Clinical Value of Minimal Residual Disease Assessed by Multiparameter Flow Cytometry in Amyloid Light Chain Amyloidosis

Abstract Purpose: To assess the feasibility and prognostic value of minimal residual disease (MRD) evaluated by multiparameter flow cytometry (MFC) in newly diagnosed amyloid light chain (AL) amyloidosis.Methods: Clinical data from 25 consecutive newly diagnosed AL amyloidosis patients with MRD data tested at 3 months after first-line therapy completion were retrospectively analysed in a single centre from 2012 to 2019. First-line therapy included 8 courses of VD or 4 courses of VD plus sequential autologous stem cell transplantation (ASCT), both without maintenance therapy.Results: Of 25 patients with very good partial response (VGPR) or better, 19 (76%) achieved MRD negativity. Baseline characteristics were not different between MRD-negative and MRD-positive patients. More ASCT patients than non-ASCT patients (90.0% vs 53.3%, P＝0.043) achieved MRD negativity. In the MRD-negative and MRD-positive groups, cardiac response was observed in 93% and 25% (P=0.019) and any organ response in 94% and 50%, respectively (P=0.023). At a median follow-up of 25.1 months, MRD-negative patients showed significantly longer progression-free survival (PFS) from diagnosis than MRD-positive patients (24.52 vs 76.39 months, P=0.004).Conclusions: MRD negativity measured by MFC at 3 months after first-line therapy completion in patients with AL amyloidosis is measurable and associated with improved organ response rates and PFS over a long follow-up.