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

ABSTRACT: The 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.

Integrated analysis of randomized controlled trials evaluating bortezomib + lenalidomide + dexamethasone or bortezomib + thalidomide + dexamethasone induction in transplant-eligible newly diagnosed multiple myeloma.

Objective: Providing the most efficacious frontline treatment for newly diagnosed multiple myeloma (NDMM) is critical for patient outcomes. No direct comparisons have been made between bortezomib + lenalidomide + dexamethasone (VRD) and bortezomib + thalidomide + dexamethasone (VTD) induction regimens in transplant-eligible NDMM. Methods: An integrated analysis was performed using patient data from four trials meeting prespecified eligibility criteria: two using VRD (PETHEMA GEM2012 and IFM 2009) and two using VTD (PETHEMA GEM2005 and IFM 2013-04). Results: The primary endpoint was met, with VRD demonstrating a noninferior rate of at least very good partial response (≥ VGPR) after induction vs VTD. GEM comparison demonstrated improvement in the ≥ VGPR rate after induction for VRD vs VTD (66.3% vs 51.2%; P = .00281) that increased after transplant (74.4% vs 53.5%). Undetectable minimal residual disease rates post induction (46.7% vs 34.9%) and post transplant (62.4% vs 47.3%) support the benefit of VRD vs VTD. Treatment-emergent adverse events leading to study and/or treatment discontinuation were less frequent with VRD (3%, GEM2012; 6%, IFM 2009) vs VTD (11%, IFM 2013-04). Conclusion: These results supported the benefit of VRD over VTD for induction in transplant-eligible patients with NDMM. The trials included are registered with ClinicalTrials.gov (NCT01916252, NCT01191060, NCT00461747, and NCT01971658).

Recovery of uninvolved heavy/light chain pair immunoparesis in newly diagnosed transplant-eligible myeloma patients complements the prognostic value of minimal residual disease detection.

Immunoparesis (IP) in multiple myeloma (MM) patients can be measured by classic assessment of immunoglobulin (Ig) levels or by analysis of the uninvolved heavy/light chain pair of the same immunoglobulin (uHLC) by the Hevylite® assay. In this study we evaluate the prognostic value of recovery from IP measured by classic total Ig and uHLC assessment in newly diagnosed MM transplant-eligible (NDMM-TE) patients with intensive treatment and its association with Minimal Residual Disease (MRD). Patients were enrolled and treated in the PETHEMA/GEM2012MENOS65 trial and continued in the PETHEMA/GEM2014MAIN trial. Total Ig (IgG, IgA and IgM) and uHLC were analyzed in a central laboratory at diagnosis, after consolidation treatment and after the first year of maintenance. MRD was analyzed by next generation flow cytometry after consolidation (sensitivity level 2x10-6). We found no differences in progression free survival (PFS) between patients who recovered and patients who didn't recover from IP after consolidation when examining classic total Ig and uHLC. However, after the first year of maintenance, in contrast to patients with classic IP, patients with recovery from uHLC IP had longer PFS than patients without recovery, with hazard ratio of 0.42 (CI95% 0.21-0.81; p=0.008). Multivariate analysis with Cox proportional-hazards regression models confirmed recovery from uHLC IP after the first year of maintenance as an independent prognostic factor for PFS, with an increase in C-statistic of 0.05 (-0.04-0.14; p<0.001) when adding uHLC IP recovery. Moreover, we observed that MRD status and uHLC IP recovery affords complementary information for risk stratification. In conclusion, recovery from uHLC IP after one year of maintenance is an independent prognostic factor for PFS in NDMM-TE patients who receive intensive treatment. Immune reconstitution, measured as recovery from uHLC IP, provides complementary prognostic information to MRD assessment.

Lenalidomide and dexamethasone maintenance with or without ixazomib, tailored by residual disease status in myeloma.

