Abstract
A case of cystitis occurring after administration of nivolumab, an anti-programmed death-1 antibody, which was considered to be an immune-related adverse event, is reported. A 62-year-old man with pulmonary squamous cell carcinoma (T4N0M1a Stage IV) was being treated with nivolumab as fourth-line chemotherapy. He was hospitalized for a fever and diarrhea after 3 courses. Fasting and antibiotic medication reduced the fever and alleviated the diarrhea. He then developed cystitis with no evidence of infection. Cystoscopy showed diffused redness and erosion of the bladder mucosa; urine cytology was negative. Imaging examinations showed no abnormalities. Urinary tract pain and hematuria due to nivolumab were diagnosed by exclusion following a bladder biopsy. Since symptomatic treatment was unsuccessful, steroid pulse therapy was given, which resolved the patient's signs and symptoms. The patient was then switched to maintenance prednisolone and tapered gradually. The 4th course of nivolumab was then resumed with concomitant administration of steroid, and it was possible to continue administration of nivolumab without progression of cystitis.