Favorable response to pembrolizumab in granulocyte colony-stimulating factor-producing upper urinary tract urothelial carcinoma.

INTRODUCTION: Granulocyte colony-stimulating factor-producing upper urinary tract urothelial carcinoma is rare, with a poor prognosis. Advanced urothelial carcinoma is currently treated with immune checkpoint inhibitors, whose efficacy for granulocyte colony-stimulating factor-producing upper urinary tract urothelial carcinoma remains unclear. CASE PRESENTATION: A 66-year-old male diagnosed with clinical stage T3N1M0 urothelial carcinoma of the right ureter with giant hydronephrosis underwent right radical nephroureterectomy. Local recurrence, leukocytosis, and elevated serum granulocyte colony-stimulating factor levels were observed approximately 3 months after surgery. Chemotherapy was started but failed to control the disease. Therefore, pembrolizumab was chosen as the second-line treatment. After this treatment, the blood leukocyte count rapidly normalized, and a clinically favorable response was achieved. There was no recurrence 10 months after the beginning of pembrolizumab treatment, which is still ongoing. CONCLUSION: Pembrolizumab may be a treatment option for advanced granulocyte colony-stimulating factor-producing upper urinary tract urothelial carcinoma.