Generic Name: fam-trastuzumab deruxtecan-nxki
Trade Name: Enhertu®

How is Enhertu used? Enhertu is approved for the treatment of adults with:

  • HER2-positive metastastic or advanced breast cancer who have received two or more treatment with anit-HER2-based regimens in the metastatic setting (this indication is approved under accelerated approval based on response rate and duration of response; continued approval may be contingent on validation of efficacy in ongoing clinical trials.
  • HER2-positive gastric or gastroesophageal junction adenocarcinoma who have received a prior Herceptin-based regimen.

Enhertu labeling contains a boxed warning to alert healthcare professionals and patients about potential severe and or life-threatening side effects including interstitial lung disease (ILD) and pneumonitis as well as embryo-fetal harm. Pregnant women should not take Enhertu.

What is the mechanism of action? Enhertu is a HER2-targeting antibody drug conjugate (ADC). ADCs are a type of targeted cancer medicine that deliver cytotoxic chemotherapy (“payload”) to cancer cells via a linker attached to a monoclonal antibody that binds to a specific target expressed on cancer cells. Enhertu is a smart chemotherapy comprised of a humanized HER2 antibody attached to a novel topoisomerase I inhibitor (DXd) payload by a tetrapeptide linker. It is designed to deliver enhanced cell destruction upon release inside the cell and reduce systemic exposure to the cytotoxic payload (or chemotherapy) compared to the way chemotherapy is commonly delivered.

How is Enhertu given (administered)? Enhertu is administered into a vein (intravenous) and the dose depends on several factors, including the size of the patient, the type of cancer and particular treatment regimen being used, and the overall health of the patient.

How are patients monitored? Patients will usually have scheduled meetings with their healthcare provider while they are being treated with Enhertu. Typically, blood will be drawn to check levels of blood cells and to monitor functions of some organ systems, such as the kidneys or liver. Patients may also undergo physical examinations, scans or other measures to assess side effects and response to therapy. Patients will also have their heart function monitored.

What are the common side effects of Enhertu among patients with breast cancer?

  • Nausea
  • Low blood cell counts (whiteblood cells, red blood cells, and/or platelets)
  • Constipation
  • Decreased appetite
  • Fatigue
  • Diarrhea
  • Vomiting
  • Low levels of potassium
  • Hair loss
  • Cough
  • Increased liver function tests

What are the common side effects of Enhertu among patients with stomach cancer?

  • Low blood cell counts (white bloodcells, red blood cells, and platelets)
  • Diarrhea
  • Low levels of blood potassium
  • Vomiting
  • Nausea
  • Constipation
  • Decreased appetite
  • Fever
  • Increased liver function tests
  • Hair loss
  • Fatigue

This is not a complete list of side effects. Some patients may experience other side effects that are not listed here. Patients may wish to discuss with their physician the other less common side effects of this drug, some of which may be serious.

Some side effects may require medical attention. Other side effects do not require medical attention and may go away during treatment. Patients should check with their physician about any side effects that continue or are bothersome.

What are the less common but potentially serious side effects of Enhertu?

  • Lung problems: cough, troublebreathing, shortness of breath, fever, other new or worsening breathingsymptoms
  • Sever neutropenia: infections,fever, chills
  • Heart problems: new orworsening shortness of breath, coughing, feeling tired, ankle or legswelling, irregular heartbeat, sudden weight gain, dizziness orlightheadedness, loss of consciousness.

What can patients do to help alleviate or prevent discomfort and side effects?

  • Pay careful attention to thephysician’s instructions and inform the physician of any side effects.
  • Maintain adequate rest andnutrition.

Are there any special precautions patients should be aware of before starting treatment?

  • It is important that patientsinform their physician of any pre-existing conditions, including heart problems.
  • Patients should inform theirphysician of any other medication they are taking (whether prescription orover-the-counter, including vitamins, herbs, etc.) as they may interferewith treatment.
  • Patients should check withtheir physician before starting any new drug or

· Talk to your doctor if you or your partner are pregnant or planning to become pregnant. Enhertu can cause fetal harm. If a man’s sexual partner is not pregnant but could become pregnant, effective birth control should be used during treatment and for four months after treatment ends. Females should use an effective method of birth control during treatment and for seven months after the last dose of Enhertu.

  • Do not breastfeed duringtreatment or for 7 months after the last dose of Enhertu.

When should patients notify their physician?

Tell your doctor if you experience any side effects that bother you or don’t go away. Also tell your doctor right away if you experience any of the following:

  • Lung problems: cough, troublebreathing, shortness of breath, fever, other new or worsening breathingsymptoms
  • Sever neutropenia: infections,fever, chills
  • Heart problems: new orworsening shortness of breath, coughing, feeling tired, ankle or legswelling, irregular heartbeat, sudden weight gain, dizziness orlightheadedness, loss of consciousness.

What is a package insert?
A package insert is required by the FDA and contains a summary of the essential scientific information needed for the safe and effective use of the drug for healthcare providers and consumers. A package insert typically includes information regarding specific indications, administration schedules, dosing, side effects, contraindications, results from some clinical trials, chemical structure, pharmacokinetics and metabolism of the specific drug. By carefully reviewing the package insert, you will get the most complete and current information about how to safely use this drug. If you do not have the package insert for the drug you are using, your pharmacist or physician may be able to provide you with a copy.

Last updated 04/21.

Important Limitations of Use
The information provided above on the drug you have selected is provided for your information only and is not a substitute for consultation with an appropriate medical doctor. We are providing this information solely as a courtesy and, as such, it is in no way a recommendation as to the safety, efficacy or appropriateness of any particular drug, regimen, dosing schedule for any particular cancer, condition or patient nor is it in any way to be considered medical advice. Patients should discuss the appropriateness of a particular drug or chemotherapy regimen with their physician.

As with any printed reference, the use of particular drugs, regimens and drug dosages may become out-of-date over time, since new information may have been published and become generally accepted after the latest update to this printed information. Please keep in mind that health care professionals are fully responsible for practicing within current standards, avoiding use of outdated regimens, employing good clinical judgment in selecting drugs and/or regimens, in calculating doses for individual patients, and verifying all dosage calculations.

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