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Background: Minimal residual disease (MRD) is one of the most relevant prognostic factors in patients with multiple myeloma (MM); however, the impact of maintenance therapy on MRD levels remains unclear. Among patients with newly diagnosed MM (NDMM) who received lenalidomide maintenance until they developed disease progression, the role of MRD status as a predictor of progression-free survival (PFS) was evaluated by multiparameter flow cytometry (MFC) and allelic-specific oligonucleotide real-time quantitative polymerase chain reaction (ASO-RQ-PCR) analysis.Methods: Seventy-three patients with NDMM enrolled in the RV-MM-EMN-441 (clinical trials.gov identifier, NCT01091831) and RV-MM-COOP-0556 (clinicaltrials.gov identifier, NCT01208766; European Myeloma Network EMN02/HO95 MM Trial) phase 3 trials who achieved at least a very good partial response after intensification/consolidation were included. The median patient age was 57 years (interquartile range, 53-61 years), and all patients received lenalidomide maintenance until they developed progression. MRD was evaluated on bone marrow after intensification/consolidation, after 6 courses of maintenance, and every 6 months thereafter until clinical relapse using both ASO-RQ-PCR (sensitivity, 10-5 ) and MFC (sensitivity, from 10-4 to 10-5 ).Results: After intensification/consolidation, 33 of 72 patients (46%) achieved a molecular complete response (m-CR), and 44 of 70 (63%) achieved a flow complete response (flow-CR). Almost 27% of patients who were MRD-positive after consolidation became MRD-negative during maintenance. After a median follow-up of 38 months, PFS was prolonged in patients who achieved negative MRD status during maintenance according to results from both ASO-RQ-PCR analysis (hazard ratio, 0.29; 95% confidence interval, 0.14-0.62; P = .0013) and MFC (hazard ratio, 0.19; 95% confidence interval, 0.09-0.41; P < .001). The impact of negative MRD status on PFS was similar in all subgroups (ASCT and no-ASCT; International Staging System stages I, II, and III; high-risk and standard-risk cytogenetics), and the two techniques were highly correlated.Conclusions: MRD status is a stronger predictor of PFS than standard risk factors, and lenalidomide maintenance further increases the rate of negative MRD results. [ABSTRACT FROM AUTHOR]

BACKGROUND: Smoldering multiple myeloma (SMM) presents a high risk of progression to symptomatic MM (sy-MM). Herein, we analyzed some predictors of development of sy-MM. In 144 patients with SMM, we also compared the risk of progression predicted by bone marrow plasma cell (BMPC) involvement on the bone marrow biopsy (BMB) versus bone marrow aspirates (BMA). METHODS: From January 1980 to July 2010, 397 patients with SMM observed in 12 centers of the Multiple Myeloma GIMEMA (Gruppo Italiano Malattie EMatologiche dell'Adulto) Latium Working Group have been analyzed. At progression to sy-MM, the severity of clinical presentation was graded according to the need of intensive supportive care. RESULTS: After a median follow-up of 135 months, the cumulative incidence of progression rates to sy-MM were 45%, 55%, and 75% at 10, 15, and 20 years, respectively. Hemoglobin ≤12.5 g/dL, monoclonal component ≥2.5 g/dL, and BMPC ≥60% were the only parameters negatively affecting the cumulative incidence of progression. In particular, 10 of 397 (2.5%) patients with BMPC ≥60% had a 5.6-fold increased risk of fast progression (within 2 years), which occurred with severe clinical manifestations in 62% of cases. BMB was more sensitive for the detection of BMPC involvement, even though BMA was a more reliable indicator of a rapid progression to sy-MM. CONCLUSIONS: The highest risk of rapid evolution to sy-MM and the severity of clinical manifestation at the progression suggest that SMM patients with a BMPC ≥60% should be treated soon after diagnosis. Moreover, BMPC is a more reliable index for progression to sy-MM if assessed by BMA. Cancer 2012. © 2012 American Cancer Society. [ABSTRACT FROM AUTHOR]