Next-generation Flow Cytometry Research Articles

Detection of clonal plasma cells in POEMS syndrome using multiparameter flow cytometry

POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein [M-protein], and skin changes) is a rare systemic disorder characterized by various symptoms caused by underlying plasma cell (PC) dyscrasia. Detection of monoclonal PCs is mandatory for the diagnosis of POEMS syndrome; however, the usefulness of EuroFlow-based next-generation flow cytometry (EuroFlow-NGF) in POEMS syndrome for detecting monoclonal PCs in bone marrow (BM) and the gating strategy suitable for flow cytometry study of POEMS syndrome remain unknown. We employed EuroFlow-NGF-based single-tube eight-color multiparameter flow cytometry (MM-flow) and established a new gating strategy (POEMS-flow) to detect the monoclonal PCs in POEMS syndrome, gating CD38 broadly from dim to bright and CD45 narrowly from negative to dim compared to MM-flow. MM-flow detected monoclonal PCs in 9/25 (36.0%) cases, including 2/2 immunofixation electrophoresis (IFE)-negative cases (100%). However, POEMS-flow detected monoclonal PCs in 18/25 cases (72.0%), including 2/2 IFE-negative cases (100%). POEMS-flow detected monoclonal PCs with immunophenotypes of CD19− in 17/18 (94.4%). In six cases where post-treatment samples were available, the size of the clones was significantly reduced after the treatment (P = 0.031). POEMS-flow can enhance the identification rate of monoclonal PCs in POEMS syndrome and become a valuable tool for the diagnosis of POEMS syndrome.

The Evolving Landscape of Flowcytometric Minimal Residual Disease Monitoring in B-Cell Precursor Acute Lymphoblastic Leukemia.

Detection of minimal residual disease (MRD) is a major independent prognostic marker in the clinical management of pediatric and adult B-cell precursor Acute Lymphoblastic Leukemia (BCP-ALL), and risk stratification nowadays heavily relies on MRD diagnostics. MRD can be detected using flow cytometry based on aberrant expression of markers (antigens) during malignant B-cell maturation. Recent advances highlight the significance of novel markers (e.g., CD58, CD81, CD304, CD73, CD66c, and CD123), improving MRD identification. Second and next-generation flow cytometry, such as the EuroFlow consortium's eight-color protocol, can achieve sensitivities down to 10-5 (comparable with the PCR-based method) if sufficient cells are acquired. The introduction of targeted therapies (especially those targeting CD19, such as blinatumomab or CAR-T19) introduces several challenges for flow cytometric MRD analysis, such as the occurrence of CD19-negative relapses. Therefore, innovative flow cytometry panels, including alternative B-cell markers (e.g., CD22 and CD24), have been designed. (Semi-)automated MRD assessment, employing machine learning algorithms and clustering tools, shows promise but does not yet allow robust and sensitive automated analysis of MRD. Future directions involve integrating artificial intelligence, further automation, and exploring multicolor spectral flow cytometry to standardize MRD assessment and enhance diagnostic and prognostic robustness of MRD diagnostics in BCP-ALL.

Evaluation of next-generation sequencing versus next-generation flow cytometry for minimal-residual-disease detection in Chinese patients with multiple myeloma

PurposeTo evaluate the efficacy of next-generation sequencing (NGS) in minimal-residual-disease (MRD) monitoring in Chinese patients with multiple myeloma (MM).MethodsThis study analyzed 60 Chinese MM patients. During MRD monitoring in these patients’ post-therapy, clonal immunoglobulin heavy chain (IGH) rearrangements were detected via NGS using LymphoTrack assays. MRD monitoring was performed using NGS or next-generation flow cytometry (NGF), and the results were compared. Additionally, the sensitivity and reproducibility of the NGS method were assessed.ResultsThe MRD detection range of the NGS method was 10–6–10–1, which suggested good linearity, with a Pearson correlation coefficient of 0.985 and a limit of detection of 10–6. Intra- and inter-assay reproducibility analyses showed that NGS exhibited 100% reproducibility with low variability in clonal cells. At diagnosis, unique clones were found in 42 patients (70.0%) with clonal IGH rearrangements, which were used as clonality markers for MRD monitoring post-therapy. Comparison of NGS and NGF for MRD monitoring showed 79.1% concordance. No samples that tested MRD-positive via NGF were found negative via NGS, indicating the higher sensitivity of NGS. MRD could be detected using NGS in 6 of 7 samples before autologous hematopoietic stem-cell transplantation, and 5 of them tested negative post-transplantation. In contrast, the NGF method could detect MRD in only 1 sample pre-transplantation.ConclusionCompared with NGF, NGS exhibits higher sensitivity and reproducibility in MRD detection and can be an effective strategy for MRD monitoring in Chinese MM patients.

Biomarkers of Efficacy and Safety of the Academic BCMA-CART ARI0002h for the Treatment of Refractory Multiple Myeloma.

B-cell maturation antigen (BCMA)-chimeric antigen receptor T-cells (CART) improve results obtained with conventional therapy in the treatment of relapsed/refractory multiple myeloma. However, the high demand and expensive costs associated with CART therapy might prove unsustainable for health systems. Academic CARTs could potentially overcome these issues. Moreover, response biomarkers and resistance mechanisms need to be identified and addressed to improve efficacy and patient selection. Here, we present clinical and ancillary results of the 60 patients treated with the academic BCMA-CART, ARI0002h, in the CARTBCMA-HCB-01 trial. We collected apheresis, final product, peripheral blood and bone marrow samples before and after infusion. We assessed BCMA, T-cell subsets, CART kinetics and antibodies, B-cell aplasia, cytokines, and measurable residual disease by next-generation flow cytometry, and correlated these to clinical outcomes. At cut-off date March 17, 2023, with a median follow-up of 23.1 months (95% CI, 9.2-37.1), overall response rate in the first 3 months was 95% [95% confidence interval (CI), 89.5-100]; cytokine release syndrome (CRS) was observed in 90% of patients (5% grades ≥3) and grade 1 immune effector cell-associated neurotoxicity syndrome was reported in 2 patients (3%). Median progression-free survival was 15.8 months (95% CI, 11.5-22.4). Surface BCMA was not predictive of response or survival, but soluble BCMA correlated with worse clinical outcomes and CRS severity. Activation marker HLA-DR in the apheresis was associated with longer progression-free survival and increased exhaustion markers correlated with poorer outcomes. ARI0002h kinetics and loss of B-cell aplasia were not predictive of relapse. Despite deep and sustained responses achieved with ARI0002h, we identified several biomarkers that correlate with poor outcomes.

Monitoring Minimal Residual Disease in Patients with Multiple Myeloma by Targeted Tracking Serum M-Protein Using Mass Spectrometry (EasyM).

