Opportunities and challenges for MRD assessment in the clinical management of multiple myeloma

Measurable residual disease (MRD) assessment is, from the methodological point of view, ready for prime time in multiple myeloma (MM). Abundant evidence underscores the value of MRD status determined using highly sensitive next-generation flow cytometry and next-generation sequencing tests in evaluating response to treatment and, therefore, prognosis in patients with this disease. MRD response assessment and monitoring might present a range of opportunities for individualized patient management. Moreover, the considerable amounts of high-quality and standardized MRD data generated in clinical trials have led to the acceptance of MRD negativity as an early end point for accelerated regulatory approval of treatments for MM. The data leave no doubt that the efficacy of new regimens in inducing deeper and durable MRD-negative responses is connected with prolonged survival. Yet, several evidential, technical and practical challenges continue to limit the implementation of MRD-guided treatment strategies in routine practice, and the use of MRD as a surrogate end point remains controversial to some. In this Review, we draw on past and present research to propose opportunities for overcoming some of these challenges, and to accelerate the use of MRD assessment for improved clinical management of patients with MM.

Are we maintaining minimal residual disease in myeloma?

Minimal residual disease (MRD) has emerged as an important prognostic maker in patients with multiple myeloma at different stages of their treatment. Moreover, it is being increasingly incorporated as an endpoint in various clinical trials. Since maintenance therapy is an integral part of myeloma treatment, especially in the upfront setting post autologous transplantation, it is imperative to understand the role of MRD testing in the maintenance stetting. This review aims to examine the utility and dynamics of MRD testing in order to elucidate its prognostic role and possible incorporation in clinical decision making processes.

Sustained bone marrow and imaging MRD negativity for 3 years drives discontinuation of maintenance post-ASCT in myeloma

ABSTRACT

Discontinuation of lenalidomide maintenance after autologous stem cell transplantation is a burning question within the multiple myeloma (MM) community, especially after the inclusion of minimal residual disease (MRD) in the disease response criteria. In this prospective study, we evaluated the conversion to MRD positivity, the treatment-free survival (TFS), and the progression-free survival (PFS) in 52 patients with MM who discontinued lenalidomide maintenance after achieving sustained bone marrow and imaging MRD negativity for 3 years. Patients who developed MRD positivity after lenalidomide discontinuation restarted lenalidomide maintenance at the same dose. The median follow-up from lenalidomide discontinuation was 3 years. Overall, 12 (23%) patients obtained MRD positivity and restarted lenalidomide maintenance. Only 4 (7.6%) patients progressed; 3 had a biochemical progression and 1 had a clinical progression. The overall median PFS was not reached, whereas the 7-year PFS from diagnosis was 90.2%. The 1-, 2-, and 3-year TFS rates were 93.9%, 91.6%, and 75.8%, respectively, whereas the 1-, 2-, and 3-year landmark PFS rates from maintenance discontinuation (study entrance) were 96.0%, 96.0%, and 92.9%, respectively. There were no statistically significant associations among age, sex, Second Revision International Staging System, type of induction therapy, and use of consolidation therapy and the effect outcomes of PFS and TFS. We conclude that maintenance discontinuation after 3 years of sustained marrow and imaging MRD negativity is associated with low rates of MRD conversion and progressive disease. Thus, in the era of modern antimyeloma treatments, a subgroup of patients may remain treatment free while in complete remission without jeopardizing disease response.

Prognostic Value of Post-Transplant MRD Negativity in Standard Versus High- and Ultra-High-Risk Multiple Myeloma Patients

Background: Cytogenetic abnormalities and the persistence of minimal residual disease (MRD) following autologous stem cell transplantation (ASCT) are two established prognostically unfavorable biomarkers in multiple myeloma (MM). Previous studies have shown that post-transplant MRD status is a powerful predictor of progression-free survival (PFS) and overall survival (OS). However, the impact of MRD remains poorly characterized in MM patients with high- or ultra-high-risk cytogenetics. Objectives: This study investigated the prognostic value of post-transplant MRD in standard- versus high- and ultra-high-risk MM. To this aim, we performed a retrospective analysis of 137 MM patients who underwent high-dose chemotherapy (HDCT) and ASCT at our institution between January 2019 and December 2021. Cytogenetics were assessed by fluorescence in situ hybridization. High-risk genomic alterations included del(17p), t(4;14), t(14;16), t(14;20), gain(1q), and TP53 mutations, with two or more alterations defining the ultra-high-risk category. MRD was assessed in bone marrow aspirates post-ASCT using flow cytometry. Results: Eighty-two (60%) patients were categorized as being at standard risk, forty (29%) as high risk, and fifteen (11%) as ultra-high risk. Median follow-up was 47 months. MRD negativity was achieved in 76 (55%) patients. At 48 months, the overall PFS rate was 61% (72%, 50%, and 32% for the standard-, high-, and ultra-high-risk subgroups, respectively; p = 0.0004), while the OS rate was 85% (89%, 79%, and 80% in standard-, high-, and ultra-high-risk MM patients, respectively; p = 0.1494). Within the standard-risk subgroup, longer PFS was observed for patients achieving MRD negativity (p = 0.0172). High- and ultra-high-risk patients showed no significant differences in PFS when stratified by MRD status, possibly due to prompt progression to MRD positivity. Conclusions: Our results suggest that high- and ultra-high-risk MM patients might benefit from closer response monitoring, including dynamic MRD assessment. Further, high- and ultra-high-risk patients might require a more intensive peri-transplant treatment.

Radiomics and Artificial Intelligence Landscape for [18F]FDG PET/CT in Multiple Myeloma

[18F]FDG PET/CT is a powerful imaging modality of high performance in multiple myeloma (MM) and is considered the appropriate method for assessing treatment response in this disease. On the other hand, due to the heterogeneous and sometimes complex patterns of bone marrow infiltration in MM, the interpretation of PET/CT can be particularly challenging, hampering interobserver reproducibility and limiting the diagnostic and prognostic ability of the modality. Although many approaches have been developed to address the issue of standardization, none can yet be considered a standard method for interpretation or objective quantification of PET/CT. Therefore, advanced diagnostic quantification approaches are needed to support and potentially guide the management of MM. In recent years, radiomics has emerged as an innovative method for high-throughput mining of image-derived features for clinical decision making, which may be particularly helpful in oncology. In addition, machine learning and deep learning, both subfields of artificial intelligence (AI) closely related to the radiomics process, have been increasingly applied to automated image analysis, offering new possibilities for a standardized evaluation of imaging modalities such as CT, PET/CT and MRI in oncology. In line with this, the initial but steadily growing literature on the application of radiomics and AI-based methods in the field of [18F]FDG PET/CT in MM has already yielded encouraging results, offering a potentially reliable tool towards optimization and standardization of interpretation in this disease. The main results of these studies are presented in this review.

