1. What is elacestrant?
Elacestrant is a hormone (endocrine) therapy.
It belongs to a group of drugs called selective oestrogen receptor degraders.
You may also hear it called by its brand name Korserdu.
2. Who might be offered elacestrant?
You may be offered elacestrant if you have or that is:
- oestrogen receptor positive
- HER2 negative
- And has a mutation in a gene called ESR1 (see below)
It’s used to treat breast cancer in women who have been through the menopause (postmenopausal). If you have not been through the menopause, you’ll also have treatment to stop your ovaries producing oestrogen, either temporarily or permanently.
It can also be taken by men who have breast cancer.
Before having elacestrant, you should already have had at least 1 hormone therapy for 12 months or more and a drug called a CDK 4/6 inhibitor (such as abemaciclib, palbociclib or ribociclib).
Elacestrant is not given for early (primary) breast cancer.
Testing for ESR1 gene mutations
As secondary breast cancer cells grow and divide, they develop changes known as acquired gene mutations.
An ESR1 gene mutation is more common in oestrogen receptor positive, HER2 negative secondary breast cancer. It’s more likely to develop if you have been on hormone therapy for a long time.
These breast cancers can be tested for an ESR1 mutation at the time of growth and spread (progression) of the cancer. This can be done with a blood test.
If the blood test shows your breast cancer has an ESR1 mutation, you may be offered elacestrant.
3. How elacestrant works
Some breast cancers use oestrogen in the body to help them grow. These are known as oestrogen receptor positive or ER-positive breast cancers.
Hormone therapies block or stop the effect of oestrogen on breast cancer cells.
Oestrogen receptors are proteins on breast cancer cells. They “receive” messages from oestrogen in the body to help them grow and divide.
An ESR1 gene mutation, seen in some secondary breast cancer cells, permanently “switches on” the oestrogen receptors. The cancer cells continue to grow and divide, becoming resistant to hormone therapy.
Elacestrant targets these cells. It blocks and destroys the oestrogen receptors so they can no longer tell the cancer cells to grow and divide.
4. How elacestrant is taken
You take elacestrant as a tablet with food. This can help reduce any nausea and vomiting.
It’s best to take it at the same time every day.
You should swallow the tablets whole. Do not chew, crush or split the tablets before swallowing. Do not take a tablet that’s broken, cracked or damaged.
The recommended dose for most people is 345mg each day.
What if I miss a dose?
If you miss a dose, you can take elacestrant immediately within 6 hours after the time you usually take it.
After more than 6 hours, or if you vomit after taking elacestrant, skip the dose for that day.
On the next day, take elacestrant at the usual time.
How long will I take elacestrant for?
You’ll have elacestrant for as long as your treatment team feels you’re benefitting from the drug and any side effects are manageable.
5. Side effects of elacestrant
Like any drug, elacestrant can cause side effects. Everyone reacts differently to drugs. Some people will have more side effects than others, while others don’t have any side effects at all. Having few or no side effects does not mean the drug is not effective.
If you’re concerned about any side effects, regardless of whether they’re listed here, tell your treatment team.
Common side effects
Effects on the blood
Elacestrant can temporarily affect the number of blood cells in the body. Blood is made up of red cells, white cells and platelets.
You’ll have regular blood tests to monitor this.
Risk of infection
Not having enough white blood cells can increase your risk of getting an infection.
Signs of an infection
Your treatment team may give you advice on reporting signs of an infection. But generally you should contact your hospital immediately if you have any of the following:
- A high temperature (over 37.5°C) or low temperature (under 36°C)
- Suddenly feeling unwell, even with a normal temperature
- Symptoms of an infection, such as a sore throat, cough, needing to pee often or feeling cold or shivery, even if you do not have a high temperature
Anaemia
Having too few red blood cells is called anaemia. If you feel breathless, dizzy or particularly tired, let your treatment team know.
Nausea and vomiting
You may feel sick (nausea) or be sick (vomit). You can be prescribed anti-sickness drugs to help with this.
Extreme tiredness (cancer-related fatigue)
Learn more about extreme tiredness (cancer-related fatigue) and how you can manage it if you’re living with primary or secondary breast canc...
Extreme tiredness (cancer-related fatigue)
Cancer-related fatigue is one of the most common symptoms in people with secondary breast cancer.
Fatigue is extreme tiredness that does not go away with rest or sleep. It has many causes, from the emotional impact of a diagnosis to side effects of treatment or growth and spread of the cancer.
Fatigue may affect how you cope with your cancer and its treatment. It can also make everyday activities harder and affect your quality of life.
Decreased 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.
Find out more about diet and changes to your appetite during treatment.
Aching or pain in the joints and muscles
You may have aches or pains in your joints and muscles, including across the chest. This can be mild and temporary but for some people it’s more severe and longer lasting.
