scholarly journals Clinical implications of loss of bone marrow minimal residual disease negativity in multiple myeloma

2021 ◽  
Author(s):  
Meera Mohan ◽  
Samantha Kendrick ◽  
Aniko Szabo ◽  
Naveen K Yarlagadda ◽  
Dinesh Atwal ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Minimal Residual Disease ◽  
Residual Disease ◽  
Progression Free Survival ◽  
Response To Treatment ◽  
Clinical Relapse ◽  
Landmark Analyses ◽  
Minimal Residual

Multiple myeloma (MM) patients frequently attain a bone marrow (BM) minimal residual disease (MRD) negativity status in response to treatment. We identified 568 patients who achieved BM MRD negativity following autologous stem cell transplantation (ASCT) and maintenance combination therapy with an immunomodulatory agent and a proteasome inhibitor. BM MRD was evaluated by next generation flow cytometry (sensitivity of 10-5 cells) at 3 to 6 months intervals. With a median follow up of 9.9 years from diagnosis (range, 0.4 - 30.9), 61% of patients maintained MRD negativity, while 39% experienced MRD conversion at a median of 6.3 years (range, 1.4 - 25). The highest risk of MRD conversion occurred within the first 5 years after treatment and was observed more often in patients with abnormal metaphase cytogenetic abnormalities (95%vs. 84%; P = 0.001). MRD conversion was associated with a high risk of relapse and preceded it by a median of 1.0 year (range, 0 - 4.9). However, 27% of MRD conversion positive patients had not yet experienced a clinical relapse with a median follow-up of 9.3 years (range, 2.2 - 21.2). Landmark analyses using time from ASCT revealed patients with MRD conversion during the first 3 years had an inferior overall and progression-free survival compared to patients with sustained MRD negativity. MRD conversion correctly predicted relapse in 70%, demonstrating the utility of serial BM MRD assessment to complement standard laboratory and imaging to make informed salvage therapy decisions.

scholarly journals The Prognostic Significance of Minimal Residual Disease Detection after Induction and ASCT to the Patients with Multiple Myeloma

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 4956-4956
Author(s):  
Weiqin Yao ◽  
Zhu Mingqing ◽  
Yao Feirong ◽  
Lingzhi Yan ◽  
Song Jin ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Minimal Residual Disease ◽  
Induction Therapy ◽  
Plasma Cells ◽  
Residual Disease ◽  
Prognostic Significance ◽  
Depth Of Response ◽  
Minimal Residual

Abstract Objective: In the last decade the outcome in multiple myeloma in CHINA has greatly improved due to the new, effective therapies including PIs and Imids. But responses to treatment and survival remains heterogeneous because of patient characteristic, disease biology and mechanisms of drug resistance. More and more studies have established the link between depth of response and improved PFS and OS. multiparameter-flow cytometry (MFC) is a main method to detect minimal residual disease(MRD) in myeloma. Sensitivity will be at least at 10-4 to 10-5 by 10-color MFC. Imaging techniques such as PET-CT are important for EMD and bone MRD detection. whole body DWI-MRI is a new imaging technique by mean of the apparent diffusion coefficient(ADC) which can qualify the depth of response to antineoplastic treatment. This study was designed to evaluate the prognostic significance of MRD by 10-color MFC and imaging to the MM patients after induction.Methods: 102 patients with newly diagnosed MM were enrolled at the First Affiliated Hospital of Soochow University from July 2015 to July 2017. All patients were diagnosed and the response were assessed by IMWG criteria. The median of age was 58 (31-75).There were 46 patients with IgG type , 24 IgA , 14 light chain, 18 others. 34 Patients in ISS stageⅠ,34 in stage Ⅱ, 30 in stage Ⅲ. All patients received 4-6 cycles of triplet bortezomib based or lenalidomide based induction therapy. Transplantation available patients received APBSCT with BUCY condition followed by 4-6 cycles of bortezomib based or lenalidomide based consolidation which were given to transplantation unavailable patients too. Lenalidomide and thalidomide were used for over 2y of maintenance therapy. Bone marrow aspirates for MRD imaging MRD assessment were obtained at the end of induction and 1year after ASCT.The median of follow-up was 13 (2-29) months.Results: According to MRD by MFC and imaging after induction therapy and 1 year after ASCT, the patients were divided into different groups. MFC negativity was 33%(29/88) after induction therapy compared with 63%(32/51) after ASCT (X2=11.636,P=0.001). After induction therapy, the median PFS was 22 months for MRD positive group compared with not reached with MRD negative group by MFC (P=0.042) in patients with very good partial remission(VGPR) and above. The 2 years PFS was 100% for those with MRD negative compared with 60% for MRD positive by imaging. The 2 years PFS was 80% for those have multiclonal normal plasma cells compared with 52.6% for those without. The median PFS was not reached for MFC MRD negative patients 1 year after ASCT compared with 20 months for positive patients. (P=0.002). Multivariate analysis including high risk cytogenetics(17p-, t(4;14), t(14;16)), sex, age, ISS, chemotherapy, ASCT, CR/VGPR, normal PCs showed that the MFC MRD and ASCT were independent prognostic factor.Conclusions: Patients with MFC MRD negative after induction therapy or ASCT is a better prognostic marker than CR or even the best marker. Imaging MRD negativity and the appearance of normal plasma cells in the bone marrow suggests a better prognosis.We will have a try to do more research on overall survival(OS),include longer follow-up and a larger number of patients enrolled. Figure. Figure. Disclosures No relevant conflicts of interest to declare.