We investigated both the clinical utilities and the prognostic impacts of the clonotypic peptide mass spectrometry (MS)-EasyM, a blood-based minimal residual disease (MRD) monitoring protocol in multiple myeloma. A total of 447 sequential serum samples from 56 patients with multiple myeloma were analyzed using EasyM. Patient-specific M-protein peptides were sequenced from diagnostic samples; sequential samples were quantified by EasyM to monitor the M-protein. The performance of EasyM was compared with serum immunofixation electrophoresis (IFE), bone marrow multiparameter flow cytometry (MFC), and next-generation flow cytometry (NGF) detection. The optimal balance of EasyM sensitivity/specificity versus NGF (10-5 sensitivity) was determined and the prognostic impact of MS-MRD status was investigated. Of the 447 serum samples detected and measured by EasyM, 397, 126, and 92 had time-matching results for comparison with serum IFE, MFC-MRD, and NGF-MRD, respectively. Using a dotp >0.9 as the MS-MRD positive, sensitivity was 99.6% versus IFE and 100.0% versus MFC and NGF. Using an MS negative cutoff informed by ROC analysis (<1.86% of that at diagnosis), EasyM sensitivity remained high versus IFE (88.3%), MFC (85.1%), and NGF (93.2%), whereas specificity increased to 90.4%, 55.8%, and 93.2%, respectively. In the multivariate analysis, older diagnostic age was an independent predictor for progression-free survival [PFS; high risk (HR), 3.15; 1.26-7.86], the best MS-MRD status (MS-MRD negative) was independent predictor for both PFS (HR, 0.25; 0.12-0.52) and overall survival (HR, 0.16; 0.06-0.40). EasyM is a highly sensitive and minimal invasive method of MRD monitoring in multiple myeloma; MS-MRD had significant predictive ability for survival outcomes.

Impact of pretransplant minimal residual disease in patients with multiple myeloma and a very good partial response or better receiving autologous hematopoietic stem cell transplantation.

The prognostic significance of minimal residual disease (MRD) status before autologous hematopoietic stem cell transplantation (autoHCT) in patients with multiple myeloma (MM) has not been clearly elucidated. Retrospective single-center study of adult MM patients who achieved ≥very good partial response (VGPR) after induction therapy from 2015 to 2021 received upfront autoHCT and had available pretransplant MRD status by next-generation flow cytometry. The cohort was divided into pretransplant MRD-negative (MRDneg) and MRD-positive (MRDpos) groups. A total of 733 patients were included in our analysis; 425 were MRDneg and 308 MRDpos at autoHCT. In the MRDpos group, more patients had high-risk cytogenetic abnormalities (48% vs. 38%, respectively; p=.025), whereas fewer patients achieved ≥CR before autoHCT (14% vs. 40%; p<.001). At day 100 after autoHCT, 37% of the MRDpos versus 71% of the MRDneg achieved ≥CR, and at best posttransplant response 65% versus 88% achieved ≥CR, respectively. After a median follow-up of 27.6months (range, 0.7-82.3), the median PFS was significantly shorter for patients in the MRDpos group compared to the MRDneg group: 48.2months (95% confidence interval [CI], 0.3-80.5) versus 80.1months (95% CI, 0.5-80.1), respectively (p<.001). There was no significant difference in overall survival between the two groups (p=.41). Pretransplant MRDpos status was predictive of shorter PFS in multivariate analysis (hazard ratio, 1.80; 95% CI, 1.31-2.46; p<.001). The impact of pretransplant MRD status was retained in most of the examined subgroups. In patients achieving ≥VGPR to induction, pretransplant MRDpos status was associated with a lower CR rate after autoHCT and a shorter PFS.

Immunophenotypic assessment of clonal plasma cells and B-cells in bone marrow and blood in the diagnostic classification of early stage monoclonal gammopathies: an iSTOPMM study

Monoclonal gammopathy of undetermined significance (MGUS) is the earliest discernible stage of multiple myeloma (MM) and Waldenström’s macroglobulinemia (WM). Early diagnosis of MG may be compromised by the low-level infiltration, undetectable to low-sensitive methodologies. Here, we investigated the prevalence and immunophenotypic profile of clonal (c) plasma cells (PC) and/or cB-lymphocytes in bone marrow (BM) and blood of subjects with a serum M-component from the iSTOPMM program, using high-sensitive next-generation flow cytometry (NGF), and its utility in the diagnostic classification of early-stage MG. We studied 164 paired BM and blood samples from 82 subjects, focusing the analysis on: 55 MGUS, 12 smoldering MM (SMM) and 8 smoldering WM (SWM). cPC were detected in 84% of the BM samples and cB-lymphocytes in 45%, coexisting in 39% of cases. In 29% of patients, the phenotypic features of cPC and/or cB-lymphocytes allowed a more accurate disease classification, including: 19/55 (35%) MGUS, 1/12 (8%) SMM and 2/8 (25%) SWM. Blood samples were informative in 49% of the BM-positive cases. We demonstrated the utility of NGF for a more accurate diagnostic classification of early-stage MG.

Predictors of unsustained measurable residual disease negativity in transplant-eligible patients with multiple myeloma

AbstractThe role of measurable residual disease (MRD) negativity as a biomarker to stop treatment is being investigated in transplant-eligible patients with multiple myeloma (MM). Thus, it is important to identify risk factors of MRD resurgence and/or progressive disease (PD) among patients achieving undetectable MRD to avoid undertreating them. Here, we studied 267 newly diagnosed transplant-eligible patients with MM enrolled in the GEM2012MENOS65 and GEM2014MAIN clinical trials who achieved MRD negativity by next-generation flow cytometry. After a median follow-up of 73 months since the first MRD negative assessment, 111 of the 267 (42%) patients showed MRD resurgence and/or PD. The only prognostic factors at diagnosis that predicted MRD resurgence and/or PD were an International Staging System (ISS) 3 and the presence of ≥0.01% circulating tumor cells (CTCs). Failure to achieve MRD negativity after induction also predicted higher risk of MRD resurgence and/or PD. Patients having 0 vs 1 vs ≥2 risk factors (ISS 3, ≥0.01% CTCs, and late MRD negativity) showed 5-year rates of MRD resurgence and/or PD of 16%, 33%, and 57%, respectively (P < .001). Thus, these easily measurable risk factors could help refine the selection of patients for whom treatment cessation after MRD negativity is being investigated in clinical trials. This trial was registered at www.clinicaltrials.gov as NCT01916252 and NCT02406144.

