A 62-year-old woman was diagnosed as having Stage IV gastric carcinoma in July 2020. From July 2020 to December 2020, oxaliplatin 150 mg plus tegafur-gimeracil-oteracil potassium capsules 40 mg (days 1-14) were administered for six courses, then tegafur-gimeracil-oteracil potassium capsules 40 mg days 1-14 were given alone in January 2021. Because of lymph node metastasis in the left clavicular and mediastinal area, she was given a regimen including sintilimab (PD-1 mAb) 200 mg, paclitaxel 200 mg (days 1-8), and tegafur-gimeracil-oteracil potassium capsules 40 mg (days 1-14) on 28 October 2022. Then, oxaliplatin 130 mg plus sintilimab (PD-1 mAb) 200 mg were given on 9 May 2022 and 1 June 2022. She did not have a medical history of hypertension, diabetes, or kidney disease.
She suffered from sudden-onset urinary irritation after three cycles of sintilimab (PD-1 mAb) treatment. Physical examination: T (Temperature) 36.3 C, P (Pulse) 70 bpm (beats per minute), R (Respiration) 16 bpm (breaths per minute), BP (Blood pressure) 110/60 mmHg. The abdomen was soft, no tenderness and rebound. Her renal percussive pain was negative. There was no edema in the lower limbs.
Urinalysis showed RBCs of 42/microl, WBCs of 17,916/microl, and proteinuria 3+. Blood tests showed WBCs of 2,300/microl (neutrophils 60.9%, eosinophils 4.3%) and C-reactive protein <0.5 mg/L. Her sCr was 56.2mumol/l (baseline sCr 56.4mumol/l). Serum T-spot and urinary Mycobacterium tuberculosis were negative. Repeated urine cultures were negative. Serum procalcitonin was negative. Biomarkers of renal tubular injury showed urinary NAG 29.2 U/L (0.3-12 U/L), urinary NGAL 247.6 U/L (normal range 0.9-82 U/L), urinary albumin/creatinine 466.9 mg/g, urinary transferrin 8.13 mg/dl (0-0.2 mg/dl), and alpha1-microglobulin 0.803 mg/dl (0-1.25 mg/dl). His 24-h urinary protein is 2.94 g. Urinary ultrasonography and CT showed mild hydronephrosis and dilation of the ureter on the left and a thickened bladder wall ( Figures 2D, E ). Bladder residual urine was negative. Antibiotics were given, and urinary symptoms were not relieved. The patient was eventually diagnosed as having immune-related ureteritis and cystitis. Methylprednisolone was given at 60 mg (body weight 44 kg, equivalent to 1.7 mg/kg/day of prednisone) intravenously after 18 days of urinary symptoms. After a week of methylprednisolone treatment, urinary symptoms were relieved and urinalysis was normal. The tapered prednisone was given at 45 mg and reduced by 5 mg per week. However, the patient discontinued prednisone by herself:assertion on 18 July 2022. And the urinary irritation symptoms and increased urinary WBC/RBC reoccurred on 21 July 2022. Prednisone was restarted at 30 mg/day and tapered gradually by 5 mg per week. Prednisone was discontinued on 26 September 2022. The last follow-up time was 10 October; urinary analysis remained negative and sCr was 55.5mumol/l. The timeline of the treatment course was summarized in  Figure 4 .