Pazopanib after Nivolumab-Induced Tumor Lysis Syndrome in a Patient with Metastatic Clear-Cell Renal Cell Carcinoma

: Nivolumab, a programmed death-1 checkpoint inhibitor, is worldwide available for metastatic renal cell carcinoma (mRCC). Limited data exist on the response to vascular endothelial growth factor receptor-tyrosine kinase inhibitor (TKI) therapy after administration of nivolu-mab. In this case study, we report on a patient with tumor lysis syndrome (TLS), which was induced by pazopanib after the administration of nivolumab. A 69-year-old woman with a primary diagnosis of mRCC received pazopanib as a fourth-line therapy, after sunitinib, axitinib, and nivolumab as first-, second-, and third-line therapies, respectively. Two weeks after the administration of pazopanib, she presented to the emergency room of our institution, complaining of fatigue associated with nausea and diarrhea. Her laboratory results showed hyperphosphatemia, hyperuricemia, hypocalcemia, and possible acute kidney injury; the results were consistent with TLS. Our case report highlights TLS as a potential reaction to pazopanib following nivolumab; and we consider careful observation is necessary when administering TKI after immune checkpoint inhibitors.