From November 2014 to May 2017, 332 patients homogeneously treated with bortezomib, lenalidomide, and dexamethasone (VRD) induction, autologous stem cell transplant, and VRD consolidation were randomly assigned to receive maintenance therapy with lenalidomide and dexamethasone (RD; 161 patients) vs RD plus ixazomib (IRD; 171 patients). RD consisted of lenalidomide 15 mg/d from days 1 to 21 plus dexamethasone 20 mg/d on days 1 to 4 and 9 to 12 at 4-week intervals, whereas in the IRD arm, oral ixazomib at a dose of 4 mg on days 1, 8, and 15 was added. Therapy for patients with negative measurable residual disease (MRD) after 24 cycles was discontinued, whereas those who tested positive for MRD remained on maintenance with RD for 36 more cycles. After a median follow-up of 69 months from the initiation of maintenance, the progression-free survival (PFS) was similar in both arms, with a 6-year PFS rate of 61.3% and 55.6% for RD and IRD, respectively (hazard ratio, 1.136; 95% confidence interval, 0.809-1.603). After 2 years of maintenance, treatment was discontinued in 163 patients with negative MRD, whereas 63 patients with positive MRD continued with RD therapy. Maintenance discontinuation in patients tested negative for MRD resulted in a low progression rate (17.2% at 4 years), even in patients with high-risk features. In summary, our results show the efficacy of RD maintenance and support the safety of maintenance therapy discontinuation in patients with negative MRD at 2 years. This trial was registered at www.clinicaltrials.gov as #NCT02406144 and at EudraCT as 2014-00055410.

Definition and Clinical Significance of the Monoclonal Gammopathy of Undetermined Significance-Like Phenotype in Patients With Monoclonal Gammopathies.

PURPOSE: The existence of patients with multiple myeloma (MM) and light-chain (AL) amyloidosis who present with a monoclonal gammopathy of undetermined significance (MGUS)-like phenotype has been hypothesized, but methods to identify this subgroup are not standardized and its clinical significance is not properly validated. PATIENTS AND METHODS: An algorithm to identify patients having MGUS-like phenotype was developed on the basis of the percentages of total bone marrow (BM) plasma cells (PC) and of clonal PC within the BM PC compartment, determined at diagnosis using flow cytometry in 548 patients with MGUS and 2,011 patients with active MM. The clinical significance of the algorithm was tested and validated in 488 patients with smoldering MM, 3,870 patients with active MM and 211 patients with AL amyloidosis. RESULTS: Patients with smoldering MM with MGUS-like phenotype showed significantly lower rates of disease progression (4.5% and 0% at 2 years in two independent series). There were no statistically significant differences in time to progression between treatment versus observation in these patients. In active newly diagnosed MM, MGUS-like phenotype retained independent prognostic value in multivariate analyses of progression-free survival (PFS; hazard ratio [HR], 0.49; P = .001) and overall survival (OS; HR, 0.56; P = .039), together with International Staging System, lactate dehydrogenase, cytogenetic risk, transplant eligibility, and complete remission status. Transplant-eligible patients with active MM with MGUS-like phenotype showed PFS and OS rates at 5 years of 79% and 96%, respectively. In this subgroup, there were no differences in PFS and OS according to complete remission and measurable residual disease status. Application of the algorithm in two independent series of patients with AL predicted for different survival. CONCLUSION: We developed an open-access algorithm for the identification of MGUS-like patients with distinct clinical outcomes. This phenotypic classification could become part of the diagnostic workup of MM and AL amyloidosis.

Intramuscular Anti-D treatment for immune thrombocytopenia: A single centre experience.

Intravenous Anti-Rhesus-D immunoglobulin (Anti-D) is a first-line treatment option for immune thrombocytopenia in non-splenectomised and RhD-positive patients. In this report, we retrospectively review our experience with intramuscular (IM) Anti-D treatment in 74 adult patients between 1990 and 2018. We found that 73% of patients showed a response; almost all of them had complete responses (68.9%), and 26% achieved complete responses sustained at least 6 months after treatment discontinuation. [Correction added on 02 December 2022, after first online publication: In the preceding sentence, '(68.89%)' has been corrected to '(68.9%)' in this version.] No significant side effects were observed with no cases of acute haemolysis or anaemia reported. We conclude from this study that IM Anti-D is an effective and safe treatment for immune thrombocytopenia.

NGS-Based Molecular Karyotyping of Multiple Myeloma: Results from the GEM12 Clinical Trial.

