Abstract
Drug-induced lupus glomerular diseases have historically been associated with hydralazine, but new drugs that modify the growth, metabolism, and immunity of cells are increasingly found to cause glomerular disease. This includes anti-tumor necrotic factor and other antibody agents used in cancer treatment. Multitarget tyrosine kinases such as regorafenib are increasingly used in metastatic malignancies with good outcomes. Currently, they are not known to have kidney complications except for proteinuria, hypertension, and electrolyte disturbances such as hypophosphatemia. We report a patient who presented within months after starting regorafenib therapy for metastatic colon cancer with acute kidney injury, proteinuria, and hematuria. Biopsy revealed endocapillary proliferative glomerulonephritis with full-house staining on immunofluorescence in the absence of any systemic manifestation of systemic lupus erythematosus. The kidney injury improved with corticosteroid treatment and discontinuation of regorafenib therapy. We discuss the possible mechanisms that led to this class IV pattern of lupus nephritis and conclude that it is likely drug-induced lupus nephritis from regorafenib.