Bortezomib and high-dose melphalan conditioning regimen in frontline multiple myeloma: an IFM randomized phase 3 study.

High-dose melphalan (HDM) and transplantation are recommended for eligible patients with multiple myeloma. No other conditioning regimen has proven to be more effective and/or safer. We previously reported in a phase 2 study that bortezomib can safely and effectively be combined with HDM (Bor-HDM), with a 32% complete response (CR) rate after transplantation. These data supported a randomized phase 3 trial. Randomization was stratified according to risk and response to induction: 300 patients were enrolled, and 154 were allocated to the experimental arm (ie, arm A) with bortezomib (1 mg/m2 intravenously [IV]) on days -6, -3, +1, and +4 and melphalan (200 mg/m2 IV) on day -2. The control arm (ie, arm B) consisted of HDM alone (200 mg/m2 IV). There were no differences in stringent CR + CR rates at day 60 posttransplant (primary end point): 22.1% in arm A vs 20.5% in arm B (P = .844). There were also no differences in undetectable minimum residual disease rates: 41.3% vs 39.4% (P = .864). Median progression-free survival was 34.0 months for arm A vs 29.6 months for arm B (adjusted HR, 0.82; 95% CI, 0.61-1.13; P = .244). The estimated 3-year overall survival was 89.5% in both arms (hazard ratio, 1.28; 95% CI, 0.62-2.64; P = .374). Sixty-nine serious adverse events occurred in 18.7% of Bor-HDM-treated patients (vs 13.1% in HDM-treated patients). The proportion of grade 3/4 AEs was similar within the 2 groups (72.0% vs 73.1%), mainly (as expected) blood and gastrointestinal disorders; 4% of patients reported grade 3/4 or painful peripheral neuropathy in arm A (vs 1.5% in arm B). In this randomized phase 3 study, a conditioning regimen with Bor-HDM did not improve efficacy end points or outcomes compared with HDM alone. The original trial was registered at www.clinicaltrials.gov as #NCT02197221.

Bortezomib, thalidomide, and dexamethasone with or without daratumumab before and after autologous stem-cell transplantation for newly diagnosed multiple myeloma (CASSIOPEIA): a randomised, open-label, phase 3 study.

BACKGROUND: Bortezomib, thalidomide, and dexamethasone (VTd) plus autologous stem-cell transplantation is standard treatment in Europe for transplant-eligible patients with newly diagnosed multiple myeloma. We evaluated whether the addition of daratumumab to VTd before and after autologous stem-cell transplantation would improve stringent complete response rate in patients with newly diagnosed multiple myeloma. METHODS: In this two-part, randomised, open-label, phase 3 CASSIOPEIA trial, we recruited transplant-eligible patients with newly diagnosed multiple myeloma at 111 European sites. Patients were randomly assigned (1:1) to receive four pre-transplant induction and two post-transplant consolidation cycles of VTd alone (VTd group) or in combination with daratumumab (D-VTd group). The primary endpoint of part 1 was stringent complete response assessed 100 days after transplantation. Part 2 (maintenance) is ongoing. The trial is registered with ClinicalTrials.gov, number NCT02541383. FINDINGS: Between Sept 22, 2015, and Aug 1, 2017, 1085 patients were enrolled at 111 European sites and were randomly assigned to the D-VTd group (n=543) or the VTd group (n=542). At day 100 after transplantation, 157 (29%) of 543 patients in the D-VTd group and 110 (20%) of 542 patients in the VTd group in the intention-to-treat population had achieved a stringent complete response (odds ratio 1·60, 95% CI 1·21-2·12, p=0·0010). 211 (39%) patients in the D-VTd group versus 141 (26%) in the VTd group achieved a complete response or better, and 346 (64%) of 543 versus 236 (44%) of 542 achieved minimal residual disease-negativity (10-5 sensitivity threshold, assessed by multiparametric flow cytometry; both p<0·0001). Median progression-free survival from first randomisation was not reached in either group (hazard ratio 0·47, 95% CI 0·33-0·67, p<0·0001). 46 deaths on study were observed (14 vs 32, 0·43, 95% CI 0·23-0·80). The most common grade 3 or 4 adverse events were neutropenia (28% vs 15%), lymphopenia (17% vs 10%), and stomatitis (13% vs 16%). INTERPRETATION: D-VTd before and after autologous stem-cell transplantation improved depth of response and progression-free survival with acceptable safety. CASSIOPEIA is the first study showing the clinical benefit of daratumumab plus standard of care in transplant-eligible patients with newly diagnosed multiple myeloma. FUNDING: The Intergroupe Francophone du Myélome and Dutch-Belgian Cooperative Trial Group for Hematology Oncology.

