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Differentiation Syndrome — SCE Medical Oncology MCQ

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HardOncological EmergenciesDifferentiation SyndromeSCE Medical Oncology

A patient receiving trastuzumab deruxtecan for metastatic breast cancer develops new exertional dyspnoea and bilateral ground-glass change. Oxygen saturation is normal at rest, infection is excluded and the MDT grades symptomatic drug-related ILD as grade 2. What is the required treatment decision?

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Correct answer: D — Permanently discontinue trastuzumab deruxtecan and commence systemic corticosteroid treatment

Symptomatic grade-two trastuzumab-deruxtecan ILD requires permanent drug discontinuation and prompt systemic corticosteroid treatment. Interrupt trastuzumab deruxtecan and restart at reduced dose after radiological resolution: rechallenge is not recommended after symptomatic grade-two ILD. Interrupt trastuzumab deruxtecan and restart at the same dose after steroid response: symptomatic ILD requires permanent discontinuation rather than temporary interruption. Continue trastuzumab deruxtecan and commence systemic corticosteroid treatment: continued exposure risks progression of a potentially fatal toxicity. Discontinue trastuzumab deruxtecan and commence prophylactic antimicrobial treatment: infection has been excluded and antimicrobial treatment does not treat drug-related ILD.

Reference: Enhertu UK summary of product characteristics (Current UK SmPC, updated 2026): https://www.medicines.org.uk/emc/product/12135/smpc