High-risk Smoldering Multiple Myeloma Research Articles

Three-dimensional telomere profiling predicts risk of progression in smoldering multiple myeloma.

Smoldering multiple myeloma (SMM) is a precursor stage that precedes multiple myeloma (MM). SMM is heterogenous with nearly 40% of patients progressing to MM in the first 5 years. The high rate of progression of SMM patients highlights the need for early intervention, which underscores the importance of identifying SMM patients with the highest risk of progression. Several risk stratification models showed utility in identifying high-risk SMM patients; however, these systems showed limited sensitivity. To date, identifying high-risk SMM patients remains an important clinical need. In this study, we present the 3-dimensional telomere profiling as a structural biomarker capable of stratifying SMM patients as a function of genomic instability. Quantifying telomere dysfunction using the TeloView technology showed utility in risk stratification of cancer patients, particularly hematological malignancies. In this study, we analyzed 168 SMM patients. We report an AUC in ROC analysis of 0.8 using a subset of the patients as a training dataset. We then conducted a blind validation on a different cohort and demonstrated a positive predictive value of 85% and negative predictive value of 73%, with sensitivity and specificity of 83% and 76%, respectively. We examined the correlation between the TeloView prediction and the 20-2-20 scoring system, and cytogenetic abnormalities. We report a correlation of 53% with the 20-2-20 scores and over 60% correlation with cytogenetic abnormalities. The result of this study presents the telomere profiling as an effective biomarker able to stratify SMM patients to their respective risk groups with high sensitivity and specificity.

The genomic profiling of high-risk smoldering myeloma patients treated with an intensive strategy unveils potential markers of resistance and progression

Smoldering multiple myeloma (SMM) precedes multiple myeloma (MM). The risk of progression of SMM patients is not uniform, thus different progression-risk models have been developed, although they are mainly based on clinical parameters. Recently, genomic predictors of progression have been defined for untreated SMM. However, the usefulness of such markers in the context of clinical trials evaluating upfront treatment in high-risk SMM (HR SMM) has not been explored yet, precluding the identification of baseline genomic alterations leading to drug resistance. For this reason, we carried out next-generation sequencing and fluorescent in-situ hybridization studies on 57 HR and ultra-high risk (UHR) SMM patients treated in the phase II GEM-CESAR clinical trial (NCT02415413). DIS3, FAM46C, and FGFR3 mutations, as well as t(4;14) and 1q alterations, were enriched in HR SMM. TRAF3 mutations were specifically associated with UHR SMM but identified cases with improved outcomes. Importantly, novel potential predictors of treatment resistance were identified: NRAS mutations and the co-occurrence of t(4;14) plus FGFR3 mutations were associated with an increased risk of biological progression. In conclusion, we have carried out for the first time a molecular characterization of HR SMM patients treated with an intensive regimen, identifying genomic predictors of poor outcomes in this setting.

Genomic Profiling to Contextualize the Results of Intervention for Smoldering Multiple Myeloma.

Early intervention for High-Risk Smoldering Multiple Myeloma (HR-SMM) achieves deep and prolonged responses. It is unclear if beneficial outcomes are due to treatment of less complex, susceptible disease or inaccuracy in clinical definition of cases entered. Here, we interrogated whole genome and whole exome sequencing for 54 patients across two HR-SMM interventional studies (NCT01572480, NCT02279394). We reveal that the genomic landscape of treated HR-SMM is generally simple as compared to Newly Diagnosed (ND)MM counterparts with less inactivation of tumor suppressor genes, RAS pathway mutations, MYC disruption, and APOBEC contribution. The absence of these events parallels that of indolent precursor conditions, possibly explaining overall excellent outcomes. However, some patients harboring genomic complexity fail to sustain response and experience resistant, progressive disease. Overall, clinical risk scores do not effectively discriminate between genomically indolent and aggressive disease. Genomic profiling can contextualize the advantage of early intervention in SMM and guide personalization of therapy.

