Next generation flow (NGF) for highly sensitive and standardized detection of minimal residual disease in multiple myeloma
Flores-Montero J (1), Flores LS (1), Paiva B (2), Puig N (3), García-Sánchez O (3), Böttcher S (4), van der Velden VH (5), Pérez-Morán JJ (3), Vidriales MB (3), García-Sanz R (3), Jimenez C (3), González M (3), Martinez-López J (6), Mateos AC (1), Grigore GE (7), Fluxá R (7), Pontes R (8), Caetano J (9), Sedek L (10), Del Cañizo MC (3), Bladé J (11), Lahuerta JJ (6), Aguilar C (12), Bárez A (13), García-Mateo A (14), Labrador J (15), Leoz P (1), Aguilera-Sanz C (16), San-Miguel J (2), Mateos MV (3), Durie B (17), van Dongen JJ (5,18), Orfao A (1).
Flow cytometry has become a highly valuable method to monitor minimal residual disease (MRD) and evaluate the depth of complete response (CR) in bone marrow (BM) of multiple myeloma (MM) after therapy.
However, current flow-MRD has lower sensitivity than molecular methods and lacks standardization. Here we report on a novel next generation flow (NGF) approach for highly-sensitive and standardized MRD detection in MM.
An optimized 2-tube 8-color antibody panel was constructed in five cycles of design-evaluation-redesign. Additionally, a bulk-lysis procedure was established for acquisition of ⩾107 cells/sample, and novel software tools were constructed for automatic plasma cell gating.
Multicenter evaluation of 110 follow-up BM from MM patients in very good partial response or CR showed a higher sensitivity for NGF-MRD vs conventional 8-color flow-MRD -MRD-positive rate of 47 vs 34% (P=0.003)-. Thus, 25% of patients classified as MRD-negative by conventional 8-color flow were MRD-positive by NGF, translating into a significantly longer progression-free survival for MRD-negative vs MRD-positive CR patients by NGF (75% PFS not reached vs 7 months; P=0.02).
This study establishes EuroFlow-based NGF as a highly-sensitive, fully-standardized approach for MRD detection in MM which overcomes the major limitations of conventional flow-MRD methods and is ready for implementation in routine diagnostics.