A 71-year-old man with a history of hoarseness and right upper extremity numbness was referred to our department for evaluation of an intrathoracic mass that was detected on chest radiography and a right kidney tumor observed on computed tomography (CT). Histopathological examination of percutaneous kidney biopsy and bronchoscopic lung biopsy specimens revealed renal clear cell carcinoma with multiple lung metastases. The patient showed a poor risk based on the International Metastatic renal cell carcinoma Database Consortium score, and nivolumab plus ipilimumab were initiated as first-line therapy. His symptoms gradually improved, following four courses of nivolumab plus ipilimumab treatment, and CT revealed shrinkage of all lesions. However, he developed diarrhea, rash, anemia, and elevated serum C-reactive protein levels (CRP) following this therapy. Diarrhea and rash were considered immune-related adverse events, and he was treated with oral prednisolone and topical corticosteroid. Nivolumab administration was discontinued because anemia worsened together with elevated serum CRP levels despite improvement in diarrhea. He subsequently developed constipation and abdominal bloating, following further treatment for 4 months. CT revealed intestinal tumor-induced intussusception, necessitating partial resection of the small intestinal tumor, which was histopathologically diagnosed as metastases. Both anemia and elevated CRP improved postoperatively. Currently, all metastatic lesions other than the resected intestine have continued to respond to treatment over 12 months after initiation of nivolumab plus ipilimumab therapy.
Keywords: nivolumab plus ipilimumab; renal cell carcinoma; small intestine metastasis.