Cytogenetic risk stratification combined with minimal residual disease status influences the therapeutic outcome and prognosis of multiple myelomas

To explore the value of cytogenetic risk stratification combined with minimal residual disease (MRD) status in predicting the therapeutic efficacy and prognosis for multiple myeloma (MM). From January 2017 to December 2023, 73 cases of newly diagnosed MM were recruited. Cytogenetic risks were stratified according to the results of fluorescence in situ hybridization (FISH); MRD status and clinical data were analyzed. The progression-free survival (PFS) and overall survival (OS), and their influencing factors were evaluated. During the median follow-up period of 30 (4-65) months, the median progression-free survival (PFS) and overall survival (OS) were 38 (95% CI 29.7, 46.3) months and 55 (95% CI 45.9, 64.1) months, respectively. In our cohort, the 3-year PFS rate was 51.0% and the 3-year OS rate was 71.0%. According to the MRD status, 31 MM patients were assigned to the MRD-positivity group and 42 to the MRD-negativity group. Significant differences were detected in the median PFS (30 months vs. 45 months, χ2 = 7.747, P = 0.005) and OS (34 months vs. 59 months, χ2 = 8.683, P = 0.003) between groups. Subgroup analyses based on the cytogenetic risk stratification (standard risk [SR] and high risk [HR]) showed that MM patients in the SR/MRD-negativity subgroup did not reach the median PFS and OS, and the median PFS (42 months vs. 33 months, P = 0.093) and OS (59 months vs. 42 months, P = 0.703) were similar between the SR/MRD-positivity and HR/MRD-negativity subgroups. In comparison to the HR/MRD-negativity subgroup, the median PFS (20 months vs. 33 months, P = 0.031) and OS (33 months vs. 42 months, P = 0.032) were significantly shorter in the HR/MRD-positivity group. Multivariate analysis showed that MRD-positivity was an independent risk factor for PFS (HR 2.874, 95% CI 1.452, 5.689; P = 0.008) and OS (HR 3.504, 95% CI 1.599, 7.676; P = 0.002) of MM. MRD status is a powerful prognostic indicator of PFS and OS in MM, but its performance is inferior to cytogenetic risk stratification. More high-risk cytogenetic abnormalities (HRCAs) indicate a worse prognosis of MM, while MRD-negativity improves HRCA-associated prognosis of MM. We recommend a risk stratification by assessing MRD status combined with HRCAs in MM patients, thus favoring the design of individualized treatment.

Minimal Residual Disease-Based End Point for Accelerated Assessment of Clinical Trials in Multiple Myeloma: A Pooled Analysis of Individual Patient Data From Multiple Randomized Trials

PURPOSE

Newly approved drugs and combinations treating multiple myeloma (MM) have resulted in substantial improvements in patients' survival. To deliver rapid access to newer therapies, an earlier end point to expedite clinical trials is needed. Our objective was to evaluate the minimal residual disease-negative complete response (MRD-CR) as an intermediate end point for progression-free survival (PFS) and overall survival (OS) in newly diagnosed (ND) transplant-eligible (NDTE) patients, ND transplant-ineligible (NDTinE) patients, and patients with relapsed/refractory (RR) MM.

PATIENTS AND METHODS

Individual patient data from 20 randomized multicenter trials were collected. Eleven studies (4,773 patients) with sufficient data were analyzed to evaluate whether 9- or 12-month MRD-CR classified at a 10-5 threshold could be reasonably likely to predict the clinical benefit of new agents regarding PFS and OS. Global odds ratio (OR) was estimated using the bivariate Plackett Copula model. Supportive evaluation included correlations of the treatment effects on MRD-CR end points and PFS/OS, evaluated by both linear regression (R2weighted least squared) and Copula (R2Copula) models.

RESULTS

The analysis demonstrated that both 9- and 12-month MRD-CR strongly correlated with PFS at patient level in NDTE patients, NDTinE patients, and patients with RRMM. Global ORs ranged from 3.06 to 16.24, all with 95% CIs excluding 1.0. Encouraging trial-level correlations (R2, 0.61-0.70) were observed by pooling three populations and were stronger (R2, 0.67-0.78) in the ND population. Similar results were observed for OS.

CONCLUSION

Our findings provided the support for use of MRD-CR classified at a 10-5 threshold at either 9 or 12 months after starting of the treatment, as an intermediate end point to support accelerated approvals, in future trials in NDTE patients, NDTinE patients, and patients with RRMM.

Minimal residual disease in multiple myeloma

Minimal Residual Disease (MRD) in multiple myeloma has emerged as a significant prognostic factor, guiding treatment strategies and enhancing patient outcomes. Despite advancements in therapies such as proteasome inhibitors, immunomodulatory drugs, monoclonal antibodies, CAR-T cell therapy, and bispecific antibodies, complete eradication of malignant plasma cells remains challenging. MRD refers to a small number of residual cancer cells that persist after treatment and require sensitive methods like next-generation flow cytometry (NGF) and next-generation sequencing (NGS) for detection. MRD negativity has been associated with improved progression-free survival (PFS) and overall survival (OS), making it a key marker in clinical trials. The clinical utility of MRD lies in its ability to predict outcomes, with sustained MRD negativity linked to prolonged survival. Furthermore, it will likely help in tailoring treatment approaches, such as therapy escalation for high-risk patients or de-escalation for those achieving MRD negativity. Despite its prognostic value, challenges remain in standardizing MRD testing, ensuring its widespread availability, and addressing variability in results based on different detection methods. Future research aims to refine MRD-guided treatment and explore novel detection techniques, such as liquid biopsies, to improve patient monitoring in multiple myeloma.

Evaluating Minimal Residual Disease Negativity as a Surrogate Endpoint for Treatment Efficacy in Multiple Myeloma: A Meta-Analysis of Randomized Controlled Trials

This meta-analysis examined the association between minimal residual disease (MRD) negativity and survival outcomes in 15 304 patients with multiple myeloma (MM) enrolled in randomized controlled trials published until June 2, 2024. Overall, there was a significant, negative and strong association between MRD negativity odds ratios and survival hazard ratios (β_PFS = -0.20, p < 0.001, β_OS = -0.12, p = 0.023). These associations remained significant for newly diagnosed patients (β_PFS = -0.35, p < 0.001), and they were consistent but not significant for relapsed/refractory patients (β_PFS = -0.06, p = 0.635). Sustained MRD negativity at 1 year was strongly correlated with prolonged PFS (β_PFS = -0.30, p < 0.001). In conclusion, this comprehensive meta-analysis supports MRD as a surrogate for survival in MM.

Dissecting the high-risk property of 1q gain/amplification in patients with newly diagnosed multiple myeloma

1q gain/amplification (1q+) is the most common cytogenetic abnormality (CA), with a frequency of 30-50% in patients with newly diagnosed multiple myeloma (NDMM). Although accumulating evidence supports 1q+ as a "high-risk" CA (HRCA), several issues remain to be addressed to understand its true prognostic property. We retrospectively analyzed a cohort of 934 patients with NDMM from three centers in China, who had baseline data available for 1q+ [including 1q21 gain (3 copies) and amplification (> 3 copies)] detected by fluorescence in situ hybridization in isolated CD138+ cells, and who received first-line treatment with novel agents including proteasome inhibitors, immunomodulatory drugs, or both. Minimal residue disease (MRD) was assessed using next-generation flow cytometry. In this cohort, 1q+ patients accounted for 53% of all patients. 1q+ patients were characterized by larger tumor burden, more advanced diseases, adverse complications, and frequent concurrence of other CAs (particularly HRCAs) at diagnosis. Concurrence of HRCAs [del(17p), t(4;14), and t(14;16); known as double-hit MM], but not standard-risk CA, markedly worsened the outcome of 1q+ patients, compared to those with 1q+ only (progression-free survival/PFS: hazard ratio/HR 1.63, 95% confidence interval/CI 1.21-2.20, P = 0.0013; overall survival/OS: HR 1.96, 95% CI 1.40-2.74, P < 0.0001). 1q+ modulated the risk levels defined by the Revised International Staging System (R-ISS). Although the overall response rate was not significantly different between patients with or without 1q+, fewer 1q+ patients achieved complete response or better and minimal residue disease negativity (MRD-). MRD- attainment substantially prolonged PFS (HR 4.03, 95% CI 2.59-6.29, P < 0.0001) and OS (HR 3.72, 95% CI 2.24-6.19, P < 0.0001) of 1q+ patients. While 1q+ patients had relatively shorter MRD- duration, sustained MRD- significantly improved the PFS and OS of 1q+ patients. Together, 1q+ is an HRCA and a major component of double-hit MM, while the risk-adapted and MRD-tailored therapy may best help manage this high-risk population.