Comparison of Conventional Versus Lineage-Specific Chimerism Analysis for Detection of Minimal Residual Disease or Relapse in Myeloid Malignancies after Myeloablative Allogeneic Hematopoietic Cell Transplantation with Respect to Clinical Follow-Up.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1641-1641
Author(s):  
Robert Zeiser ◽  
Alexandros Spyridonidis ◽  
Ralph Waesch ◽  
Gabriele Ihorst ◽  
Carsten Grullich ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Confidence Interval ◽  
Minimal Residual Disease ◽  
Hematopoietic Cell Transplantation ◽  
Residual Disease ◽  
Bone Marrow Examination ◽  
Clinical Relapse ◽  
Chimerism Analysis ◽  
Minimal Residual

Abstract In order to detect minimal residual disease (MRD) or relapse after allogeneic hematopoietic cell transplantation (aHCT) the immunophenotype of the original leukemic clone can be used for separation of distinct cell populations, expected to harbor malignant cells. Since conventional (CCA) and lineage-specific (LCA) chimerism analysis as diagnostic means have potential pitfalls, the present study assesses the results of both methods, to determine how predictive the evaluations prior to a hematological relapse were with respect to the risk that the patient would develop a relapse during the course of his disease. 118 individuals with acute myeloid leukemia (n=98) and myelodysplastic syndrome (n=20), investigated with CCA and LCA, were evaluated with a median follow-up of 26.6 months (range: 8–47). Subset chimerism samples were cell-separated by using immunomagnetic beads with respect to the patient’s leukemia phenotype, expressed at diagnosis. Mean purity of the positive-selected CD34 fractions were 97% (93–99%). PCR products were analyzed and quantified by capillary electrophoresis. 33 patients experienced a clinical relapse after aHCT. CCA and LCA detected a mixed chimerism (MC) in 27/118 and 25/118 patients, respectively. MC was detected at a median of 27 (12–54) and 34 (10–71) days before clinical relapse by CCA and LCA, respectively. LCA reached a significantly higher sensitivitiy than CCA with 91% (CI:54–98%) as compared to 83% (CI: 69–91%) and was also more sensitive as compared to bone marrow morphology examination (BME) (61%; CI:44–75%). Specificity was also higher with LCA (98%, CI: 89–100%) as compared to CCA (92%; CI: 75–99%) and BME (91%; CI: 82–96%). Our data suggest a higher sensitivity and specificity of LCA as compared to CCA and BME with respect to the clinical follow-up. We conclude from these data that due to the high predictive value subset chimerism monitoring may be employed for clinical decision making concerning adoptive immunotherapy after myeloablative aHCT for patients with AML and MDS, especially when lacking other molecular markers for detection of MRD. Differential accuracy of Lineage-specific versus Conventional Chimerism analysis Lineage-specific Chimerism analysis (LCA) Conventional Chimerism analysis (CCA) Bone marrow examination (BME) Sensitivity and specificity of lineage specific (LCA), conventional (CCA) chimerism analysis and bone marrow examination (BME) with respect to the event that the patient would develop a relapse in the clinical follow-up. Sensitivity in % (Confidence interval) 91 (54–98) 83 (69–91) 61 (44–75) Specificity in %(Confidence interval) 98 (89–100) 92 (75–99) 91 (82–96)

Evaluation of minimal residual disease in relapsed/refractory multiple myeloma patients treated with venetoclax or placebo in combination with bortezomib and dexamethasone: BELLINI study analyses.