Determining hemodilution in diagnostic bone marrow aspirated samples in plasma cell disorders by next-generation flow cytometry: Proposal for a bone marrow quality index

Hemodilution of bone marrow (BM) aspirates is a limitation of multiparameter flow cytometry (MFC) in plasma cell disorders. There is a need for a validated approach for assessing sample quality and the distribution of non-plasma cell BM populations by MFC could provide a solution. We evaluated BM-associated cell populations, assessed by next-generation flow cytometry (NGF) and white blood cell (WBC) count in 351 BM aspirated samples from 219 participants with plasma cell disorders in the Iceland Screens, Treats, or Prevents MM study (iStopMM), as markers of hemodilution by their discriminatory ability between first and (generally more hemodiluted) second pull BM aspirated samples. The most discriminating markers were used to derive a novel BM quality index (BMQI). Nucleated red blood cells and myeloid precursors provided the greatest discriminatory ability between first vs second pull samples (area under the curve (AUC): 0.87 and 0.85, respectively), significantly better than B cell precursors (AUC = 0.64; p < 0.001), mast cells (AUC = 0.65; p < 0.001), and the BM WBC count (AUC = 0.77; p < 0.05). We generated a novel BMQI that is intrinsic to current NGF protocols, for evaluating quality of diagnostic BM samples and suggest the use of a BMQI scoring system for interpreting results and guiding appropriate actions.

Monitoring Minimal Residual Disease in Patients with Multiple Myeloma By Tracking Serum M-Protein Using Mass Spectrometry

Objective： We performed this retrospective real-world study to evaluate the clinical utility of blood-based mass spectrometry for longitudinal M-protein monitoring during the disease course of patients of multiple myeloma（MM）. Methods：We initially analyzed serial serum samples of 56 patients with MM by clonal peptide MS Method named EasyM MS, then we compared the MS results with those determined using serum immunofixation electrophoresis (IFE),multiparameter flow cytometry (MFC), next-generation flow cytometry (NGF), to establish the concordance between different disease-monitoring protocols. A sensitivity for MFC MRD negativity of at least 1×10 -4 anda sensitivity for NGF MRD negativity of at least 1×10 -5.Additionally, we determined the optimal cutoff value of EasyM MS negativity to satisfy both the sensitivity and specificity between MS and NGF, and explored the prognostic impact of MS-MRD status. Results：The median diagnostic age of 56 NDMM patients was 56 years old, including 34 males (60.7%). There were 38 patients with IgG type MP and 18 patients with IgA type MP. 47 patients (83.9%) chose to receive proteasome inhibitor - based induction therapy, and a total of 44 patients (78.6%) received first-line ASCT treatment.Among 56 MM patients，38 patients with IgG type MP can further identify IgG subclasses through mass spectrometry. Additionally, 56 patients with MM have successfully used MS to identify their unique clonal peptides of MP. 56 patients provided a total of 447 samples of serum and all sequential serum samples were successfully measured by using the MS method. The initial comparison of the performance of blood-based MS-MRD with that of the conventional M-protein diagnostic method IFE used . Among the 397 comparable results collected at similar timepoints, 70.8% (281/397) of the samples were both M-MRD- and IFE-positive, 3.3% (13/397) were both MS-MRD- and IFE-negative, 25.7% (102/397) were MS-MRD-positive and IFE-negative.Flow cytometry MRD was performed on 218 bone marrow aspirates in this cohort, including 126 analyzed with MFC and 92 analyzed with NGF. MS-MRD detection was also performed on comparable serum acquired at the same time points. The sensitivity of MS-MRD was 100.0% in comparison with both MFC and NGF, with specificity of 1.9% and 22.2%, respectively. Considering the overly high sensitivity of EasyM at a cutoff of dotp &amp;gt;0.9, we used the sensitivity of NGF as the standard for detection (i.e., a detection sensitivity ≤10 -5) and set the EasyM MS negative cutoff value using ROC analysis, determined to be &amp;lt;1.86% of that at first diagnosis. Using these assumptions, we again performed the aforementioned analyses comparing the sensitivity and specificity between EasyM and IFE, MFC, and NGF. Under this scenario, the sensitivity of EasyM remained high in comparison with IFE (88.3%), MFC (85.1%), and NGF (93.2%), but the specificity was also greatly increased to 90.4%, 55.8%, and 93.2%, respectively. We then divided patients into MS-positive and MS-negative groups according to whether they achieved MS-MRD negativity, and median PFS and OS were calculated for each group. The median PFS of the MS-positive and MS-negative groups was 20.6 (95% CI: 16.6, 24.6) and 61.8 (39.7, 83.9) months, respectively . The median OS was 55.7 (95% CI:31.8, 79.5) months for the MS-positive group and not reached (NR) for the MS-negative group ,Both mPFS and mOS were significantly longer among the MS-negative group compared with the MS-positive group (both p &amp;lt; 0.001). Conclusion：EasyM exhibits high sensitivity and minimally invasive technological advantages, and also has important significance in efficacy evaluation and prognosis evaluation. In the future, EasyM MS detection can be used as a minimally invasive MRD monitoring method based on peripheral blood in clinical practice.

Impact of Pre-Transplant Minimal Residual Disease in Patients with Multiple Myeloma with ≥ Very Good Partial Response Receiving Autologous Hematopoietic Stem Cell Transplantation