Evidence-based Korean guidelines for the clinical management of multiple myeloma: addressing 12 key clinical questions

Multiple myeloma (MM), a hematological malignancy, is characterized by malignant plasma cell proliferation in the bone marrow. Recent treatment advances have significantly improved patient outcomes associated with MM. In this study, we aimed to develop comprehensive, evidence-based guidelines for the diagnosis, prognosis, and treatment of MM. We identified 12 key clinical questions essential for MM management, guiding the extensive literature review and meta-analysis of the study. Our guidelines provide evidence-based recommendations by integrating patient preferences with survey data. These recommendations include current and emerging diagnostic tools, therapeutic agents, and treatment strategies. By prioritizing a patient-centered approach and rigorous data analysis, these guidelines were developed to enhance MM management, both in Korea and globally.

Soluble B-cell maturation antigen levels for disease monitoring in oligosecretory and nonsecretory relapsed multiple myeloma

ABSTRACT

Soluble B-cell maturation antigen (sBCMA) is elevated on multiple myeloma (MM) cells. We investigated whether sBCMA levels correlated with other myeloma tumor volume indicators and its utility in monitoring oligosecretory/nonsecretory (O-S/Non-S) MM. In 115 patients with newly diagnosed MM, sBCMA was compared with M-protein levels, bone marrow plasma cells (BMPCs), circulating tumor cells (CTCs), and total diffusion volume (tDV; estimated by whole-body diffusion-weighted magnetic resonance imaging) at diagnosis. sBCMA levels increased significantly with International Staging System stage, chromosome 1q21 gain/amplification, and CTC levels. sBCMA also correlated strongly with %BMPC (r = 0.65) and moderately with tDV (r = 0.55) and paraprotein levels (involved immunoglobulin in IgG and IgA subtypes, r = 0.44 and 0.4; involved free light-chain levels in light-chain-only MM, r = 0.61, all P < .05). Longitudinal changes in sBCMA were consistent with disease status in both 17 O-S/Non-S and other secretory MM cases. Furthermore, sBCMA levels increased as early as 6 months prerelapse in almost all O-S/Non-S relapsed patients. Thus, sBCMA correlates strongly with total tumor volume in MM, as assessed using different modalities. We suggest that sBCMA is useful, not only for monitoring responses in patients with O-S/Non-S MM but also for early relapse detection and prediction.

Is t(11;14) Always a Standard-Risk Cytogenetic Abnormality? Results From GEM05MENOS65 and GEM2012 PETHEMA/GEM Transplantation Trials

PURPOSE

Recent studies describe inferior outcomes in newly diagnosed multiple myeloma (NDMM) patients with t(11;14) treated with novel agents.

MATERIALS AND METHODS

We analyzed 240 NDMM transplant eligible (TE) patients who received triplet induction regimen in the GEM05MENOS65 (bortezomib, thalidomide and dexamethasone - VTD) and GEM2012 (bortezomib, lenalidomide and dexamethasone - VRD) clinical trials.

RESULTS

t(11;14) and standard risk (SR) non-t(11;14) were prevalent in 51 (21%) and 189 (79%) patients, respectively. Patients with t(11;14) treated with VTD had a lower overall response rate (ORR) (84% vs. 97%, P = .044) and lower negative minimal residual disease (MRD) (7.7% vs 35.1%, P = .049) after induction, as compared to SR non-t(11;14), while there were no differences in ORR (87% vs. 89%) or negative MRD (13.2% vs. 24.4%, P = .2) for these 2 subgroups in patients treated with VRD. The presence of t(11;14) impacted negatively on PFS in patients with VTD (hazard ratio 2.70; P = .005), while no differences were observed in those treated with VRD.

CONCLUSION

TE NDMM patients harboring t(11;14) had an inferior outcome compared with SR patients when receiving induction therapy with VTD while no differences were observed when receiving a lenalidomide containing regimen.

A Pilot Study of UM171-Expanded Cord Blood Grafts for Tandem Auto/Allogeneic Hematopoietic Cell Transplant in High and Ultra-High-Risk Myeloma Patients

Multiple myeloma (MM) remains associated with a poor outcome, particularly in patients with advanced disease and high-risk (HR) cytogenetics. To date, the only curative treatment is allogeneic (allo) hematopoietic cell transplantation (HCT), but high incidences of graft versus host disease (GVHD), nonrelapse mortality (NRM) and disease progression remain important obstacles. Cord blood (CB) transplantation has been associated with low rates of relapse and chronic (c) GVHD, but its use has declined because of high incidences of infections, severe acute GVHD and high NRM. In other hematologic malignancies, UM171-expanded CB transplants have led to improved outcomes, allowing for the selection of smaller, better HLA-matched units. We aimed to investigate the safety and feasibility of single UM171-expanded single CB unit transplantation in frontline tandem auto/allo HCT for HR/ultra-HR MM patients. Newly diagnosed MM patients ≤ 65 years with an ISS stage II/III and del(17p), t(4;14), t(14;16), t(14;20), del(1p) or +1q, R-ISS 3, ≥ 2 cytogenetic abnormalities, or plasma cell leukemia without a sibling donor and availability of a 5-7/8 matched CB graft with ≥ 0.5 x 105 CD34+/kg and ≥ 1.5 x 107 TNCs/kg were eligible to this phase I/II prospective study (ClinicalTrials.gov NCT03441958). After induction and autologous HCT, patients received a reduced intensity conditioning regimen and were infused with 7-day UM171-expanded CD34+ cells, along with the lymphocytes contained in the CD34-negative fraction. The primary endpoints were feasibility of UM171 expansion, safety, kinetics of engraftment, incidences and maximum grades of acute and cGVHD at 1 and 2 years, assessment of measurable residual disease (MRD) and quality of life (QoL). Between 05/2018 and 11/2021, 20 patients were enrolled. One patient had an unsuccessful CB expansion with UM171, leaving 19 patients with a median age of 56 years. Median CD34+ cell dose infused after expansion was 4.62 x 106/kg (range: 0.79 to 5.76). Median times to achieve absolute neutrophil counts of 0.1 and 0.5 x 109/L were D+6 and D+10.5; median time to reach ≥ 20 x 109/L platelets was D+36. Full donor chimerism was achieved in all cell lineages by D+120 in recipients of reduced intensity conditioning. Cumulative incidences of grade II-IV, grade III-IV acute GVHD and moderate/severe cGVHD at 12 months were 68.4% (95% CI: 46 to 90), 5.3% (95% CI: 0% to 16%), and 10.5% (95% CI: 0% to 25%), respectively. With a median follow-up of 2.9 years (range: 0.46 to 5.3), cumulative incidences of relapse, PFS, OS and NRM at 3 years were 36.8% (95% CI: 14 to 59), 47.4% (95% CI: 29 to 76), 68.4% (95% CI: 50 to 93) and 15.8% (95%CI: 0 to 33), respectively. Median time to complete immunosuppression discontinuation was D+238. No unexpected adverse events were observed. Only one of 7 patients alive at 2 years with negative MRD at transplant has relapsed. Non-relapsing patients had a QoL after transplant similar to the general population. UM171-expanded CB transplant in HR/ultra-HR myeloma patients is feasible and allows the use of single CB units with a low risk of cGVHD. Patients with negative pretransplant MRD might benefit most from a UM171-expanded CB transplant.