Carfilzomib Weekly plus Melphalan and Prednisone in Newly Diagnosed Transplant-Ineligible Multiple Myeloma (IFM 2012-03): A Phase I Trial.

PURPOSE: Carfilzomib is a novel generation proteasome inhibitor. The Carmysap trial demonstrated that twice-weekly KMP (carfilzomib, melphalan, prednisone) might challenge the MPV (melphalan, prednisone, bortezomib) standard. We sought to study KMP weekly, allowing to increase carfilzomib's dose with maintained efficacy and improved safety profile. PATIENTS AND METHODS: IFM2012-03, a phase I multicenter study of KMP weekly in elderly patients with newly diagnosed multiple myeloma (eNDMM), aimed to determine the MTD of carfilzomib. Carfilzomib was given intravenously at 36, 45, 56, and 70 mg/m2/day on days 1, 8, 15, and 22 with melphalan and prednisone, for nine 35-day induction cycles, followed by carfilzomib maintenance for 1 year. Three dose-limiting toxicities (DLT) determined MTD at the lower dose. RESULTS: Thirty eNDMMs were treated, 6 per cohort at 36, 45, and 56 mg/m2 and 12 at 70 mg/m². There was one DLT at 36 mg/m2 (lymphopenia), one at 45 mg/m2 (lysis syndrome), two at 56 mg/m2 (cardiac insufficiency and febrile neutropenia), and two at 70 mg/m2 (vomiting and elevated liver enzymes). The safety profile was acceptable; however, specific attention must be paid to the risk of cardiovascular events, especially for elderly patients. The overall response rate was 93.3%, with 46.6% complete response. CONCLUSIONS: The MTD dose of carfilzomib was 70 mg/m2 in this KMP weekly study in eNDMM. Response rates, and especially CR rate, were remarkable in this population, and would benefit from being assessed in a larger-scale study. The IFM2012-03 study demonstrated that the MTD of carfilzomib weekly is 70 mg/m2 in eNDMM, and 56 mg/m2 for patients older than 75 years. Carfilzomib used weekly in combination has a good efficacy and safety profile in eNDMM.

Minimal residual disease negativity using deep sequencing is a major prognostic factor in multiple myeloma.

The introduction of novel agents has led to major improvements in clinical outcomes for patients with multiple myeloma. To shorten evaluation times for new treatments, health agencies are currently examining minimal residual disease (MRD) as a surrogate end point in clinical trials. We assessed the prognostic value of MRD, measured during maintenance therapy by next-generation sequencing (NGS). MRD negativity was defined as the absence of tumor plasma cell within 1 000 000 bone marrow cells (<10-6). Data were analyzed from a recent clinical trial that evaluated the role of transplantation in newly diagnosed myeloma patients treated with lenalidomide, bortezomib, and dexamethasone (RVD). MRD negativity was achieved at least once during maintenance in 127 patients (25%). At the start of maintenance therapy, MRD was a strong prognostic factor for both progression-free survival (adjusted hazard ratio, 0.22; 95% confidence interval, 0.15-0.34; P < .001) and overall survival (adjusted hazard ratio, 0.24; 95% confidence interval, 0.11-0.54; P = .001). Patients who were MRD negative had a higher probability of prolonged progression-free survival than patients with detectable residual disease, regardless of treatment group (RVD vs transplant), cytogenetic risk profile, or International Staging System disease stage at diagnosis. These results were similar after completion of maintenance therapy. Our findings confirm the value of MRD status, as determined by NGS, as a prognostic biomarker in multiple myeloma, and suggest that this approach could be used to adapt treatment strategies in future clinical trials.

