A case of nephrotic syndrome diagnosed as AL amyloidosis treated by daratumumab: a case report

Abstract Background: Nephrotic syndrome caused by immunoglobulin light chain (AL) amyloidosis has a poor prognosis with conventional treatment. Daratumumab has been shown to kidney and cardiac prognoses in amyloidosis. However, few studies have reported treatments for AL amyloidosis followed by nephrotic syndrome. We report a case of nephrotic syndrome caused by AL amyloidosis, who had resistance against conventional treatment, and whose disease was significantly improved after the administration of daratumumab. Case presentation: A 71-year-old woman developed acute leg edema, and 6 months later, she was diagnosed with nephrotic syndrome (The urine protein-creatinine ratio (UPCR) 5.98 g/g Cr, albumin 2.6 g/dL) and acute kidney injury at our hospital. She was diagnosed with renal amyloidosis by renal biopsy and bone marrow puncture revealed monoclonal gammopathy of undetermined significance. She was treated with a combination of cyclophosphamide, bortezomib, and dexamethasone. However, her proteinuria had not improved 1 year later, and she developed liver amyloidosis, which led to gradual weakness. She was readmitted to hospital and started a combination of daratumumab plus conventional therapy. UPCR was decreased to 1–2 g/gCr, and liver amyloidosis improved significantly. Moreover, she had a hematologic complete response. Conclusions: Daratumumab combined with conventional therapy might improve nephrotic syndrome with AL amyloidosis.