Successful Treatment of Acute Tubulointerstitial Nephritis Related to Immune Checkpoint Inhibitor with a Very Rapid Steroid Taper

Introduction: Acute interstitial nephritis (AIN) is the most common renal immune related adverse event of immune checkpoint inhibitors (ICIs). Current treatment guidelines (based on expert consesus) for persistent grade 2 AKI or higher, suggest discontinuation of ICIs and start of Prednisone 1-2 mg/kg until creatinine improves, followed by gradual taper over 4-6 weeks. Due to steroid related toxicities and concern for negation of antitumor impact of ICIs, rapid steroid tapering regimens have been described, occuring over at little as 3 weeks. We describe a case whereby biopsy proven AIN related to ICI was effectively treated with a steroid course, tapered off in only 16 days. Case Description: 72 year old male with past history of non small cell lung cancer (squamous cell) of right middle lobe with metastatsis to the pericardium was receiving Pembrolizumab 200 mg every 3 weeks. Baseline serum creatinine was 0.7 - 1.0 mg/dL. After 16 months of therapy, creatinine rose to 2.0 and peaked at 3.42 mg/dL. Kidney biopsy showed acute tubulointerstitial nephritis, with mild activity and no chronicity (immunotherapy associated). He was initiated on Prednisone 80 mg daily for 4 days, then 60 mg daily for 3 days, then 30 mg daily for 3 days, then 15 mg daily for 3 days, then 5 mg for 3 days, then stopped. Serum creatinine improved briskly over the course of therapy, down to 1.22 mg/dL and 1.04 mg/dL a week after steroid discontinuation. Discussion: Previous literature has noted more than 85% of patients with ICI-induced interstital nephritis have favorable response to corticosteroids. Most guideline based approaches suggest continuation of 1-2 mg/kg Prednisone equivalent per day until creatinine returns to <1.5 fold baseline, followed by taper over an additional 4-6 weeks. There has been great motivation to enact more rapid tapering regimens, most of which involve getting to 10 mg/day dose within 3 weeks time. Prior series have shown no difference in dose or duration of steroids in those with complete renal recovery compared to those with partial or no remission. Although the steroid course was indeed longer on average. Our case highlights a favorable renal outcome with an extremely rapid (16 day) Prednisone taper. This suggests such a strategy may be appropriate and ideally prospective studies will help to clarify future rapid taper guidelines.