Salvage therapy post pomalidomide-based regimen in relapsed/refractory myeloma.

The combination of pomalidomide and low-dose dexamethasone (Pom-Dex) has proved effective and safe in patients with end-stage relapsed/refractory multiple myeloma (RRMM), otherwise characterized by a very poor outcome. MM remains an incurable disease with unavoidable relapses, and the outcome after pomalidomide is still dismal. However, some patients demonstrate prolonged survival even beyond pomalidomide therapy.We sought to analyze the treatment of RRMM patients following Pom-Dex therapy and the response and survival after this next treatment line.We studied 134 patients treated with Pom-Dex until progression across two IFM studies. Seventy percent of these patients received further therapy after Pom-Dex. Among the treated patients, one third responded and one third maintained stable disease. The median OS for treated patients was 12 months (6.5;17), with 22 and 12.5% of patients surviving beyond 2 and 3 years, respectively. The factors associated with a better outcome were exposure to a triplet-based regimen containing a novel agent, response to therapy, absence of adverse cytogenetic, and a longer time from diagnosis to post pomalidomide therapy.This study suggests that patients relapsing after Pom-Dex therapy can still benefit from a further line of treatment. A subset of these treated patients even displayed a prolonged OS, while the prognosis remained very poor without treatment. An active approach could therefore be recommended even in this adverse situation, however guided by the patients' prognosis factors.

Heavy + light chain analysis to assign myeloma response is analogous to the IMWG response criteria.

Automated serum heavy + light chain (HLC) immunoassays can measure the intact immunoglobulins of each light chain type separately. We though to compare HLC assays with electrophoretic techniques in determining International Myeloma Working Group (IMWG) response criteria. 114 myeloma patients from 2 trials were included. HLC measurements were made utilizing archived sera and response assessments compared with those based on electrophoretic analysis at the time of the trials. Assessments at ∼90 days and maximal response were compared as was the power of the 2 techniques for predicting later responses, overall survival, and progression. The kappa statistic indicated good agreement between the 2 methods for determining IMWG response criteria, although HLC measurements might give better predictions of subsequent responses and frequently gave an earlier indication of change. HLC measurements could represent an alternative to electrophoretic techniques in determining IMWG response. Validation with a greater range of patient responses is needed for confirmation.

Effect of High-Cutoff Hemodialysis vs Conventional Hemodialysis on Hemodialysis Independence Among Patients With Myeloma Cast Nephropathy: A Randomized Clinical Trial.

