Belzutifan (WELIREG®)
What is belzutifan (WELIREG®)?
Belzutifan is also called WELIREG®. It is a type of targeted therapy drug called a HIF-2 alpha inhibitor.
Belzutifan is used to treat kidney cancer (renal cell cancer). It may sometimes be used to treat other cancers.
It is best to read this information with our general information about targeted therapy drugs and the type of cancer you have.
Your cancer team will talk to you about this treatment and its possible side effects before you agree (consent) to have treatment.
More information about this treatment
This information is correct at time of publishing. But sometimes the types of cancer this treatment is used for, or treatment side effects, may change between revision dates.
You can talk to your cancer team if you want more detailed information about this treatment. Or visit the electronic Medicines Compendium (eMC) website, which has patient information leaflets (PIL) for individual drugs.
How belzutifan is given
You have belzutifan as tablets so you can take it at home. You may have it with other cancer drugs.
During a course of treatment, you will meet someone from your cancer team, such as a:
- cancer doctor
- specialist nurse
- specialist pharmacist.
This is who we mean when we mention doctor, nurse or pharmacist in this information.
During your course of treatment, you will have regular blood tests. Your cancer team will also regularly check the levels of oxygen in your blood. This is a painless test done using a monitor clip on your finger. The tests check that it is safe for you to have treatment.
You will meet with a doctor, nurse or pharmacist before you have treatment. They will talk to you about your test results and ask how you have been feeling. If your test results are okay, the pharmacy team will prepare your targeted therapy.
Your course of treatment
You take belzutifan once a day, every day. You usually keep taking this treatment as long as it is effective and the side effects are manageable.
Your cancer team will discuss your treatment plan with you. They will give you the tablets to take home. They may also give you anti-sickness drugs and other medicines to take home.
Take all your capsules or tablets exactly as your cancer team tell you to. This is important to make sure the treatment works as well as possible for you.
Taking belzutifan tablets
You can take belzutifan tablets with or without food. Swallow them whole with a glass of water. Do not chew, break or crush them. Try to take them at the same time every day.
If you forget to take the tablets, take the missed dose as soon as possible within the same day. If a full day has passed, do not take the missed dose. Take your next dose at the usual time the next day. Do not take a double dose.
If you are sick (vomit) just after taking the tablets, take your next dose at the usual time. Do not take a double dose.
Contact the hospital on the 24-hour number you have been given for advice.
Other things to remember about your tablets:
- Keep them in the original package and at room temperature, away from moisture, heat and direct sunlight.
- Keep them safe, where children cannot see or reach them.
- Do not throw away unused tablets. Return them to your cancer team at the hospital.
About side effects
We explain the most common side effects of this treatment here. We also include some that are less common.
You may get some of the side effects we mention, but you are unlikely to get all of them. And you may have some side effects, including rarer ones, that we have not listed here.
Other cancer treatments may cause different side effects. If you are also having other cancer treatment, you may have other side effects.
Always tell your doctor, nurse or pharmacist about any side effects you have. They can give you:
- drugs to help control some side effects
- advice about managing side effects.
It is important to take any drugs exactly as explained. This means they will be more likely to work for you.
Serious and life-threatening side effects
Some cancer treatments can cause serious side effects. Sometimes, these may be life-threatening. Your doctor, nurse or pharmacist can explain the risk of these side effects to you.
Contact the hospital
Your doctor, nurse or pharmacist will give you 24-hour contact numbers for the hospital. If you feel unwell or need advice, you can call at any time of the day or night. Save these numbers in your phone or keep them somewhere safe.
Very common side effects
Anaemia (low number of red blood cells)
This treatment can reduce the number of red blood cells in your blood. Red blood cells carry oxygen around the body. If the number of red blood cells is low, this is called anaemia. You may feel:
- very low in energy
- breathless
- dizzy and light-headed.
If you have these symptoms, contact the hospital straight away on the 24-hour number. You may need treatment for anaemia. If you are very anaemic, you may need a drip to give you extra red blood cells. This is called a blood transfusion.
Feeling tired (fatigue)
Feeling tired is a common side effect of this treatment. Tell your cancer team if you find this difficult to manage or if it gets worse. Try to pace yourself and plan your day so you have time to rest. Gentle exercise, like short walks, can help you feel less tired.
