A Case of Minimal Change Disease in a Patient Receiving Immune Checkpoint Inhibitor.

Immunotherapies, particularly immune checkpoint inhibitors, are increasingly used in cancer treatment but can cause immune-related adverse events, including rare renal complications. We report the case of a 72-year-old man with metastatic melanoma receiving combination ipilimumab and nivolumab who presented with progressive bilateral lower limb oedema. Investigations demonstrated severe hypoalbuminemia and nephrotic-range proteinuria. Autoimmune investigations were unremarkable, while kidney biopsy showed diffuse podocyte foot process effacement without immune deposits on electron microscopy, consistent with minimal change disease. The patient was treated with high-dose prednisolone, diuretics and albumin replacement, resulting in resolution of oedema, recovery of serum albumin and progressive reduction in proteinuria. Immune checkpoint inhibitor-associated minimal change disease is believed to be mediated by dysregulated cytotoxic T-cell activation causing podocyte injury. Non-steroidal anti-inflammatory drug exposure may potentially increase susceptibility to podocyte injury and the development of minimal change disease. This case highlights the importance of recognising nephrotic syndrome as a rare immune-related adverse event of immune checkpoint inhibitor therapy, as prompt diagnosis and corticosteroid treatment are associated with favourable renal outcomes.