Importance: Cast nephropathy is the main cause of acute kidney injury in multiple myeloma and persistent reduction in kidney function strongly affects prognosis. Strategies to rapidly remove nephrotoxic serum-free light chains combined with novel antimyeloma agents have not been evaluated prospectively. Objective: To compare the hemodialysis independence rate among patients newly diagnosed with myeloma cast nephropathy treated with hemodialysis using a high-cutoff dialyzer (with very large membrane pores and high permeability to immunoglobulin light chains) or a conventional high-flux dialyzer (with small pores and lower permeability). Design, Setting, and Participants: Randomized clinical trial involving 98 patients with biopsy-proven myeloma cast nephropathy requiring hemodialysis treated at 48 French centers between July 2011 and June 2016; the final date of follow-up was June 29, 2016. Interventions: Intensive hemodialysis (eight 5-hour sessions over 10 days) with either a high-cutoff dialyzer (46 patients) or a conventional high-flux dialyzer (48 patients). All patients received the same chemotherapy regimen of bortezomib and dexamethasone. Main Outcomes and Measures: Primary end point was hemodialysis independence at 3 months; secondary end points: hemodialysis independence rates at 6 and 12 months, hemodialysis- and chemotherapy-related adverse events, and death. Results: Among 98 randomized patients, 94 (96%) (median age, 68.8 years [interquartile range, 61.2-75.3 years]; 45% women) were included in the modified intent-to-treat analysis. The hemodialysis independence rate at 3 months was 41.3% (n = 19) in the high-cutoff hemodialysis group vs 33.3% (n = 16) in the conventional hemodialysis group (between-group difference, 8.0% [95% CI, -12.0% to 27.9%], P = .42); at 6 months, the rate was 56.5% (n = 26) vs 35.4% (n = 17), respectively (between-group difference, 21.1% [95% CI, 0.9% to 41.3%], P = .04); and at 12 months, the rate was 60.9% (n = 28) vs 37.5% (n = 18) (between-group difference, 23.4% [95% CI, 3.2% to 43.5%], P = .02). The incidence of hemodialysis-related adverse events was 43% in the high-cutoff hemodialysis group vs 39% in the conventional hemodialysis group; chemotherapy-related serious adverse events, 39% vs 37%, respectively; and at 12 months, 9 patients vs 10 patients died. Conclusions and Relevance: Among patients with myeloma cast nephropathy treated with a bortezomib-based chemotherapy regimen, the use of high-cutoff hemodialysis compared with conventional hemodialysis did not result in a statistically significant difference in hemodialysis independence at 3 months. However, the study may have been underpowered to identify an early clinically important difference. Trial Registration: clinicaltrials.gov Identifier: NCT01208818.

VTD is superior to VCD prior to intensive therapy in multiple myeloma: results of the prospective IFM2013-04 trial.

The Intergroupe Francophone du Myélome conducted a randomized trial to compare bortezomib-thalidomide-dexamethasone (VTD) with bortezomib-cyclophosphamide-dexamethasone (VCD) as induction before high-dose therapy and autologous stem cell transplantation (ASCT) in patients with newly diagnosed multiple myeloma. Overall, a total of 340 patients were centrally randomly assigned to receive VTD or VCD. After 4 cycles, on an intent-to-treat basis, 66.3% of the patients in the VTD arm achieved at least a very good partial response (primary end point) vs 56.2% in the VCD arm (P = .05). In addition, the overall response rate was significantly higher in the VTD arm (92.3% vs 83.4% in the VCD arm; P = .01). Hematologic toxicity was higher in the VCD arm, with significantly increased rates of grade 3 and 4 anemia, thrombocytopenia, and neutropenia. On the other hand, the rate of peripheral neuropathy (PN) was significantly higher in the VTD arm. With the exception of hematologic adverse events and PN, other grade 3 or 4 toxicities were rare, with no significant differences between the VTD and VCD arms. Our data support the preferential use of VTD rather than VCD in preparation for ASCT. This trial was registered at www.clinicaltrials.gov as #NCT01564537 and at EudraCT as #2013-003174-27.

Impact of renal impairment on outcomes with lenalidomide and dexamethasone treatment in the FIRST trial, a randomized, open-label phase 3 trial in transplant-ineligible patients with multiple myeloma.

