Neratinib (Nerlynx) for primary breast cancer

Neratinib is a targeted therapy drug that blocks the growth and spread of breast cancer. 

Neratinib is the drug’s non-branded name. Its brand name is Nerlynx.

Neratinib may be offered to people who have primary breast cancer that is both:

• Hormone receptor positive (breast cancer that’s helped to grow by the hormones oestrogen or progesterone)
• HER2-positive (breast cancer that has a higher-than-normal level of the HER2 protein)

When is it given?

Neratinib is given after you have surgery and have completed treatment with trastuzumab. Neratinib should be started within 1 year of finishing trastuzumab.

If you have pertuzumab after surgery, you will not be offered neratinib. However, you may be offered neratinib if you only had pertuzumab before surgery.

Targeted therapies block the growth and spread of cancer. They target and interfere with processes in the cells that help cancer grow.

Some breast cancer cells have a higher-than-normal level of a protein called HER2 on their surface, which makes them grow more quickly.

This is called HER2-positive breast cancer. 

Neratinib blocks HER2 and 2 other proteins that also help breast cancer cells to grow.

There are different tests to measure HER2 levels, which are done on breast tissue removed during a biopsy or surgery. 

If your cancer is found to be HER2-negative, then neratinib will not be of benefit to you.

Neratinib is taken as a tablet.

The recommended starting dose is 240mg (six 40mg tablets) taken once a day. 

You will take neratinib for 1 year.

The tablets should be taken with food, preferably in the morning. 

What happens if I miss a dose?

If you miss a dose of neratinib, do not take an extra dose to make up for the 1 you missed. Take the usual dose the next day.

Like any drug, neratinib can cause side effects. Everyone reacts differently to drugs and some people have more side effects than others. 

Side effects can usually be managed and the ones described here may not affect you.

If you’re worried about any side effects, regardless of whether they’re listed here, talk to your treatment team.

Common side effects

Diarrhoea

Diarrhoea is a very common side effect of neratinib and it can be severe. This may cause dehydration. 

You’ll be prescribed drugs to take as soon as you begin neratinib to help prevent diarrhoea.

It’s important to take these regularly to start with. Your treatment team might advise you to start taking them before your treatment with neratinib starts. They’ll tell you how long to take these drugs for and when to stop taking them.

Contact your treatment team if you have diarrhoea 4 or more times in 24 hours.

Drink plenty of fluids to avoid getting dehydrated.

Sometimes your treatment team may recommend reducing the dose of neratinib or stopping altogether if diarrhoea is very severe. 

Some people are advised to reduce the amount of fibre in their diet while taking this drug. Your treatment team may recommend seeing a dietitian to discuss adapting your diet.

Feeling sick (nausea) and being sick (vomiting)

You may have nausea and vomiting. 

Anti-sickness drugs can be prescribed to help if you do have this side effect.

Extreme tiredness 

Fatigue is extreme tiredness that does not go away with rest or sleep. It’s a very common side effect of neratinib.

If you think you have fatigue, tell your GP or treatment team. They can assess you and offer advice on how to manage your energy levels. 

Find out more about managing fatigue.

Stomach (tummy) pain

You may have some pain in your tummy or feel bloated. Tell your treatment team if you have this.

Rash

This can be uncomfortable but using a moisturiser and a high-factor sunscreen may help. Occasionally, you might need antibiotics if the rash gets infected.

Your treatment team may suggest drugs such as antihistamines to reduce any itching.

Loss of appetite

You may not feel like eating, especially if you’re feeling sick. 

It might help to eat small meals regularly and drink plenty of liquids. 

Some people lose weight while taking neratinib.

Sore mouth

Your mouth may become sore or dry and you may get ulcers. 

You may be given mouthwash to reduce soreness of the mouth and gums and to try to stop mouth ulcers developing. Looking after your mouth, including your teeth and gums, is very important during treatment.

Muscle spasms

You may have some painful twitching of the muscles (muscle spasms) while taking neratinib. 

Drinking plenty of fluids and doing regular exercise may help.

Your treatment team may also suggest a blood test to check your magnesium and potassium levels.

Less common side effects

Liver changes

Neratinib can affect how the liver works. 

You’ll have blood tests to check your liver function while you’re having treatment.

Sometimes neratinib may be delayed or the dose reduced if tests show any problems with your liver.