It can often be relieved with mild pain relief like paracetamol or an anti-inflammatory drug such as ibuprofen. Before using anti-inflammatory pain relief, ask your doctor about the correct dose, how long you should use it for and any possible side effects, especially if you have a stomach ulcer or asthma.
Exercise that gently stretches your joints or strengthens your muscles to better support your joints, such as yoga or Pilates, may help improve your symptoms. Brisk walking can also be beneficial. It’s important to check with your specialist before starting any new type of exercise.
A physiotherapist may also be able to suggest exercises to help.
If the pain is severe, it may be helpful to see a pain management specialist at a pain clinic.
Diarrhoea and constipation
Contact your treatment team if you have diarrhoea 4 or more times in 24 hours as they can prescribe drugs to help.
Drink plenty of fluids to avoid getting dehydrated.
Menopausal symptoms
You may have menopausal symptoms such as hot flushes, sweating and sleep disturbance.
Find out more about managing menopausal symptoms.
Other common side effects
Other common side effects of elacestrant can include:
- Headaches
- Indigestion
- Tummy (abdominal) pain
- Back pain
Less Common side effects
Sore mouth
Elacestrant can cause your mouth to become sore. If you have a sore mouth, contact your treatment team as soon as possible. They can give you advice and treatment to help relieve pain and stop it getting worse.
Skin rash
You may develop a skin rash or itchy or dry skin while taking elacestrant. Your pharmacist, GP or treatment team can tell you what products you can use on your skin to help.
Other less common side effects
Other less common side effects of elacestrant can include:
- Dizziness and fainting
- Breathlessness
- Cough
- Bone pain
Rare side effects
Liver changes
Elacestrant can affect how the liver works.
You’ll have blood tests to check your liver function while you’re having treatment.
Sometimes elacestrant may be delayed or the dose reduced if tests show any problems with your liver.
Contact your treatment team immediately 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
6. Other important information
Blood clots
People with breast cancer have a higher risk of blood clots.
Taking elacestrant also increases the 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.
Blood clot symptoms
Contact your treatment team or go to your local A&E department straight away if you have any of the following symptoms:
- Pain in your arm or leg
- Redness/discolouration of the skin of the arm or leg
- Heat and swelling of the arm or leg
- Swelling, redness or tenderness where a central line is inserted to give chemotherapy, for example in the arm, chest area or up into the neck
- Shortness of breath
- Pain or tightness in the chest
- Unexplained cough or coughing up blood
Find out more about blood clots.
People taking elacestrant need to be aware of the risk of blood clots and ways to reduce this.
Long periods of inactivity can increase your risk of developing blood clots. If you’re planning a long-distance plane, car or train journey, you can get advice from your treatment team or GP.
If you need to have treatment or surgery that will reduce your mobility, discuss with your specialist whether you need to stop taking elacestrant before and after this.
Can I take elacestrant with other drugs?
There are a number of drugs that can affect the way elacestrant works. Elacestrant can also affect the way some other medicines work.
If you’re taking any other prescribed or over-the-counter medicines, let your treatment team know.
Herbal medicines, supplements and foods
When taking elacestrant:
- Do not take anything containing St John’s wort
- Do not eat grapefruit or drink grapefruit juice
Many people consider taking herbal products or supplements while having treatment for breast cancer. However, the exact effect and safety of taking these after a diagnosis of breast cancer is not fully understood.
Ask your treatment team or pharmacist before taking herbal products or supplements.
Sex, contraception and pregnancy
You can still have sex during treatment. It’s thought that drugs cannot pass into vaginal fluids or semen, but this cannot be completely ruled out.
Most treatment teams will advise using barrier methods of contraception, such as condoms, during treatment.
Women are advised not to become pregnant while having treatment because elacestrant can harm a developing baby. If you have not been through the menopause, talk to your team about the most suitable method of contraception for you. It’s still possible to become pregnant even if your periods are irregular or have stopped.
Fertility
It’s not clear whether elacestrant affects fertility but it’s thought it may decrease it.
If you were diagnosed with locally advanced or secondary breast cancer before you started or completed a family, you may be concerned about your fertility. You can talk to your treatment team about any possible fertility preservation options before starting treatment.
Breastfeeding
You’ll be advised not to breastfeed during treatment with elacestrant. This is because there is a chance that your baby may absorb the drug through your breast milk, which can cause harm.
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 having treatment.
For more information about vaccines, including COVID-19 and flu vaccines, see our information on vaccines and breast cancer.
7. Further support
If you’ve been diagnosed with breast cancer, it’s natural to feel lonely or isolated.
You may find it helpful to talk to someone who has been through a similar experience to you.
Our Living with Secondary Breast Cancer service can help you meet others in a similar situation, and offers helpful support and information in a relaxed environment – see below.
You might also find it helpful to join one of our Live Chat sessions, or visit our confidential online forum.
Find out more about our support services below.
