Supplementary Material for: Drug-Induced Sclerosing Cholangitis Leading to Discontinuation of Treat-ment in a Patient with Metastatic Breast Cancer: a case report

Background
Drug induced sclerosing cholangitis (SC) is uncommon and has been only rarely reported with paclitaxel, bevacizumab, or trastuzumab deruxtecan (T-DXd). We report a suspected SC following these therapies for metastatic breast cancer, underscoring a possible association with taxane based chemotherapy and antibody or antibody drug conjugates.
Case presentation
A 58-year-old woman with metastatic hormone receptor-positive, human epidermal growth fac-tor receptor 2-low breast cancer developed cholangitis 17 days after receiving the first cycle of T-DXd, following prior treatment with paclitaxel and bevacizumab. The symptoms improved with antibiotic therapy. However, fever and jaundice recurred on day 49. Imaging studies revealed intrahepatic and extrahepatic bile duct dilation and stricture. SC was suspected based on imaging and clinical course. Histopathological examination showed fibrosis without evidence of malignancy or infiltration by IgG4-positive cells, raising suspicion of drug-induced SC. Due to repeated episodes of cholangitis, the patient’s performance status deteriorated, making further chemotherapy unfeasible. The patient opted for best supportive care and died on day 108.
Conclusions
This case highlights the possibility of SC as a delayed adverse event of anticancer chemotherapy. Clinicians should consider drug-induced SC when unexplained biliary strictures arise during or after chemotherapy, as early recognition may impact prognosis and treatment planning.