Long‐term outcomes of renal <scp>AL</scp> amyloidosis patients undergoing autologous stem cell transplantation: Validating the performance of the renal staging system

Renal AL amyloidosis can be complicated by end-stage renal disease (ESRD) requiring renal replacement therapy (RRT). In this study, we describe the long-term outcomes of renal AL amyloidosis patients undergoing autologous stem cell transplantation (ASCT) and assess the utility of the renal staging system. Retrospective study of renal AL patients (n = 697; Mayo Clinic, Boston University) who underwent ASCT between 2003 and 2020. Renal stage was assigned based on 24-h proteinuria and estimated glomerular filtration rate measurements. Renal survival was defined as the time from ASCT until initiation of RRT, while patients who were not placed on RRT were censored at their last follow-up. With a median follow-up of 10.4 years, RRT was required in 149 patients (21%). The median time from ASCT to ESRD was 3.4 years, with late events of progression to ESRD seen >10 years from ASCT. Pre-ASCT renal stage was significantly associated with the cumulative incidence of RRT: 3-year RRT rate was 3%, 10%, and 37% for renal stages I, II, and III, respectively. However, in the 2012-2020 period subset, a significant decrease in ESRD risk was noted across all renal stages (3-year RRT 0%, 5%, and 24%, respectively). In multivariate analysis, renal survival was independently associated with the pre-ASCT renal stage, lambda isotype, bone marrow plasmacytosis ≥20%, post-ASCT hematologic response, and year of ASCT. Long-term outcomes of renal AL amyloidosis treated with ASCT are presented. Renal stage reliably predicts renal outcomes in patients with AL undergoing ASCT, despite a reduction in the proportion of patients progressing to RRT in recent years.