再発子宮体がんに対するデュルバルマブ投与後の免疫介助性血小板減少症：症例報告

The use of immune checkpoint inhibitors (ICIs) has expanded the therapeutic landscape for advanced or recurrent endometrial carcinoma. Durvalumab-a programmed death-ligand 1 (PD-L1) inhibitor-demonstrated clinical benefit in the 2023 DUO-E trial when combined with carboplatin and paclitaxel. Immune thrombocytopenia (ITP) is an uncommon but potentially life-threatening immune-related adverse event (irAE). A 73-year-old woman with recurrent endometrial carcinoma developed severe ITP after three cycles of paclitaxel, carboplatin, and durvalumab. Fourteen days after cycle 3 she presented with pyelonephritis, bacteremia, and acute disseminated intravascular coagulation (DIC). Despite infection control, her platelet count declined to 1 × 10³/μL, with epistaxis, hematuria, and melena. Suspecting ITP as an irAE, intravenous immunoglobulin (IVIG 10 g/day × 5 days) and high-dose intravenous prednisolone (1 mg/kg/day) were administered. Platelet counts improved gradually to 85 × 10³/μL by hospital day 32, and she was discharged on a steroid taper. This appears to be the first Japanese report of durvalumab-associated ITP in endometrial carcinoma. Clinicians should maintain a high index of suspicion for ITP when unexpected thrombocytopenia or bleeding occurs during durvalumab therapy and initiate prompt treatment.