Selinexor, daratumumab, bortezomib and dexamethasone for the treatment of patients with relapsed or refractory multiple myeloma: results of the phase II, non-randomized, multicenter GEM-SELIBORDARA study.

The treatment landscape for multiple myeloma has significantly evolved in the last decade. Notwithstanding, a large proportion of patients continue to relapse and novel combinations continue to be needed. In this phase 2 study, selinexor, a first-in-class inhibitor of exportin-1 was evaluated in combination with standard daratumumab-bortezomib-dexamethasone (DVd), for the treatment of relapsed and refractory multiple myeloma (RRMM). The aim of the trial was to assess the efficacy and safety of the combination of selinexor with DVd (S-DVd). A total of 57 patients were enrolled in the two parts of the study. Part 1 enrolled a heavily pretreated population with at least 3 prior lines of therapy and part 2 enrolled an early relapse population with at least 1 prior therapy. The primary endpoint was complete response (CR) rate in part 2 and overall response rate (ORR) in part 1. In the latter, 24 patients were treated with a median of 3 prior lines. Overall response rate (ORR) was 50% with 2 CR. Median progressionfree survival (PFS) was 7 months. In part 2, 33 patients were enrolled, with a median of 1 prior lines. ORR was 82% and CR or better was 33%. Median PFS was 24 months. In lenalidomide refractory patients, a median PFS of 22.1 months was observed. Thrombocytopenia was the most common hematological adverse event (69%; grade 3-4: 34%) and nausea, the most frequent nonhematological AE (38%; grade 3-4: 6%). 62% of the patients required dose modifications. In summary, although the primary endpoint of the study was not met, the combination of S-DVd showed encouraging clinical efficacy with a generally manageable safety profile representing a potential option for the treatment of RRMM patients.

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.

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.

Large T cell clones expressing immune checkpoints increase during multiple myeloma evolution and predict treatment resistance.

Tumor recognition by T cells is essential for antitumor immunity. A comprehensive characterization of T cell diversity may be key to understanding the success of immunomodulatory drugs and failure of PD-1 blockade in tumors such as multiple myeloma (MM). Here, we use single-cell RNA and T cell receptor sequencing to characterize bone marrow T cells from healthy adults (n = 4) and patients with precursor (n = 8) and full-blown MM (n = 10). Large T cell clones from patients with MM expressed multiple immune checkpoints, suggesting a potentially dysfunctional phenotype. Dual targeting of PD-1 + LAG3 or PD-1 + TIGIT partially restored their function in mice with MM. We identify phenotypic hallmarks of large intratumoral T cell clones, and demonstrate that the CD27- and CD27+ T cell ratio, measured by flow cytometry, may serve as a surrogate of clonal T cell expansions and an independent prognostic factor in 543 patients with MM treated with lenalidomide-based treatment combinations.

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.

Randomized phase II study of weekly carfilzomib 70 mg/m2 and dexamethasone with or without cyclophosphamide in relapsed and/or refractory multiple myeloma patients.

In this randomized phase II study (GEM-KyCyDex, clinicaltrials gov. Identifier: NCT03336073), the combination of weekly carfilzomib 70 mg/m2, cyclophosphamide and dexamethasone (KCd) was compared to carfilzomib and dexamethasone (Kd) in relapsed/refractory multiple myeloma (RRMM) after 1-3 prior lines (PL). One hundred and ninety-seven patients were included and randomized 1:1 to receive KCd (97 patients) or Kd (100 patients) in 28-day cycles until progressive disease or unacceptable toxicity occurred. Patient median age was 70 years, and the median number of PL was one (range, 1-3). More than 90% of patients had previously been exposed to proteasome inhibitors, approximetely 70% to immunomodulators, and approximetely 50% were refractory to their last line (mainly lenalidomide) in both groups. After a median follow-up of 37 months, median progression-free survival (PFS) was 19.1 and 16.6 months in KCd and Kd, respectively (P=0.577). Of note, in the post hoc analysis of the lenalidomide-refractory population, the addition of cyclophosphamide to Kd resulted in a significant benefit in terms of PFS: 18.4 versus 11.3 months (hazard ratio =1.7, 95% confidence interval: 1.1-2.7; P=0.043). The overall response rate and the percentage of patients who achieved complete response was around 70% and 20% in both groups. The addition of cyclophosphamide to Kd did not result in any safety signal, except for severe infections (7% vs. 2%). In conclusion, the combination of cyclophosphamide with Kd 70 mg/m2 weekly does not improve outcomes as compared with Kd alone in RRMM after 1-3 PL, but a significant benefit in PFS was observed with the triplet combination in the lenalidomide-refractory population. The administration of weekly carfilzomib 70 mg/m2 was safe and convenient, and, overall, the toxicity was manageable in both arms.

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.

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.

Circulating Tumor and Immune Cells for Minimally Invasive Risk Stratification of Smoldering Multiple Myeloma.

