Patient Information Leaflet: Package Insert

Enhertu 100 mg powder for concentrate for solution for infusion

trastuzumab deruxtecán

This medicine is subject to additional monitoring, which will speed up the detection of new information about its safety. You can contribute by reporting any adverse effects you may experience. The final part of section 4 includes information on how to report these adverse effects.

Read this leaflet carefully before you receive this medicine, as it contains important information for you.

• Keep this leaflet, as you may need to read it again.
• If you have any questions, consult your doctor or nurse.
• If you experience any adverse effects, consult your doctor or nurse, even if they are not listed in this leaflet. See section 4.

What is Enhertu

Enhertu is a cancer medication that contains the active ingredient trastuzumab deruxtecán. One part of the medication is a monoclonal antibody that specifically binds to cells containing the HER2 protein on their surface (HER2-positive), as some cancer cells do. The other active part of Enhertu is DXd, a substance that can kill cancer cells. Once the medication binds to HER2-positive cancer cells, DXd enters the cells and kills them.

What is Enhertu used for

Enhertu is used to treat adults who have:

• HER2-positive breast cancer-positivethat has spread to other parts of the body (metastatic disease) or that cannot be removed by surgery, and who have tried one or more treatments specifically for HER2-positive breast cancer;
• breast cancer with low HER2 expression or very low HER2 expressionthat has spread to other parts of the body (metastatic disease) or that cannot be removed by surgery and who have received previous treatment. A test will be performed to ensure that Enhertu is suitable for you;
• non-small cell lung cancer with a HER2 mutationthat has spread to other parts of the body or that cannot be removed by surgery and who have received previous treatment. A test will be performed to ensure that Enhertu is suitable for you;
• HER2-positive stomach cancer-positivethat has spread to other parts of the body or to nearby areas of the stomach that cannot be removed by surgery and who have also tried another treatment specifically for HER2-positive stomach cancer.

Do not administer Enhertu

• if you are allergic to trastuzumab deruxtecán or any of the other components of this medication (listed in section6).

If you are unsure if you are allergic, consult your doctor or nurse before Enhertu is administered to you.

Warnings and precautions

Consult your doctor or nurse before Enhertu is administered to you, or during treatment, if you have:

• shortness of breath, lack of breath, fever, or other new or worsening respiratory problems. These may be symptoms of a severe 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 need to monitor your lungs while you are taking this medication;
• chills, fever, mouth sores, stomach pain, or pain when urinating. These may be symptoms of an infection caused by a decrease in a type of white blood cell called neutrophils;
• new or worsening shortness of breath, cough, fatigue, swelling of the ankles or legs, irregular heartbeats, sudden weight gain, dizziness, or loss of consciousness. These may be symptoms of a condition in which the heart is not pumping enough blood (decreased left ventricular ejection fraction);
• liver problems. Your doctor may need to monitor your liver while you are taking this medication.

Your doctor will perform tests before and during treatment with Enhertu.

Children and adolescents

Enhertu is not recommended for individuals under 18years of age. This is because there is no information on how it works in this age group.

Other medications and Enhertu

Inform your doctor or nurse if you are taking, have taken recently, or may need to take any other medication.

Pregnancy, breastfeeding, and fertility

• Pregnancy

Do not useEnhertu during pregnancy because this medication may harm the fetus.

If you are pregnant, think you may be pregnant, or plan to become pregnant before or during treatment, consult your doctor immediately.

• Breastfeeding

Do not breastfeedduring treatment with Enhertu or for 7months after your last dose. This is because it is not known if Enhertu passes into breast milk. Discuss this with your doctor.

• Contraceptives

Use an effective contraceptive method (birth control) to prevent pregnancy while receiving treatment with Enhertu.

Women taking Enhertu should continue using the contraceptive for at least 7months after the last dose of Enhertu.

Men taking Enhertu whose partner may become pregnant should use an effective contraceptive method:

-during treatment and

-for at least 4months after the last dose of Enhertu.

Consult your doctor to determine the best contraceptive for you. Also, consult your doctor before stopping contraceptive use.