Background: Minimal residual disease (MRD) has emerged as one of the most important prognostic markers in patients with multiple myeloma (MM). However, the prognostic significance of MRD status prior to autologous hematopoietic stem cell transplantation (autoHCT) has not been clearly elucidated. Methods: In this retrospective single-center study we included adult MM patients who achieved ≥VGPR after induction therapy between 2015-2021, received an upfront autoHCT and had available data for pre-transplant MRD status by next-generation flow cytometry (NGF). The sensitivity of our assay is 1/10 -5 cells (0.001%) based on acquisition and analysis of at least 2 million events. We divided the cohort into pre-transplant MRD negative (MRDneg) and MRD positive (MRDpos) groups. Primary endpoints were progression-free survival (PFS) and overall survival (OS). Results: A total of 734 patients were included in our analysis, 425 were MRDneg and 309 were MRDpos at autoHCT. Median age of the entire cohort was 60 (range 25-82) years and 436 (59%) were male. In the MRDpos group, more patients had high-risk cytogenetic abnormalities (48% vs. 38%, respectively; p=0.025), while fewer patients had achieved &amp;gt;CR prior to autoHCT (14% vs. 40%; p&amp;lt;0.001) (Table 1). At day 100 after autoHCT, 37% of the MRDpos achieved &amp;gt;CR vs. 71% of the MRDneg group, and at best post-transplant response 65% vs. 88% achieved &amp;gt;CR, respectively. At day 100, 16% of the patients in the MRDpos group achieved MRD negative ≥VGPR vs. 27% in the MRDneg group, and at best post-transplant response 33% vs. 37% achieved MRD negative ≥VGPR, respectively. After a median follow up of 27.6 months (0.7-82.3), the median PFS of the entire cohort was 63.4 months (95% CI 0.3-8.5), and median OS was 80.0 months (95% CI 0.3-82.3). Median PFS was significantly shorter for patients in the MRDpos group compared to MRDneg: 48.2 months (95% CI 0.3-80.5) vs. 80.1 months (95% CI 0.5-80.1), respectively; p&amp;lt;0.001 (Figure 1). There was no significant difference in OS between the two groups (p=0.41). Pre-transplant MRDpos status (HR 1.80, 95% CI 1.31-2.46; p&amp;lt;0.001) and high-risk cytogenetics (HR 1.86, 95% CI 1.32-2.61; p&amp;lt;0.001) were predictive of shorter PFS in MVA. Use of post-transplant maintenance was predictive of longer PFS (HR 0.49, 95% CI 0.34-0.69; p&amp;lt;0.001) and OS (HR 0.19, 95% CI 0.11-0.32; p&amp;lt;0.001) in MVA. In a subset analysis, pre-transplant MRD status remained highly predictive of PFS in patients with high-risk cytogenetics (HR 1.48; 95% CI 1.03-2.11; p=0.033) as well as non-high-risk cytogenetics (HR 1.75; 95% CI 1.13-2.70; p=0.012) and in patients with a response of VGPR prior to transplant (HR 1.79; 95% CI 1.33-2.42; p&amp;lt;0.001). Similarly, in patients with R-ISS stage I and II MM, pre-transplant MRD status was highly predictive of PFS [(HR 2.28; 95% CI 1.21-4.29; p=0.011) and (HR 1.73; 95% CI 1.17-2.56; p=0.006), respectively]. However, for patients with R-ISS III disease (HR 2.00; p=0.079), for patients with a response of ≥CR prior to transplant (HR=0.85; p=0.67) and for patients ≥65 years (HR=1.46; p=0.062) the pre-transplant MRD status was not significantly predictive of PFS. Conclusions: In patients achieving &amp;gt;VGPR to induction, pre-transplant MRDpos status was associated with a lower CR rate after autoHCT and a shorter PFS.

Evaluation of Easym, a Clonotypic Mass Spectrometry Assay, and Euroflow Minimal Residual Disease Assessment in Multiple Myeloma

Introduction: Minimal residual disease (MRD) negativity is increasingly recognised as the optimal measure of therapeutic response for multiple myeloma (MM) patients and is associated with improved survival. Bone marrow (BM) assessment of MRD with next-generation sequencing (NGS) or next-generation flow cytometry (NGF) can achieve a minimum sensitivity of 10 -5 however an invasive procedure is required. Additionally, this single-site BM biopsy may be limited by specimen quality and failure to capture the spatial heterogeneity of MM. Peripheral blood-based mass spectrometry (PB-based MS) offers the potential for highly sensitive, non-invasive sequential MRD assessment. EasyM is a PB clonotypic MS assay involving de novo amino acid sequencing of the full-length M-protein and quantification of unique peptides with parallel reaction monitoring. EasyM has been compared to 8-colour multiparameter flow cytometry with a sensitivity of 10 -4 (Liyasova et al, Clin Cancer Res, 2021) and clonoSEQ (Slade et al, Blood, 2022), but not to NGF to our knowledge. In this context, we have evaluated EasyM in MM patients undergoing sequential NGF (EuroFlow platform) MRD assessment. Methods: We retrospectively identified MM patients enrolled in the Australasian Leukaemia and Lymphoma Group MM19 (ACTRN12616000772448) and MM21 (ACTRN12618001490268) trials with measurable M-protein ≥2g/L by serum protein electrophoresis and/or free light chains ≥100mg/L at baseline. Briefly, the MM19 trial evaluated the addition of ixazomib to thalidomide and dexamethasone consolidation therapy for 12 months in transplant eligible newly diagnosed MM (TE NDMM) patients undergoing front-line autologous stem cell transplantation (ASCT), whilst the MM21 trial evaluated an intensive salvage approach using daratumumab-lenalidomide-dexamethasone (DRd) as re-induction (DRd x 4 cycles) and post-ASCT consolidation (DRd x 12 cycles followed by R maintenance until disease progression) in TE NDMM patients failing (&amp;lt;partial response as best response) front-line bortezomib-based induction therapy. NGF MRD status was determined using the standardised 8-colour EuroFlow platform at pre-ASCT, post-ASCT, and end of consolidation timepoints in MM19 and MM21 patients and additionally post-cycle 2 of consolidation in MM21 patients. Matched serum samples were evaluated with the EasyM assay. Concordance between NGF and MS was assessed by the Chi-squared and McNemar's tests. Results: A total of 43 patients were identified for analysis, with 9 MM19 and 34 MM 21 patients. 1 patient was not sequenced due to low baseline values and 2 patients had no clonotypic target tryptic peptides to monitor MRD. EasyM was undetectable (MS-) in 3 (8%) patients. 2 patients achieved MS- pre-ASCT and the third achieved MS- post-cycle 2 of consolidation. All 3 patients remain in complete response (CR) at 44-48 months post-ASCT. Sequential MS (Figure 1) revealed rising EasyM levels in 2 patients, preceding relapse by 15 and 25 months; of note, 1 patient had matched BM and was NGF MRD negative. Serum samples for MS with matched BM for NGF (Table 1) were available for 25 patients pre-ASCT, 32 post-ASCT, 26 post-cycle 2 of consolidation, and 28 end of consolidation with NGF MRD negativity (NGF-) of 8%, 31%, 38%, and 75% at these timepoints, respectively. Of the 111 matched samples in total, 43 (39%) were NGF- but only 7 (6%) were MS-, and 73 (66%) were concordant. The Chi-squared test for association between MS and NGF was not significant at all 4 timepoints. The McNemar's test p-values were &amp;gt;0.999, 0.004, 0.008, and &amp;lt;0.001 for the 4 timepoints, indicating that MS+/NGF- were more likely than MS-/NGF+ discordances at all timepoints except for pre-ASCT. Of the 30 matched samples with confirmed CR status, 5 (17%) were MS+/NGF+, 19 (63%) were MS+/NGF-, and 6 (20%) were MS-/NGF- (Chi-squared and McNemar's p-values of 0.549 and &amp;lt;0.001). Conclusion: This preliminary data highlights the potential of EasyM for sequential PB-based clonotypic MS MRD monitoring in MM. Concordance with standard BM NGF was poor, with 63% of samples with confirmed CR showing detectable M-protein by EasyM but NGF MRD negativity, consistent with the higher sensitivity of EasyM. Comparison of larger sample sets and validation through prospective clinical trials is warranted to better assess the clinical utility of EasyM and rationalise BM-based assessment for MM patients.