Next-generation sequencing (NGS) has greatly improved our ability to detect the genomic aberrations occurring in multiple myeloma (MM); however, its transfer to routine clinical labs and its validation in clinical trials remains to be established. We designed a capture-based NGS targeted panel to identify, in a single assay, known genetic alterations for the prognostic stratification of MM. The NGS panel was designed for the simultaneous study of single nucleotide and copy number variations, insertions and deletions, chromosomal translocations and V(D)J rearrangements. The panel was validated using a cohort of 149 MM patients enrolled in the GEM2012MENOS65 clinical trial. The results showed great global accuracy, with positive and negative predictive values close to 90% when compared with available data from fluorescence in situ hybridization and whole-exome sequencing. While the treatments used in the clinical trial showed high efficacy, patients defined as high-risk by the panel had shorter progression-free survival (p = 0.0015). As expected, the mutational status of TP53 was significant in predicting patient outcomes (p = 0.021). The NGS panel also efficiently detected clonal IGH rearrangements in 81% of patients. In conclusion, molecular karyotyping using a targeted NGS panel can identify relevant prognostic chromosomal abnormalities and translocations for the clinical management of MM patients.

Lenalidomide-dexamethasone versus observation in high-risk smoldering myeloma after 12 years of median follow-up time: A randomized, open-label study.

BACKGROUND: Smoldering multiple myeloma (SMM) is a heterogeneous disease in terms of progression to myeloma (MM), but its standard of care continues to be observation. METHODS: The QuiRedex phase 3 trial initiated in 2007 included 119 high-risk patients with SMM randomized to treatment or observation. Treatment consisted of nine 4-week induction cycles (lenalidomide [Rd], 25 mg on days 1-21 plus dexamethasone, 20 mg on days 1-4 and 12-15), followed by maintenance (R, 10 mg on days 1-21) for up to 2 years. The primary end-point was time to progression (TTP) to myeloma based on per protocol population. Secondary end-points were overall survival (OS), response rate, and safety. An update of the trial after a long-term follow-up is presented here. This trial was registered with ClinicalTrials.gov (NCT00480363). FINDINGS: After a median follow-up time of 12.5 years (range: 10.4-13.6), the median TTP to MM was 2.1 years in the observation arm and 9.5 years in the Rd arm (HR: 0.28, 95% CI: 0.18-0.44, p < 0.0001). The median OS was 8.5 years in the abstention arm and not reached in the Rd group (HR: 0.57, 95% CI: 0.34-0.95, p = 0.032). Patients who progressed received optimized treatments according to the standards of care, and the OS from progression was comparable in both arms (p = 0.96). INTERPRETATION: This analysis confirms that early treatment with Rd for high-risk SMM translates into a sustained benefit in both TTP and OS. FUNDING: Pethema (Spanish Program for the Treatment of Hematologic Diseases), Spain.

Single versus tandem autologous stem-cell transplantation in patients with newly diagnosed multiple myeloma and high-risk cytogenetics. A retrospective, open-label study of the PETHEMA/Spanish Myeloma Group (GEM).

Tandem ASCT has been suggested as a valid approach to improve the prognosis of patients with MM and HR cytogenetic. In this observational, retrospective study, 213 patients with newly diagnosed MM and HR cytogenetic in 35 hospitals from the Spanish Myeloma Group underwent single or tandem ASCT between January 2015 and December 2019 after induction with VTD/VRD. HR cytogenetic was defined as having ≥1 of the following: del17p, t(4;14), t(14;16) or gain 1q21. More patients in the tandem group had R-ISS 3 and >1 cytogenetic abnormality at diagnosis. With a median follow-up of 31 months (range, 10-82), PFS after single ASCT was 41 months versus 48 months with tandem ASCT (p = 0.33). PFS in patients with del17p undergoing single ASCT was 41 months, while 52% of patients undergoing tandem ASCT were alive and disease free at 48 months. In conclusion, tandem ASCT partly overcomes the bad prognosis of HR cytogenetic.

Circulating Tumor Cells for the Staging of Patients With Newly Diagnosed Transplant-Eligible Multiple Myeloma.