• Fertility

If you are a man being treated with Enhertu, do not conceive a child during 4months after treatment and seek advice on sperm preservation before treatment because the medication may reduce fertility.Therefore, discuss this with your doctor before starting treatment.

Driving and operating machinery

It is unlikely that Enhertu will reduce your ability to drive or operate machinery. Be cautious if you feel tired, dizzy, or have a headache.

Enhertu contains polysorbate80

This medication contains 1.5mg of polysorbate80 in each vial of 100mg.

Polysorbates may cause allergic reactions. Inform your doctor if you have any known allergies.

Enhertu will be administered in a hospital or clinic:

Like all medicines, this medicine can cause side effects, although not everyone will experience them. If you experience any side effect, consult your doctor, even if it is a side effect that does not appear in this leaflet.

Consult your doctor immediatelyif you notice any of the following symptoms. They may be signs of a serious, possibly life-threatening illness. Receiving medical treatment immediately may help prevent these problems from becoming more serious.

Very common(may affect more than 1 in 10people)

• Pulmonary disease called interstitial lung disease with symptoms that may include cough, shortness of breath, fever, or other new or worsening respiratory problems.
• Infection caused by a decrease in neutrophils (a type of white blood cell) with symptoms that may include chills, fever, mouth sores, stomach pain, or pain when urinating.
• Heart problem calledleft ventricular dysfunctionwith symptoms that may include new or worsening shortness of breath, cough, fatigue, swelling of ankles or legs, irregular heartbeats, sudden weight gain, dizziness, or loss of consciousness.

Other side effects

The frequency and severity of side effects may vary depending on the dose received.Inform your doctor or nurse if you notice any of the following side effects:

Very common(may affect more than 1 in 10people)

• Nausea (feeling like vomiting), vomiting
• Fatigue
• Decreased appetite
• Blood tests indicating a decrease in red or white blood cells, or platelets
• Hair loss
• Diarrhea
• Constipation
• Blood tests indicating an increase in liver enzyme levels such as transaminases
• Muscle and bone pain
• Abdominal pain (stomach pain)
• Fever
• Weight loss
• Pneumonia
• Upper respiratory tract infections, including symptoms similar to the flu
• Headache
• Blistering or sores around the mouth
• Cough
• Blood tests indicating low potassium levels in the blood
• Swelling of the ankles and feet
• Indigestion
• Difficulty breathing
• Altered sense of taste/bad taste in the mouth

Common(may affect up to 1 in 10people)

• Nosebleeds
• Dizziness
• Rash
• Blood tests indicating an increase in bilirubin, alkaline phosphatase, or creatinine levelsa
• Blood tests indicating a decrease in red or white blood cells, or platelets (pancytopenia)
• Itching
• Dry eyes
• Skin discoloration
• Blurred vision
• Thirst, dry mouth
• Swelling
• Fever accompanied by a decrease in the number of white blood cells called neutrophils
• Stomach inflammation
• Excess gas in the stomach or intestines
• Reactions related to the infusion of the medication that may include fever, chills, flushing, itching, or skin rash

Reporting side effects

If you experience any type of side effect, consult your doctor or nurse, even if it is a possible side effect that does not appear in this leaflet. You can also report them directly through theSpanish System for Pharmacovigilance of Medicines for Human Use:www.notificaRAM.es.By reporting side effects, you can contribute to providing more information on the safety of this medication.

Enhertu will be stored by healthcare professionals in the hospital or clinic where you receive treatment. The storage information is as follows:

• Keep this medication out of the sight and reach of children.
• Do not use this medication after the expiration date that appears on the box and vial after CAD/EXP. The expiration date is the last day of the month indicated.
• Store in a refrigerator (between 2°C and 8°C). Do not freeze.
• The prepared infusion solution is stable for up to 24 hours at a temperature between 2°C and 8°C protected from light, and should be discarded after this time.

Medications should not be thrown away through drains or in the trash. Ask your pharmacist how to dispose of the containers and medications you no longer need. In this way, you will help protect the environment.

Composition of Enhertu

• The active ingredient is trastuzumab deruxtecán.

