Autologous Stem Cell Transplant for IgM-Associated Amyloid Light-Chain Amyloidosis

IgM-related amyloid light-chain (AL) amyloidosis is a rare disease, with patients presenting with more renal and neurologic involvement and less cardiac involvement compared with those with non–IgM-related disease. We retrospectively reviewed 38 patients receiving autologous stem cell transplant (ASCT) for IgM-related AL amyloidosis at the Mayo Clinic between May 1999 and June 2018. Median age was 61years, and 71% were men. The most common organs involved were renal (63%), neurologic (32%), and cardiac (26%). The median difference between involved and uninvolved free light chains was 6.2mg/dL, and most patients had early Mayo stage disease (87% Mayo stage I 2004 and 74% Mayo stage I 2012). The overall response rate was 92%, with 76% of patients achieving at least a very good partial response. Renal response was seen in 65% of patients (15/23; median time, 18 months post-ASCT; range 3 to 52) and cardiac response in 60% of patients (6/10; median time, 12 months post-ASCT; range 10 to 35). Median progression-free survival (PFS) and overall survival (OS) was 48 and 106 months, respectively. Organ response predicted better PFS and OS (median PFS, 93 months for organ response versus 16 months for no organ response [P =.0006]; and median OS, 123 months for organ response versus 41 months for no organ response [P =.02]). Two patients died within 100days of transplant, representing a 5% 100-day mortality. ASCT is an effective therapy that can be safely delivered to carefully selected patients with IgM-related AL amyloidosis.