Euroflow-Based Ultrasensitive NGF for the Evaluation of Bone Marrow Minimal Residual Disease in Multiple Myeloma

Background: Euroflow next-generation flow cytometry sensitively assesses minimal residual disease (MRD) in multiple myeloma (MM). It is widely adopted in labs worldwide for tracking disease progression, therapy efficacy, and decision-making in MM trials. Euroflow MRD significantly enhances MM patient outcomes, alongside advancements in anti-cancer approaches like BiTEs, CAR-T cells, and ADCs, resulting in increased overall survival rates. However, blood-based methods do not always align with bone marrow PC analysis, requiring heightened sensitivity to detect residual malignant cells post-therapy. The recent BloodFlow method, achieves remarkable sensitivity up to 10 -8 by enriching CD138 + PCs from 50 mL peripheral blood. In this study, we compare conventional Euroflow BM-MRD with the ultrasensitive method using CD138 enrichment of BM cells before analysis. Methods: BM-MRD followed Euroflow group guidelines. For ultrasensitive assessment, CD138 + plasma cells were isolated using CD138 MicroBeads. Data analysis was performed with Infinicyt software. Automatic gate and identification tool was used for conventional MRD, while data was manually analyzed for ultrasensitive MRD assessment. Results: We compared conventional and ultrasensitive MRD in the bone marrow of 70 MM patients. All positive MRDs using conventional NGF remained positive with ultrasensitive MRD. Notably, among 40 patients with negative conventional NGF-MRD, 5 cases turned positive after ultrasensitive MRD, by detecting aPCs from 0,0003 to 0,002% in all nucleated cells in the bone marrow. Patients 1, 2, and 3, diagnosed between 2020 and 2022, were in CR during assessment. Patients 4 and 5, diagnosed in 2016 and 2014 respectively, underwent multiple therapies, two autologous hematopoietic cell transplants, and patient 5 also had an allogeneic hematopoietic cell transplant. Ultrasensitive MRD for patients 4 and 5 was done after anti-BCMA CAR T cell therapy. The CD138 isolation approach allowed evaluating BM-MRD at detection levels of 10 -8 cells. Further studies using ultrasensitive MRD will prospectively evaluate the predictive value of the assay in patients with NDMM, especially with high and ultra-high-risk disease. Conclusions: This study demonstrates the significant advantages of direct CD138 enrichment over bulk lysis for detecting residual malignant PCs in MM. Ultrasensitive MRD offers superior sensitivity compared to conventional MRD, a critical factor in the era of more effective therapies leading to deeper responses. Currently, we are prospectively assessing the clinical benefits in a larger patient cohort.

Safety and Efficacy Outcomes for Patients with High-Risk Multiple Myeloma Receiving Idecabtagene Vicleucel: The MD Anderson Experience

Background: There is a paucity of data regarding the impact of high-risk features on the efficacy and safety of B-cell maturation antigen (BCMA)-directed autologous chimeric antigen receptor (CAR)-T therapy in patients with multiple myeloma (MM). Methods: In this retrospective single-center study we included all MM patients who received idecabtagene vicleucel (ide-cel) between 12/2019-10/2022, either in the setting of a clinical trial (i.e. KarMMa-2 and KarMMa-3) or as a standard of care (SOC). We evaluated the impact of high-risk disease features on the efficacy and safety outcomes. Patients with high-risk MM (HRMM) were defined as having at least one of the following: high-risk cytogenetic abnormalities prior to CAR-T infusion (deletion 17p, translocation (t)(4:14), t(14:16) or 1q gain/amplification (1q+)), extramedullary disease (EMD), plasma cell leukemia and Revised International Staging System (R-ISS) stage 3. Minimal residual disease (MRD) was evaluated using 8-color next-generation flow cytometry (NGF), with a sensitivity of 1/10-5 cells (0.001%) based on the acquisition and analysis of at least 2 million events. Efficacy outcomes included response rates, progression free survival (PFS) and overall survival (OS). Safety outcomes included incidence/grade of cytokine release syndrome (CRS), Immune effector cell-associated neurotoxicity syndrome (ICANS), hematological toxicity and infections. Results: A total of 74 patients were included in our analysis, 49 received SOC ide-cel and 25 were treated on clinical trial. The median age was 65.3 (range 37.9-90.3) years, and 49 patients (66%) were male. Median number of previous lines of therapy was 6 (range 1-18). The HRMM group included 52 patients (70%), and the most prevalent high-risk features were high-risk cytogenetic abnormalities (43%, most often 1q+ (n=26, 81%), followed by del17p (n=17, 33%), t(4:14) (n=9, 17%) and t(14:16) (n=4, 8%)) and EMD (19%). Seventy five percent of patients who received SOC ide-cel had HRMM compared to 25% of those who received ide-cel on clinical trial (p=0.014). Compared to patients with standard-risk MM (SRMM), those with HRMM more often had disease refractory to proteasome inhibitors (p=0.042) or anti-CD38 antibodies (p=0.01), and more often received bridging therapy prior to CAR-T infusion (p=0.021). After bridging therapy, 43% of HRMM patients had progressive disease, compared to 20% of SRMM patients (p=0.21). Sixty seven percent of the entire cohort received prior BCMA-directed therapy before ide-cel, without a significant difference between the two risk groups (p=0.80) ( Table 1). For the entire cohort, overall response rate was 85%, and 51% achieved ≥CR at best response. There was no significant difference between the HRMM and SRMM groups in response rates or in rates of MRD negativity at day 30 and at 3/6/9 months after CAR-T infusion, yet fewer HRMM had MRD negativity at 12 months after CAR-T (50% vs. 100% of evaluable patients, p=0.019). The 6-months PFS for the HRMM group and the SRMM group was 64% and 81%, respectively (p=0.11) ( Figure 1A), and the 6-months OS was 80% and 90%, respectively (p=0.067) ( Figure 1B); Thirty-nine patients in the HRMM group developed CRS (83% of evaluable patients), including one grade 3 and one grade 5 CRS, compared to 15 (75%, p=0.65) in the SRMM group (all grade &amp;lt;3). Eight patients in the HRMM group developed ICANS (17%), including two grade 4 ICANS, compared to 3 (15%, p=0.93) in the SRMM group (all grade &amp;lt;3). We did not observe a difference in rates of neutropenia (p=0.63), anemia (p=0.75) or thrombocytopenia (p=0.53) by day 30, and also not in the rates of infection (p=0.16) between the two groups. In multivariate analysis on the entire cohort, receiving &amp;lt;4 prior lines of therapy (HR 0.06, 95% CI 0.004-0.71, p=0.026) and ECOG≤2 (HR 0.07, 95% CI 0.08-0.53, p=0.01) were associated with superior OS. Conclusions: Patients with HRMM receiving ide-cel had mostly comparable response rates compared to those with SRMM. HRMM patients had numerically worse PFS and OS compared to patients with SRMM, though not reaching statistical significance. Overall rates of CRS/ICANS were comparable between the two groups, yet only patients with HRMM had grade ≥3 of these complications. Patients who received ide-cel after less than four previous lines of therapy had better overall survival.

