PD-1 Inhibitor Therapy in a Patient with Preexisting P-ANCAVasculitis: A Case Report and Review of the Literature

Recurrent endometrial cancer after definitive therapy is a lethal disease. Recently, immune checkpoint inhibitors (ICI)have improved the management of mismatch repair-deficient (MSI-H) endometrial cancer. Autoimmune side effects are known tooccur with ICI. As a result, patients with preexisting autoimmune diseases are excluded from studies involving these drugs. This hasled to challenges in clinical practice regarding the use of ICI in otherwise eligible patients with underlying autoimmune disease.Case Presentation. We present the case of an 81-year-old woman with an underlying autoimmune vasculitis and recurrent,metastatic endometrial adenocarcinoma with microsatellite instability, who was treated with an immune checkpoint inhibitor.This patient received pembrolizumab, an immune checkpoint inhibitor that targets the programmed cell death-1 immunecheckpoint. Ultimately, she was treated for 4 months with pembrolizumab and benefited from stable disease during this period.She remained asymptomatic from her underlying autoimmune P-ANCA vasculitis. A review of the scientific literature revealsseveral cases of the successful use of immune checkpoint inhibitors in patients with autoimmune diseases, including systemiclupus erythematosus, rheumatoid arthritis, and inflammatory bowel disease.Conclusion. This is one of thefirst reports of apatient with an underlying autoimmune vasculitis successfully treated with an immune checkpoint inhibitor withoutexacerbating her underlying autoimmune condition. Carefully selected patients with underlying autoimmune vasculitis can besafely treated with ICI.