A Unique Case of Benralizumab Treatment for Drug-Induced Acute Interstitial Nephritis

Introduction: Acute interstitial nephritis (AIN) is a common cause of acute kidney injury (AKI), which may be induced by infections, systemic and localized autoimmune processes, or most commonly drug-induced. AIN may result in fibrosis and permanent kidney damage. Treatment options for drug induced AIN mainly steroids, although evidence of efficacy is lacking. Case Description: A 55-year-old male, presented with abdominal pain, vomiting and anuria following excessive alcohol intake. Medical history included hypertension treated with ramipril and amlodipine, and recently, etoricoxib for back pain. Patient developed severe AKI despite fluid resuscitation and cessation of Etrocoxib, and required hemodialysis. Kidney biopsy showed AIN with numerous eosinophil infiltrates (figure 1A). Prominent eosinophiluria was observed in the urianalisis persistently throughout treatment (figure 1B). High-dose steroids intravenously did not improve urine output. Following informed consent Benralizumab (30 mcg SC) was given off label. Kidney function recovered immediately, with polyuria ensuing within hours (<12 hr) of treatment, and coincided with a complete disappearance of eosinophils and leukocytes in the urine at 48 hours after treatment (figure 1C). Patient was weaned off dialysis within a few days while renal function normalized. Discussion: Benralizumab, a humanized monoclonal antibody targeting interleukin 5 (IL5) α receptor, is used for severe eosinophilic asthma. Benralizumab has been used in different diseases in which pathophysiology mechanism implicates eosinophil-mediated response such as eosinophilic cystitis and eosinophilic esophagitis. This case highlights a future potential use of anti IL5 receptor treatment for AIN which involves rich eosinophilic inflammation of the kidneys. To our knowledge this is the first reported case of Benralizumab treatment for drug induced AIN.