This International Myeloma Working Group consensus updates the disease defi nition of multiple myeloma to include validated biomarkers in addition to existing requirements of attributable CRAB features (hypercalcaemia, renal failure, anaemia, and bone lesions). These changes are based on the identifi cation of biomarkers associated with near inevitable development of CRAB features in patients who would otherwise be regarded as having smouldering multiple myeloma. A delay in application of the label of multiple myeloma and postponement of therapy could be detrimental to these patients. In addition to this change, we clarify and update the underlying laboratory and radiographic variables that fulfi l the criteria for the presence of myeloma-defi ning CRAB features, and the histological and monoclonal protein requirements for the disease diagnosis. Finally, we provide specifi c metrics that new biomarkers should meet for inclusion in the disease defi nition. The International Myeloma Working Group recommends the implementation of these criteria in routine practice and in future clinical trials, and recommends that future studies analyse any diff erences in outcome that might occur as a result of the new disease defi nition.

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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.

Minimal residual disease (MRD) assessment is standard in many hematologic malignancies but is considered investigational in multiple myeloma (MM). We report a prospective analysis of the prognostic importance of MRD detection by multiparameter flow cytometry (MFC) in 295 newly diagnosed MM patients uniformly treated in the GEM2000 protocol VBMCP/VBAD induction plus autologous stem cell transplantation [ASCT]). MRD status by MFC was determined at day 100after ASCT. Progression-free survival (PFS; median 71 vs 37 months, P < .001) and overall survival (OS; median not reached vs 89 months, P ‫؍‬ .002) were longer in patients who were MRD negative versus MRD positive at day 100 after ASCT. Similar prognostic differentiation was seen in 147 patients who achieved immunofixation-negative complete response after ASCT. Moreover, MRD ؊ immunofixation-negative (IFx ؊ ) patients and MRD ؊ IFx ؉ patients had significantly longer PFS than MRD ؉ IFx ؊ patients. Multivariate analysis identified MRD status by MFC at day 100 after ASCT as the most important independent prognostic factor for PFS (HR ‫؍‬ 3.64, P ‫؍‬ . IntroductionIn most hematologic malignancies, response to front-line therapy is a good predictor of prognosis, with the longest survival seen in patients achieving an optimal response. This paradigm is represented by chronic myeloid leukemia (CML), in which hematologic, cytogenetic, and molecular remissions define progressively better response to therapy. In consequence, investigations to define these levels of remission are mandatory in routine clinical practice for treatment stratification and assessment of prognosis. 1 The situation is similar for other malignancies such as acute promyelocytic leukemia (APL) or acute lymphoblastic leukemia (ALL). 2,3 For this reason, there are continuous efforts to improve the sensitivity of the methods used to assess response to therapy, mainly through the introduction and refinement of both molecular and immunophenotyping approaches, as well as imaging techniques.Multiple myeloma (MM) should be no exception to this paradigm. For many years, the major goal of MM therapy was to achieve partial response (PR) or disease stabilization. 4,5 With the introduction of high-dose therapy plus autologous stem cell transplantation (HDT/ASCT), the new goal became the achievement of complete response (CR), defined as absence of M-protein by immunofixation (IFx) and less than 5% plasma cells (PCs) in bone marrow (BM). 6,7 More recently, the International Myeloma Working Group proposed a new response category of "stringent CR," which requires normalization of the free light chain ratio and the absence of residual clonal cells in the BM by immunohistochemistry or immunofluorescence. 8 As noted previously, the assessment of minimal residual disease (MRD), residual tumor cells persisting after therapy, is part of the standard of care in many hematologic malignancies, whereas in MM this is still considered investigational. Thus, MRD studies in MM have involved mainly small series of patients or have...

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Early treatment for patients with high-risk smoldering myeloma delays progression to active disease and increases overall survival. (Funded by Celgene; ClinicalTrials.gov number, NCT00480363.).

Key Points• MRD assessment by sequencing is prognostic of TTP and OS in multiple myeloma patients.• Among patients in complete response, MRD assessment by sequencing enables identification of 2 distinct subgroups with different TTP.We assessed the prognostic value of minimal residual disease (MRD) detection in multiple myeloma (MM) patients using a sequencing-based platform in bone marrow samples from 133 MM patients in at least very good partial response (VGPR) after front-line therapy.Deep sequencing was carried out in patients in whom a high-frequency myeloma clone was identified and MRD was assessed using the IGH-VDJ H , IGH-DJ H , and IGK assays. The results were contrasted with those of multiparametric flow cytometry (MFC) and allelespecific oligonucleotide polymerase chain reaction (ASO-PCR).

We analyzed the DNA methylome of ten subpopulations spanning the entire B cell differentiation program by whole-genome bisulfite sequencing and high-density microarrays. We observed that non-CpG methylation disappeared upon B cell commitment, whereas CpG methylation changed extensively during B cell maturation, showing an accumulative pattern and affecting around 30% of all measured CpG sites. Early differentiation stages mainly displayed enhancer demethylation, which was associated with upregulation of key B cell transcription factors and affected multiple genes involved in B cell biology. Late differentiation stages, in contrast, showed extensive demethylation of heterochromatin and methylation gain at Polycomb-repressed areas, and genes with apparent functional impact in B cells were not affected. This signature, which has previously been linked to aging and cancer, was particularly widespread in mature cells with an extended lifespan. Comparing B cell neoplasms with their normal counterparts, we determined that they frequently acquire methylation changes in regions already undergoing dynamic methylation during normal B cell differentiation.