Real-World Evidence on Prognostic Value of MRD in Multiple Myeloma Using Flow Cytometry

Minimal residual disease (MRD) is one of the most important prognostic factors in multiple myeloma (MM) and a valid surrogate for progression-free survival (PFS) and overall survival (OS). Recently, MRD negativity was approved as an early clinical endpoint for accelerated drug approval in MM. Nevertheless, there is limited evidence of MRD utility in real-world setting. In this retrospective multicenter study, we report outcomes of 331 newly diagnosed MM patients with MRD evaluation at Day+100 after autologous stem cell transplantation using flow cytometry with a median limit of detection of 0.001%. MRD negativity was reached in 47% of patients and was associated with significantly prolonged median PFS (49.2 months vs. 18.4 months; hazard ratios (HR) = 0.37; p < 0.001) and OS (not reached vs. 74.9 months; HR = 0.50; p = 0.007). Achieving MRD negativity was associated with PFS improvements regardless of age, International Staging System (ISS) stage, lactate dedydrogenase (LDH) level, or cytogenetic risk. Importantly, MRD positive patients benefited from lenalidomide maintenance versus no maintenance (18-months PFS: 81% vs. 46%; HR = 0.24; p = 0.002) while in MRD negative patients such benefit was not observed (p = 0.747). The outcomes of our real-world study recapitulate results from clinical trials including meta-analyses and support the idea that MRD positive patients profit more from lenalidomide maintenance than MRD negative ones.

Clinical significance of complete remission and measurable residual disease in relapsed/refractory multiple myeloma patients treated with T-cell redirecting immunotherapy

The impact of measurable residual disease (MRD) in relapse/refractory multiple myeloma (RRMM) patients treated with T-cell redirecting immunotherapy is uncertain. We analyzed MRD dynamics using next-generation flow in 201 patients treated in clinical trials with chimeric antigen receptor (CAR) T cells and T-cell engagers (TCE). Achieving MRD negativity at 10-6 was associated with 89% reduction in the risk of progression and/or death. Survival outcomes were improved in patients with sustained versus transient MRD negativity and were dismal in those who remained MRD positive. The intent-to-treat MRD negative rates were higher in patients treated with CAR T cells versus TCE. However, among patients achieving MRD negativity, there were no differences in survival outcomes when stratified according to treatment with CAR T cells versus TCE. In multivariate analysis including the number of prior lines of treatment, International Staging System, cytogenetic risk, extramedullary disease and type of T-cell redirecting immunotherapy, only the complete remission (CR) and MRD statuses showed independent prognostic value for progression-free and overall survival. In conclusion, our study shows that deep and sustained MRD negative CR is the most relevant prognostic factor and should be considered as the treatment endpoint in RRMM patients treated with CAR T cells and TCE.

The significance of free light-chain ratio in light-chain monoclonal gammopathy of undetermined significance: a flow cytometry sub-study of the iStopMM screening study

Light-chain (LC) monoclonal gammopathy of undetermined significance (MGUS) is a precursor of multiple myeloma (MM) and related conditions. LC-MGUS is characterized by free light-chain (FLC) levels outside defined reference intervals, indirectly indicating underlying plasma cell (PC) monoclonality. Next-generation flow cytometry (NGF) was used to evaluate clonal PC presence in bone marrow (BM) samples from individuals with LC-MGUS in the iStopMM study, aiming to assess the predictive value of the FLC ratio for clonal PC presence and its prognostic implications. BM samples from 61 individuals with LC monoclonal gammopathy were analyzed. Clonal plasma cells were detected in 53.6% of LC-MGUS samples (n = 28) and in all samples from individuals with more advanced conditions (n = 33). The FLC ratio was predictive of clonal PC presence for kappa-involved FLC ratios (p < 0.05; n = 42), with an optimal cutoff of 3.15 (96.7% sensitivity, 91.7% specificity). Of 195 individuals with kappa-involved LC-MGUS in follow-up within the iStopMM study, none with FLC ratios >1.65 to 3.15 progressed to MM (n = 124), whereas 4/71 (5.6%) with FLC ratios >3.15 progressed over median follow-up of 55 months. These findings support using a kappa-involved FLC ratio cutoff of >3.15 to more accurately identify individuals at increased risk of developing symptomatic PC disorders.

EANM guidelines on the use of [18F]FDG PET/CT in diagnosis, staging, prognostication, therapy assessment, and restaging of plasma cell disorders

We provide updated guidance and standards for the indication, acquisition, and interpretation of [18F]FDG PET/CT for plasma cell disorders. Procedures and characteristics are reported and different scenarios for the clinical use of [18F]FDG PET/CT are discussed. This document provides clinicians and technicians with the best available evidence to support the implementation of [18F]FDG PET/CT imaging in routine practice and future research.

Measurable Residual Disease in Mantle Cell Lymphoma: The Unbearable Lightness of Being Undetectable

PURPOSE OF REVIEW

This paper evaluates the benefits and limitations of detecting measurable residual disease (MRD) in mantle cell lymphoma (MCL) and assesses its prognostic value. It also aims to highlight the importance of detecting low MRD levels post-treatment and their application in clinical practice.

RECENT FINDINGS

Recent studies show that MRD levels predict relapse and survival outcomes in hematologic neoplasms, including MCL. RT-qPCR is currently the most used method due to its high reproducibility and sensitivity. Ideal MRD detection should be highly sensitive, cost-effective, and applicable to a wide demographic of patients. This paper concludes that MRD detection has prognostic value in MCL but faces limitations in sensitivity and specificity. Further research is needed to establish the significance of low MRD levels before integrating these methods into clinical practice. Improved MRD detection technologies and understanding their impact on clinical outcomes will guide better patient management in MCL.

Expression profile of Bcl-2 family proteins in newly diagnosed multiple myeloma patients

Antiapoptotic Bcl-2 family proteins are involved in myeloma cell survival. To date, their expression in multiple myeloma (MM) patients has mostly been analyzed at the RNA level. In the present study, we quantified for the first time the protein expression of the Bcl2-family members using a capillary electrophoresis immunoassay in 120 newly diagnosed MM patients, aged ≤65 years, treated in the context of the PETHEMA/GEM2012 study. We found that the pattern of expression of Bcl-2 family proteins was highly heterogeneous among patients. Although cases with t(11;14) had significantly higher levels of Bcl-2/Bcl-xL and Bcl-2+Bim+Bax/Bcl-xL ratios than those without t(11;14), the presence of this translocation was not synonymous with such high levels of expression. Conversely, some patients with other genetic alterations also showed higher levels of those ratios. Survival analysis revealed that the high expression of Bad and Puma proteins was associated with significantly longer overall survival (p = 0.001 and p < 0.001, respectively). Bcl-2 protein ratios predicting sensitivity to venetoclax in vitro were also able to distinguish patients with shorter time to progression after triplet-based induction therapy and ASCT. This is the first study to assess the expression of the most important Bcl-2 family proteins by a quantitative method in a large set of MM patients according to their cytogenetic abnormalities. We shed light on the impact of these proteins on MM prognosis, which could help to consider the levels of proteins involved in apoptosis in the development of new therapeutic strategies.