Abstract 5186: Spatial single-cell deconvolution of the bone marrow microenvironment to define predictive biomarker for response to immunotherapy in patients treated with a check point inhibitor in smoldering multiple myeloma, phase II trial of nivolumab in combination with lenalidomide and low dose dexamethasone

Abstract Background:The immune system is critical for response and resistance in all cancer types and therapies. Patients with Smoldering Multiple Myeloma (SMM) have altered immune cell composition in the bone marrow (BM). However, little is known about the role of BM spatial immune profiling in patients treated with checkpoint inhibitors in MM. Methods: We performed spatial profiling with imaging mass cytometry of trephine biopsies of the BM (n=15; pre-treatment n=7 and post-treatment n=8) from patients with high-risk SMM enrolled in a phase II trial of nivolumab in combination with lenalidomide and low dose dexamethasone (NCT02903381). Patients received 6 cycles of induction therapy of nivolumab (240mg) at days 1 and 15, in combination with lenalidomide (25mg) at days 1-21 and dexamethasone at days 1, 8, and 15. The induction phase was followed by nivolumab (240mg) and lenalidomide (25mg) maintenance for another 6 cycles. A treatment cycle was defined as 28 consecutive days for a total of 12 months period. Event monitoring was performed up to 3 years. The primary efficacy outcome was progression-free survival 2 years after treatment. Results: Eight patients were enrolled on this study from January 2017 to June 2017. The study was put on hold due to the toxicity of checkpoint inhibitors observed in other trials of MM. The median age for all patients at enrolment was 60 years (range 49 to 81), with 5 males (62%) and 3 females (38%). All patients met criteria for high risk SMM disease. Median follow-up for all 8 patients was 38.7 months. Median overall survival was not reached; median progression-free survival was 33.8 months. Seven total patients had a response of Minimal Response (MR) or better, and 4 patients who initially responded eventually progressed. The total number of patients who were followed for at least two years and remained progression-free was 4 of 8 evaluable patients (50%; 90% CI: 19 - 81%).Spatial profiling with a panel of 37 markers on the pre-treatment samples allowed us to assess the states and abundances of multiple immune subpopulations, including rare regulatory NK cells. To assess the accuracy of our cell type annotation, we correlated the proportion of malignant plasma cells identified per patient with the value determined by pathologists for clinical diagnosis. These measures were significantly positively correlated (R=0.92, p<0.01). Spatial neighborhood analysis revealed statistically significant interactions enriched in the responders, even with our small sample size (t-test; p < 0.05). Conclusions and future directions: This pilot study suggests that BM spatial immune profiling before receiving immune check point inhibitors can be a biomarker for response in patients with SMM. Citation Format: Yoshinobu Konishi, Giuseppe Tarantino, Yiwen He, Romanos Sklavenitis-Pistofidis, Sujal I. Shah, Katherine Towle, Christian J. Cea-Curry, Oksana Zavidij, Ruben D. Carrasco, Scott J. Rodig, Jon C. Aster, David Liu, Gad Getz, Irene M. Ghobrial. Spatial single-cell deconvolution of the bone marrow microenvironment to define predictive biomarker for response to immunotherapy in patients treated with a check point inhibitor in smoldering multiple myeloma, phase II trial of nivolumab in combination with lenalidomide and low dose dexamethasone [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5186.

Mode of progression in smoldering multiple myeloma: a study of 406 patients

The approach to patients with high-risk smoldering multiple myeloma (SMM) varies among clinicians; while some advocate early intervention, others reserve treatment at progression to multiple myeloma (MM). We aimed to describe the myeloma-defining events (MDEs) and clinical presentations leading to MM diagnosis among SMM patients seen at our institution. We included 406 patients diagnosed with SMM between 2013–2022, seen at Mayo Clinic, Rochester, MN. The 2018 Mayo 20/2/20 criteria were used for risk stratification. Median follow-up was 3.9 years. Among high-risk patients who did not receive treatment in the SMM phase (n = 71), 51 progressed by last follow-up; the MDEs included: bone lesions (37%), anemia (35%), hypercalcemia (8%), and renal failure (6%); 24% met MM criteria based on marrow plasmacytosis (≥60%) and/or free light chain ratio (>100); 45% had clinically significant MDEs (hypercalcemia, renal insufficiency, and/or bone lesions). MM diagnosis was made based on surveillance labs/imaging(45%), testing obtained due to provider suspicion for progression (14%), bone pain (20%), and hospitalization/ED presentations due to MM complications/symptoms (4%). The presentation was undocumented in 14%. A high proportion (45%) of patients with high-risk SMM on active surveillance develop end-organ damage at progression. About a quarter of patients who progress to MM are not diagnosed based on routine interval surveillance testing.

