symptoms of a blood clot include:

  • pain, redness or swelling in a leg or arm
  • breathlessness
  • chest pain.

If you have any of these symptoms, contact a doctor straight away.

A blood clot is serious, but can be treated with drugs that thin the blood. Your doctor or nurse can give you more information.

Other medicines

Some medicines can affect how this treatment works or be harmful when you are having it. Always tell your cancer doctor about any drugs you are taking or planning to take, such as:

  • medicines you have been prescribed
  • medicines you buy in a shop or chemist
  • vitamins, herbal drugs and complementary therapies.

Tell other doctors, pharmacists or dentists who prescribe or give you medicines that you are having this cancer treatment.

You can visit the electronic Medicines Compendium (eMC) for more detailed information about your treatment.

Vaccinations

Vaccinations can reduce your risk of getting certain infections. Your doctor or nurse may talk to you about having vaccinations.

Doctors usually recommend that people with cancer have a flu vaccination and a coronavirus vaccination. These are both inactivated vaccinations that can help reduce the risk of infection. People with weak immune systems can have these, as they are not live vaccinations.

If your immune system is weak, you need to avoid live vaccinations. This is because they can make you unwell. Live vaccines, such as shingles, contain a very weak version of the illness they are vaccinating you against. Your cancer doctor or GP can tell you more about live and inactivated vaccinations.

Fertility

Some cancer drugs can affect whether you can get pregnant or make someone pregnant. If you are worried about this, it is important to talk with your doctor before you start treatment.

Contraception

Your doctor will advise you not to get pregnant or make someone pregnant while having this treatment. The drugs may harm a developing baby. It is important to use contraception during your treatment and for a while after treatment finishes. Your doctor, nurse or pharmacist can tell you more about this.

Breastfeeding

Women are advised not to breastfeed while having this treatment. This is because the drugs could be passed to the baby through breast milk.

Medical and dental treatment

If you need medical treatment for any reason other than cancer, always tell the doctors and nurses that you are having cancer treatment. Give them the contact details for your cancer doctor so they can ask for advice.

If you think you need dental treatment, talk to your cancer doctor or nurse. Always tell your dentist you are having cancer treatment.