PURPOSE: Patients with multiple myeloma (MM) may show patchy bone marrow (BM) infiltration and extramedullary disease. Notwithstanding, quantification of plasma cells (PCs) continues to be performed in BM since the clinical translation of circulating tumor cells (CTCs) remains undefined. PATIENTS AND METHODS: CTCs were measured in peripheral blood (PB) of 374 patients with newly diagnosed MM enrolled in the GEM2012MENOS65 and GEM2014MAIN trials. Treatment included bortezomib, lenalidomide, and dexamethasone induction followed by autologous transplant, consolidation, and maintenance. Next-generation flow cytometry was used to evaluate CTCs in PB at diagnosis and measurable residual disease (MRD) in BM throughout treatment. RESULTS: CTCs were detected in 92% (344 of 374) of patients with newly diagnosed MM. The correlation between the percentages of CTCs and BM PCs was modest. Increasing logarithmic percentages of CTCs were associated with inferior progression-free survival (PFS). A cutoff of 0.01% CTCs showed an independent prognostic value (hazard ratio: 2.02; 95% CI, 1.3 to 3.1; P = .001) in multivariable PFS analysis including the International Staging System, lactate dehydrogenase levels, and cytogenetics. The combination of the four prognostic factors significantly improved risk stratification. Outcomes according to the percentage of CTCs and depth of response to treatment showed that patients with undetectable CTCs had exceptional PFS regardless of complete remission and MRD status. In all other cases with detectable CTCs, only achieving MRD negativity (and not complete remission) demonstrated a statistically significant increase in PFS. CONCLUSION: Evaluation of CTCs in PB outperformed quantification of BM PCs. The detection of ≥ 0.01% CTCs could be a new risk factor in novel staging systems for patients with transplant-eligible MM.

Prognostic Value of Serum Paraprotein Response Kinetics in Patients With Newly Diagnosed Multiple Myeloma.

INTRODUCTION: Response kinetics is a well-established prognostic marker in acute lymphoblastic leukemia. The situation is not clear in multiple myeloma (MM) despite having a biomarker for response monitoring (monoclonal component [MC]). MATERIALS AND METHODS: We developed a mathematical model to assess the prognostic value of serum MC response kinetics during 6 induction cycles, in 373 NDMM transplanted patients treated in the GEM2012Menos65 clinical trial. The model calculated a "resistance" parameter that reflects the stagnation in the response after an initial descent. RESULTS: Two patient subgroups were defined based on low and high resistance, that respectively captured sensitive and refractory kinetics, with progression-free survival (PFS) at 5 years of 72% and 59% (HR 0.64, 95% CI 0.44-0.93; P = .02). Resistance significantly correlated with depth of response measured after consolidation (80.9% CR and 68.4% minimal residual disease negativity in patients with sensitive vs. 31% and 20% in those with refractory kinetics). Furthermore, it modulated the impact of reaching CR after consolidation; thus, within CR patients those with refractory kinetics had significantly shorter PFS than those with sensitive kinetics (median 54 months vs. NR; P = .02). Minimal residual disease negativity abrogated this effect. Our study also questions the benefit of rapid responders compared to late responders (5-year PFS 59.7% vs. 76.5%, respectively [P < .002]). Of note, 85% of patients considered as late responders were classified as having sensitive kinetics. CONCLUSION: This semi-mechanistic modeling of M-component kinetics could be of great value to identify patients at risk of early treatment failure, who may benefit from early rescue intervention strategies.

Unsupervised machine learning improves risk stratification in newly diagnosed multiple myeloma: an analysis of the Spanish Myeloma Group.

The International Staging System (ISS) and the Revised International Staging System (R-ISS) are commonly used prognostic scores in multiple myeloma (MM). These methods have significant gaps, particularly among intermediate-risk groups. The aim of this study was to improve risk stratification in newly diagnosed MM patients using data from three different trials developed by the Spanish Myeloma Group. For this, we applied an unsupervised machine learning clusterization technique on a set of clinical, biochemical and cytogenetic variables, and we identified two novel clusters of patients with significantly different survival. The prognostic precision of this clusterization was superior to those of ISS and R-ISS scores, and appeared to be particularly useful to improve risk stratification among R-ISS 2 patients. Additionally, patients assigned to the low-risk cluster in the GEM05 over 65 years trial had a significant survival benefit when treated with VMP as compared with VTD. In conclusion, we describe a simple prognostic model for newly diagnosed MM whose predictions are independent of the ISS and R-ISS scores. Notably, the model is particularly useful in order to re-classify R-ISS score 2 patients in 2 different prognostic subgroups. The combination of ISS, R-ISS and unsupervised machine learning clusterization brings a promising approximation to improve MM risk stratification.