Genomic Profiling to Interpret the Outcomes of Early Intervention for High-Risk Smoldering Myeloma

Introduction Early intervention for High-Risk Smoldering Multiple Myeloma (HR-SMM) achieves deeper and more prolonged responses compared to Newly Diagnosed (ND) MM. Various clinical risk models estimate the risk of SMM progression to MM but there is significant discordance between them (Hill et al., JAMA Onc. 2021). It is unclear if beneficial outcomes of interventional studies in HR-SMM are due to treatment of less complex, susceptible disease or inaccuracy in clinical definition of cases entered. Methods To gain greater biologic insight into treatment outcomes, we performed the first whole genome sequencing (WGS) analysis of treated HR-SMM for 27 patients treated with carfilzomib, lenalidomide, and dexamethasone (KRd) and R maintenance (NCT01572480, presented in parallel). We pooled genomic features from 27 patients with HR-SMM treated with Elotuzumab (Elo)R+/-d; (E-PRISM). Genomic features were compared to those of 701 patients with NDMM from CoMMpass (NCT01454297). Results After a median follow-up of 52.8 months, median PFS was not reached with KRd/R. After 8 cycles of KRd, 19 (70.3%) achieved minimal residual disease (MRD) negativity (LOD 10 -5). At data cutoff, June 13, 2023, 14 patients (51.9%) achieved sustained MRD-negativity, 6 patients (22.2%) lost an initial MRD-negative response and 5 patients clinically progressed (18.5%). Overall, there was discordance between risk models: 3 patients (11.1%) were HR by Mayo2008 criteria, 14 (51.9%) by Mayo 20/2/20, 18 (66.7%) by PETHEMA, and 21 (77.8%) by Rajkumar/Landgren/Mateos criteria (Rajkumar et al., Blood. 2015). Eighteen (66.7%) met criteria for 2 or more scores. The estimated 5-year risk of progression ranged 4.8 to 82.1% (Pangea, median 18.6%). We compared the pooled HR-SMM to NDMM from CoMMpass. The frequency of HR translocations was similar (t(4;14), t(14;16), t(14;20); p>0.05). Consistent with the early disease stage of SMM, mutations of NRAS were lower in SMM (p = <0.001) as were events at the MYC locus (8q24; p <0.001) and gains of 1q (p = 0.039). Next, tumor suppressor genes (TSG) were interrogated together with copy number loss at their loci. Consistent with their late onset in tumor evolution, aberrations at key TSG were less common in HR-SMM (p < 0.05): CDKN2C, CYLD, TENT5C, FUBP1, MAX, NCOR1, NF1, NFKBIA, PRDM1, RB1, RPL5,and TRAF3 (p < 0.05). In a genome-corrected comparison, APOBEC (SBS2+SBS13) mutational signatures were diminished in KRd WGS compared to 60 Dara-KRd-treated NDMM (Maura et al., ASH. 2021; 48% vs 87%, p < 0.001) and in E-PRISM vs CoMMpass (15% vs 45%, p = 0.001). We next related genomic features associated with HR-SMM to treatment outcomes. Patients treated with KRd/R had yearly MRD testing and gain1q, MYC dysregulation via loss of MAX, and t(4:14) were all associated with failure to sustain MRD-negativity. Across pooled HR-SMM, inactivation of CYLD, CREBBP, MAX, and HIST1H2BK; t(4;14), APOBEC expression, loss at select GISTIC peaks ( Fig 1A) and chromothripsis all were associated with HR-SMM progression in the face of triplet therapy (p<0.05). Presence of any one or more of these features was associated with progression (p = 0.005; Fig1B). Conversely, no clinical risk score was able to discern those with this molecular high risk. Conclusion In patients treated on 2 parallel clinical trials for HR-SMM, we found a uniform and relative genomic simplicity. Moreover, non-progressors appear genomically similar to patients with non-progressive/stable MGUS and SMM under observation (Oben et al., Nat Comm 2021). However, within clinical HR-SMM, a set of high-risk genomic features portends progression despite intervention. These results suggest that clinical risk scores do not effectively discriminate between genomically indolent and aggressive disease. Though possible that results reflect treatment before the acquisition of key drivers, prior data suggest that many of these high-risk features are not acquired within the 5 years preceding clinical diagnosis of MM (Bolli et al., Nat Comm. 2018; Bustoros et al., J Clin Onc. 2020). Altogether, these results support the use of genomics to contextualize the advantage of early intervention in SMM (i.e., to avoid overtreatment of non-progressors and to better identify cases likely to progress without therapy). Fig1A: Heatmap of High-Risk Features in Patients treated with KRD/R and EPRISM. Fig1B: Kaplan-Meier curve for time to progression by presence of HR features for KRD/R.