Contact your treatment team straight away if you have any of the following symptoms:

• Yellowing of your skin or the whites of your eyes (jaundice)
• Pain on your right side under the ribs
• Bleeding or bruising more easily than normal
• Feeling more tired
• Your pee being dark brown

Kidney problems

Neratinib can cause changes to the way the kidneys work. You’ll have regular blood tests during your treatment to check this. 

Urinary tract infections (UTIs)

If it hurts when you pee, you need the toilet more often than usual and only pass small amounts, tell your treatment team. You may have an infection and need antibiotics.

Nosebleeds

Some people have nosebleeds while taking neratinib. Tell your treatment team if this happens.

If your nose feels dry and uncomfortable, it can help to put some petroleum jelly (such as Vaseline) just inside the nostrils.

Dry or cracked skin

You may have dry skin including mild scaling (where your skin becomes flaky), roughness, tightness or itching.

It may help to:

• Use a moisturiser regularly and avoid perfumed products
• Protect your hands when doing household or outdoor chores
• Rinse and dry your hands carefully, particularly after contact with cleaning products
• Pat your skin dry with a soft towel, rather than rubbing vigorously
• Take care when shaving
• Wear cotton clothes where possible next to the skin and wash clothes in mild detergent

Nail changes

Some people have nail problems while taking neratinib, such as nail splitting or colour change. Speak to your GP or treatment team if this is worrying you.

Medicines and food to avoid when taking neratinib

Some drugs should not be taken with neratinib. 

Tell your treatment team about any prescribed or over-the-counter medicines you’re taking. 

If a healthcare professional, such as your GP or dentist, prescribes a new drug, tell them you’re taking neratinib.

You should not take neratinib with anything containing St John’s Wort. Ask your treatment team before taking any herbal medicines or supplements.

Avoid eating grapefruit and pomegranate or drinking grapefruit or pomegranate juice while taking neratinib. They may interact with neratinib and affect how the medicine works.

Blood clots

People with breast cancer have a higher risk of blood clots such as a DVT (deep vein thrombosis).

If you have a DVT, there’s a risk part of the blood clot could break away and travel to the lung. This is known as a pulmonary embolism (PE). 

Blood clots can be life-threatening and should be treated quickly.

Sex and contraception

Taking neratinib while pregnant may be harmful to a developing baby. Some women can still get pregnant even if their periods are irregular or have stopped.

Women taking neratinib should use an effective barrier contraception during treatment and continue for 1 month after completing their treatment.

Men taking neratinib should use barrier contraception during treatment and for 3 months after completing their treatment if their partner can get pregnant.

It’s not known if taking neratinib affects fertility.

Breastfeeding and neratinib 

It’s not known if neratinib passes to a baby through breast milk. Speak to your treatment team if you plan to breastfeed. 

Travel and vaccinations 

If you’re planning a holiday or need to travel overseas, check with your treatment team first. 

You should not have any live vaccines while you’re taking neratinib. 

Live vaccines include: 

• Mumps
• Measles
• Rubella (German measles)
• Polio
• BCG (tuberculosis)
• The Zostavax shingles vaccine (there is another non-live shingles vaccine called Shingrix that people with weakened immune systems can have)
• Yellow fever

Live vaccines contain a small amount of live virus or bacteria. If you have a weakened immune system, which you may do during treatment, they could be harmful.

It’s safe to have these vaccinations 6 months after your treatment finishes. Talk to your GP or treatment team before having any vaccinations.

If someone you have close contact with needs to have a live vaccine, speak to your treatment team or GP. They can advise what precautions you may need to take depending on the vaccination.

COVID-19 vaccination  

If you’re having chemotherapy or targeted therapies, you’re advised to speak to your treatment team about the best time to have a COVID-19 vaccination.

Flu vaccination

Anyone at risk of a weakened immune system, and therefore more prone to infection, should have the flu vaccine. This includes people due to have, or already having, treatment for breast cancer.

The flu vaccine is not a live vaccine so does not contain any active viruses.

Talk to your treatment team about the best time to have your flu jab.

Being diagnosed with breast cancer can make you feel lonely and isolated.

Many people find it helps to talk to someone who has been through the same experience as them. You can ask questions and chat to other people on our online forum. 

For further information and support or to talk things through, you can call our free helpline. See below for ways to get in touch.