Background: Primary systemic (AL) amyloidosis is a rare plasma cell disorder characterized by soft-tissue deposition of monoclonal light chain fragments. High-dose melphalan followed by autologous stem cell transplantation currently has become the treatment of choice. Favorable outcome is ensured with achievement of hematologic response, but little is known about organ response. This study was undertaken to determine the prognostic importance of renal response after high-dose melphalan and stem cell transplantation.
Methods: All patients with AL amyloidosis who underwent autologous stem cell transplantation between 1996 and December 2002 were selected for study. Renal response is defined as a 50% or greater reduction in proteinuria with less than 25% decline in renal function. Exclusion criteria included pretransplantation dialysis therapy or dialysis dependence posttransplantation, treatment mortality, lack of proteinuria assessment posttransplantation, and baseline proteinuria with protein less than 1 g/d.
Results: Of 105 patients, 47 were excluded for stated reasons. Renal response was achieved in 60.3% of evaluated patients. Proteinuria was reduced by greater than 90% in 37.9% and returned to normal in 15.5%. Median response time was 12 months. Renal response was associated with a greater increase in serum albumin level (P = 0.001), maintenance of renal function (P < 0.001), and better survival (P = 0.0003). Renal responders had better survival regardless of hematologic response (P = 0.01 to 0.05).
Conclusion: Currently, high-dose melphalan followed by stem cell transplantation is the most effective treatment for AL amyloidosis for those who are eligible. Our data show that renal response after high-dose melphalan followed by stem cell transplantation is associated with improved survival. Renal response is an independent marker of treatment success and can be used in cases in which determination of hematologic response is difficult.