Genome Sequencing to Discover Drivers of Clonal Expansion in Smoldering Multiple Myeloma

Background Better prediction models are required to identify patients with high-risk smoldering multiple myeloma (SMM) who can benefit from early intervention therapy before progression. Several studies have reported heterogeneity of genetic abnormalities found at the SMM stage, but whether any mutations are sufficient to cause, or instead prevent progression, remains an important open question. We leveraged whole-genome sequencing (WGS) in a large cohort of precursor patients, including repeated assessment over time, to discover drivers of disease growth and monitor malignant transformation to multiple myeloma (MM). Methods WGS was performed on tumor and normal cells from 141 untreated patients with SMM or Monoclonal Gammopathy of Undetermined Significance (MGUS) from the PCROWD study. Moreover, this dataset was combined with genomic data from the literature totaling 1,034 patients with WGS and/or exomes sampled across MM stages for comparative analysis and biomarker discovery. MutSig2CV, GISTIC2, and a novel method for structural variants were used to establish the list of candidate drivers across disease stages, with statistical power to detect myeloma drivers from points mutations found in ≥2% of patients. Longitudinal WGS data were analyzed with the PhylogicNDT suite of tools to characterize clonal competition in treated and untreated patients. Results Patients were followed for a median time of 20 months from the sample date (range: 3 to 78 months), during which 11 progressed. Patients evenly distributed across 20/2/20 stages: 44 Low-Risk (37%), 29 Intermediate-Risk (24%), 47 High-Risk (39%) SMM were combined with 20 MGUS, showing our method is reliable to perform WGS in lower disease burden settings. A validation cohort comprising 61 SMM with a median follow-up time of 36 months (range: 5 to 121), with 22 progressions was used to corroborate our findings. As significant drivers could be specifically enriched among indolent disease (i.e., protective alleles), we ran de novo driver mutation discovery across MM stages. In addition to well-characterized MM drivers ( KRAS, NRAS, etc.), 16 new candidate genes were found significantly mutated, including IKFZ3 (Aiolos), a transcription factor and direct target of degradation with lenalidomide therapy, harboring frameshift and stop-gain mutations in the protein dimerization domain which could affect complete differentiation of plasma cells. Mutants in KRAS found primarily at codons Q61, G12, G13, and A146, were found in all disease risk groups and associated with progression to overt myeloma (Odds Ratio: 6.1, CI95%: [1.4, 27], p=0.01, q<0.1). Next, we investigated genes targeted by copy-number abnormalities and found candidates in four regions with focal gains, including on chr(1q21), chr(8q24)( MYC), chr(3q26), and chr(16p13) encompassing BCMA. These genes have higher expression in patients with broad gain (e.g. BCMA: P=8.8E-3) or focal amplification (e.g. BCMA: P=6.2E-5), and therefore are likely to be underlying targets of the rearrangements driving cancer growth. Of note, BCMA antigen point mutations remained undetected in SMM, therefore patients with gain(16p) represent an attractive population for targeted therapy with anti-BCMA agents, in particular when the gain is clonal (n=3/8, 38%). In 15 patients, serial sampling of tumor cells allowed longitudinal WGS analyses and reconstruction of phylogenetic trees of disease clones (2 to 3 timepoints, 4 progressors, median 14 months). Maintenance of the major clone with subclonal structure evolving over time was confirmed in all patients, and we observed a steady increase in the cancer cell fraction of known MM mutations (del(13q), KRAS, DIS3 loss of function) in untreated patients. In one patient receiving early interventional treatment, a 70% reduction of M-spike concentration was achieved after four cycles of therapy; however, partial response was found in tandem with the selection of a high-risk del(1p) and of a KRAS activating G12S mutation, before increase and clinical progression to MM. Conclusion These results highlight the power of genomic profiling in MM for early detection, discovery of novel drivers, monitoring of clonal selection and transformation to malignant disease. We show SMM is not a simple genomically-mature disorder, but rather a dynamic state with competing subclones, which could be leveraged for therapeutic interventions.