Renal impairment is associated with poor prognosis in myeloma. This analysis of the pivotal phase 3 FIRST trial examined the impact of renally adapted dosing of lenalidomide and dexamethasone on outcomes of patients with different degrees of renal impairment. Transplant-ineligible patients not requiring dialysis were randomized 1:1:1 to receive continuous lenalidomide and dexamethasone until disease progression (n=535) or for 18 cycles (72 weeks; n=541), or melphalan, prednisone, and thalidomide for 12 cycles (72 weeks; n=547). Follow-up is ongoing. Patients were grouped by baseline creatinine clearance into no (≥ 80 mL/min [n=389]), mild (≥ 50 to < 80 mL/min [n=715]), moderate (≥ 30 to < 50 mL/min [n=372]), and severe impairment (< 30 mL/min [n=147]) subgroups. Continuous lenalidomide and dexamethasone therapy reduced the risk of progression or death in no, mild, and moderate renal impairment subgroups vs. melphalan, prednisone, and thalidomide therapy (HR = 0.67, 0.70, and 0.65, respectively). Overall survival benefits were observed with continuous lenalidomide and dexamethasone treatment vs. melphalan, prednisone, and thalidomide treatment in no or mild renal impairment subgroups. Renal function improved from baseline in 52.6% of lenalidomide and dexamethasone-treated patients. The safety profile of continuous lenalidomide and dexamethasone was consistent across renal subgroups, except for grade 3/4 anemia and rash, which increased with increasing severity of renal impairment. Continuous lenalidomide and dexamethasone treatment, with renally adapted lenalidomide dosing, was effective for most transplant-ineligible patients with myeloma and renal impairment. Trial registration: ClinicalTrials.gov (NCT00689936); EudraCT (2007-004823-39). Funding: Intergroupe Francophone du Myélome and the Celgene Corporation.

Phase 1/2 study of carfilzomib plus melphalan and prednisone in patients aged over 65 years with newly diagnosed multiple myeloma.

This phase 1/2 dose-escalation study investigated the combination of carfilzomib with melphalan and prednisone (CMP) in patients aged >65 years with newly diagnosed multiple myeloma (MM). Melphalan and prednisone were administered orally on days 1 to 4; carfilzomib was IV administered on days 1, 2, 8, 9, 22, 23, 29, and 30 of a 42-day cycle. Patients received up to 9 cycles of CMP. In the phase 1 dose-escalation portion, the primary objectives were to determine the incidence of dose-limiting toxicities during the first cycle of CMP treatment to define the maximal tolerated dose (MTD) of carfilzomib. In the phase 2 portion, the primary objective was to evaluate the overall response rate (ORR) of CMP. In the phase 1 portion of the study, 24 patients received CMP at carfilzomib dosing levels of 20 mg/m(2), 27 mg/m(2), 36 mg/m(2), and 45 mg/m(2). The MTD was established as 36 mg/m(2). In the phase 2 portion of the study, 44 patients were enrolled at the MTD. Among 50 efficacy-evaluable patients treated at the MTD, the ORR was 90%. The projected 3-year overall survival rate was 80%. The combination of CMP was observed to be effective in elderly patients with newly diagnosed MM. This trial was registered at www.clinicaltrials.gov as #NCT01279694 (Eudract identifier 2010-019462-92).

Pomalidomide plus low-dose dexamethasone in multiple myeloma with deletion 17p and/or translocation (4;14): IFM 2010-02 trial results.

The combination of pomalidomide and low-dose dexamethasone (Pom-Dex) can be safely administered to patients with end-stage relapsed/refractory multiple myeloma (RRMM). However, we observed a shorter median progression-free survival (PFS) and overall survival (OS) in these patients when characterized with adverse cytogenetics (deletion 17p and translocation [4;14]) in the Intergroupe Francophone Myélome (IFM) 2009-02 trial. We then sought to determine whether MM with adverse cytogenetics would benefit more from Pom-Dex if exposed earlier in the multicenter IFM 2010-02 trial. The intention-to-treat population included 50 patients, with a median age of 63 years (38% were ≥65 years). Interestingly, there was a striking difference in time to progression (TTP), duration of response, and overall response rate (ORR) according to the presence of del(17p) compared with t(4;14) (TTP, 7.3 vs 2.8 months; duration of response, 8.3 vs 2.4 months; and ORR, 32% vs 15%). OS was prolonged after Pom-Dex, particularly in t(4;14), given the short TTP, suggesting that patients were rescued at relapse with further lines of therapy. Pom-Dex, a doublet immunomodulatory drug-based regimen, is active and well tolerated in adverse cytogenetic patients with early RRMM, particularly in those with del(17p), who are characterized by a high and rapid development of a refractoriness state and known for their poor prognosis. Future studies will determine the underlying mechanisms of Pom-Dex activity in del(17p). This trial is registered at www.clinicaltrials.gov as #NCT01745640.