The Phase 2 CARTITUDE-2 Trial: Updated Efficacy and Safety of Ciltacabtagene Autoleucel in Patients with Multiple Myeloma and 1-3 Prior Lines of Therapy (Cohort A) and with Early Relapse after First Line Treatment (Cohort B)

Introduction: CARTITUDE-2 (NCT04133636) is a phase 2, multicohort study evaluating the safety and efficacy of ciltacabtagene autoleucel (cilta-cel), an anti-BCMA chimeric antigen receptor (CAR)-T cell therapy, in various populations of patients with multiple myeloma (MM). We previously reported 17-month median follow-up results from cohort A (1-3 prior lines of therapy [LOT] and lenalidomide [len]-refractory) and 18-month median follow-up results from cohort B (early relapse: ≤12 months after either autologous stem cell transplant [ASCT] or start of initial anti-myeloma treatment, if not transplanted). Cilta-cel is also under evaluation in patients with len-refractory MM after 1-3 LOT in the phase 3 CARTITUDE-4 study, which showed cilta-cel significantly prolonged progression-free survival (PFS) vs standard of care (HR, 0.26) at a median follow-up of 16 months. Here, we present updated efficacy and safety data from CARTITUDE-2 cohorts A and B, both with a median follow-up of ~29 months. Methods: Patients in cohorts A and B, all naive to CAR-T and/or anti-BCMA therapies, received a single cilta-cel infusion (target dose 0.75×10 6 CAR+ viable T cells/kg) 5-7 days after lymphodepletion. In both cohorts, the primary endpoint was minimal residual disease (MRD)-negativity (10 -5 threshold, by next-generation sequencing or next-generation flow cytometry). Management strategies were implemented after the phase 1b/2 CARTITUDE-1 study to reduce risk of movement and neurocognitive treatment-emergent adverse events (MNTs). Results: As of April 2023, 20 patients in cohort A had received cilta-cel (median follow-up, 29.9 months; 35% with high-risk cytogenetics; median 2 prior LOT; 95% refractory to last LOT; 40% triple-class refractory; 85% with prior ASCT). At the same data cut-off, 19 patients in cohort B hadreceived cilta-cel (median follow-up, 27.9 months; 16% with high-risk cytogenetics; 79% refractory to last LOT; 16% triple-class refractory; 79% with prior ASCT). All (100%) 17 MRD-evaluable patients in cohort A and 14 (93%) of 15 MRD-evaluable patients in cohort B achieved MRD negativity (10 -5 threshold). Eight (40%) of 20 patients in cohort A and 10 (53%) of 19 patients in cohort B sustained MRD negativity at 10 -5 for ≥6 months (Table 1). In the 20 patients in cohort A and 19 in cohort B, cilta-cel led to overall response rates of 95% (complete response or better [≥CR], 90%) and 100% (≥CR, 90%), respectively. Median PFS was not reached in either cohort, and 24-month PFS rates were 75% in cohort A and 73% in cohort B; respective 24-month overall survival rates were 75% and 84%. In cohort A, hematologic treatment-emergent adverse events (TEAEs) occurring between 17.1- and 29.9-month median follow-up included maximum grade (gr) 3/4 leukopenia in 1 patient (all gr,12 total; 60%), maximum gr 3/4 lymphopenia in 2 patients (all gr,16 total; 80%), and maximum gr 3/4 thrombocytopenia in 1 patient (all gr,16 total; 80%). In cohort B, no new patients reported hematologic TEAEs between 18.0- and 27.9-month median follow-up (Table 2). In cohort A, no new patients had CAR-T cell neurotoxicity, and no patients had a second primary malignancy (SPM). In cohort B, no new patients had MNTs, but other neurotoxicity (gr 2 sensory loss) occurred in 1 additional patient (all gr, 5 total; 26%) and resolved; and SPM (gr 4 choroid melanoma) occurred in 1 additional patient (all gr, 2 total; 11%). One new death (total 5) occurred in cohort A on day 666 due to progressive disease, and 1 new death (total 4) occurred in cohort B on day 749 due to cardiac arrest (not treatment related). Conclusions: These longer-term follow-up data show that patients treated with cilta-cel in earlier LOT, both those with len-refractory MM after 1-3 LOT (cohort A) and those with early relapse (cohort B), experienced deep and durable responses. No new CAR-T-related safety signals, except for 1 additional CAR-T cell neurotoxicity in cohort B, were reported. Cohort A provides insight into potential longer-term survival outcomes that may be expected in the phase 3 CARTITUDE-4 trial, which enrolled the same patient population but has shorter follow-up thus far. The long-term cohort B data highlight the durable efficacy of cilta-cel in patients who had early relapse; this is a functionally high-risk population for whom standard risk factors, including a high-risk cytogenetic profile, may not predict risk of relapse and for whom there is significant unmet need.

Predicting an Underlying Clonal Plasma Cell Population in Light-Chain Monoclonal Gammopathy of Undetermined Significance Using Free Light-Chain Ratio