Phase II Trial of Daratumumab, Bortezomib, Lenalidomide and Dexamethasone in High-Risk Smoldering Multiple Myeloma

Background: Daratumumab, bortezomib, lenalidomide and dexamethasone (D-RVD) has shown high rates of minimal residual disease (MRD) negativity in newly-diagnosed multiple myeloma (MM) and is now a standard regimen in transplant-eligible patients. Lenalidomide has shown to delay progression in patients with high-risk smoldering multiple myeloma (HR-SMM) and curative intent trials with carfilzomib-based therapy and stem cell transplantation have been recently reported in HR-SMM leading to deep responses but with concern for treatment-related toxicities. Thus, we proposed to examine the activity and safety of fixed duration D-RVD in patients with HR-SMM, with MRD-adaptive duration of therapy. Methods: This is a phase II, open-label study evaluating D-RVD in HR-SMM. Eligibility criteria includes HR-SMM per Mayo 2018 “20-2-20” model and other previously established criteria including Mayo 2008 criteria, PETHEMA criteria, evolving type of SMM, and high-risk FISH. Treatment with D-RVD is 2 years (24 cycles) with daratumumab subcutaneous (SQ) per standard dose and schedule, bortezomib 1.3mg/m2 SQ on days 1, 8, 15 for cycles 1-6 then biweekly until completion of cycle 24, lenalidomide 25mg on days 1-21 for cycles 1-6 followed by 15mg d1-21 from cycles 7-24 with weekly low dose dexamethasone. All eligible patients undergo stem cell collection after 6 cycles of therapy. The primary objective is rate of MRD-negativity at 2 years. Secondary objectives include PFS, ORR, and safety. In part 2 of the study, patients that are MRD-positive after 2 years of treatment will be randomized to observation vs continued therapy with daratumumab and lenalidomide for an additional 24 months. The primary objective of part 2 is rate of MRD conversion from positive to negative. Results: At the time of data cut off in May 2023, 38 patients have been enrolled to part 1 with a median follow up of 18 months. The median age is 62 years old (range 36-77) with 23 females (61%) and 15 males (39%). The median plasmacytosis of enrolled patients was 20%, with median M-protein of 2.17 g/dL and median FLC ratio of 8.1. Twenty-four patients (62%) had at least one high-risk FISH abnormality (fifteen with 1q gain, four with t(4;14), one with t(14;16) and one with del 17p). Eight patients (21%) had more than one high-risk FISH abnormality. Most common grade 3 toxicities included neutropenia (13%), ALT increased (8%), and diarrhea (8%). Upper respiratory infections occurred in 61% of patients but were mostly low-grade (COVID-19 infection in 11 patients, 1 with grade 3). No patients discontinued therapy due to toxicity. Of the 35 patients that completed at least 2 cycles of therapy, the ORR is 100% with 43% CR, 34% VGPR and 17% PR with responses deepening over time. Seventy-seven percent of patients achieved VGPR or greater. MRD was evaluable in 22 patients at 6 months with MRD negativity rate of 59% and 14% at thresholds of 10 -5 and 10 -6, respectively. At 12 months, 20 patients were MRD-evaluable with 65% and 20% achieving MRD negativity at 10 -5and 10 -6, respectively. Of the 10 MRD-evaluable patients at 24 months, 60% were MRD negative at 10 -5 and 40% at 10 -6. No patients have progressed on treatment. Stem cell collection was successful in all eligible patients with average stem cell yield of 5.53 x 10 6 CD34+ cells/kg. Conclusions: D-RVD in HR-SMM demonstrates significant activity, including a 100% ORR and high rates of MRD-negative disease, preventing progression to overt myeloma.

