Histological complete response with nivolumab for renal cell carcinoma with multiple metastases: A case report

The present case report describes a case of left renal clear cell carcinoma with brain, lung, para-aortic, and lymph node metastases (cT1bN1M1) in a 52-year-old Japanese male. The patient received sequential anticancer treatments with pazopanib, everolimus, and axitinib, but exhibited treatment-resistant tumor growth. Treatment with nivolumab resulted in a complete response in metastatic sites. However, the residual renal tumor, which was enhanced by contrast medium, required radical nephrectomy. Pathological analyses of the renal tumor revealed that it consisted of fibrotic and lymphocyte-infiltrated tissues in which morphological cancer cells were not detected. The majority of lymphocytes were cluster of differentiation (CD)8-positive, suggesting that cancer cells were attacked by these lymphocytes. Retrospective analyses of renal cell carcinoma tissues, which were biopsied before the anticancer treatment, revealed their infiltration by CD8-positive T cells. To the best of our knowledge, this is the first case report to examine renal tissue prior to and following treatment with nivolumab using immunohistochemical analysis.