Patient leaflet - Enhertu 100 mg powder for concentrate for solution for infusion
What Enhertu is used for
Enhertu is used to treat adults who have:
HER2-positive breast cancer that has spread to other
parts of the body (metastatic disease) or cannot be removed by surgery, and have tried one or more other treatments specifically for HER2-positive breast cancer. • HER2-low or HER2-ultralow breast cancer that has
spread to other parts of the body (metastatic disease) or cannot be removed by surgery and have received prior therapy. A test will be performed to make sure Enhertu is right for you.
HER2-mutant non-small cell lung cancer that has
spread to other parts of the body or cannot be removed by surgery and have tried a prior treatment. A test will be performed to make sure Enhertu is right for you. • HER2-positive stomach cancer that has spread to
other parts of the body or to areas near the stomach that cannot be removed by surgery and have also tried another treatment specifically for HER2-positive stomach cancer.
Other HER2-positive solid tumours that have spread
to other parts of the body (metastatic disease) or cannot be removed by surgery and who have also received prior treatment or who have no other treatment options. A test will be performed to make sure Enhertu is right for you.
2. WHAT YOU NEED TO KNOW BEFORE YOU ARE GIVEN ENHERTU
You must not be given Enhertu
if you are allergic to trastuzumab deruxtecan or any of
the other ingredients of this medicine (listed in section 6). If you are not sure if you are allergic, talk to your doctor or nurse before you are given Enhertu.
Warnings and precautions
Talk to your doctor or nurse before you are given Enhertu, or during treatment, if you have:
cough, shortness of breath, fever, or other new or
worsening breathing problems. These may be symptoms of a serious and potentially fatal lung disease called interstitial lung disease. A history of lung disease or kidney problems may increase the risk of developing interstitial lung disease. Your doctor may have to monitor your lungs while you are taking this medicine. • chills, fever, sores in your mouth, stomach pain or pain
when urinating. These may be symptoms of an infection caused by a reduced number of white blood cells called neutrophils.
new or worsening shortness of breath, cough, tiredness,
swelling of ankles or legs, irregular heartbeat, sudden weight gain, dizziness, or loss of consciousness. These may be symptoms of a condition in which your heart cannot pump blood well enough (decreased left ventricular ejection fraction).
liver problems. Your doctor may have to monitor your
liver while you are taking this medicine.
Your doctor will carry out tests before and during treatment with Enhertu.
Children and adolescents
Enhertu is not recommended for anyone under the age of 18 years. This is because there is no information on how well it works in this age group.
Other medicines and Enhertu
Tell your doctor or nurse if you are taking, have recently taken or might take any other medicines.
Pregnancy, breast-feeding, contraception and fertility
Pregnancy
Enhertu is not recommended during pregnancy because this medicine may harm the unborn baby. Speak with your doctor immediately if you are pregnant, think you may be pregnant or are planning to become pregnant before or during treatment.
Breast-feeding
You should not breast-feed during treatment with Enhertu and for at least 7 months after your last dose. This is because it is not known whether Enhertu passes into breast milk. Talk to your doctor about this. • Contraception
Use effective contraception (birth control) to avoid becoming pregnant while being treated with Enhertu. Women taking Enhertu should continue contraception for at least 7 months after the last dose of Enhertu. Men taking Enhertu whose partner may become pregnant should use effective contraception: – during treatment and
- for at least 4 months after the last dose of Enhertu. Talk to your doctor about the best contraception for you. Also talk to your doctor before you stop your contraception.
Fertility
If you are a man being treated with Enhertu, you should not father a child for 4 months after treatment and take advice on conserving sperm before treatment because the medicine may reduce your fertility. Therefore, discuss this with your doctor before starting treatment.
Driving and using machines
Enhertu is not likely to reduce your ability to drive or use machines. Be careful if you feel tired, dizzy, or have a headache.
Enhertu contains polysorbate 80
This medicine contains 1.5 mg of polysorbate 80 in each 100 mg vial.
Polysorbates may cause allergic reactions. Tell your doctor if you have any known allergies.
3. HOW YOU ARE GIVEN ENHERTU
Enhertu will be given to you in a hospital or clinic: • The recommended dose of Enhertu for the treatment of:
HER2-positive, HER2-low, or HER2-ultralow breast cancer is 5.4 mg for every kilogram of your weight, every 3 weeks.
