Salvage tacrolimus therapy for steroid-refractory immune-related adverse event-associated sclerosing cholangitis

Immune-related adverse event-associated sclerosing cholangitis (irAE-SC) is a rare and often steroid-refractory biliary complication for which optimal treatment has not been established. A 54-year-old woman undergoing pembrolizumab-based chemotherapy for recurrent cervical cancer developed cholestatic liver enzyme abnormalities and epigastric pain 3 months after treatment initiation. Imaging studies demonstrated bile duct wall thickening without obstruction, and she was diagnosed with irAE-SC after excluding other causes. High-dose corticosteroid therapy initially improved her condition; however, cholangitis relapsed during steroid tapering. Additional immunosuppressive therapies, including mycophenolate mofetil and azathioprine, failed to control the disease, and liver dysfunction progressively worsened, with total bilirubin increasing to 12.0 mg/dL. Tacrolimus (TAC) was subsequently introduced with trough-guided dosing, resulting in gradual improvement in liver enzyme levels and bilirubin. Follow-up magnetic resonance cholangiopancreatography demonstrated mild improvement in intrahepatic bile duct dilatation. The patient remained clinically stable without cancer progression during long-term follow-up. This case suggests that TAC may be an effective salvage therapy for steroid-refractory irAE-SC and highlights the potential role of calcineurin inhibition in selected refractory cases.