Renal thrombotic microangiopathy during nintedanib treatment for idiopathic pulmonary fibrosis
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Agents that block vascular endothelial growth factor (VEGF) and its downstream pathway have been reported to be associated with nephrotoxicity including hypertension, proteinuria, and renal dysfunction. Bevacizumab, a monoclonal antibody against VEGF, is known to cause thrombotic microangiopathy (TMA), while tyrosine kinase inhibitors (TKIs) that block VEGF downstream are mainly associated with minimal change disease or focal segmental glomerulosclerosis. The question regarding the source of the diverse phenotypes of nephrotoxicity associated with these agents remains enigmatic. Nintedanib, a multitargeted TKI, blocks fibroblast growth factor and platelet-derived growth factor receptor as well as VEGF receptor, and is indicated for the treatment of idiopathic pulmonary fibrosis. We describe a case of a 45-year-old male who presented with isolated proteinuria of 1.3 g/g Cr 3 years after beginning nintedanib treatment. The kidney biopsy revealed histological features consistent with renal TMA. He underwent single lung transplantation 6 months later, which enabled cessation of nintedanib, and, 1 month later, his proteinuria results were negative. Unlike other types of TKIs, the pathological findings of nintedanib-induced nephrotoxicities have been limitedly reported. This is the first case of isolated proteinuria likely caused by nintedanib-induced TMA.