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. 8547-8547
Author(s):  
Philippe Moreau ◽  
Simon J. Harrison ◽  
Michele Cavo ◽  
Javier de La Rubia ◽  
Rakesh Popat ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Minimal Residual Disease ◽  
Residual Disease ◽  
Proteasome Inhibitors ◽  
Progression Free Survival ◽  
Synergistic Activity ◽  
Refractory Multiple Myeloma ◽  
D 20 ◽  
Minimal Residual

8547 Background: Venetoclax (Ven) is a selective, potent BCL-2 inhibitor that has synergistic activity with bortezomib (B) and dexamethasone (d). In the Phase 3 BELLINI trial, addition of Ven to Bd significantly improved median progression-free survival (PFS) and response rates, including minimal residual disease (MRD) negativity, but resulted in increased mortality vs placebo (Pbo). Here, we determine whether MRD negativity was associated with longer PFS and OS in relapsed/refractory multiple myeloma (RRMM) patients treated with Ven+Bd in the BELLINI dataset. Methods: In BELLINI (NCT02755597), RRMM patients (pts) sensitive or naïve to proteasome inhibitors with 1-3 prior lines of therapy were randomized 2:1 to Ven (800 mg) or Pbo plus B (1.3 mg/m2) and d (20 mg). Next-gen sequencing MRD assessments were done on bone marrow aspirates at the time of suspected CR/sCR, and 6- and 12-months post confirmation of CR/sCR. Patients with a missing or indeterminate assessment were considered MRD positive. Evaluation of MRD in biomarker-defined subgroups (cytogenetics and BCL2 expression) was also performed and will be presented. Results: In total, 291 pts were randomized; 194 to Ven, 97 to Pbo. As of 13 Sep 2019, the median follow-up was 29 months. Ven + Bd demonstrated significantly higher MRD negativity rates ( < 10−5), including a higher proportion of pts achieving sustained MRD negativity (Table). In the Ven arm, the median (m)PFS was not reached for MRD negative pts vs 16.2 months for MRD positive pts (HR = 0.23, 95% CI: 0.10-0.54, p < 0.001). While the mOS was not reached in the Ven arm, OS was significantly longer for MRD negative vs MRD positive pts (HR = 0.25, 95% CI: 0.08-0.80, p = 0.0194). Conclusions: The addition of Ven to Bd resulted in deep and durable responses, including higher rates of MRD negativity. MRD negativity in the context of Ven was associated with prolonged survival in patients with RRMM, consistent with the broader MRD body of evidence with other therapies in MM. Clinical trial information: NCT02755597 . [Table: see text]

Depth of response and minimal residual disease status in ultra high-risk multiple myeloma and plasma cell leukemia treated with daratumumab, bortezomib, lenalidomide, cyclophosphamide and dexamethasone (Dara-CVRd): Results of the UK optimum/MUKnine trial.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. 8001-8001
Author(s):  
Martin F. Kaiser ◽  
Andrew Hall ◽  
Katrina Walker ◽  
Ruth De Tute ◽  
Sadie Roberts ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
High Risk ◽  
Minimal Residual Disease ◽  
Plasma Cell ◽  
Residual Disease ◽  
Cell Leukemia ◽  
Ultra High Risk ◽  
Grade 3 ◽  
Minimal Residual

