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Anti-HER2 antibody-drug conjugate

Trastuzumab deruxtecan (Specialist drug)

Brand names: Enhertu

Trastuzumab deruxtecan is an antibody-drug conjugate used under specialist supervision for HER2-positive and HER2-low breast cancer and other HER2-expressing tumours.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

A HER2-targeting antibody delivers a topoisomerase I inhibitor payload selectively to HER2-expressing tumour cells, causing DNA damage and cell death.

Prescribing in practice

  • Interstitial lung disease and pneumonitis can be serious or fatal — monitor for respiratory symptoms and interrupt or stop treatment as indicated.
  • It is a specialist oncology antibody-drug conjugate and is not interchangeable with other trastuzumab products.
  • Nausea, neutropenia and infusion reactions are common and antiemetic prophylaxis is recommended per the SPC.

Monitoring

Monitor full blood count, left ventricular ejection fraction and for new or worsening respiratory symptoms before and during treatment.

Counselling the patient

  • Report any new cough, breathlessness or fever urgently as these may indicate lung inflammation.
  • Effective contraception is required during and after treatment.
  • Report signs of infection or any infusion reaction promptly.

Evidence & guidelines

Efficacy is supported by the DESTINY-Breast trial programme and reflected in NICE appraisals.

Reference: NICE TA704/TA889; SmPC; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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