PURPOSE: Early intervention in smoldering multiple myeloma (SMM) requires optimal risk stratification to avoid under- and overtreatment. We hypothesized that replacing bone marrow (BM) plasma cells (PC) for circulating tumor cells (CTC), and adding immune biomarkers in peripheral blood (PB) for the identification of patients at risk of progression due to lost immune surveillance, could improve the International Myeloma Working Group 20/2/20 model. EXPERIMENTAL DESIGN: We report the outcomes of 150 patients with SMM enrolled in the iMMunocell study, in which serial assessment of tumor and immune cells in PB was performed every 6 months for a period of 3 years since enrollment. RESULTS: Patients with >0.015% versus ≤0.015% CTCs at baseline had a median time-to-progression of 17 months versus not reached (HR, 4.9; P < 0.001). Presence of >20% BM PCs had no prognostic value in a multivariate analysis that included serum free light-chain ratio >20, >2 g/dL M-protein, and >0.015% CTCs. The 20/2/20 and 20/2/0.015 models yielded similar risk stratification (C-index of 0.76 and 0.78). The combination of the 20/2/0.015 model with an immune risk score based on the percentages of SLAN+ and SLAN- nonclassical monocytes, CD69+HLADR+ cytotoxic NK cells, and CD4+CXCR3+ stem central memory T cells, allowed patient' stratification into low, intermediate-low, intermediate-high, and high-risk disease with 0%, 20%, 39%, and 73% rates of progression at 2 years. CONCLUSIONS: This study showed that CTCs outperform BM PCs for assessing tumor burden. Additional analysis in larger series are needed to define a consensus cutoff of CTCs for minimally invasive stratification of SMM.

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.

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.

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.

Minimal Residual Disease in Multiple Myeloma: Something Old, Something New.

The game-changing outcome effect, due to the generalized use of novel agents in MM, has cre-ated a paradigm shift. Achieving frequent deep responses has placed MM among those neoplasms where the rationale for assessing MRD is fulfilled. However, its implementation in MM has raised specific questions: how might we weight standard measures against deep MRD in the emerging CAR-T setting? Which high sensitivity method to choose? Are current response criteria still useful? In this work, we address lessons learned from the use of MRD in other neoplasms, the steps followed for the harmonization of current methods for comprehensively measuring MRD, and the challenges that new therapies and concepts pose in the MM clinical field.

Tumor cells in light-chain amyloidosis and myeloma show distinct transcriptional rewiring of normal plasma cell development.

Although light-chain amyloidosis (AL) and multiple myeloma (MM) are characterized by tumor plasma cell (PC) expansion in bone marrow (BM), their clinical presentation differs. Previous attempts to identify unique pathogenic mechanisms behind such differences were unsuccessful, and no studies have investigated the differentiation stage of tumor PCs in patients with AL and MM. We sought to define a transcriptional atlas of normal PC development in secondary lymphoid organs (SLOs), peripheral blood (PB), and BM for comparison with the transcriptional programs (TPs) of tumor PCs in AL, MM, and monoclonal gammopathy of undetermined significance (MGUS). Based on bulk and single-cell RNA sequencing, we observed 13 TPs during transition of normal PCs throughout SLOs, PB, and BM. We further noted the following: CD39 outperforms CD19 to discriminate newborn from long-lived BM-PCs; tumor PCs expressed the most advantageous TPs of normal PC differentiation; AL shares greater similarity to SLO-PCs whereas MM is transcriptionally closer to PB-PCs and newborn BM-PCs; patients with AL and MM enriched in immature TPs had inferior survival; and protein N-linked glycosylation-related TPs are upregulated in AL. Collectively, we provide a novel resource to understand normal PC development and the transcriptional reorganization of AL and other monoclonal gammopathies.

Lenalidomide and dexamethasone with or without clarithromycin in patients with multiple myeloma ineligible for autologous transplant: a randomized trial.

Although case-control analyses have suggested an additive value with the association of clarithromycin to continuous lenalidomide and dexamethasone (Rd), there are not phase III trials confirming these results. In this phase III trial, 286 patients with MM ineligible for ASCT received Rd with or without clarithromycin until disease progression or unacceptable toxicity. The primary endpoint was progression-free survival (PFS). With a median follow-up of 19 months (range, 0-54), no significant differences in the median PFS were observed between the two arms (C-Rd 23 months, Rd 29 months; HR 0.783, p = 0.14), despite a higher rate of complete response (CR) or better in the C-Rd group (22.6% vs 14.4%, p = 0.048). The most common G3-4 adverse events were neutropenia [12% vs 19%] and infections [30% vs 25%], similar between the two arms; however, the percentage of toxic deaths was higher in the C-Rd group (36/50 [72%] vs 22/40 [55%], p = 0.09). The addition of clarithromycin to Rd in untreated transplant ineligible MM patients does not improve PFS despite increasing the ≥CR rate due to the higher number of toxic deaths in the C-Rd arm. Side effects related to overexposure to steroids due to its delayed clearance induced by clarithromycin in this elderly population could explain these results. The trial was registered in clinicaltrials.gov with the name GEM-CLARIDEX: Ld vs BiRd and with the following identifier NCT02575144. The full trial protocol can be accessed from ClinicalTrials.gov. This study received financial support from BMS/Celgene.

