Outcomes of Patients with Light Chain Amyloidosis Who Had Autologous Stem Cell Transplantation with 3 or More Organs Involved.

Prior reports have suggested that 3 or more organs involved is a contraindication for autologous stem cell transplant (ASCT) in amyloid light chain (AL) amyloidosis. Therefore, most centers limit transplantation to patients who have no more than 2 organs significantly involved. We retrospectively reviewed all patients with AL amyloidosis with ≥3 involved organs and who had ASCT between 1996 and 2015 at Mayo Clinic, Rochester, Minnesota to assess transplant safety and outcomes. Seventy-five patients with ≥3 organs involved underwent ASCT. Median age at diagnosis was 54 years, and 67% were men. The heart was involved in 95%, followed by the kidneys (84%). Thirty-eight patients (51%) had no induction treatment before ASCT. Full-dose melphalan (200 mg/m2) was given in 45%, and the remainder received 140 mg/m2. Overall hematologic response rate was 75%. The median progression-free survival (PFS) and overall survival (OS) were 16 and 68 months, respectively. The 100-day mortality was 16%, and 44 patients (59%) died during follow-up. The most common causes of death were cardiovascular events (32%) and progressive amyloidosis (25%). On multivariable analysis, predictors for PFS were Mayo 2012 stage III/IV (relative risk [RR], 3.3; P = .0012) and hematologic response (at least very good partial response; RR, .4; P = .012). An N-terminal pro-brain natriuretic peptide (NT-proBNP) level of ≥2000 pg/mL was an independent predictor for shorter PFS (RR, 2.6; P = .013). Predictors for OS included any hematologic response (RR, .12; P = .0015), melphalan 200 mg/m2 (RR, .2; P = .014), and Mayo 2012 stage III/IV (RR, 7.7; P = .0002). An NT-proBNP level ≥ 2000 pg/mL was a powerful predictor of OS (RR, 4; P = .013). The number of organs involved (3 versus >3) did not significantly impact PFS or OS. We conclude that the high prevalence and severity of cardiac involvement are the main drivers for the poor outcome in patients who have ≥3 organs involved. Using selection criteria defined for safe transplantation in cardiac amyloidosis should result in low therapy-related mortality independent of the number of organs involved. The severity of cardiac involvement should be the major criterion for transplanting patients with AL amyloidosis that have ≥3 organs involved and not merely the number of organs involved.