#1150 Neutrophil rich infiltrate in immunotherapy induced acute interstitial nephritis

Abstract

Abstract Background and Aims Acute interstitial nephritis (AIN) is a well-recognized cause of acute kidney injury (AKI) in patients treated with Immune checkpoint inhibitors (ICI). Kidney biopsy typically shows tubular interstitial infiltration with well-differentiated mononuclear cells with occasional granulomas and eosinophils. Neutrophil rich tubular interstitial infiltration is typically associated with pyelonephritis. We report a case series of neutrophil rich ICI induced AIN. Method After obtaining approval from the institutional review board, medical records of the nephrology service at a large cancer center were reviewed. Patients were included in the study if they underwent a kidney biopsy for the diagnosis of ICI associated AKI, the biopsy was consistent with atypical AIN with neutrophil rich infiltrate, there was no glomerular involvement, they exhibited no symptoms of pyelonephritis including but not limited to fever, nausea, vomiting, flank pain and dysuria and had a negative urine culture. Results Forty eight patients who had a biopsy proven ICI associated AIN were identified from the medical records. Four (8.3%) patients met the study criteria (Table 1). There were three males and one female. The mean age was 75.5 years. One patient had a history of pre-existing CKD stage 3. Mean number of ICI therapy cycles prior to the development of AIN was seven with two patients treated with pembrolizumab (2 and 14 cycles), one patient treated with nivolumab (1 cycle) and one patient treated with the combination of nivolumab and ipilimumab (2 cycles). All patients presented with asymptomatic rise in serum creatinine (sCr). Kidney biopsy showed neutrophil rich infiltrate and neutrophilic tubulitis in all patients. Neutrophilic casts were present in three biopsies. One patient had evidence of granulomatous inflammation. All patients had mild to moderate interstitial fibrosis. Three patients were initially treated with flat dose prednisone 60 mg daily and one was treated with weight adjusted dose of prednisone 1 mg/kg at 75 mg/day. Three patients had complete renal recovery (sCr < 0.5 mg/dl above baseline) after steroid taper. One patient developed a relapse but achieved partial recovery (sCr < 2x baseline) after the second taper. Two patients remain alive three and 12 months after the kidney biopsy. Two patients died due to the progression of cancer two and 10 months after the biopsy. Conclusion AIN with neutrophil rich infiltrate likely represents a subset of ICI induced AIN. In the absence of clinical signs of pyelonephritis and with evidence of negative urine cultures the treatment should be geared towards addressing inflammation with systemic corticosteroids which have been shown to be effective in management of ICU induced AIN. Avoidance of antibiotics in this setting would lead to better antibiotic stewardship.