Nephrotic-range proteinuria in a patient with a renal allograft treated with sorafenib for metastatic renal-cell carcinoma

A 51-year-old man with immunoglobulin A (IgA) nephropathy developed metastatic renal-cell carcinoma of his native right kidney, 3.5 years post kidney transplant. At that time renal function was stable with the presence of only mild proteinuria. Shortly after chemotherapy with sorafenib [anti-vascular endothelial growth factor (VEGF)] was initiated, progressive renal impairment, hypertension, and nephrotic-range proteinuria developed. Allograft biopsy showed extensive IgA nephropathy. After withdrawal of the anti-VEGF therapy, however, renal function and blood pressure improved, and proteinuria diminished. Based on the clinical course and histopathological findings we hypothesize that sorafenib may induce nephrotic-range proteinuria and renal impairment, possibly through anti-VEGF-mediated effects on the progression of IgA nephropathy.