A simple score to predict early severe infections in patients with newly diagnosed multiple myeloma.

Infections remain a common complication in patients with multiple myeloma (MM) and are associated with morbidity and mortality. A risk score to predict the probability of early severe infection could help to identify the patients that would benefit from preventive measures. We undertook a post hoc analysis of infections in four clinical trials from the Spanish Myeloma Group, involving a total of 1347 patients (847 transplant candidates). Regarding the GEM2010 > 65 trial, antibiotic prophylaxis was mandatory, so we excluded it from the final analysis. The incidence of severe infection episodes within the first 6 months was 13.8%, and majority of the patients experiencing the first episode before 4 months (11.1%). 1.2% of patients died because of infections within the first 6 months (1% before 4 months). Variables associated with increased risk of severe infection in the first 4 months included serum albumin ≤30 g/L, ECOG > 1, male sex, and non-IgA type MM. A simple risk score with these variables facilitated the identification of three risk groups with different probabilities of severe infection within the first 4 months: low-risk (score 0-2) 8.2%; intermediate-risk (score 3) 19.2%; and high-risk (score 4) 28.3%. Patients with intermediate/high risk could be candidates for prophylactic antibiotic therapies.

Mass spectrometry vs immunofixation for treatment monitoring in multiple myeloma.

Monitoring of the monoclonal protein (M-protein) by electrophoresis and/or immunofixation (IFE) has long been used to assess treatment response in multiple myeloma (MM). However, with the use of highly effective therapies, the M-protein becomes frequently undetectable, and more sensitive methods had to be explored. We applied IFE and mass spectrometry (EXENT&FLC-MS) in serum samples from newly diagnosed MM patients enrolled in the PETHEMA/GEM2012MENOS65 obtained at baseline (n = 223), and after induction (n = 183), autologous stem cell transplantation (n = 173), and consolidation (n = 173). At baseline, the isotypes identified with both methods fully matched in 82.1% of samples; in the rest but 2 cases, EXENT&FLC-MS provided additional information to IFE with regards to the M-protein(s). Overall, the results of EXENT&FLC-MS and IFE were concordant in >80% of cases, being most discordances due to EXENT&FLC-MS+ but IFE- cases. After consolidation, IFE was not able to discriminate 2 cohorts with different median progression-free survival (PFS), but EXENT&FLC-MS did so; furthermore, among IFE- patients, EXENT&FLC-MS identified 2 groups with significantly different median PFS (P = .0008). In conclusion, compared with IFE, EXENT&FLC-MS is more sensitive to detect the M-protein of patients with MM, both at baseline and during treatment, and provides a more accurate prediction of patients' outcome. This trial was registered at www.clinicaltrials.gov as #NCT01916252.

A Machine Learning Model Based on Tumor and Immune Biomarkers to Predict Undetectable MRD and Survival Outcomes in Multiple Myeloma.

PURPOSE: Undetectable measurable residual disease (MRD) is a surrogate of prolonged survival in multiple myeloma. Thus, treatment individualization based on the probability of a patient achieving undetectable MRD with a singular regimen could represent a new concept toward personalized treatment, with fast assessment of its success. This has never been investigated; therefore, we sought to define a machine learning model to predict undetectable MRD at the onset of multiple myeloma. EXPERIMENTAL DESIGN: This study included 487 newly diagnosed patients with multiple myeloma. The training (n = 152) and internal validation cohorts (n = 149) consisted of 301 transplant-eligible patients with active multiple myeloma enrolled in the GEM2012MENOS65 trial. Two external validation cohorts were defined by 76 high-risk transplant-eligible patients with smoldering multiple myeloma enrolled in the Grupo Español de Mieloma(GEM)-CESAR trial, and 110 transplant-ineligible elderly patients enrolled in the GEM-CLARIDEX trial. RESULTS: The most effective model to predict MRD status resulted from integrating cytogenetic [t(4;14) and/or del(17p13)], tumor burden (bone marrow plasma cell clonality and circulating tumor cells), and immune-related biomarkers. Accurate predictions of MRD outcomes were achieved in 71% of cases in the GEM2012MENOS65 trial (n = 214/301) and 72% in the external validation cohorts (n = 134/186). The model also predicted sustained MRD negativity from consolidation onto 2 years maintenance (GEM2014MAIN). High-confidence prediction of undetectable MRD at diagnosis identified a subgroup of patients with active multiple myeloma with 80% and 93% progression-free and overall survival rates at 5 years. CONCLUSIONS: It is possible to accurately predict MRD outcomes using an integrative, weighted model defined by machine learning algorithms. This is a new concept toward individualized treatment in multiple myeloma. See related commentary by Pawlyn and Davies, p. 2482.

