Clinical Perspectives on Drug-Induced Lung Injury Associated with Trastuzumab Deruxtecan: Real-World Evidence and Implications

Introduction: Trastuzumab deruxtecan (T-DXd) is used to treat human epidermal growth factor receptor 2-positive breast cancer, non-small cell lung cancer, and gastric cancer, with reports of favorable treatment outcomes. However, drug-induced lung injury associated with trastuzumab deruxtecan (T-DXd) therapy presents a significant challenge, with its incidence and clinical progression remaining poorly characterized in real-world settings. Methods: We enrolled 16 patients at Tokyo Medical University Hachioji Medical Center, Japan, between April 2020 and December 2024 who were suspected of drug-induced lung injury arising from T-DXd therapy. We categorized members of our patient cohort on the basis of the presence or absence of drug-induced lung injury and provided a detailed report. Results: Four out of 16 patients developed drug-induced lung injury within a median time period of 10.32 months (95% Confidence Interval: 9.26-NA). There was no difference in the clinical background between patients with and without drug-induced lung injury. Two patients exhibited the organizing pneumonia pattern, while two displayed the diffuse alveolar damage (DAD) pattern. One patient succumbed to the condition. Conclusion: It is difficult to predict the onset of drug-induced lung injury due to T-DXd, and the prognosis is poor in drug-induced lung injury that presents the DAD pattern.