Minimal residual disease by flow cytometry and allelic-specific oligonucleotide real-time quantitative polymerase chain reaction in patients with myeloma receiving lenalidomide maintenance: A pooled analysis.

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.

Prospective evaluation of minimal residual disease in the phase II FORTE trial: a head-to-head comparison between multiparameter flow cytometry and next-generation sequencing.

Background: Limited data are available on the concordance between multiparameter flow cytometry (MFC) and next-generation sequencing (NGS) for minimal residual disease (MRD) detection in a large trial for multiple myeloma (MM) patients. Methods: MRD was explored in the FORTE trial for transplant-eligible MM patients randomised to three carfilzomib-based induction-intensification-consolidation treatments and carfilzomib-lenalidomide (KR) vs R maintenance. MRD was assessed by 8-colour 2nd-generation flow cytometry in patients with ≥very good partial response before maintenance. NGS was performed in case of suspected complete response (CR) in a correlative subanalysis. Biological/prognostic concordance between MFC and NGS, conversion to MRD negativity during maintenance, and 1-year/2-year sustained MRD negativity were explored. Findings: Between September 28, 2015 and December 22, 2021, 2020 samples were available for MFC and 728 for the simultaneous MFC/NGS correlation in the "suspected CR population". Median follow-up was 62 months. Biological agreement was 87% at the 10-5 and 83% at the 10-6 cut-offs. A remarkable prognostic concordance was observed: hazard ratios in MFC-MRD and NGS-MRD-negative vs -positive patients were 0.29 and 0.27 for progression-free survival (PFS) and 0.35 and 0.31 for overall survival, respectively (p < 0.05). During maintenance, 4-year PFS was 91% and 97% in 1-year sustained MFC-MRD-negative and NGS-MRD-negative patients (10-5), respectively, and 99% and 97% in 2-year sustained MFC-MRD-negative and NGS-MRD-negative patients, regardless of treatment received. The conversion rate from pre-maintenance MRD positivity to negativity during maintenance was significantly higher with KR vs R both by MFC (46% vs 30%, p = 0.046) and NGS (56% vs 30%, p = 0.046). Interpretation: The significant biological/clinical concordance between MFC and NGS at the same sensitivity suggests their possible use in the evaluation of one of the currently strongest predictors of outcome. Funding: Amgen, Celgene/Bristol Myers Squibb, Multiple Myeloma Research Foundation.

Impact of minimal residual disease standardised assessment by FDG-PET/CT in transplant-eligible patients with newly diagnosed multiple myeloma enrolled in the imaging sub-study of the FORTE trial.

Background: 18F-FDG-PET/CT is the current standard technique to define minimal residual disease (MRD) outside the bone marrow (BM) in multiple myeloma (MM), recently standardised applying the Deauville scores (DS) to focal lesions (FS) and bone marrow uptake (BMS) and defining the complete metabolic response (CMR) as uptake below the liver background (DS <4). Methods: In this analysis, we aimed at confirming the role of CMR, and complementarity with BM multiparameter flow cytometry (MFC) at 10-5, in an independent cohort of newly diagnosed transplant-eligible MM patients previously enrolled in the phase II randomised FORTE trial. 109 of the 474 global patients enrolled in the trial between February 23, 2015, and April 5, 2017, who had paired PET/CT (performed at baseline [B] and preceding maintenance therapy [PM]) and MFC evaluation, were included in this analysis. Findings: At B, 93% of patients had focal lesions within the bones (FS ≥4 in 89%) and 99% increased BM uptake (BMS ≥4 in 61%). At PM, CMR was achieved in 63% of patients, which was a strong predictor for prolonged PFS in univariate analysis at landmark time PM (HR 0.40, P = 0.0065) and in Cox multivariate analysis (HR 0.31, P = 0.0023). Regarding OS, a trend in favour of CMR was present in univariate (HR 0.44, P = 0.094), and Cox multivariate model (HR 0.17, P = 0.0037). Patients achieving both PET/CT CMR and MFC negativity at PM showed significantly extended PFS in univariate (HR 0.45, P = 0.020) and multivariate analysis (HR 0.41, P = 0.015). Interpretation: We herein confirm the applicability and validity of DS criteria to define CMR and its prognostic relevance and complementarity with MFC at the BM level. Funding: Amgen, Celgene/Bristol Myers Squibb, Italian Ministry of Health (RC-2022-2773423).

Assessment of Molecular Residual Disease Using Circulating Tumor DNA to Identify Multiple Myeloma Patients at High Risk of Relapse.

BACKGROUND: Despite treatment with high-dose chemotherapy followed by autologous stem cell transplantation (AHCT), patients with multiple myeloma (MM) invariably relapse. Molecular residual disease (MRD)-negativity post-AHCT has emerged as an important prognostic marker predicting the duration of remission. Current techniques for MRD assessment involve bone marrow (BM) aspirate sampling, which is invasive, subject to sample variability and is limited by spatial heterogeneity. We compared the performance of a non-invasive, circulating tumor DNA (ctDNA)-based MRD assay with multiparameter flow cytometry (MFC) of marrow aspirate to predict relapse in AHCT recipients with MM. METHODS: MRD assessment using ctDNA was retrospectively analyzed on 80 plasma samples collected at different time points from 28 patients, post-AHCT. MFC was used to assess MRD from BM biopsy. Individual archived BM aspirate slides or formalin-fixed paraffin-embedded slides from the time of MM diagnosis and matched blood were used to assess MRD at 3 months, post-AHCT, using a personalized, tumor-informed ctDNA assay. RESULTS: ctDNA was detectable in 70.8% (17/24) of pre-AHCT patients and 53.6% (15/28) of post-AHCT patients (3-month time point). Of the 15 post-AHCT ctDNA-positive patients, 14 relapsed on follow-up. The median PFS for ctDNA-positive patients was 31 months, and that for ctDNA-negative patients was 84 months (HR: 5.6; 95%CI: 1.8-17;p=0.0003). No significant difference in PFS was observed in patients stratified by MFC-based MRD status (HR 1.2; 95%CI: 0.3-3.4;p=0.73). The positive predictive value for ctDNA was also significantly higher than MFC (93.3% vs. 68.4%). CONCLUSIONS: This study demonstrates tumor-informed ctDNA analysis is strongly predictive of MM relapse.