8001 Background: Patients with ultra high-risk (UHiR) newly diagnosed multiple myeloma (NDMM) and patients with plasma cell leukemia (PCL) continue to have dismal outcomes and are underrepresented in clinical trials. Recently, improved responses with anti-CD38 monoclonal antibody combination therapy have been reported for NDMM patients. We report here outcomes for NDMM UHiR and PCL patients treated in the OPTIMUM/MUKnine (NCT03188172) trial with daratumumab, cyclophosphamide, bortezomib, lenalidomide, dexamethasone (Dara-CVRd) induction, augmented high-dose melphalan (HDMEL) and ASCT. With final analysis follow-up surpassed in Feb 2021, we report here early protocol defined endpoints from induction to day 100 post ASCT. Methods: Between Sep 2017 and Jul 2019, 107 patients with UHiR NDMM by central trial genetic (≥2 high risk lesions: t(4;14), t(14;16), t(14;20), gain(1q), del(1p), del(17p)) or gene expression SKY92 (SkylineDx) profiling, or with PCL (circulating plasmablasts > 20%) were included in OPTIMUM across 39 UK hospitals. Patients received up to 6 cycles of Dara-CVRd induction, HDMEL and ASCT augmented with bortezomib, followed by Dara-VR(d) consolidation for 18 cycles and Dara-R maintenance. Primary trial endpoints are minimal residual disease (MRD) status post ASCT and progression-free survival. Secondary endpoints include response, safety and quality of life. Data is complete but subject to further data cleaning prior to conference. Results: Median follow-up for the 107 patients in the safety population was 22.2 months (95% CI: 20.6 – 23.9). Two patients died during induction due to infection. Bone marrow aspirates suitable for MRD assessment by flow cytometry (10-5 sensitivity) were available for 81% of patients at end of induction and 78% at D100 post ASCT. Responses in the intention to treat population at end of induction were 94% ORR with 22% CR, 58% VGPR, 15% PR, 1% PD, 5% timepoint not reached (TNR; withdrew, became ineligible or died) and at D100 post ASCT 83% ORR with 47% CR, 32% VGPR, 5% PR, 7% PD, 10% TNR. MRD status was 41% MRDneg, 40% MRDpos and 19% not evaluable post induction and 64% MRDneg, 14% MRDpos and 22% not evaluable at D100 post ASCT. Responses at D100 post ASCT were lower in PCL with 22% CR, 22% VGPR, 22% PR, 22% PD, 12% TNR. Most frequent grade 3/4 AEs during induction were neutropenia (21%), thrombocytopenia (12%) and infection (12%). Grade 3 neuropathy rate was 3.7%. Conclusions: This is to our knowledge the first report on a trial for UHiR NDMM and PCL investigating Dara-CVRd induction and augmented ASCT. Response rates were high in this difficult-to-treat patient population, with toxicity comparable to other induction regimens. However, some early progressions highlight the need for innovative approaches to UHiR NDMM. Clinical trial information: NCT03188172.

Analysis of minimal residual disease in bone marrow by NGF and in peripheral blood by mass spectrometry in newly diagnosed multiple myeloma patients enrolled in the GEM2012MENOS65 clinical trial.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. 8010-8010
Author(s):  
Noemi Puig ◽  
Bruno Paiva ◽  
Teresa Contreras ◽  
M. Teresa Cedena ◽  
Laura Rosiñol ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Multiple Myeloma ◽  
Bone Marrow ◽  
Minimal Residual Disease ◽  
Peripheral Blood ◽  
Prognostic Value ◽  
Residual Disease ◽  
Newly Diagnosed ◽  
Time Points ◽  
Minimal Residual

8010 Background: Analysis of minimal residual disease (MRD) in the bone marrow (BM) of patients with multiple myeloma (MM) is accepted by the IMWG to evaluate treatment efficacy and is a well-established prognostic factor. However, there is an unmet need to explore the clinical value of MRD in peripheral blood (PB). Methods: Newly diagnosed MM patients enrolled in the GEM2012MENOS65 trial received six induction (Ind) cycles of bortezomib, lenalidomide, and dexamethasone (VRD) followed by autologous stem cell transplantation (ASCT) and 2 further cycles of consolidation (Cons) with VRD. MRD was analyzed in BM using Next Generation Flow (NGF) and in serum by Mass Spectrometry (MS) using IgG/A/M, κ, λ, free κ and free λ specific beads, both after Ind, at day 100 after ASCT, and after Cons. Sequential samples from the first 184 patients were analyzed. Results: Results of both methods were in agreement (NGF+/MS+ and NGF-/MS-) in 83% of cases post-Ind (152/184), 80% post-ASCT (139/174) and 76% post-Cons (128/169). Stratifying by the log range of MRD by NGF, discordances (NGF+/MS- and NGF-/MS+) seemed to increase at the lower MRD ranges, being 22%, 21% and 19% from ≥10−5 to <10−4 and 21%, 21%, 23% at ≥x10−6(post-Ind, ASCT and Cons, respectively). Analysis of discordances showed that they could be partly explained by the higher percentages of cases found to be positive by MS as compared by NGF at part of the time-points analyzed and at each log range of MRD. From ≥10−5 to <10−4, MRD was detected by NGF in 36%, 28%, 20% of cases post-Ind, ASCT and Cons, respectively vs MS in 37%, 29%, 21% of them; at ≥x10−6, NGF was positive in 11%, 14%, 19% of cases vs MS in 23%, 19% and 16% of them. Considering NGF as a reference, the negative predictive value (NPV) of MS per MRD range (≥10−5 to <10−4 and ≥x10−6, respectively) was: post-Ind: 83% (p<0,0001), 94% (p=0,034); post-ASCT 86% (p<0,0001), 90% (p=0,022); post-Cons 89% (p<0,0001), 85% (p=0,0469). Despite these discordances, the prognostic value of each technique in terms of undetectable MRD and progression-free survival (PFS) was consistent at all time-points (Table) and further, discordant cases (NGF+/MS- and NGF-/MS+) did not display a significantly different PFS as compared to NGF-/MS- cases. Conclusions: The results of MRD assessed by NGF in BM and by MS in PB show a significant concordance and are associated with a similar prognostic value analyzed in terms of PFS. Given its high NPV, MRD in peripheral blood by MS provides a gateway for BM aspiration/biopsy and MRD assessment by NGF.[Table: see text]

