A PI3K inhibitor tablet used with hormone therapy in breast cancer
Alpelisib
A targeted tablet used with hormone therapy for some breast cancers carrying a PIK3CA gene change.
What is Alpelisib?
Alpelisib is a targeted cancer medicine called a PI3K inhibitor, used with hormone therapy for certain hormone-receptor-positive, HER2-negative breast cancers that carry a change in the PIK3CA gene. It works by blocking a growth pathway the cancer relies on. It is taken by mouth once a day with food. Its most important side effect is a sharp rise in blood sugar, which needs close monitoring and sometimes treatment, and it can also cause serious skin rashes and diarrhoea, so it is used under careful specialist supervision.
Education and reference only. This is a plain-language guide to Alpelisib — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Alpelisib is a targeted cancer treatment known as a PI3K inhibitor. It is used for some kinds of breast cancer that are hormone-receptor-positive and HER2-negative and that carry a specific genetic change called a PIK3CA mutation, confirmed by a test. It is taken by mouth and is given together with a hormone-blocking medicine. Because it can strongly affect blood sugar, it is started and supervised by a cancer specialist team alongside checks of blood glucose, and people may need support to keep their sugar levels controlled.
How it works
Some breast cancers have a change in the PIK3CA gene that switches on a growth pathway called PI3K, which drives the cancer cells to grow and survive. Alpelisib blocks the PI3K pathway, removing one of the signals the cancer uses to grow, and it is combined with hormone therapy to tackle the cancer from two directions. Because PI3K also helps the body control blood sugar, blocking it can cause blood sugar to rise sharply, which is why glucose is monitored closely. It is taken every day for as long as it controls the cancer and is tolerated.
Company & origin
Originated / developed by: Specialist manufacturer.
A targeted cancer medicine used in the UK for some hormone-receptor-positive, HER2-negative breast cancers that carry a PIK3CA change, taken with hormone therapy.
Practical use
How to take Alpelisib
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it by mouth once a day with food, at about the same time each day.
- Swallow the tablets whole with water; do not chew, crush or split them.
- Check your blood sugar as advised and watch for signs of high sugar such as extra thirst, passing more urine or blurred vision.
- Report any new, spreading or blistering rash straight away, and treat diarrhoea early while keeping your fluids up.
- Keep taking it as prescribed unless your specialist tells you to pause or stop.
Weighing it up
Advantages & disadvantages of Alpelisib
Advantages
- A targeted tablet that, with hormone therapy, can help control breast cancers carrying a PIK3CA change.
- Taken by mouth at home rather than as an infusion.
- Aimed at a specific genetic change that drives the cancer.
Disadvantages
- Can cause a sharp and potentially serious rise in blood sugar that needs close monitoring.
- Can cause serious skin rashes, including rare severe reactions.
- Commonly causes diarrhoea, and it is not suitable in pregnancy.
Practical use
Good to know
The single most important thing to know about alpelisib is that it can cause a sharp rise in blood sugar, even in people who do not have diabetes; blood sugar is checked before and during treatment, and people are told the warning signs of high sugar, such as increased thirst, passing more urine, blurred vision and tiredness. Sometimes a glucose-lowering medicine is needed alongside it. It can also cause serious skin rashes, including rare but severe reactions, so any new or spreading rash, blistering or peeling should be reported straight away. Diarrhoea is common and should be treated early with plenty of fluids. It is taken with food. As with other targeted cancer medicines, it can harm a developing baby, so effective contraception is needed during treatment and for a time afterwards.
Who should not take it / use with caution
- People who have had a serious allergic reaction to alpelisib should not take it.
- It must not be used in pregnancy, as it can harm a developing baby, and effective contraception is needed during treatment and for a time after.
- It is used with great care in people with poorly controlled diabetes or a history of severe skin reactions.
- It should only be used under specialist cancer care with regular blood-sugar monitoring.
Monitoring
- Checking blood sugar before and regularly during treatment.
- Watching closely for skin rashes, especially early in treatment.
- Reviewing diarrhoea, weight, appetite and other blood tests over time.
Side effects
- A sharp rise in blood sugar, which can be serious and needs monitoring and sometimes treatment.
- Skin rashes, which can occasionally be severe with blistering or peeling.
- Diarrhoea, nausea, tiredness and loss of appetite.
- Mouth soreness and changes in some other blood tests.
Key interactions
- Tell your team about all your medicines, including any for diabetes, which may need adjusting.
- Some medicines can affect how alpelisib works, so a full medicines list is important.
- Care is needed with medicines that can also affect blood sugar or the skin.
Available as: Tablets taken by mouth.
Answers
Alpelisib: frequently asked questions
What is alpelisib used for?
It is a targeted medicine used with hormone therapy for certain hormone-receptor-positive, HER2-negative breast cancers that carry a change in the PIK3CA gene, confirmed by a test.
Why does it affect blood sugar?
The pathway it blocks also helps control blood sugar, so blocking it can make blood sugar rise sharply, which is why glucose is monitored closely and sometimes treated.
What rash should worry me?
Any new or spreading rash, especially with blistering or peeling, should be reported straight away, as alpelisib can rarely cause severe skin reactions.
Should I take it with food?
Yes, it is taken with food once a day at about the same time, which helps the medicine work as intended.
Is it safe in pregnancy?
No. It can harm a developing baby, so effective contraception is needed during treatment and for a time afterwards; discuss any plans with your specialist.
Authoritative sources
- BNF
- NICE CKS
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