Introduction: The management of light-chain (LC) monoclonal gammopathy of undetermined significance (MGUS) presents inherent challenges as the key diagnostic factor - abnormal free-light chain (FLC) levels - only indirectly implies the presence of an underlying clonal cell population. Moreover, the lack of M protein, used in current risk-stratification models, necessitates a distinct approach for risk assessment in LC-MGUS. Using next-generation flow cytometry (NGF), we assessed clonal plasma cell presence in bone marrow (BM) samples from individuals with LC monoclonal gammopathies. This approach enabled us to evaluate the predictive value of FLC ratio for an underlying clonal plasma cell population in LC-MGUS and its prognostic implications. Aim: To evaluate the association between FLC ratio and the presence of clonal plasma cells in the BM of individuals with LC monoclonal gammopathies as well as the risk of progression. Methods: The study is a part of the Iceland Screens, Treats, or Prevents Multiple Myeloma (iStopMM) study, a population-based screening study for multiple myeloma (MM) precursors and randomized trial of follow-up strategies. We included screened individuals with an abnormal FLC ratio (&amp;lt;0.26 or &amp;gt;1.65) and elevated involved LC (kappa ≥19.4 mg/L or lambda ≥26.3 mg/L) (Freelite, The Binding Site), with no detected M protein. Those with previously known MM or related disorders were excluded. NGF was used to determine clonal plasma cell presence in BM samples. Logistic regression was used to assess the relationship between FLC ratio (used as involved/uninvolved ratio throughout the study) and clonal plasma cell presence. Receiver operating characteristic (ROC) curve analysis was used to assess the predictive ability of FLC ratio for clonal plasma cell presence in LC-MGUS and to determine an optimal cutoff value. Kaplan-Meier analysis was used to assess time to progression to more advanced plasma cell disorder for LC-MGUS, stratified by the FLC ratio cutoff. A linear mixed-effects model was used to evaluate the change in FLC ratio (expressed as fold change relative to the screening sample) over time for those with FLC ratio below the cutoff at screening. Results: After screening 75,422 individuals, 1,965 with LC disease were included, with median age of 71 years (range of 42-100 years), and a median FLC ratio of 1.85. Most (95.4%) had involved FLC of type kappa. Clonal plasma cells were identified by NGF in 8/21 (38.1%) LC-MGUS, and all LC-smoldering MM (SMM) (n=21) and LC-MM (n=7) cases. A significant prediction of clonal plasma cell presence was found for FLC ratio (OR=6.47; p=0.012; n=49), supported by ROC curve analysis for LC-MGUS (AUC=0.94; n=21), identifying FLC ratio of 3.15 as optimal cutoff (92% sensitivity, 100% specificity). Of the 254 individuals randomized to active follow-up within the iStopMM study, baseline diagnosis distribution was 223 (87.8%) LC-MGUS, 22 (8.7%) LC-SMM, 7 (2.8%) LC-MM, 1 (0.4%) solitary plasmacytoma, and 1 (0.4%) chronic lymphocytic leukemia. Among these, 123 (representing 88% of the screened study cohort) had FLC ratio &amp;lt;3.15 at screening, thereof 122 (99.2%) with LC-MGUS and 1 (0.8%) with solitary plasmacytoma. No disease progression was observed for individuals with FLC ratio &amp;lt;3.15 (n=100) over a median follow-up of 46 months. Conversely, disease progression occurred in 13/97 (13.4%) LC-MGUS with ≥3.15 FLC ratio (9 to SMM, 3 to MM, and 1 to smoldering Waldenströms macroglobulinemia) during median follow-up of 42 months (p=0.00018 vs FLC ratio &amp;lt;3.15) (Figure). The linear mixed-effects model of 454 repeated FLC from 128 individuals with &amp;lt;3.15 FLC ratio at screening did not indicate significant change in FLC ratio over a median follow-up of 48 months. Conclusions: In this study, we utilized NGF to confirm an underlying clonal plasma cell population in BM of individuals with LC-MGUS and evaluate its association with involved/uninvolved FLC ratio. Clonal plasma cells were detected in a minority of LC-MGUS (38.1%), for which FLC ratio was found to be highly predictive. An FLC ratio cutoff of 3.15 optimally discriminated based on clonal plasma cell presence, and we found no evidence of progressive disease in LC-MGUS below this cutoff during follow-up. Altogether, the more stringent FLC ratio cutoff can assist in determining the likelihood of an underlying clonal plasma cell population in LC-MGUS and may, as such, help to guide the management of LC-MGUS.

Minimally Invasive Assessment of Measurable Residual Disease (MRD) in Multiple Myeloma (MM)

BACKGROUND MRD is an established test in MM clinical trials but not in routine practice. A hindrance to its wider adoption is invasive bone marrow (BM) aspirates. Thus, the possibility of assessing MRD using minimally invasive methods could be paramount to facilitate its transition from clinical trials to routine practice, but also to improve patients' (pts) quality of life and to generate more meaningful MRD results based on periodic assessments instead of limited time points. However, the methods developed for MRD evaluation in BM are less sensitive when used in peripheral blood (PB). AIM Investigate the complementarity and prognostic value of new multimodal minimally invasive MRD assessment in MM. METHODS This study included 243 transplant eligible and ineligible pts who were on maintenance or observation at the time of MRD assessment in PETHEMA/GEM clinical trials. In all cases, MRD was evaluated in PB using BloodFlow, which is a highly sensitive method (10 -7) that combines immunomagnetic enrichment with next-generation flow (NGF) cytometry. Periodic assessment of MRD in peripheral blood (PB) using BloodFlow was performed every six months. In 27 patients, MRD was further investigated in cfDNA using CloneSight, a highly sensitive (10 -4) next-generation sequencing method based on pt-specific mini-panels of multiplexed amplicons covering somatic mutations identified at diagnosis. In 169 of the 243 patients, MRD was analyzed in the serum using Quantitative Immunoprecipitation Mass Spectrometry (QIP-MS) with anti-IgG/A/M, total κ and λ beads. RESULTS BloodFlow was performed in a total of 867 PB samples, out of which 77 (9%) were MRD positive. The median number of CTCs/µL was 0.016 (range, 0.0003 - 0.29). In 506 of the 867 assessments, MRD was simultaneously analyzed in the BM using NGF. The concordance between BloodFlow in PB and NGF in BM was 78.9% (70.4% double negative and 8.5% double positive MRD results). The frequency of BloodFlow-/NGF+ and BloodFlow+/NGF- discordant assessments was 20.3% and 0.8%, respectively. Serial assessment of MRD in PB using BloodFlow showed that 221 of the 243 (91%) pts had sustained MRD negativity and 13 (5%) were persistently positive. MRD conversions from negative to positive were noted in 9 (4%) pts. The landmark median PFS from the latest MRD assessment was not reached (NR) vs 3 months in negative vs positive patients (HR: 0.09, P &amp;lt; .001). Of note, only 11 of the 221 (5%) MRD negative pts relapsed thus far. Of the 27 pts in whom MRD was simultaneously analyzed in cfDNA using CloneSight, five were MRD positive. The landmark median PFS from the latest MRD assessment was NR vs 5 months in negative vs positive pts (HR: 0.23, P = .057). The number of patients with BloodFlow-/CloneSight-, BloodFlow+/CloneSight-, BloodFlow-/CloneSight+ and BloodFlow+/CloneSight+ results were 17, 5, 2 and 3. The landmark median PFS from the latest MRD assessment in patients with double negative MRD vs positive by either method was NR vs 8 months (HR: 0.20, P = .056). Of note, only 2 of the 17 double negative MRD patients relapsed thus far. Of the 169 pts in whom MRD was simultaneously analyzed in serum using QIP-MS, 37 (22%) were MRD positive. The landmark median PFS from the latest MRD assessment was NR in negative and positive patients (HR: 0.13, P &amp;lt; .001). The number of patients with BloodFlow-/QIPMS-, BloodFlow+/QIPMS-, BloodFlow-/QIPMS+ and BloodFlow+/QIPMS+ results were 130, 2, 26 and 11. The landmark median PFS from the latest MRD assessment in patients with double negative MRD vs positive by either method was NR and 8 months, respectively (HR: 0.07, P &amp;lt; .001). Of note, only 3 of the 130 (2%) double negative MRD patients relapsed thus far. The negative predictive value (NPV) of a double negative MRD detection in PB/serum using BloodFlow/QIP-MS and MRD negativity in BM using NGF was 86%. CONCLUSIONS This is the first study of multimodal minimally invasive MRD assessment in MM. Our results show that BloodFlow, CloneSight and QIP-MS are empowered to detect MRD with high sensitivity in PB, cfDNA and serum. The presence of CTCs, mutations and M-component was systematically associated with dismal PFS. The complementarity between these methods achieved a high NPV of MRD negativity in BM, and enabled the identification of multimodal MRD negative pts with very low risk of relapse. Thus, this study paves the way towards minimally invasive MRD assessment in MM pts on maintenance or observation.