A vial of powder for concentrate for solution for infusion contains 100mg of trastuzumab deruxtecán. After reconstitution, a vial of 5ml of solution contains 20mg/ml of trastuzumab deruxtecán.

• The other components are L-histidine, L-histidine hydrochloride monohydrate, sucrose, and polisorbate80.

Appearance of the productand contents of the container

Enhertu is a lyophilized powder of white to light yellowish color that is presented in an amber transparent vial with a rubber stopper, an aluminum cap, and a plastic typeextraíbleclosure.

Each box contains one vial.

Marketing Authorization Holder

Daiichi Sankyo Europe GmbH

Zielstattstrasse 48

81379 Munich

Germany

Responsible Person

Daiichi Sankyo Europe GmbH

Luitpoldstrasse 1

85276 Pfaffenhofen

Germany

For further information about this medicinal product, please contact the local representative of the marketing authorization holder:

Last update of this leaflet:03/2025.

This medicinal product has been authorised under a «conditional approval». This type of approval means that more information is expected to be obtained about this medicinal product.

The European Medicines Agency will review the new information about this medicinal product at least once a year and this leaflet will be updated as necessary.

Other sources of information

Further information about this medicinal product is available on the website of the European Medicines Agency:https://www.ema.europa.eu.

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This information is intended for healthcare professionals:

To avoid medication errors, check the labels on the vials to ensure that the medicinal product being prepared and administered is Enhertu (trastuzumab deruxtecán) and not trastuzumab or trastuzumab emtansine.

Follow the appropriate procedures for the preparation of chemotherapeutic agents. Use an appropriate aseptic technique for the following reconstitution and dilution procedures.

Reconstitution

• Reconstitute immediately before dilution.
• You may need to use more than one vial to obtain the full dose. Calculate the dose (mg), the total volume of Enhertu reconstituted solution needed, and the number of Enhertu vials needed.
• Reconstitute each vial of 100mg using a sterile syringe to slowly inject 5ml of water for injection into each vial to obtain a final concentration of 20mg/ml.
• Gently rotate the vial until it is fully dissolved. Do not agitate.
• From a microbiological point of view, the product should be used immediately.If not used immediately,its chemical and physical stability has been demonstrated for a maximum of 48hours at a temperature between 2°C and 8°C. Storethe reconstituted Enhertu vials in a refrigerator at a temperature between 2°C and 8°C, protected from light. Do not freeze.
• The reconstituted product does not contain any preservative and is intended for single use.

Dilution

• Extract the calculated amount from the (the) vial(s) using a sterile syringe. Inspect the reconstituted solution for the presence of particles or change in color. The solution must be transparent and colorless to light yellowish. Do not use the solution if visible particles or if the solution is turbid or has changed color.
• Dilute the calculated volume of Enhertu reconstituted solution in a 100ml infusion bag containing 5% glucose solution for infusion. Do not use sodium chloride solution. It is recommended to use a polyvinyl chloride or polyolefin (copolymer of ethylene and propylene) infusion bag.
• Gently invert the infusion bag to mix the solution well. Do not agitate.
• Cover the infusion bag to protect it from light.
• If not used immediately, store at room temperature(≤30°C)for a period of up to 4hours, counting the preparation and infusion time, or in a refrigerator at a temperature between 2°C and 8°C for a period of up to 24hours, protected from light. Do not freeze.
• Discard any unused portion remaining in the vial.

Administration

• If the prepared infusion solution is stored refrigerated (2°C to 8°C), it is recommended to allow the solution to equilibrate to room temperature before administering it,protected from light.

• Administer Enhertu as an intravenous infusion only through an in-line filter of 0.20 or 0.22micras of polyethersulfone (PES) or polysulfone (PS).
• The initial dose must be administered as an intravenous infusion of 90minutes. If the previous infusion was well tolerated, subsequent doses of Enhertu can be administered as infusions of 30minutes. Do not administer as a rapid intravenous injection or bolus.
• Cover the infusion bag to protect it from light.
• Do not mix Enhertu with other medicinal products or administer other medicinal products through the same intravenous route.

Elimination

The unused medicinal product and all materials that have come into contact with it will be disposed of in accordance with local regulations.