- HER2-mutant non-small cell lung cancer is 5.4 mg for every kilogram of your weight, every 3 weeks.
- HER2-positive stomach cancer is 6.4 mg for every kilogram of your weight, every 3 weeks.
- Other HER2-positive solid tumours is 5.4 mg for every kilogram of your weight, every 3 weeks. • Your doctor or nurse will give you Enhertu by infusion
(drip) into your vein.
Your first infusion will be given over 90 minutes. If this
goes well, the infusion on your next visits may be given over 30 minutes.
Your doctor will decide how many treatments you need. • Before each Enhertu infusion, your doctor may give you
medicines to help prevent nausea and vomiting. • If you get infusion-related symptoms, your doctor or
nurse may slow down your infusion or interrupt or stop your treatment.
Before and during treatment with Enhertu, your doctor
will carry out tests that may include:
- blood tests to check your blood cells, liver and kidneys.
- testing to check your heart and lungs.
Your doctor may lower your dose, or temporarily or
permanently stop your treatment depending on your side effects.
If you miss an appointment to get Enhertu
Contact your doctor right away to reschedule your appointment.
It is very important that you do not miss a dose of this medicine.
If you stop receiving Enhertu
Do not stop treatment with Enhertu without checking with your doctor.
If you have any further questions on the use of this medicine, ask your doctor or nurse.
4. POSSIBLE SIDE EFFECTS
Like all medicines, this medicine can cause side effects, although not everybody gets them. Tell your doctor if you get any side effects, including those not listed in this leaflet. Speak with your doctor immediately if you notice any of the following symptoms. They may be signs of a serious, possibly fatal, condition. Getting medical treatment right away may help keep these problems from becoming more serious.
Very common (may affect more than 1 in 10 people) • A lung disease called interstitial lung disease with
symptoms that can include cough, shortness of breath, fever, or other new or worsening breathing problems • An infection caused by reduced number of neutrophils
(a type of white blood cell) with symptoms that can include chills, fever, sores in your mouth, stomach pain or pain when urinating
A heart problem called left ventricular dysfunction with
symptoms that can include new or worsening shortness of breath, cough, tiredness, swelling of ankles or legs, irregular heartbeat, sudden weight gain, dizziness or unconsciousness
Other side effects
The frequency and severity of side effects may vary with the dose you received. Tell your doctor or nurse if you notice any of the following side effects:
Very common (may affect more than 1 in 10 people) • nausea (feeling sick), vomiting
- tiredness
blood tests showing decreased red or white blood cells,
or platelets
- decreased appetite
- hair loss
- diarrhoea
- constipation
blood tests showing increased levels of the liver
enzymes such as transaminases
- pain in muscles and bones
- abdominal (belly) pain
- weight loss
- fever
infections of the nose and throat, including flu-like
symptoms
headache
- blood tests showing low blood potassium levels • blisters in or around your mouth
- cough
- indigestion
- swelling of ankles and feet
Common (may affect up to 1 in 10 people)
- breathing difficulties
- infection of the lungs
- blood tests showing increased levels of alkaline phosphatase, bilirubin or creatinine
- nosebleed
- dizziness
- rash
- blood tests showing decreased red blood cells, white blood cells, and platelets (pancytopenia)
- altered/bad taste in mouth
- dry eye
- itching
- bloating
- blurred vision
- skin discolouration
- feeling thirsty, dry mouth
- fever along with a decreased number of white blood cells called neutrophils
- excessive gas in the stomach or intestine • inflammation of the stomach
- reactions related to the infusion of the medicine which may include fever, chills, flushing, itching or rash
Reporting of side effects
If you get any side effects, talk to your doctor or pharmacist. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme Website: http://www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects you can help provide more information on the safety of this medicine.
5. HOW TO STORE ENHERTU
Enhertu will be stored by healthcare professionals at the hospital or clinic where you receive treatment. The storage details are as follows:
- Keep this medicine out of the sight and reach of children. • Do not use this medicine after the expiry date which is stated on the outer carton and vial after EXP. The expiry date refers to the last day of that month.
Store in a refrigerator (2 °C – 8 °C). Store in the original carton in order to protect from light. Do not freeze. • The prepared solution for infusion is stable for up to
24 hours at 2 °C – 8 °C protected from light and must be discarded thereafter.
Do not throw away any medicines via wastewater or household waste. Ask your pharmacist how to throw away medicines you no longer use. These measures will help to protect the environment.