ASXL1 but not TET2 mutations adversely impact overall survival of patients suffering systemic mastocytosis with associated clonal hematologic non-mast-cell diseases.

Systemic mastocytosis with associated hematologic clonal non-mast cell disease (SM-AHNMD) is a rare and heterogeneous subtype of SM and few studies on this specific entity have been reported. Sixty two patients with Systemic mastocytosis with associated hematologic clonal non-mast cell disease (SM-AHNMD) were presented. Myeloid AHNMD was the most frequent (82%) cases. This subset of patients were older, had more cutaneous lesions, splenomegaly, liver enlargement, ascites; lower bone mineral density and hemoglobin levels and higher tryptase level than lymphoid AHNMD. Defects in KIT, TET2, ASXL1 and CBL were positive in 87%, 27%, 14%, and 11% of cases respectively. The overall survival of patients with SM-AHNMD was 85.2 months. Within the myeloid group, SM-MPN fared better than SM-MDS or SM-AML (p = 0.044,). In univariate analysis, the presence of C-findings, the AHNMD subtypes (SM-MDS/CMML/AML versus SM-MPN/hypereosinophilia) (p = 0.044), Neutropenia (p = 0.015), high monocyte level (p = 0.015) and the presence of ASXL1 mutation had detrimental effects on OS (p = 0.007). In multivariate analysis and penalized Cox model, only the presence of ASXL1 mutation remained an independent prognostic factor that negatively affected OS (p = 0.035). SM-AHNMD is heterogeneous with variable prognosis according to the type of the AHNMD. ASXL1 is mutated in a subset of myeloid AHNMD and adversely impact on OS.

MELISSE, a large multicentric observational study to determine risk factors of venous thromboembolism in patients with multiple myeloma treated with immunomodulatory drugs.

Immunomodulatory drugs (IMiDs) are associated with an increased risk of venous thromboembolism (VTE) in multiple myeloma (MM) patients. We designed MELISSE, a multicentre prospective observational study, to evaluate VTE incidence and identify risk factors in IMiDs-treated MM. Our objective was to determine the real-life practice of VTE prophylaxis strategy. A total of 524 MM patients were included, and we planned to collect information at baseline, at four and at 12 months, on MM therapy, on VTE risk factors and management. VTE incidence was 7% (n=31), including 2.5% pulmonary embolism (PE) (n=11), similar at four or 12 months. VTE was observed at all risk assessment levels, although the increased risk assessment level correlated to a lower rate of VTE, maybe due to the implemented thromboprophylaxis strategy. VTE occurred in 7% on aspirin vs 3% on low-molecular-weight heparin (LMWH) prophylaxis, and none on vitamin K antagonists (VKA). New risk factors for VTE in IMiDs-treated MM were identified. In conclusion, VTE prophylaxis is compulsory in IMiDs-treated MM, based on individualised VTE risk assessment. Anticoagulation prophylaxis with LMWH should clearly be prioritised in MM patients with high VTE risk, along with VKA. Further prospective studies will identify most relevant VTE risk factors in IMiDs-treated MM to select accurately which MM patients should receive LMWH prophylaxis and for which duration to optimise VTE risk reduction.

The translocation t(4;14) can be present only in minor subclones in multiple myeloma.