Measurable residual disease (MRD)-testing in haematological cancers: A giant leap forward or sideways?

Measurable residual disease (MRD)-testing is used in many haematological cancers to estimate relapse risk and to direct therapy. Sometimes MRD-test results are used for regulatory approval. However, some people including regulators wrongfully believe results of MRD-testing are highly accurate and of proven efficacy in directing therapy. We review MRD-testing technologies and evaluate the accuracy of MRD-testing for predicting relapse and the strength of evidence supporting efficacy of MRD-guided therapy. We show that at the individual level MRD-test results are often an inaccurate relapse predictor. Also, no convincing data indicate that increasing therapy-intensity based on a positive MRD-test reduces relapse risk or improves survival. We caution against adjusting therapy-intensity based solely on results of MRD-testing.

Dynamics of minimal residual disease and its clinical implications in multiple myeloma: A retrospective real-life analysis

BACKGROUND

Minimal residual disease (MRD) testing is a promising approach to tailor the treatment of multiple myeloma (MM). However, several major concerns remain to be addressed before moving it into daily practice, most of which stem from the dynamic nature of the MRD status. Thus, it is crucial to understand the MRD dynamics and propose its clinical implications.

METHODS

We retrospectively analysed the data of patients with newly diagnosed MM (NDMM) who had flow cytometry-based MRD tests at multiple time points after initiation of therapy. The impact of undetectable MRD (including attainment, duration and loss) on clinical outcomes was analysed.

RESULTS

In a cohort of 220 patients with NDMM, attainment of MRD- offered favourable outcomes (P < 0.0001 for both progression-free survival (PFS) and overall survival (OS)), regardless of baseline risk factors. Notably, MRD- duration ≥12 months was associated with an 83 % (95 % confidence interval (CI), 0.09-0.34; P < 0.0001) or 69 % (95 % CI, 0.13-0.76; P = 0.0098) reduction in risk of progression/death or death, while the longer MRD- was sustained, the better the outcome was. Loss of MRD- led to poor PFS (hazard ratio (HR) 0.01, 95 % CI 0-0.06, P < 0.0001) and OS (HR 0.03, 95 % CI 0-0.24, P = 0.0008). Most patients (70 %) who lost MRD- status carried high-risk cytogenetic abnormalities (HRCAs). While MRD- was temporally inconsistent with conventional therapeutic responses (eg ≥ complete remission or very good partial response), it predicted disease progression or recurrence more robustly than the latter. Last, the predictive value of the MRD status was independent of baseline risk factors (eg high-risk cytogenetic abnormality, International Staging System (ISS) or Revised (R-)ISS staging).

CONCLUSIONS

Longitudinal assessment of MRD during the treatment course and follow-up is required for monitoring disease progression or relapse, to guide treatment decisions. Accordingly, a prospective study is currently ongoing to investigate the feasibility and benefit of the MRD-tailored therapy according to the longitudinal changes of the MRD status.

Evaluation of the Prognostic Value of the Mayo Additive Staging System and Minimal Residual Disease in Newly Diagnosed Multiple Myeloma Patients

INTRODUCTION

This study aimed to evaluate the prognostic value of the Mayo additive staging system (MASS) and minimal residual disease (MRD) in newly diagnosed multiple myeloma (NDMM) patients.

METHODS

A total of 238 NDMM patients were enrolled in Beijing Chaoyang Hospital. Fluorescence in-situ hybridization and next-generation flow cytometry were used to examine cytogenetic abnormalities and MRD, respectively. The patients were classified into three groups to compare the effects on progression-free survival (PFS). Univariate and multivariate analyses were applied to identify the survival-related factors.

RESULTS

For MASS group, the PFS was significant difference in MASS I, II, and III patients (p = 0.0006); the patients with sustained MRD-negative, non-sustained MRD-negative, sustained MRD-positive, and non-sustained MRD-positive were divided into Groups 1, 2, 3, and 4, respectively. The Group 1 patients had superior PFS than Groups 2 and 3 patients (p < 0.05), but no difference in PFS was observed for Group 2 versus Group 3, Group 2 versus Group 4, and Group 3 versus Group 4 patients. For the MASS and MRD groups, among Groups 2, 3, and 4, MASS I patients had a superior PFS, while III patients showed the opposite result. Strikingly, no difference in PFS for Group 1 patients regardless of the MASS stage was observed. Despite being in MASS II and III, the PFS of Group 1 patients was longer than those with the other three groups. Response to treatment was an independent prognostic factor for MM patients.

CONCLUSION

Patients with an accumulation of high-risk factors and MRD-positive have poor outcomes. Sustained MRD-negative may improve high-risk patients' prognoses.

Immunoparesis recovery in newly diagnosed transplant ineligible multiple myeloma patients, an independent prognostic factor that complements minimal residual disease

Information on the prognostic value of immunoparesis (IP) recovery in multiple myeloma (MM) patients has been only generated in some observational and retrospective studies. We have evaluated the prognostic impact of IP recovery and its association with minimal residual disease (MRD) in a series of 113 newly diagnosed transplant-ineligible (NDTI) patients, that received fix duration treatment (18 cycles of VMP/lenalidomide-dexamethasone) within the PETHEMA/GEM2010MAS65 trial and who achieved CR or VGPR. Immunoglobulin levels were measured at diagnosis, at the end of treatment (after cycle 18th) and during subsequent follow up whereas MRD was analyzed only at the end of the treatment (after cycle 18th). We found that patients who had IP at diagnosis and recovered it during or after treatment had longer progression free survival (PFS) [p < 0.001; HR 0.32 (0.19-0.52)] and longer overall survival (OS) [p = 0.007; HR 0.40 (0.20-0.80)] compared to those who failed to recover it. When we analyzed IP recovery in MRD negative patients, we found that those cases with IP recovery had longer PFS [p = 0.007; HR 0.31 (0.13-0.76)] and longer OS [p = 0.012; HR 0.21 (0.06-0.80)] as compared to MRD negative patients but without IP recovery. In conclusion, IP recovery confers better prognosis in NDTI-MM patients with fixed duration treatment who achieve CR or VGPR and the prognostic value of MRD can be complemented when combined with IP recovery.

SOHO State of the Art Updates and Next Questions: Diagnosis and Management of Monoclonal Gammopathy of Undetermined Significance and Smoldering Multiple Myeloma

Monoclonal proteins are common, with a prevalence in the United States around 5% and the incidence increases with age. Although most patients are asymptomatic, the vast majority of cases are caused by a clonal plasma cell disorder. Monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM) are asymptomatic precursor conditions with variable risk of progression to multiple myeloma (MM). In recent years, significant progress has been made to better understand the factors that lead to the development of symptoms and progression to myeloma. In this review, we summarize the current diagnosis treatment guidelines for MGUS and SMM and highlight recent advances that underscore a shifting paradigm in the evaluation and management of plasma cell precursor conditions.

