*PURPOSE: Immune checkpoint inhibitors (ICI) are increasingly being used for the treatment of many cancers. However most clinical trials of ICI excluded Solid Organ Transplant Recipients (SOTRs). Data on the use of ICI in renal transplant recipients is sparse. ICI associated renal transplant rejection have been described in few case series. Here we report a case of AKI due to Acute Cellular Rejection (ACR) caused by ICI use in a renal transplant recipient. *METHODS: A 74 year old man with living related donor renal transplant four years ago as well as metastatic Merkel cell carcinoma. He was initiated on treatment with Nivolumab two weeks prior to admission. The patient presented with nausea, vomiting and decreased urine output. He was found to have AKI with creatinine of 8.92 mg/dL (baseline Cr of 1.2 mg/dL). He was initiated on hemodialysis and started on empiric pulse dose steroids. A renal biopsy was obtained which revealed diffuse acute tubular necrosis and ACR classified as Banff 1A (i2,t2). *RESULTS: A final diagnosis of AKI due to ICI use resulting in ACR was made. A multidisciplinary discussion involving the patient, transplant nephrology and oncology teams was held. The patient was treated with steroid taper. A decision was made to rechallenge the patient with ICI in the future. *CONCLUSIONS: Data regarding the use of ICI in SOTRs is limited. In a recent systemic review, ICI associated kidney transplant rejection has been reported in 40% of patients, however, mortality has been linked to cancer progression and not rejection.The identified classes of ICI induced renal transplant rejections described previously include ACR (33%), mixed cellular and antibody mediated (17%) and unspecified rejections (50%) . Our case demonstrates the importance of recognizing the renal adverse events associated with ICI use and emphasizes the significance of a patient centered multidisciplinary approach. [

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]CITATION INFORMATION: Abdalla M., Kirby M., Costa N., Kwon D., Hallak P. Immune Checkpoint Inhibitor Induced Acute Cellular Rejection of a Living Donor Kidney Transplant AJT, Volume 23, Issue 6, Supplement 1.

Madeline Kirby MD

Medstar Georgetown University Hospital

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