Deep MRD profiling defines outcome and unveils different modes of treatment resistance in standard- and high-risk myeloma.

Patients with multiple myeloma (MM) carrying standard- or high-risk cytogenetic abnormalities (CAs) achieve similar complete response (CR) rates, but the later have inferior progression-free survival (PFS). This questions the legitimacy of CR as a treatment endpoint and represents a biological conundrum regarding the nature of tumor reservoirs that persist after therapy in high-risk MM. We used next-generation flow (NGF) cytometry to evaluate measurable residual disease (MRD) in MM patients with standard- vs high-risk CAs (n = 300 and 90, respectively) enrolled in the PETHEMA/GEM2012MENOS65 trial, and to identify mechanisms that determine MRD resistance in both patient subgroups (n = 40). The 36-month PFS rates were higher than 90% in patients with standard- or high-risk CAs achieving undetectable MRD. Persistent MRD resulted in a median PFS of âˆ¼3 and 2 years in patients with standard- and high-risk CAs, respectively. Further use of NGF to isolate MRD, followed by whole-exome sequencing of paired diagnostic and MRD tumor cells, revealed greater clonal selection in patients with standard-risk CAs, higher genomic instability with acquisition of new mutations in high-risk MM, and no unifying genetic event driving MRD resistance. Conversely, RNA sequencing of diagnostic and MRD tumor cells uncovered the selection of MRD clones with singular transcriptional programs and reactive oxygen species-mediated MRD resistance in high-risk MM. Our study supports undetectable MRD as a treatment endpoint for patients with MM who have high-risk CAs and proposes characterizing MRD clones to understand and overcome MRD resistance. This trial is registered at www.clinicaltrials.gov as #NCT01916252.

Immunogenomic identification and characterization of granulocytic myeloid-derived suppressor cells in multiple myeloma.

Granulocytic myeloid-derived suppressor cells (G-MDSCs) promote tumor growth and immunosuppression in multiple myeloma (MM). However, their phenotype is not well established for accurate monitoring or clinical translation. We aimed to provide the phenotypic profile of G-MDSCs based on their prognostic significance in MM, immunosuppressive potential, and molecular program. The preestablished phenotype of G-MDSCs was evaluated in bone marrow samples from controls and MM patients using multidimensional flow cytometry; surprisingly, we found that CD11b+CD14-CD15+CD33+HLADR- cells overlapped with common eosinophils and neutrophils, which were not expanded in MM patients. Therefore, we relied on automated clustering to unbiasedly identify all granulocytic subsets in the tumor microenvironment: basophils, eosinophils, and immature, intermediate, and mature neutrophils. In a series of 267 newly diagnosed MM patients (GEM2012MENOS65 trial), only the frequency of mature neutrophils at diagnosis was significantly associated with patient outcome, and a high mature neutrophil/T-cell ratio resulted in inferior progression-free survival (P < .001). Upon fluorescence-activated cell sorting of each neutrophil subset, T-cell proliferation decreased in the presence of mature neutrophils (0.5-fold; P = .016), and the cytotoxic potential of T cells engaged by a BCMA×CD3-bispecific antibody increased notably with the depletion of mature neutrophils (fourfold; P = .0007). Most interestingly, RNA sequencing of the 3 subsets revealed that G-MDSC-related genes were specifically upregulated in mature neutrophils from MM patients vs controls because of differential chromatin accessibility. Taken together, our results establish a correlation between the clinical significance, immunosuppressive potential, and transcriptional network of well-defined neutrophil subsets, providing for the first time a set of optimal markers (CD11b/CD13/CD16) for accurate monitoring of G-MDSCs in MM.