Fixed Duration Combination Therapy with Carfilzomib, Lenalidomide, and Dexamethasone Followed By Lenalidomide Maintenance Leads to High Rates of Sustained MRD Negativity in Patients with High-Risk Smoldering Multiple Myeloma: Long Term Follow up of an Investigator Initiated Phase 2 Trial

Background: Patients with high-risk smoldering multiple myeloma (HR-SMM) have a 5-year risk of progression to symptomatic multiple myeloma of approximately 75% and a median time to progression of less than 2 years (Lakshman et al., Blood Cancer J 2018) (Rajkumar et al., Blood 2015). We previously reported the primary results of our phase 2 trial of carfilzomib, lenalidomide, and dexamethasone followed by lenalidomide maintenance (KRd-R) as prevention of symptomatic multiple myeloma in patients with HR-SMM (Kazandjian et al., JAMA Onc 2021). Herein, we present follow-up data after all patients have completed lenalidomide maintenance to evaluate the durability of responses off therapy. Methods: Patients with HR-SMM based on the Mayo Clinic, PETHEMA, and/or Rajkumar, Mateos, and Landgren criteria were eligible for enrollment in this single-center phase 2 investigator-initiated study. Patients received eight 28-day cycles (induction) of carfilzomib, 20/36 mg/m 2, with dexamethasone 20/10 (days 1,2, 8, 9, 15, 16) and lenalidomide 25 mg (days 1-21), followed by 2 years of maintenance therapy with lenalidomide 10 mg (days 1-21). The primary endpoint was the rate of minimum residual disease negative complete responses (MRD negative CR) at the end of induction as assessed by multicolor flow cytometry (MRD sensitivity 10 -5). Secondary objectives included progression to overt clinical multiple myeloma (end-organ damage or myeloma-defining event) or death (clinical PFS) and biochemical progression (PD) by IMWG criteria (biochemical PFS). Results: A total of54 patients were enrolled and started treatment between May 29, 2012 and July 23, 2020. Full patient demographics and baseline disease characteristics were previously reported. (Kazandjian et al., JAMA Onc 2021) At the data cut-off of July 17, 2023, the median follow-up time was 60.2 months (range: 33.7 - 127.8). As previously reported, 38 patients (70.4%) achieved MRD negative CR by the end of induction. The median duration of MRD negative CR was 57.4 months (95% CI: 44.6 - 97.2). To date, durability of MRD negative CR has been observed up to 120.6 months and 21 patients (39%) have remained MRD negative for over 2 years (95% CI: 25.9 - 53.1%). (Figure 1) All patients attained a PR or better and the median duration of response has still not been reached. At 60 months, 75.1% of patients maintained their response (95% CI: 59.9 - 85.2%). The median clinical PFS has also not been reached. Only 5 out of 54 (9.3%; 95% CI: 3.1-20.3%) patients have progressed to clinical multiple myeloma. At 60 months, 92.7% of patients were free from clinical progression (95% CI: 78.1 - 97.9%). The probability of being free of clinical progression at 100 months was 78.9% (95% CI: 51.9 - 91.8%). While the median biochemical PFS has not been reached, patients who were MRD negative by the end of induction had significantly less risk of having biochemical progression compared to patients who still had measurable disease at completion of induction (median biochemical PFS NR vs. 41.8 (HR 0.168 (95% CI: 0.060 - 0.474) (P value < 0.0001) (Figure 2). As previously reported, KRd-R was well tolerated, with no grade 4 non-hematologic adverse events and manageable low-grade toxicities. Discussion: Treatment of patients with HR-SMM with KRd-R has led to deep and durable remissions. At a median of 5 years of follow-up, this trial has yet to reach a median clinical PFS, indicating success in preventing serious end organ damage. However, it is still unclear if the beneficial outcomes seen in HR-SMM interventional studies are due to treatment of more susceptible disease or inherently less aggressive disease. An abstract evaluating the genomic profile of patients from this trial has been submitted to the meeting separately. Future prospective trials must capture and eventually select HR profiles based on validated genomic signatures. This study suggests that patients who achieve MRD negative remissions after induction therapy have prolonged biochemical PFS. However, further follow-up time is needed to fully understand the rates of clinical PFS and OS. To evaluate if additional treatment duration to achieve MRD negativity would be beneficial we have designed a trial using daratumumab, carfilzomib, and dexamethasone utilizing an adaptive treatment duration based on MRD status for patients with HR-SMM which is currently enrolling participants (NCT04933539).

