Anti‐Melanoma Differentiation‐Associated Gene 5 Antibody‐Positive Interstitial Lung Disease, Induced by Enfortumab Vedotin Plus Pembrolizumab for Advanced Urothelial Carcinoma

Introduction: Anti-melanoma differentiation-associated gene 5 antibody-positive interstitial lung disease is a rare but fatal adverse event following immune checkpoint inhibitor treatment for cancers. However, such cases have not been previously reported in patients with urothelial carcinoma. Case Presentation: A 79-year-old Japanese woman with advanced unresectable bladder cancer was treated with first-line enfortumab vedotin plus pembrolizumab. During the second treatment cycle, interstitial lung disease developed, and the patient immediately received steroid pulse therapy. As interstitial lung disease rapidly progressed after the initiation of steroid pulse therapy, immunosuppressive treatment with cyclophosphamide and tacrolimus was added. However, interstitial lung disease did not improve, and the patient died on day 54 after initiating treatment. Detailed antibody examination revealed positive anti-melanoma differentiation-associated gene 5 antibodies. Conclusion: We report the first case of anti-melanoma differentiation-associated gene 5 antibody-positive interstitial lung disease induced by enfortumab vedotin plus pembrolizumab in a patient with advanced urothelial carcinoma.