Low circulating tumor cell levels correlate with favorable outcomes and distinct biological features in multiple myeloma

There is growing interest in multiple myeloma (MM) circulating tumor cells (CTCs), but their rareness in peripheral blood (PB) and inconsistency in cutoffs question their clinical utility. Herein, we applied next-generation flow cytometry in 550 bone marrow (BM) and matched PB samples to define an optimal CTC cutoff for both transplant-eligible and transplant-ineligible newly diagnosed MM (NDMM) patients. Deep phenotyping was performed to investigate unique microenvironmental features associated with CTC dissemination. CTCs were detected in 90% of patients (median 0.01%; range: 0.0002%-12.6%) and increased levels associated with adverse features. Correlations were observed between high CTC percentages and a diffused MRI pattern, a distinct BM composition characterized by altered B-cell differentiation together with an expansion of effector cells and tumor-associated macrophages, as well as a greater phenotypic dissimilarity between BM and PB clonal cells. Progression-free survival (PFS) and overall survival (OS) gradually worsened with each logarithmic increment of CTCs. Conversely, NDMM patients without CTCs showed unprecedented outcomes, with 5-year PFS and OS rates of 83% and 97%, respectively. A cutoff of 0.02% CTCs was independent of the ISS, LDH, and cytogenetics in a multivariate analysis of risk factors for PFS. The 0.02% CTC cutoff synergized with the MGUS-like phenotype and the R-ISS for improving the risk stratification systems. MRD negativity was less frequent if CTCs were ≥0.02% at diagnosis, but whenever achieved, the poor prognosis of these patients was abrogated. This study shows the clinical utility of CTC assessment in MM and provides evidence toward a consensus cutoff for risk stratification.

Identification of Therapy-Induced Clonal Evolution and Resistance Pathways in Minimal Residual Clones in Multiple Myeloma through Single-Cell Sequencing

PURPOSE

In multiple myeloma (MM), therapy-induced clonal evolution is associated with treatment resistance and is one of the most important hindrances toward a cure for MM. To further understand the molecular mechanisms controlling the clonal evolution of MM, we applied single-cell RNA sequencing (scRNA-seq) to paired diagnostic and posttreatment bone marrow (BM) samples.

EXPERIMENTAL DESIGN

scRNA-seq was performed on 38 BM samples from patients with monoclonal gammopathy of undetermined significance (n = 1), MM patients at diagnosis (n = 19), MM posttreatment (n = 17), and one healthy donor (HD). The single-cell transcriptome data of malignant plasma cells (PC) and the surrounding immune microenvironment were analyzed.

RESULTS

Profiling by scRNA-seq data revealed three primary trajectories of transcriptional evolution after treatment: clonal elimination in patients with undetectable minimal residual disease (MRD-) and clonal stabilization and clonal selection in detectable MRD (MRD+) patients. We noted a metabolic shift toward fatty acid oxidation in cycling-resistant PCs, whereas selective PCs favored the NF-κB pathway. Intriguingly, when comparing the genetic and transcriptional dynamics, we found a significant correlation between genetic and nongenetic factors in driving the clonal evolution. Furthermore, we identified variations in cellular interactions between malignant PCs and the tumor microenvironment. Selective PCs showed the most robust cellular interactions with the tumor microenvironment.

CONCLUSIONS

These data suggest that MM cells could rapidly adapt to induction treatment through transcriptional adaptation, metabolic adaptation, and specialized immune evasion. Targeting therapy-induced resistance mechanisms may help to avert refractory disease in MM.

Mass spectrometry-based assessment of M protein in peripheral blood during maintenance therapy in multiple myeloma

ABSTRACT

Mass spectrometry (MS) can detect multiple myeloma-derived monoclonal proteins in the peripheral blood (PB) with high sensitivity, potentially serving as a PB assay for measurable residual disease (MRD). This study evaluated the significance of PB MS MRD negativity during posttransplant therapy in patients with newly diagnosed multiple myeloma. Serum samples from 138 patients treated in the phase 3 ATLAS trial of posttransplant maintenance with either carfilzomib, lenalidomide, and dexamethasone, or with lenalidomide alone were analyzed using EXENT MS methodology. We established feasibility of measuring MRD by MS in the PB in the posttransplant setting, despite unavailability of pretreatment calibration samples. There was high agreement between MRD by MS in the PB and paired bone marrow (BM) MRD results at the 10-5 threshold, assessed by either next-generation sequencing (NGS) or multiparameter flow cytometry (MFC) (70% and 67%, respectively). Agreement between PB MS and both BM MRD methods was lowest early after transplant and increased with time. MS negativity was associated with improved progression-free survival (PFS), which, in landmark analysis, reached statistical significance after 18 cycles after transplant. Combined PB/BM MRD negativity by MFC or NGS was associated with superior PFS compared with MRD negativity by only 1 modality. Sustained MS negativity carried similar prognostic performance to sustained BM MRD negativity at the 10-5 threshold. Overall, posttransplant MS assessment was feasible and provided additional prognostic information to BM MRD negativity. Further studies are needed to confirm the role and optimal timing of MS in disease evaluation algorithms. The ATLAS trial is registered at www.clinicaltrials.gov as #NCT02659293.

Minimal Residual Disease Status in Multiple Myeloma 1 Year After Autologous Hematopoietic Cell Transplantation and Lenalidomide Maintenance Are Associated With Long-Term Overall Survival

PURPOSE

Prognostic Immunophenotyping in Myeloma Response (PRIMeR) is an ancillary study of minimal residual disease (MRD) assessment for multiple myeloma by next-generation multiparameter flow cytometry (MFC). Patients were enrolled on a three-arm randomized control trial (Blood and Marrow Transplants Clinical Trials Network 0702 Stem Cell Transplant for Myeloma in Combination of Novel Agents [STaMINA]; ClinicalTrials.gov identifier: NCT01109004).

METHODS

Four hundred and thirty-five patients consented to the MRD panel, which included 10 monoclonal antibodies measured via six-color MFC. MRD was measured at baseline/preautologous hematopoietic cell transplant (BL/preAutoHCT), premaintenance (PM), and 1 year (Y1) after AutoHCT with a sensitivity of 10-5 to 10-6. The primary objective was to assess MRD-negative (MRDneg) at 1 year after AutoHCT and progression-free survival and overall survival (PFS/OS).

RESULTS

Similar to the STaMINA results, at a median follow-up of 70 months, there was no significant difference in PFS/OS by treatment arm in the PRIMeR patients. MRDneg at all three time points was associated with significantly improved PFS, and MRDneg at Y1 had significantly longer OS. Multivariate analysis of PFS, adjusting for disease risk and treatment arm, demonstrated hazard ratios (HRs) in MRD-positive patients compared with MRDneg patients at BL, PM, and Y1 of 1.55 (P = .0074), 1.83 (P = .0007), and 3.61 (P < .0001), respectively. Corresponding HRs for OS were 1.19 (P = .48), 0.88 (P = .68), and 3.36 (P < .001). Patients with sustained MRDneg or who converted to MRDneg by Y1 had similar PFS/OS.

CONCLUSION

To our knowledge, this first, prospective US cooperative group, multicenter study demonstrates that MRDneg at Y1 after AutoHCT with lenalidomide maintenance is prognostic for improved 6-year PFS and OS. Serial MRD measurements may direct trials to test how further therapy may improve long-term PFS and OS.

