Two case reports of immune checkpoint therapy on chromophobe renal cell carcinoma with sarcomatoid differentiation.

Renal cell carcinoma (RCC) is the most predominant type of kidney cancer in adults and comprises several histological subtypes. Among them, the chromophobe RCC (ChRCC) with sarcomatoid differentiation is a rare subtype, and its therapeutic strategy remains unclear. Hence, to provide more information on effective therapeutic strategies against ChRCC, we report two cases of ChRCC with sarcomatoid differentiation treated with nivolumab monotherapy or ipilimumab-nivolumab combination therapy. One patient was treated with nivolumab monotherapy after the failure of sunitinib, while the other was treated with ipilimumab-nivolumab combination therapy as a first-line option. The therapeutic strategies adopted in both cases were effective, but the patients experienced immune-related adverse events such as interstitial nephritis and colitis. Thus, our report indicates that immune checkpoint therapy is effective for ChRCCs with sarcomatoid differentiation.