Idelalisib (Zydelig®)

Idelalisib comes as tablets you take at home. Idelalisib may be given on its own or with other cancer drugs, such as rituximab.

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. This is to check that it is safe for you to have treatment. The tests will also check how well your liver is working.

You will meet with a doctor, nurse or pharmacist before you have treatment. They will talk to you about your blood results and ask how you have been feeling.

You usually take idelalisib for as long as:

• it is still working for you 
• and the side effects can be managed.

Your cancer team will discuss your treatment plan with you. They will give you the tablets to take home. They may give you tablets of different strengths. Always take them exactly as they tell you to. This is important to make sure they work as well as possible for you. Do not stop taking them without talking to your doctor, nurse or pharmacist.

Your cancer team may also give you anti-sickness drugs and other medicines to take home. Take all your capsules or tablets exactly as they tell you to.

You usually take idelalisib twice a day. The tablets must be swallowed whole with a glass of water. They should not be chewed, broken or crushed. Take them at the same time every day. Idelalisib can be taken with or without food.

If you forget to take the tablets, take the missed dose as soon as possible if it is less than 6 hours late. If more than 6 hours has passed, take the next dose at the usual time. Do not take a double dose.

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.
• if you are sick (vomit) just after taking them, do not take an extra dose. Take your next dose at the usual time.
• Do not throw away unused tablets. Return them to your cancer team at the hospital.

These side effects happen to 10 or more people in every 100 people (10% or more) who have this treatment.

This treatment can reduce the number of white blood cells in your blood. These cells fight infection. If your white blood cell count is low, you may be more likely to get an infection. A low white blood cell count is called neutropenia.

An infection can be very serious when the number of white blood cells is low. It is important to get any infection treated as soon as possible. If you have any of the following symptoms, contact the hospital straight away on the 24-hour number:

• a temperature above 37.5°C 
• a temperature below 36°C
• you feel unwell, even with a normal temperature
• you have symptoms of an infection.

Symptoms of an infection include:

• feeling shivery and shaking
• a sore throat
• a cough
• breathlessness
• diarrhoea
• needing to pass urine (pee) often, or discomfort when you pass urine.

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

You will have regular blood tests during treatment. If your white blood cell count is low, your doctor may stop your treatment for a short time, until your cell count increases. Sometimes they will reduce the dose of your treatment.

You may have diarrhoea or tummy (abdominal) pain. This treatment can also cause inflammation of the bowel (colitis) which can be very serious. 

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

Contact the hospital straight away on the 24-hour number if you have any of the following symptoms during treatment, or after treatment ends:

• You have diarrhoea 4 or more times in a day. 
• You have a moderate increase in stoma activity. 
• You have uncomfortable tummy cramps. 
• You have diarrhoea at night. 
• Your temperature is over 37.5°C.
• There is blood or mucus in your stool.

You may need to go into hospital to have fluids through a drip or treatments such as steroids.

This treatment may cause inflammation in the skin. This is usually mild, but if it is not treated it can become serious. You may need creams, steroids or other medicines to treat skin problems. If you notice skin changes during treatment, or after treatment ends, contact the hospital on the 24-hour number as soon as possible. Skin changes can include: 

• a rash or bumps on the skin
• dry or itchy skin
• patches of white or paler skin.

To protect your skin from the sun, use suncream with an SPF of at least 30. SPF stands for sun protection factor. Cover up with clothing and a hat. 

Contact the hospital straight away on the 24-hour number if you have any of these symptoms:

• a rash that is spreading
• blistering or peeling skin
• flu-like symptoms, such as a high temperature and joint pain. 

These symptoms can be a sign of a serious skin reaction that needs to be treated immediately in hospital.

This treatment can affect how the liver works. You will have regular blood tests to check this. Sometimes liver changes can be serious. Contact the hospital straight away on the 24-hour number if you have any of these symptoms:

• yellow skin or eyes
• feeling very sleepy
• dark urine (pee)
• unexplained bleeding or bruising
• pain in the right side of your tummy (abdomen).

This treatment can increase the level of a type of fat called triglyceride in your blood. You will have regular blood tests to check this.

Cytomegalovirus (CMV) is a very common virus that many people have. It does not usually cause any problems or symptoms. Most people don’t know they have it. The body’s immune system usually controls it so that it is inactive (dormant). Once you have the virus in your body it stays there for life.

If you have CMV, taking idelalisib may make CMV active again. You will have regular blood tests to check for this. If CMV does becomes active you will be given treatment for this straightaway. Treatment is usually with tablets.

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.

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.

Cancer doctors usually recommend that people with cancer have vaccinations for flu and coronavirus (covid). They may also recommend other vaccines, such as Shingrix^® for shingles. These all help reduce your risk of serious illness from these infections. Most people can have these vaccines, including people with weak immune systems.

You should not have live vaccines if your immune system is weak. This includes if you are having or recently had chemotherapy, radiotherapy or other cancer treatments that affect your immune system. Live vaccines can make you unwell because they contain a very weak version of the illness they protect you against. There are several live vaccines, including 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.

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. 

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.

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.

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.