Management of Trastuzumab Deruxtecan-Induced Heart Failure and Pneumonitis in a Patient with HER2-Positive Metastatic Breast Cancer

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Seyyar M., Can Şancı P., Çabuk D.

Avicenna Anatolian journal of medicine, vol.2, no.1, pp.22-24, 2025 (Non Peer-Reviewed Journal)

• Publication Type: Article / Case Report
• Volume: 2 Issue: 1
• Publication Date: 2025
• Doi Number: 10.5281/zenodo.15570010
• Journal Name: Avicenna Anatolian journal of medicine
• Page Numbers: pp.22-24
• Open Archive Collection: AVESIS Open Access Collection
• Kocaeli University Affiliated: Yes

Abstract

We report a case of a 49-year-old female with HER2-positive metastatic breast cancer treated with trastuzumab

deruxtecan (T-DXd) after progression on multiple prior lines of therapy. Following the third cycle, she developed

dyspnea and was admitted to the coronary intensive care unit with heart failure and pulmonary edema.

Echocardiography revealed an ejection fraction (EF) of 10-15%. Imaging demonstrated unilateral pleural effusion

and bilateral pulmonary infiltrates. Clinical findings were attributed to T-DXd-induced heart failure, bicytopenia,

and pneumonitis. Despite initial improvement with corticosteroid therapy, long-term follow-up revealed worsening

thrombocytopenia and development of severe pneumonitis, leading to discontinuation of T-DXd. The patient

ultimately succumbed to sepsis. This case highlights the import