Sintilimab treatment for ureteral carcinoma following bladder cancer leads to leukopenia: a case report.

Herein, we present a case report of sintilimab treatment for a patient with ureteral cancer reoccurring after bladder cancer, and exploration of the mechanism of adverse reactions from the aspects of intestinal flora and immunity. We have reported a case of leukopenia in a patient with recurrent ureteral cancer after bladder cancer who was treated with sintilimab. A 52-year-old Chinese man with a history of hypertension and diabetes presented with lower urinary tract symptoms, including painless hematuria, frequent and urgent urination, and micturition without pain. Computed tomography (CT) and 3-dimensional (3D) reconstruction suggested bladder space occupation, bladder cancer was pathologically confirmed after laser resection of the bladder tumor, which then recurred and was subject to reoperation. After 8 months, B-mode ultrasonography indicated left ureter occupation, and the patient began sintilimab immunotherapy according to the outcome of immunohistochemistry (IHC) and immune checkpoint inhibitor (ICI) evaluation. The patient was treated with sintilimab a total of 6 times. After the first treatment, the patient was in stable condition. The second treatment was discontinued due to renal insufficiency. The patient was then treated with renal and liver protection for 1.5 months, followed by 5 rounds of immunotherapy. After the sixth round of immunotherapy, the patient presented with leukopenia. In order to determine the causes of adverse reactions, we analyzed the changes of intestinal flora of patients before and after immunotherapy, and summarized the immune function indicators of patients during immunotherapy. The leucopenia induced by sintilimab may be related to intestinal flora and immunity.