Concordance in measurable residual disease result after first and second induction cycle in acute myeloid leukemia: An outcome- and cost-analysis.

Measurable residual disease (MRD) measured using multiparameter flow-cytometry (MFC) has proven to be an important prognostic biomarker in acute myeloid leukemia (AML). In addition, MRD is increasingly used to guide consolidation treatment towards a non-allogenic stem cell transplantation treatment for MRD-negative patients in the ELN-2017 intermediate risk group. Currently, measurement of MFC-MRD in bone marrow is used for clinical decision making after 2 cycles of induction chemotherapy. However, measurement after 1 cycle has also been shown to have prognostic value, so the optimal time point remains a question of debate. We assessed the independent prognostic value of MRD results at either time point and concordance between these for 273 AML patients treated within and according to the HOVON-SAKK 92, 102, 103 and 132 trials. Cumulative incidence of relapse, event free survival and overall survival were significantly better for MRD-negative (<0.1%) patients compared to MRD-positive patients after cycle 1 and cycle 2 (p ≤ 0.002, for all comparisons). A total of 196 patients (71.8%) were MRD-negative after cycle 1, of which the vast majority remained negative after cycle 2 (180 patients; 91.8%). In contrast, of the 77 MRD-positive patients after cycle 1, only 41 patients (53.2%) remained positive. A cost reduction of -€571,751 per 100 patients could be achieved by initiating the donor search based on the MRD-result after cycle 1. This equals to a 50.7% cost reduction compared to the current care strategy in which the donor search is initiated for all patients. These results show that MRD after cycle 1 has prognostic value and is highly concordant with MRD status after cycle 2. When MRD-MFC is used to guide consolidation treatment (allo vs non-allo) in intermediate risk patients, allogeneic donor search may be postponed or omitted after cycle 1. Since the majority of MRD-negative patients remain negative after cycle 2, this could safely reduce the number of allogeneic donor searches and reduce costs.

The Prognostic Value of Early Detection of Minimal Residual Disease as Defined by Flow Cytometry and Gene Mutation Clearance for Myelodysplastic Syndrome Patients After Myeloablative Allogeneic Hematopoietic Stem-Cell Transplantation.

High relapse incidence remains a major problem for myelodysplastic syndrome (MDS) patients who have received an allogeneic hematopoietic stem-cell transplantation (allo-HSCT). We retrospectively analyzed the correlations between clinical outcomes and minimal residual disease (MRD) by using mutations (MUT) and flow cytometry (FCM) analysis of 115 MDS patients with allo-HSCT. We divided 115 MDS patients into four groups based on molecular genetics and FCM MRD results at day 30 post-HSCT. There were significant differences in the 2-year progression-free survival (PFS) between the FCMhigh MUTpos and FCMlow MUTneg groups (20% vs 79%, P < 0.001). In addition, by univariate analysis, we found that an IPSS-R score ≥4 pre-HSCT (HR, 5.061; P=0.007), DNMT3A mutations (HR, 2.291; P=0.052), TP53 mutations (HR, 3.946; P=0.011), and poor and very poor revised International Prognostic Scoring System (IPSS-R) cytogenetic risk (HR, 4.906; P < 0.001) were poor risk factors for PFS. In multivariate analysis, we found that an IPSS-R score ≥ 4 pre-HSCT (HR, 4.488; P=0.015), DNMT3A mutations (HR, 2.385; P=0.049), positive FCM MRD combined with persistence gene mutations at day 30 (HR, 5.198; P=0.013) were independent risk factors for disease progression. In conclusion, our data indicated that monitoring MRD by FCM combined with gene mutation clearance at day 30 could help in the prediction of disease progression for MDS patients after transplantation.

Immunophenotypic Detection of Measurable Residual (Stem Cell) Disease Using LAIP Approach in Acute Myeloid Leukemia.

Half of the patients with acute myeloid leukemia (AML), who achieve complete remission after chemotherapy treatment, will ultimately experience a relapse. Measurable residual disease (MRD) is an important post-treatment risk factor in AML, because it gives additional information about the depth of the remission. Within MRD, the small population of leukemic stem cells (LSCs) is thought to be at the base of the actual relapse. In this protocol, the flow cytometric detection of MRD and LSCs herein is outlined. We give a detailed overview of the sampling procedures for optimal multiparameter flow cytometry assessment of both MRD and LSC, using leukemia associated immunophenotypes (LAIPs) and LSC markers. Moreover, an overview of the gating strategies to detect LAIPs and LSC markers is provided. This protocol serves as guidance for flow cytometric detection of measurable residual (stem cell) disease necessary for proper therapeutic decision making in AML patients. © 2019 The Authors. Basic Protocol 1: Immunophenotypic LAIP detection for measurable residual disease monitoring Basic Protocol 2: Immunophenotypic detection of CD34+CD38- leukemic stem cells.