Maintenance therapy for cytogenetically high-risk multiple myeloma: landscape in the era of novel drugs

Although the significant strides in novel therapeutic approaches have prolonged the survival of multiple myeloma (MM) patients, the unfavorable prognosis of cytogenetically high-risk newly diagnosed MM (NDMM) remains intractable with the lack of consensus regarding the choice of maintenance regimens. Therefore, this study was initiated with the aim of examining the effectiveness of various maintenance treatments for this group of patients in jeopardy. Overall, 17 studies with 1937 high-risk NDMM patients were included in the network meta-analysis. Combination therapies involving novel drugs presented encouraging prospects in the maintenance phase, while the patients and circumstances for the application of different regimens still needed to be further distinguished and clarified. To investigate the current status of maintenance therapy of high-risk NDMM patients in clinical practice, a real-world cohort of high-risk NDMM was retrospectively incorporated 80 patients with lenalidomide maintenance and 53 patients with bortezomib maintenance, presenting the median PFS of 31.7 months and 30.4 months, respectively (p = 0.874, HR = 0.966, 95% CI: 0.628-1.486). Collectively, this study illuminated the present constraints of conventional approaches during the maintenance phase for high-risk NDMM patients while highlighting the future potential associated with enhanced regimens integrating novel medications.

What clinicians should know about surrogate end points in hematologic malignancies

ABSTRACT

Use of surrogates as primary end points is commonplace in hematology/oncology clinical trials. As opposed to prognostic markers, surrogates are end points that can be measured early and yet can still capture the full effect of treatment, because it would be captured by the true outcome (eg, overall survival). We discuss the level of evidence of the most commonly used end points in hematology and share recommendations on how to apply and evaluate surrogate end points in research and clinical practice. Based on the statistical literature, this clinician-friendly review intends to build a bridge between clinicians and surrogacy specialists.

[Chinese expert consensus on minimal residual disease detection in multiple myeloma based on bone marrow samples (2024)]

Multiple myeloma (MM) is the second most common hematologic malignant tumor. Standard holistic treatment model and new drug-based regimens have greatly improved the survival of patients with MM; however, minimal residual disease (MRD) causes relapse in most patients. Therefore, combining MRD testing on the basis of traditional serological efficacy evaluation is necessary to achieve a more accurate assessment of the patient's disease status. At present, next-generation flow cytometry (NGF) and next-generation sequencing (NGS) are the mainstream technologies for detecting MRD based on bone marrow samples. To standardize and normalize MRD detection, the expert group discussed and formulated Chinese expert consensus on the application of NGF and NGS technology for bone marrow MRD detection in patients with MM.

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.

Randomized comparison between KTd and KRd induction therapy followed by maintenance therapy with K or observation in transplant-ineligible patients with newly diagnosed multiple myeloma

Randomized comparison between KTd and KRd induction followed by second randomization to carfilzomib in transplant-ineligable patients with newly diagnosed multiple myeloma.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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 27.6 months (range, 0.7-82.3), the median PFS was significantly shorter for patients in the MRDpos group compared to the MRDneg group: 48.2 months (95% confidence interval [CI], 0.3-80.5) versus 80.1 months (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.

CONCLUSIONS

In patients achieving ≥VGPR to induction, pretransplant MRDpos status was associated with a lower CR rate after autoHCT and a shorter PFS.

Circulating tumor plasma cells and peripheral blood measurable residual disease assessment in multiple myeloma patients not planned for upfront transplant

Circulating tumor plasma cells (CTPCs) provide a noninvasive alternative for measuring tumor burden in newly diagnosed multiple myeloma (NDMM). Moreover, measurable residual disease (MRD) assessment in peripheral blood (PBMRD) can provide an ideal alternative to bone marrow MRD, which is limited by its painful nature and technical challenges. However, the clinical significance of PBMRD in NDMM still remains uncertain. Additionally, data on CTPC in NDMM patients not treated with transplant are scarce. We prospectively studied CTPC and PBMRD in 141 NDMM patients using highly sensitive multicolor flow cytometry (HS-MFC). PBMRD was monitored at the end of three cycles (PBMRD1) and six cycles (PBMRD2) of chemotherapy in patients with detectable baseline CTPC. Patients received bortezomib-based triplet therapy and were not planned for an upfront transplant. Among baseline risk factors, CTPC ≥ 0.01% was independently associated with poor progression-free survival (PFS) (hazard ratio [HR] = 2.77; p = 0.0047) and overall survival (OS) (HR = 2.9; p = 0.023) on multivariate analysis. In patients with detectable baseline CTPC, undetectable PBMRD at both subsequent time points was associated with longer PFS (HR = 0.46; p = 0.0037), whereas detectable PBMRD at any time point was associated with short OS (HR = 3.25; p = 0.004). Undetectable combined PBMRD (PBMRD1 and PBMRD2) outperformed the serum-immunofixation-based response. On multivariate analysis, detectable PBMRD at any time point was independently associated with poor PFS (HR = 2.0; p = 0.025) and OS (HR = 3.97; p = 0.013). Thus, our findings showed that CTPC and PBMRD assessment using HS-MFC provides a robust, noninvasive biomarker for NDMM patients not planned for an upfront transplant. Sequential PBMRD monitoring has great potential to improve the impact of the existing risk stratification and response assessment models.

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

PURPOSE

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.

EXPERIMENTAL DESIGN

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.

RESULTS

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).

CONCLUSIONS

EasyM is a highly sensitive and minimal invasive method of MRD monitoring in multiple myeloma; MS-MRD had significant predictive ability for survival outcomes.

Ixazomib, Lenalidomide, and Dexamethasone (IRD) Treatment with Cytogenetic Risk-Based Maintenance in Transplant-Eligible Myeloma: A Phase 2 Multicenter Study by the Nordic Myeloma Study Group

Scarce data exist on double maintenance in transplant-eligible high-risk (HR) newly diagnosed multiple myeloma (NDMM) patients. This prospective phase 2 study enrolled 120 transplant-eligible NDMM patients. The treatment consisted of four cycles of ixazomib-lenalidomide-dexamethasone (IRD) induction plus autologous stem cell transplantation followed by IRD consolidation and cytogenetic risk-based maintenance therapy with lenalidomide + ixazomib (IR) for HR patients and lenalidomide (R) alone for NHR patients. The main endpoint of the study was undetectable minimal residual disease (MRD) with sensitivity of <10-5 by flow cytometry at any time, and other endpoints were progression-free survival (PFS) and overall survival (OS). We present the preplanned analysis after the last patient has been two years on maintenance. At any time during protocol treatment, 28% (34/120) had MRD < 10-5 at least once. At two years on maintenance, 66% of the patients in the HR group and 76% in the NHR group were progression-free (p = 0.395) and 36% (43/120) were CR or better, of which 42% (18/43) had undetectable flow MRD <10-5. Altogether 95% of the patients with sustained MRD <10-5, 82% of the patients who turned MRD-positive, and 61% of those with positive MRD had no disease progression at two years on maintenance (p < 0.001). To conclude, prolonged maintenance with all-oral ixazomib plus lenalidomide might improve PFS in HR patients.

Real-world prognostic significance of attaining minimal residual disease negativity in newly diagnosed multiple myeloma

The aim of the study was to evaluate the prognostic impact of minimal residual disease (MRD) in the real-world setting and the interaction between MRD and molecular risk, clinical response and autologous stem-cell transplant (ASCT). A retrospective analysis of 275 newly diagnosed multiple myeloma (NDMM) patients who achieved very good partial remission (VGPR) or better before maintenance were involved. We examined MRD status by multiparameter flow cytometry (MFC). At a median follow-up of 37 months (4-88 months), In patients who achieved ≥ VGPR, those with MRD negativity had significantly longer PFS (51 vs. 26 months; P < 0.001) and OS (Not reached: NR vs. 62 months, P < 0.001) than those with MRD positivity. MRD positivity was the independent prognostic factor for PFS with hazard ratios of 2.650 (95% CI 1.755-4.033, P < 0.001) and OS with hazard ratios of 2.122 (95% CI 1.155-3.899, P = 0.015). Achieving MRD negativity was able to ameliorate a poor prognosis associated with genetic high risk. MRD negativity was associated with better PFS regardless of ASCT treatment. MRD status was more predictable for clinical outcome than conventional clinical responses. Moreover, Sustained MRD negativity ≥ 12 or ≥ 24 months improved both PFS and OS. Patients with NDMM who achieved MRD-negative status or sustained MRD negativity had deep remission and improved clinical outcomes regardless of high-risk cytogenetics, ASCT and clinical responses in a real-world setting.