PURPOSE: Although the translocation t(4;14) is supposed to be a primary event in multiple myeloma, we have been surprised to observe that in large relapse series of patients, the t(4;14) can be observed only in subpopulations of plasma cells, in contrast to what is seen at diagnosis. This observation raised the question of possible subclones harboring the translocation that would be observable only at the time of relapse. EXPERIMENTAL DESIGN: To address this issue, we analyzed by FISH a cohort of 306 patients for whom we had at least two samples obtained at different disease phases. RESULTS: We observed a "gain" of the t(4;14) in 14 patients, and conversely, a "loss" of the translocation in 11 patients. Two hypotheses were raised: either an acquisition of the translocation during evolution or the existence of small t(4;14)-positive subclones at the time of diagnosis. To address this question, we had the opportunity to analyze two patients at the time of diagnosis by RT-PCR (reverse transcription-polymerase chain reaction) to look for the chimeric Eµ-MMSET transcript, and one patient positive at diagnosis, but negative at relapse. The samples were positive, supporting the second hypothesis. Furthermore, the IGH sequences of two patients who "lose" the t(4;14) were identical at diagnosis and relapse, confirming the existence of a common ancestral clone. CONCLUSION: Thus, the conclusion of this study is that the t(4;14) is not a primary event in multiple myeloma and that it can be present in silent subclones at diagnosis, but also at relapse.

Chromosomal abnormalities are major prognostic factors in elderly patients with multiple myeloma: the intergroupe francophone du myélome experience.

PURPOSE: Chromosomal abnormalities, especially t(4;14) and del(17p), are major prognostic factors in patients with multiple myeloma (MM). However, this has been especially demonstrated in patients age < 66 years treated with intensive approaches. The goal of this study was to address this issue in elderly patients treated with conventional-dose chemotherapy. PATIENTS AND METHODS: To answer this important question, we retrospectively analyzed a series of 1,890 patients (median age, 72 years; range, 66 to 94 years), including 1,095 with updated data on treatment modalities and survival. RESULTS: This large study first showed that the incidence of t(4;14) was not uniform over age, with a marked decrease in the oldest patients. Second, it showed that both t(4;14) and del(17p) retained their prognostic value in elderly patients treated with melphalan and prednisone-based chemotherapy. CONCLUSION: t(4;14) and del(17p) are major prognostic factors in elderly patients with MM, both for progression-free and overall survival, indicating that these two abnormalities should be investigated at diagnosis of MM, regardless of age.

[Comparative analysis of immunoglobulin free light chains quantification by Freelite™ (The Binding Site) and N Latex FLC (Siemens) methods]. / Étude comparative du dosage des chaînes légères libres d'immunoglobulines par technique Freelite™ (The Binding Site) et N Latex FLC (Siemens).

Serum immunoglobulin free light chain assay has proved to be an invaluable biological tool for diagnosis and monitoring of monoclonal gammopathies including multiple myeloma, primary amyloidosis, solitary plasmocytoma or monoclonal gammopathy of undetermined significance. Free light chain quantification, although essential, cannot be achieved by serum protein electrophoresis either because there is no monoclonal peak or because the peak is hidden in beta or alpha-globulin fraction. As for serum protein immunofixation, this major test allows the typing of the paraprotein but does not provide any quantitative evaluation. Hence, the development of free light chain assays constitutes a significant improvement in the management of these patients. In this context, we compared the results of serum free light chains quantification and of calculation of the ratio kappa/lambda, indicator of monoclonality, in forty samples performed on BN ProSpec(®) analyzer, with the two methods available on the European market. This comparative analysis provided evidence of a good correlation of results between the two methods. However, we noticed clinically significant differences in four samples. In addition, this evaluation highlighted the fact that all free light chain results must be biologically validated on the light of different criteria such as serum protein electrophoresis, serum protein immunofixation, presence of proteinuria, presence of renal failure, and additional clinical data, in order to ascertain the best interpretation for clinical use.