Steroid Refractory Immune Checkpoint Induced Acute Interstitial Nephritis Salvaged by Mycophenolate Mofetil

Abstract

Immune checkpoint inhibitors (ICIs) have revolutionized the field of medical oncology. This class of medications block molecules responsible for inhibiting the immune response to cancer, allowing for immune system activation, tumor recognition and destruction of cancer cells. A unique side-effect of these drugs involves the immune-mediated destruction of healthy tissue, known as immune-related adverse events (irAEs). One example is the autoimmune destruction of renal tissue associated with development of acute interstitial nephritis (AIN). Here, we present a case of a patient with metastatic bladder cancer treated with an ICI who developed AIN that was refractory to glucocorticoid therapy and salvaged by mycophenolate mofetil. The case illustrates the unique mechanism by which toxicity can occur, demonstrates the concept of delayed irAEs, and highlights the prolonged, durable responses patients with cancer can have to immunotherapy, even after treatment is discontinued.