LAUSR

Immunotherapy has revolutionized the treatment of various neoplasms, although it is not without adverse events. Acute tubulointerstitial nephritis (ATIN) is the most common histopathological finding in kidney biopsies of patients with acute renal failure (ARF) and the use of Checkpoint Inhibitors (CPI). Our goal is to describe the clinical, analytical, and histological characteristics of tubulointerstitial nephritis attributed to the use of CPIs (CITN). A retrospective, descriptive observational study of patients diagnosed with CPI-related tubulointerstitial nephritis (CITN) from January 2018 to February 2023 in the Nephrology Department of the Infanta Sofía University Hospital. The statistical analysis was performed using the SPSS® platform. We describe a total of 9 patients, 8 received anti-PD1 and 1 received anti-PDL1. Regarding the cancer diagnoses, 4 were urological (all treated with nivolumab), 4 were lung cancer (one treated with nivolumab, another with nivolumab and pemetrexed, and 2 with pembrolizumab), and 1 was infiltrating breast cancer (treated with atezolizumab). At the time of diagnosis, 4 patients had locally advanced neoplasia, and 5 had metastases. In relation to concomitant treatment, 6 patients were on proton pump inhibitors (PPIs), 3 were using NSAIDs, and 1 was on antibiotics. One patient was on a triple combination therapy. Forty-four percent experienced other immune-mediated side effects. The average latency period from the initiation of CPI to acute renal failure (ARF) was 6 months. The median maximum creatinine level was 1.98 mg/dl. Forty-four percent of cases presented with eosinophilia, hematuria, and leukocyturia. The median albuminuria was 310 mg/g. A kidney biopsy was performed in 55% of cases. Severe interstitial infiltration was found in 56% of cases, with eosinophils and plasma cells present in 82% and 75% of cases, respectively. Treatment was carried out with corticosteroids, with an average cumulative dose of 1831 mg. More pulses were administered, but with lower doses (125 × 3). The average recovery time was 42 days, with no differences when comparing corticosteroid doses used. Seventy-eight percent of patients showed favorable outcomes with a 62% reduction in creatinine levels. At the end of follow-up, the median creatinine was 1.24 mg/dl with albuminuria of 150 mg/g. Twenty-two percent of patients did not recover renal function. In our cohort, unlike what is described in the literature, the presence of eosinophilia is more frequently observed in the clinical presentation, and there is a higher percentage of eosinophils and plasma cells in the kidney biopsy. The latency period is similar to the data described in various reviews. In our study, there seems to be a trend toward using lower shock doses of corticosteroids (125 × 3), likely due to a shift in the management of interstitial nephritis currently.