Consolidation and Maintenance in Newly Diagnosed Multiple Myeloma

2021 ◽  
pp. JCO.21.01045
Author(s):  
Pieter Sonneveld ◽  
Meletios A. Dimopoulos ◽  
Meral Beksac ◽  
Bronno van der Holt ◽  
Sara Aquino ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Minimal Residual Disease ◽  
Residual Disease ◽  
Progression Free Survival ◽  
Complete Response ◽  
Primary Study ◽  
Controlled Clinical Trial ◽  
Newly Diagnosed ◽  
Consolidation Treatment ◽  
Minimal Residual

PURPOSE To address the role of consolidation treatment for newly diagnosed, transplant eligible patients with multiple myeloma in a controlled clinical trial. PATIENTS AND METHODS The EMN02/HOVON95 trial compared consolidation treatment with two cycles of bortezomib, lenalidomide, and dexamethasone (VRD) or no consolidation after induction and intensification therapy, followed by continuous lenalidomide maintenance. Primary study end point was progression-free survival (PFS). RESULTS Eight hundred seventy-eight eligible patients were randomly assigned to receive VRD consolidation (451 patients) or no consolidation (427 patients). At a median follow-up of 74.8 months, median PFS with adjustment for pretreatment was prolonged in patients randomly assigned to VRD consolidation (59.3 v 42.9 months, hazard ratio [HR] = 0.81; 95% CI, 0.68 to 0.96; P = .016). The PFS benefit was observed across most predefined subgroups, including revised International Staging System (ISS) stage, cytogenetics, and prior treatment. Revised ISS3 stage (HR, 2.00; 95% CI, 1.41 to 2.86) and ampl1q (HR, 1.67; 95% CI, 1.37 to 2.04) were significant adverse prognostic factors. The median duration of maintenance was 33 months (interquartile range 13-86 months). Response ≥ complete response (CR) after consolidation versus no consolidation before start of maintenance was 34% versus 18%, respectively ( P < .001). Response ≥ CR on protocol including maintenance was 59% with consolidation and 46% without ( P < .001). Minimal residual disease analysis by flow cytometry in a subgroup of 226 patients with CR or stringent complete response or very good partial response before start of maintenance demonstrated a 74% minimal residual disease–negativity rate in VRD-treated patients. Toxicity from VRD was acceptable and manageable. CONCLUSION Consolidation treatment with VRD followed by lenalidomide maintenance improves PFS and depth of response in newly diagnosed patients with multiple myeloma as compared to maintenance alone.

scholarly journals Minimal residual disease may predict bone marrow relapse in patients with hairy cell leukemia treated with 2-chlorodeoxyadenosine

Blood ◽  
1996 ◽  
Vol 87 (4) ◽  
pp. 1556-1560 ◽  
Author(s):  
S Wheaton ◽  
MS Tallman ◽  
D Hakimian ◽  
L Peterson
Keyword(s):  
Bone Marrow ◽  
Minimal Residual Disease ◽  
Hairy Cell Leukemia ◽  
Residual Disease ◽  
Hairy Cell ◽  
Cell Leukemia ◽  
Hematoxylin And Eosin ◽  
Anti Cd20 ◽  
Minimal Residual

