Next Generation Flow for highly sensitive and standardized detection of minimal residual disease in multiple myeloma.

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. In addition, 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 (VGPR) 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% progression-free survival 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.

[Monoclonal component in visceral leishmaniasis: a rare association that can lead to misdiagnosis]. / Componente monoclonal en leishmaniasis visceral: rara asociación que puede conducir a un falso diagnóstico.

The detection of monoclonal components is exceptional in patients with visceral leishmaniasis (VL). The cases are here reported of two patients with VL in a non-endemic area and monoclonal components which posed problems for the differential diagnosis with other entities associated with the presence of paraproteins. The predominant clinical manifestations in both cases were general symptoms, fever and severe spleen enlargement. One patient had a monoclonal triple band in urine and the other several oligoclonal bands in serum. In the initial bone marrow aspiration smear no parasites were observed in any of the two cases but a remarkable plasmacytosis in one of them. The presence of increased serum titers of anti-Leishmania antibodies was the first demonstrative finding of VL. The diagnosis was confirmed with positive culture of Leishmania and therapy with pentavalent antimonials was successful in both cases. The different diagnostic possibilities are discussed and the possibility of VL is emphasized even in non-endemic areas when monoclonal components in serum or urine specimens are found and consistent clinical findings are present.