Longitudinal genetically detectable minimal residual disease by fluorescence in situ hybridization confers a poor prognosis in myeloma

Background

Deeper depth of response (DpR) after induction therapy, especially gain of negative minimal residual disease (MRD), has been linked to prolonged survival in multiple myeloma (MM). However, flow-MRD examination focuses on the numbers but not on the biological characteristics of residual plasma cells (PCs).

Objectives

To explore whether the genetic features of residual tumor cells affect the survival time of patients with MM.

Design

A retrospective cohort study.

Methods

We investigated the clonality of cytogenetic abnormalities (CAs) of the residual PCs using interphase fluorescence in situ hybridization (iFISH) in the National Longitudinal Cohort of Hematological Diseases in China (NCT04645199). Here, a longitudinal cohort of 269 patients with patient-paired diagnostic and post-induction iFISH results was analyzed.

Results

Persistent CAs after induction therapy were detected in about half of the patients (118/269, 43%), and patients with undetectable CAs showed significantly improved survival compared with those with genetically detectable MRD [median progression-free survival (mPFS): 59.7 versus 35.7 months, p < 0.001; median overall survival (mOS): 97.1 versus 68.8 months, p = 0.011]. In addition, different patterns of therapy-induced clonal evolution were observed by comparing the clonal structure of residual PCs with paired baseline samples. Patients who maintained at a high risk during follow-up had the worst survival (mPFS: 30.5 months; mOS: 54.4 months), while those who returned to lower risk or had iFISH- at both time points had the best survival (mPFS: 62.0 months, mOS: not reached).

Conclusion

These findings highlighted the prognostic value of genetic testing in residual tumor cells, which may provide a deep understanding of clonal evolution and guide clinical therapeutic strategies.

Autologous Stem Cell Transplant in Hodgkin's and Non-Hodgkin's Lymphoma, Multiple Myeloma, and AL Amyloidosis

Human body cells are stem cell (SC) derivatives originating from bone marrow. Their special characteristics include their capacity to support the formation and self-repair of the cells. Cancer cells multiply uncontrollably and invade healthy tissues, making stem cell transplants a viable option for cancer patients undergoing high-dose chemotherapy (HDC). When chemotherapy is used at very high doses to eradicate all cancer cells from aggressive tumors, blood-forming cells and leukocytes are either completely or partially destroyed. Autologous stem cell transplantation (ASCT) is necessary for patients in those circumstances. The patients who undergo autologous transplants receive their own stem cells (SCs). The transplanted stem cells first come into contact with the bone marrow and then undergo engraftment, before differentiating into blood cells. ASCT is one of the most significant and innovative strategies for treating diseases. Here we focus on the treatment of Hodgkin's lymphoma, non-Hodgkin's lymphoma, multiple myeloma, and AL amyloidosis, using ASCT. This review provides a comprehensive picture of the effectiveness and the safety of ASCT as a therapeutic approach for these diseases, based on the currently available evidence.

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.

Multiple myeloma following bone metastasis of renal cell carcinoma: a case report

Background

The clinical manifestations of multiple myeloma (MM) and bone metastatic tumor are both systemic bone pain, which is difficult to distinguish from imaging manifestations, leading to misdiagnosis and missed diagnosis.

Case summary

We reported a man with a unique case whose tumors were MM with bone metastatic tumor of clear cell renal cell carcinoma (CCRCC). Computed tomography (CT) showed multifocal osteolytic bone destruction, while magnetic resonance imaging (MRI) showed multifocal bone marrow infiltration with soft tissue mass. Pathology and immunohistochemistry established the diagnosis of the coexistence of myeloma with bone metastatic tumor of CCRCC in the spine. Immunotherapy and systemic chemotherapy were adopted in the clinic, and vertebral decompression was performed after anemia was corrected. This case with MM and bone metastatic tumor of CCRCC received radiotherapy and immunotherapy and acquired satisfying outcome after 1 year of follow-up.

Conclusion

It is difficult to differentiate MM and bone metastatic tumor on imaging, especially when there are bone lesions at the same time, which is an easily missed diagnosis and needs to be comprehensively evaluated in combination with functional procedures, clinical laboratory tests, and histopathology.

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.

Pure red cell aplasia and minimal residual disease conversion associated with immune reconstitution in a patient with high-risk multiple myeloma

A second bone marrow aspiration and biopsy showed pure red cell aplasia in this case.

Recommendations for the study of monoclonal gammopathies in the clinical laboratory. A consensus of the Spanish Society of Laboratory Medicine and the Spanish Society of Hematology and Hemotherapy. Part I: Update on laboratory tests for the study of monoclonal gammopathies

Monoclonal gammopathies (MG) are characterized by the proliferation of plasma cells that produce identical abnormal immunoglobulins (intact or some of their subunits). This abnormal immunoglobulin component is called monoclonal protein (M-protein), and is considered a biomarker of proliferative activity. The identification, characterization and measurement of M-protein is essential for the management of MG. We conducted a systematic review of the different tests and measurement methods used in the clinical laboratory for the study of M-protein in serum and urine, the biochemistry and hematology tests necessary for clinical evaluation, and studies in bone marrow, peripheral blood and other tissues. This review included literature published between 2009 and 2022. The paper discusses the main methodological characteristics and limitations, as well as the purpose and clinical value of the different tests used in the diagnosis, prognosis, monitoring and assessment of treatment response in MG. Included are methods for the study of M-protein, namely electrophoresis, measurement of immunoglobulin levels, serum free light chains, immunoglobulin heavy chain/light chain pairs, and mass spectrometry, and for the bone marrow examination, morphological analysis, cytogenetics, molecular techniques, and multiparameter flow cytometry.

Potential future direction of measurable residual disease evaluation in multiple myeloma

Multiple myeloma remains an incurable disease plagued by high relapse rates. Deeper and more sustainable responses, however, have been consistently shown to improve outcomes and could eventually pave the way to achieving a cure. Our understanding of disease response has surpassed complete response (CR), because the current definitions are suboptimal, and the treatment goal should aim even beyond stringent CR, toward molecular and flow CR, that is, measurable residual disease (MRD) negativity. It has been more than 20 years since the discrepancy in the outcome between patients in CR with and without MRD has been demonstrated, and the field has come a long way from multiparameter flow cytometry to next-generation flow and next-generation sequencing, able to detect up to a limit of detection of a single myeloma cell from 1 million healthy counterparts. This review aims to summarize the current available data regarding MRD but also its potential future use as a coprimary outcome both in clinical and trial settings as a survival surrogate as well as its use to evaluate treatment efficacy and for adaptive response-based and early-rescue therapy. Furthermore, we discuss whether these concepts are applicable in different settings (eg, newly diagnosed and relapsed/refractory myeloma, patients who are eligible and ineligible for tansplant, and standard- and high-risk disease).