If you feel sleepy, do not drive or use machinery.
Dizziness
Feeling sick
Your doctor, nurse or pharmacist will prescribe anti-sickness drugs to help prevent or control sickness. Take the drugs exactly as they tell you to, even if you do not feel sick. It is easier to prevent sickness than to treat it after it has started.
If you feel sick, take small sips of fluid often and eat small amounts regularly. It is important to drink enough fluids. If you continue to feel sick, or if you are sick (vomit) 1 to 2 times in 24 hours, contact the hospital on the 24-hour number as soon as possible. They will give you advice. They may change your anti-sickness treatment. Let them know if you still feel sick.
Effects on the lungs
This treatment can cause changes to the lungs. This can cause lower than normal oxygen levels in the blood. Your cancer team will check your blood oxygen levels regularly. If you smoke, ask your cancer team about advice and support to stop.
Tell your doctor, nurse or pharmacist if you develop:
- a cough that does not go away
- wheezing
- breathlessness.
You should also tell them if any existing breathing problems get worse. You may have tests to check your lungs.
Other important information
Blood clot risk
Cancer and some cancer treatments can increase the risk of a blood clot. Contact the hospital straight away on the 24-hour number if you have any of these symptoms during or after treatment:
- throbbing pain or swelling in a leg or arm
- reddening of the skin in the area – if you have black or brown skin, this can be harder to notice, but the skin might become darker
- suddenly feeling breathless or coughing.
Always call 999 if you have:
- chest pain
- difficulty breathing.
A blood clot is serious, but it can be treated with drugs called anticoagulants. These thin the blood. Your doctor, nurse or pharmacist can give you more information about preventing and treating blood clots.
Other medicines
Some medicines can affect how this treatment works or be harmful while you are having it. Always tell your cancer doctor, nurse or pharmacist about any drugs you are taking or planning to take, such as:
- medicines you have been prescribed
- medicines you buy in a shop, pharmacy or online
- vitamins or supplements
- herbal drugs and complementary or homeopathic therapies
- recreational drugs – for example, cannabis.
Vaccinations
Doctors usually recommend that people with cancer have vaccinations for flu and for coronavirus (covid). These help reduce your risk of serious illness from these infections. Most people can have these vaccines, including people with weak immune systems.
If your immune system is weak, you should not have live vaccinations. Live vaccines can make you unwell because they contain a very weak version of the illness they will protect you against. Live vaccines include Zostavax®, which is a shingles vaccine, and the yellow fever vaccine.
It is important to ask your doctor, nurse or pharmacist for advice about having vaccinations. They can explain what vaccines are right for you and when it is best to have them.
Contraception
Your doctor, nurse or pharmacist will advise you not to get pregnant or make someone pregnant while having this treatment and for some time afterwards. The drugs may harm a developing baby. It is important to use contraception to prevent pregnancy. Follow their advice about:
- what types of contraception to use
- how long after treatment you should continue to use contraception.
Breastfeeding
You are advised not to breastfeed while having this treatment, or for some time after treatment ends. This is because the drugs could be passed to the baby through breast milk.
Your doctor, nurse or pharmacist can give you more information.
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.
Medical and dental treatment
If you need medical treatment for any reason other than cancer, always tell the healthcare professional that you are having cancer treatment. Give them the contact details for your cancer doctor or cancer team so they can ask for advice.
If you have appointments with a dentist, always tell them you are having cancer treatment. Talk to your cancer team before you have any dental treatment.
About our information
This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer.
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References
Visit the electronic Medicines Compendium (eMC) to download a Patient Information Leaflet (PIL) for more detailed information. The leaflet lists all known side effects.
Date reviewed
Our cancer information meets the PIF TICK quality mark.
This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.
The language we use
We want everyone affected by cancer to feel our information is written for them.
We want our information to be as clear as possible. To do this, we try to:
- use plain English
- explain medical words
- use short sentences
- use illustrations to explain text
- structure the information clearly
- make sure important points are clear.
We use gender-inclusive language and talk to our readers as ‘you’ so that everyone feels included. Where clinically necessary we use the terms ‘men’ and ‘women’ or ‘male’ and ‘female’. For example, we do so when talking about parts of the body or mentioning statistics or research about who is affected.
You can read more about how we produce our information here.