Measurable Residual Disease by Next-Generation Flow Cytometry in Multiple Myeloma.

PURPOSE: Assessing measurable residual disease (MRD) has become standard with many tumors, but the clinical meaning of MRD in multiple myeloma (MM) remains uncertain, particularly when assessed by next-generation flow (NGF) cytometry. Thus, we aimed to determine the applicability and sensitivity of the flow MRD-negative criterion defined by the International Myeloma Working Group (IMWG). PATIENTS AND METHODS: In the PETHEMA/GEM2012MENOS65 trial, 458 patients with newly diagnosed MM had longitudinal assessment of MRD after six induction cycles with bortezomib, lenalidomide, and dexamethasone (VRD), autologous transplantation, and two consolidation courses with VRD. MRD was assessed in 1,100 bone marrow samples from 397 patients; the 61 patients without MRD data discontinued treatment during induction and were considered MRD positive for intent-to-treat analysis. The median limit of detection achieved by NGF was 2.9 × 10-6. Patients received maintenance (lenalidomide ± ixazomib) according to the companion PETHEMA/GEM2014MAIN trial. RESULTS: Overall, 205 (45%) of 458 patients had undetectable MRD after consolidation, and only 14 of them (7%) have experienced progression thus far; seven of these 14 displayed extraosseous plasmacytomas at diagnosis and/or relapse. Using time-dependent analysis, patients with undetectable MRD had an 82% reduction in the risk of progression or death (hazard ratio, 0.18; 95% CI, 0.11 to 0.30; P < .001) and an 88% reduction in the risk of death (hazard ratio, 0.12; 95% CI, 0.05 to 0.29; P < .001). Timing of undetectable MRD (after induction v intensification) had no impact on patient survival. Attaining undetectable MRD overcame poor prognostic features at diagnosis, including high-risk cytogenetics. By contrast, patients with Revised International Staging System III status and positive MRD had dismal progression-free and overall survivals (median, 14 and 17 months, respectively). Maintenance increased the rate of undetectable MRD by 17%. CONCLUSION: The IMWG flow MRD-negative response criterion is highly applicable and sensitive to evaluate treatment efficacy in MM.

Bortezomib, lenalidomide, and dexamethasone as induction therapy prior to autologous transplant in multiple myeloma.

Achieving and maintaining a high-quality response is the treatment goal for patients with newly diagnosed multiple myeloma (NDMM). The phase 3 PETHEMA/GEM2012 study, in 458 patients aged ≤65 years with NDMM, is evaluating bortezomib (subcutaneous) + lenalidomide + dexamethasone (VRD) for 6 cycles followed by autologous stem cell transplant (ASCT) conditioned with IV busulfan + melphalan vs melphalan and posttransplant consolidation with 2 cycles of VRD. We present grouped response analysis of induction, transplant, and consolidation. Responses deepened over time; in patients who initiated cycle 6 of induction (n = 426), the rates of a very good partial response or better were 55.6% by cycle 3, 63.8% by cycle 4, 68.3% by cycle 5, and 70.4% after induction. The complete response rate of 33.4% after induction in the intent-to-treat (ITT) population, which was similar in the 92 patients with high-risk cytogenetics (34.8%), also deepened with further treatment (44.1% after ASCT and 50.2% after consolidation). Rates of undetectable minimal residual disease (median 3 × 10-6 sensitivity) in the ITT population also increased from induction (28.8%) to transplant (42.1%) and consolidation (45.2%). The most common grade ≥3 treatment-emergent adverse events during induction were neutropenia (12.9%) and infection (9.2%). Grade ≥2 peripheral neuropathy (grouped term) during induction was 17.0%, with a low frequency of grade 3 (3.7%) and grade 4 (0.2%) events. VRD is an effective and well-tolerated regimen for induction in NDMM with deepening response throughout induction and over the course of treatment. This trial was registered at www.clinicaltrials.gov as #NCT01916252 and EudraCT as #2012-005683-10.