Successful pembrolizumab treatment in a patient with metastatic urothelial carcinoma and underlying overlap syndrome involving systemic sclerosis and systemic lupus erythematosus

Introduction The safety and efficacy of pembrolizumab administration in patients with urothelial carcinoma and underlying autoimmune disease (including overlap syndrome) is unknown. Case presentation We present the case of a 67‐year‐old woman with cT3N2M0 metastatic renal pelvic cancer who had been treated with prednisolone for overlap syndrome involving systemic sclerosis and systemic lupus erythematosus for 20 years. She had a remarkable response to pembrolizumab as a third‐line systemic therapy, wherein the tumor reduced in size and all regional lymph node and pulmonary metastases disappeared. She did not develop any immune‐related adverse events or autoimmune disease flare‐ups during the treatment. Conclusion This case report suggests that pembrolizumab could be beneficial to patients with urothelial carcinoma and underlying well‐controlled overlap syndrome.