Minimal residual disease (MRD) can be detected in bone marrow core biopsies of patients with hairy cell leukemia (HCL) after treatment with 2-chlorodeoxyadenosine (2-CdA) using immunohistochemical (IHC) techniques. The purpose of this study was to determine whether the presence of MRD predicts bone marrow relapse. We studied paraffin- embedded bone marrow core biopsies from 39 patients with HCL in complete remission (CR) 3 months after a single cycle of 2-CdA. Biopsies performed 3 months posttherapy and annually thereafter were examined by routine hematoxylin and eosin (H&E) staining and IHC using the monoclonal antibodies (MoAbs) anti-CD45RO, anti-CD20, and DBA.44. At 3 months after therapy, 5 of 39 (13%) patients had MRD detectable by IHC that was not evident by routine H&E staining. Two of the five patients (40%) with MRD at 3 months have relapsed, whereas only 2 of 27 (7%) patients with no MRD and at least 1 year of follow up relapsed (P = .11). Over the 3-year follow-up period, two additional patients developed MRD. Overall, three of six (50%) patients with MRD detected at any time after therapy have relapsed, whereas only 1 of 25 (4%) patients without MRD has relapsed (P = .016). These data suggest that the presence of MRD after treatment with 2-CdA may predict relapse.

Minimal Residual Disease Studies in Multiple Myeloma Patients Achieving Complete Remission after Autologous Peripheral Blood Stem Cell Transplantation (APBSCT) by RQ-PCR.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2418-2418 ◽  
Author(s):  
M. E. Sarasquete ◽  
R. García-Sanz ◽  
A. Balanzategui ◽  
P. Martínez-Sánchez ◽  
J. Martínez-López ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Minimal Residual Disease ◽  
Residual Disease ◽  
Progression Free Survival ◽  
High Rate ◽  
Taqman Probe ◽  
Patient Specific ◽  
Standard Curve ◽  
The Impact ◽  
Minimal Residual

Abstract Multiple myeloma (MM) remains as an incurable disease although new therapies can achieve a high rate of complete remissions (CR). Unfortunately, most patients ultimately relapse due to the persistence of minimal residual disease (MRD), and only a minority could be cured. Detection and quantification of these cells is an important tool for monitoring these patients and predicting a potential relapse. Here we analyze by RQ-PCR the MRD in MM patients achieving CR in order to classify them into different risk categories. MATERIAL AND METHODS: 38 MM patients uniformly treated according to the GEM-2000 (Spanish group for Myeloma) protocol, and that have achieved CR following PBSCT were included in the study. 22 were IgG, 9 IgA, 6 B-J and 1 non-secretory (κ/λ 21/16). 27 were male & 11 female with a median age of 58 (range 48–65). Bone marrow samples obtained at diagnosis and 3 months after transplant were analyzed. Complete (VDJH) and incomplete (DJH) Ig rearrangements were amplified with the Biomed-2 strategy (Leukemia2003;17:2257). PCR clonal products were sequenced on an ABI Prism 377 Sequence detector. VH, DH and JH segments were identified by comparing with germinal sequences on V-Base and BLAST databases. An ASO primer at the N-region was designed for each patient with the OLIGO 6.0 software. RQ-PCR was then performed on an ABI Prism 7700 using the ASO specific forward primer, a JH reverse intronic primer (JH1–6) and a TaqMan probe (JH1,2,4,5, JH3 or JH6) to amplify the patient specific rearrangement. Sample quality and quantity was controlled evaluating the standard curve of the albumin gene amplification. MRD was calculated according to ΔCT method. RESULTS: In 14 out of the cases included in the study, MRD investigation was not possible because the N-region was not longer enough to design the ASO primer (n=3), poor quality in the diagnostic sample to obtain the standard curve (n=8) or low plasma cell infiltration at diagnosis to obtain correct dilutions (n=3). The remaining 24 patients were classified into different risk groups according to the MRD level obtained 3 months after transplantation with a cut-off point of 0.01% tumor cells. Thus, progression free survival (PFS) was longer in those patients with MRD< 10−4 (p=0.03, figure 1A). By contrast, upon comparing the impact on PFS of immofixation (IFX) in these 24 patients that were in CR (defined by conventional electrophoresis criteria), it was observed that patients with IFX (−) didn’t showed a different outcome from those IFX (+) (figure 1B). CONCLUSION: In summary, although RQ-PCR is a labor and time-consuming technique, it is an useful tool for monitoring MRD in MM. The level of 10−4 can contribute to classify patients into 2 groups (high and low MRD) with different risk of relapse that can be used to design specific therapies.

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