Filanesib in combination with pomalidomide and dexamethasone in refractory MM patients: safety and efficacy, and association with alpha 1-acid glycoprotein (AAG) levels. Phase Ib/II Pomdefil clinical trial conducted by the Spanish MM group.

This phase I/II trial evaluated the combination of the kinesin spindle protein inhibitor filanesib with pomalidomide and dexamethasone in relapsed or refractory multiple myeloma (RRMM) patients. Forty-seven RRMM patients with a median of three prior lines (2-8) and 94% refractory to lenalidomide were included: 14 in phase I and 33 in phase II. The recommended dose was 1·25 mg/m2 of filanesib on days 1, 2, 15, 16, with pomalidomide 4 mg on days 1-21 and dexamethasone 40 mg weekly. The defined threshold for success was achieved, with 18 out of 31 patients obtaining at least minor response (MR) in the phase II. In the global population, 51% of patients achieved at least partial response (PR) and 60% ≥MR, resulting in a median progression-free survival (mPFS) of seven months and overall survival (OS) of 19 months. The main toxicity was haematological. Importantly, patients with low serum levels of alpha 1-acid glycoprotein (AAG) at baseline (<800 mg/l) had a superior response (overall response rate of 62% vs. 17%; P = 0·04), which also translated into a longer mPFS (9 vs. 2 months; P = 0·014). In summary, filanesib with pomalidomide and dexamethasone is active in RRMM although with significant haematological toxicity. Most importantly, high levels of AAG can identify patients unlikely to respond to this strategy. Trial registration: clinicaltrials.gov identifier: NCT02384083.

Pembrolizumab as Consolidation Strategy in Patients with Multiple Myeloma: Results of the GEM-Pembresid Clinical Trial.

PD1 expression in CD4+ and CD8+ T cells is increased after treatment in multiple myeloma patients with persistent disease. The GEM-Pembresid trial analyzed the efficacy and safety of pembrolizumab as consolidation in patients achieving at least very good partial response but with persistent measurable disease after first- or second-line treatment. Moreover, the characteristics of the immune system were investigated to identify potential biomarkers of response to pembrolizumab. One out of the 17 evaluable patients showed a decrease in the amount of M-protein, although a potential late effect of high-dose melphalan could not be ruled out. Fourteen adverse events were considered related to pembrolizumab, two of which (G3 diarrhea and G2 pneumonitis) prompted treatment discontinuation and all resolving without sequelae. Interestingly, pembrolizumab induced a decrease in the percentage of NK cells at cycle 3, due to the reduction of the circulating and adaptive subsets (0.615 vs. 0.43, p = 0.007; 1.12 vs. 0.86, p = 0.02). In the early progressors, a significantly lower expression of PD1 in CD8+ effector memory T cells (MFI 1327 vs. 926, p = 0.03) was observed. In conclusion, pembrolizumab used as consolidation monotherapy shows an acceptable toxicity profile but did not improve responses in this MM patient population. The trial was registered at clinicaltrials.gov with identifier NCT02636010 and with EUDRACT number 2015-003359-23.

Biological and clinical significance of dysplastic hematopoiesis in patients with newly diagnosed multiple myeloma.

Risk of developing myelodysplastic syndrome (MDS) is significantly increased in both multiple myeloma (MM) and monoclonal gammopathy of undetermined significance, suggesting that it is therapy independent. However, the incidence and sequelae of dysplastic hematopoiesis at diagnosis are unknown. Here, we used multidimensional flow cytometry (MFC) to prospectively screen for the presence of MDS-associated phenotypic alterations (MDS-PA) in the bone marrow of 285 patients with MM enrolled in the PETHEMA/GEM2012MENOS65 trial (#NCT01916252). We investigated the clinical significance of monocytic MDS-PA in a larger series of 1252 patients enrolled in 4 PETHEMA/GEM protocols. At diagnosis, 33 (11.6%) of 285 cases displayed MDS-PA. Bulk and single-cell-targeted sequencing of MDS recurrently mutated genes in CD34+ progenitors (and dysplastic lineages) from 67 patients revealed clonal hematopoiesis in 13 (50%) of 26 cases with MDS-PA vs 9 (22%) of 41 without MDS-PA; TET2 and NRAS were the most frequently mutated genes. Dynamics of MDS-PA at diagnosis and after autologous transplant were evaluated in 86 of 285 patients and showed that in most cases (69 of 86 [80%]), MDS-PA either persisted or remained absent in patients with or without MDS-PA at diagnosis, respectively. Noteworthy, MDS-associated mutations infrequently emerged after high-dose therapy. Based on MFC profiling, patients with MDS-PA have altered hematopoiesis and T regulatory cell distribution in the tumor microenvironment. Importantly, the presence of monocytic MDS-PA at diagnosis anticipated greater risk of hematologic toxicity and was independently associated with inferior progression-free survival (hazard ratio, 1.5; P = .02) and overall survival (hazard ratio, 1.7; P = .01). This study reveals the biological and clinical significance of dysplastic hematopoiesis in newly diagnosed MM, which can be screened with moderate sensitivity using cost-effective MFC.