6. CONTENTS OF THE PACK AND OTHER INFORMATION
What Enhertu contains
The active substance is trastuzumab deruxtecan.
One vial of powder for concentrate for solution for infusion contains 100 mg of trastuzumab deruxtecan. After reconstitution, one vial of 5 mL solution contains 20 mg/mL of trastuzumab deruxtecan.
- The other ingredients are L-histidine, L-histidine hydrochloride monohydrate, sucrose, polysorbate 80 (E433).
What Enhertu looks like and contents of the pack
Enhertu is a white to yellowish-white lyophilised powder supplied in a clear amber vial with a rubber stopper, aluminium seal and plastic flip-off cap.
Each carton contains 1 vial.
Marketing Authorisation Holder
Daiichi Sankyo UK Ltd
Building 4
Uxbridge Business Park
Sanderson Road
Uxbridge
UB8 1DH
Package leaflet: Information for the patient
ENHERTU® 100 mg
powder for concentrate for solution for infusion
trastuzumab deruxtecan
GB XXXXXX
Manufacturer
Daiichi Sankyo Europe GmbH
Luitpoldstrasse 1
85276 Pfaffenhofen
Germany
For any information about this medicine, please contact: Daiichi Sankyo UK Ltd.
Tel: +44 (0) 800 028 5122
This leaflet was last revised in June 2026.
This medicine has been given ‘conditional approval’. This 
means that there is more evidence to come about this medicine. The MHRA will review new information on this medicine at least every year and this leaflet will be updated as necessary.
The following information is intended for healthcare professionals only:
In order to prevent medicinal product errors, check the vial labels to ensure that the medicinal product being prepared and administered is Enhertu (trastuzumab deruxtecan) and not trastuzumab or trastuzumab emtansine.
Appropriate procedures for the preparation of chemotherapeutic medicinal products should be used. Appropriate aseptic technique should be used for the following reconstitution and dilution procedures.
Reconstitution
Reconstitute immediately before dilution. • More than one vial may be needed for a full dose.
Calculate the dose (mg), the total volume of reconstituted Enhertu solution required, and the number of vial(s) of Enhertu needed.
- Reconstitute each 100 mg vial using a sterile syringe to slowly inject 5 mL of water for injection into each vial to obtain a final concentration of 20 mg/mL. • Swirl the vial gently until completely dissolved. Do not shake.
- From a microbiological point of view, the product should be used immediately. If not used immediately, chemical and physical in-use stability has been demonstrated for up to 48 hours at 2 ºC to 8 ºC. Store the reconstituted Enhertu vials in a refrigerator at 2 ºC to 8 ºC, protected from light. Do not freeze.
- The reconstituted product contains no preservative and is intended for single use only.
Dilution
- Withdraw the calculated amount from the vial(s) using a sterile syringe. Inspect the reconstituted solution for particulates and discolouration. The solution should be clear and colourless to light yellow. Do not use if visible particles are observed or if the solution is cloudy or discoloured.
- Dilute the calculated volume of reconstituted Enhertu in an infusion bag containing 100 mL of 5 % glucose solution for infusion. Do not use sodium chloride solution. An infusion bag made of polyvinylchloride or polyolefin (copolymer of ethylene and polypropylene) is recommended.
- Gently invert the infusion bag to thoroughly mix the solution. Do not shake.
Cover the infusion bag to protect from light. • If not used immediately, store at room temperature
(≤ 30 ºC) for up to 4 hours including preparation and infusion or in a refrigerator at 2 ºC to 8 ºC for up to 24 hours, protected from light. Do not freeze. • Discard any unused portion left in the vial.
Administration
If the prepared infusion solution was stored refrigerated
(2 ºC to 8 ºC), it is recommended that the solution be allowed to equilibrate to room temperature prior to administration, protected from light.
- Administer Enhertu as an intravenous infusion only with a 0.20 or 0.22 micron in-line polyethersulfone (PES) or polysulfone (PS) filter.
The initial dose should be administered as a 90-minute intravenous infusion. If the prior infusion was well tolerated, subsequent doses of Enhertu may be administered as 30-minute infusions. Do not administer as an intravenous push or bolus.
- Cover the infusion bag to protect from light. • Do not mix Enhertu with other medicinal products or administer other medicinal products through the same intravenous line.
Disposal
Any unused medicinal product or waste material should be disposed of in accordance with local requirements.