Current and Future PET Imaging for Multiple Myeloma.

Positron emission tomography (PET) is an imaging modality used for the noninvasive assessment of tumor staging and response to therapy. PET with 18F labeled fluorodeoxyglucose (18F-FDG PET) is widely used to assess the active and inactive lesions in patients with multiple myeloma (MM). Despite the availability of 18F-FDG PET for the management of MM, PET imaging is less sensitive than next-generation flow cytometry and sequencing. Therefore, the novel PET radiotracers 64Cu-LLP2A, 68Ga-pentixafor, and 89Zr-daratumumab have been developed to target the cell surface antigens of MM cells. Furthermore, recent studies attempted to visualize the tumor-infiltrating lymphocytes using PET imaging in patients with cancer to investigate their prognostic effect; however, these studies have not yet been performed in MM patients. This review summarizes the recent studies on PET with 18F-FDG and novel radiotracers for the detection of MM and the resulting preclinical research using MM mouse models and clinical studies. Novel PET technologies may be useful for developing therapeutic strategies for MM in the future.

Carfilzomib, lenalidomide, and dexamethasone (KRd) versus elotuzumab and KRd in transplant-eligible patients with newly diagnosed multiple myeloma: Post-induction response and MRD results from an open-label randomized phase 3 study.

8000 Background: In medically fit patients with newly diagnosed (ND) multiple myeloma (MM), triplet or quadruplet induction regimens, high-dose chemotherapy (HDT) and autologous stem cell transplant (ASCT) remain a standard of care. Carfilzomib (K), lenalidomide (R) and dexamethasone (d, KRd) induction/consolidation has proven exceptionally effective. Elotuzumab (E), an anti-SLAMF-7 monoclonal antibody bears favorable tolerability in relapsed/refractory MM while its role in NDMM remains unclear. Methods: Transplant-eligible (TE) NDMM patients (pts) up to 70 years (yrs) were randomized 1:1 to receive six cycles (C) of KRd or E-KRd, (chemomobilisation for ASCT after C3), single (tandem, if &lt;CR/high risk NDMM) HDT/ASCT, followed by four consolidation C (KRd/E-KRd) and R or ER maintenance. Induction (IND, 28-day C) consisted of K on D1/2, 8/9 and 15/16 (20 mg/m² IV on D 1/2 in C1 and 36 mg/m² thereafter), R (25 mg PO, D1-21) and d (36/40 mg D 1, 8, 15, 22). E was given on D 1, 8, 15, and 22 (C1/C2) and on D 1 and 15 (C3-6; 10 mg/kg IV). After IND, pts underwent restaging when bone marrow was analyzed for minimal residual disease (MRD) by next-generation flow cytometry. The first co-primary endpoint of the study was the rate of pts who were in ≥ VGPR and were MRD negative. The study is registered as NCT03948035. Results: 579 pts (574 of whom received treatment) were randomized between 08/2018 and 10/2021 at 52 sites and included in the intent-to-treat analysis. Median age was 60 (range, 31-71) yrs.15.4% had ISS stage III disease. 108/459 evaluable pts (23.5%) had high-risk cytogenetics (del[17p]; t[4;14]; t[14;16]; ≥ 3 1q21 copies). 525/574 pts (91.5%) completed 6 IND cycles. MRD negativity and ≥ VGPR was achieved in 145 of E-KRd (49.8%) and 102 (35.4%) of KRd patients, respectively (p=.0005). 212 (72.9%) of E-KRd versus 177 (62.5%) of KRd patients experienced treatment-emergent AEs (TEAEs) of ≥ grade 3. Febrile neutropenia occurred in 26 (6.4%) E-KRd versus 14 (4.9%) KRd pts. Grade 3/4 thrombocytopenia was seen in 36 (12.4%) E-KRd and 30 (10.6%) KRd pts. Pneumonia occurred in 24 E-KRd (8.2%) and 18 KRd (6.4%) pts. Grade 3/4 cardiac events occurred in 16 E-KRd (5.5%) and of grades 3 to 5 in 16 (5.7%) of KRd pts. 12 E-KRd (4%) and 9 KRd (3.2%) pts had COVID-19 infections with one grade 5 event each (0.3% and 0.4%, respectively). Three pts on E-KRd (1.0%) versus 7 on KRd (2.5%) died on induction due to infections (N=3), MM progression (2), AML (1), a cardiac event (N=1), other (N=3). Conclusions: In this study, the addition of elotuzumab to KRd significantly improved the rate of early, deep (≥ VGPR) MRD-negative remission in TE NDMM. E-KRd pts had slightly more TEAEs. Events were mainly hematotoxicity. To the best of our knowledge, this is the first study to show a benefit for the addition of elotuzumab to a front-line regimen. Clinical trial information: NCT03948035 .

Impact of clonal plasma cells in autografts on outcomes in high-risk multiple myeloma patients

Most patients with multiple myeloma (MM) undergoing autologous hematopoietic stem cell transplantation (autoHCT) eventually relapse, perhaps due to the presence of clonal plasma cells (CPC) in the autograft. We conducted a retrospective analysis to evaluate the impact of CPC in the autograft on the outcomes of high-risk chromosomal abnormalities (HRMM) patients undergoing autoHCT between 2008 and 2018. Patients were divided into CPC+ or CPC− in the autograft by next-generation flow cytometry (NGF). There were 75 CPC + autografts (18%) and 341 CPC− (82%). The CPC + group was less likely to achieve MRD-negative complete remission post-transplant (11% vs. 42%; p < 0.001). Median progression free survival (PFS) and overall survival (OS) were (12.8 vs. 32.1 months) and (36.4 vs. 81.2 months) in the CPC + and CPC− groups, respectively (both p < 0.001). Also in the subset of patients with MRD-negative ≥VGPR prior to autoHCT, those with CPC + autografts had inferior PFS (HR 4.21, p = 0.006) and OS (HR 7.04, p = 0.002) compared to CPC-. In multivariable analysis, the degree of CPC positivity in the autograft was independently predictive of worse PFS (HR 1.50, p = 0.001) and OS (HR 1.37, p = 0.001). In conclusion, both the presence and degree of CPC in the autograft were highly predictive of inferior PFS and OS.