Longitudinal Screening of Mutant Hematopoietic Progenitor Cells (HPC) in Multiple Myeloma (MM) and Its Association with Secondary Primary Malignancies (SPM)

Background: The incidence of SPM in transplant eligible MM patients (pts) receiving lenalidomide maintenance is ≥ 12% and is associated with inferior overall survival (OS). Recent evidence suggests that while clonal hematopoiesis does not increase the risk of SPM, specific TP53 mutant HPC may expand under lenalidomide treatment and give rise to therapy related myeloid neoplasms and acute lymphoblastic leukemia. Genetic screening may facilitate personalized treatment to minimize the risk of SPM. However, there are no longitudinal studies in purified HPC to inform on the evolution of specific gene mutations and its association with clinical outcomes. Aim: Analyze the mutational landscape of HPC at diagnosis and throughout lenalidomide based regimens. Methods: This study included 335 pts: 43 with high risk smoldering MM, 223 transplant eligible and 69 ineligible active MM respectively enrolled in the CESAR, GEM2012MENOS/GEM2014MAIN and CLARIDEX clinical trials. Of the 335 pts analyzed at diagnosis, 60 were further investigated after induction, 30 at day 100 after autologous transplant (ASCT) and 47 during maintenance. Two or more studies were available throughout treatment in 36 pts. Fluorescence activated cell sorting of CD34+ HPC was performed in a total of 500 bone marrow aspirates. DNA was analyzed with a panel of 55 genes recurrently mutated in myeloid neoplasms. Sequencing depth was >1000x in 95% of nucleotides. Criteria to filter out included synonymous, intronic, invalid-transcript, 5'UTR, panel error and single nucleotide polymorphisms. The criteria to filter in was a AMP/ACMG classification of uncertain significance, likely pathogenic or pathogenic. Only the latter two were included in downstream analysis. Results: HPC from 184 of the 335 (55%) pts were mutated. The frequency in high-risk smoldering MM, transplant eligible and ineligible active MM was 46%, 26% and 35%, respectively. The genes more frequently mutated were DNMT3A (n=94, 52%), TP53 (n=29, 16%) and TET2 (n=28, 15%). The median variant allele frequency was 4.9, 7.5 and 7.0, respectively. In a pt-paired analysis between diagnosis and induction, 8 mutations were present in both time points, 25 became undetectable and 22 were acquired during treatment. The latter (eg, PPM1D and SF3B1) were observed in 14 of the 60 (23%) pts. In the 30 pts with paired samples at diagnosis and at day 100 after ASCT, 4 mutations were present in both time points, 48 became undetectable and only 3 were acquired during treatment ( ATRX, MPL and SAMDL9). Thus, the frequency of mutant HPC was higher at diagnosis vs ASCT (23% vs 5%, P <.001). In a pt-paired analysis between diagnosis and maintenance, 13 mutations were present in both time points, 12 became undetectable and 30 were acquired during treatment. The latter (eg, PPM1D and SF3B1) were observed in 24 of the 47 (51%) pts screened at both time points, and after a median of 5 years since diagnosis. With a median follow-up of 6 years, 17 of the 335 (5%) pts developed SPM. Mutant HPC were detected in 13 of the 17 pts. Accordingly, presence of mutant HPC was associated with a 2-fold increased risk of SPM (OR: 2.3; P = .03). Of the 13 pts, 3 showed mutations at diagnosis and in 8 these emerged during maintenance. The only case developing a myeloid neoplasm had a TP53 mutation present during maintenance that was undetectable at diagnosis. Pts with mutant vs non-mutated HPC at diagnosis showed similar OS (6y rates of 86% and 81%, respectively; P =.46). Similarly, there were no differences in OS of pts with emerging mutations vs those without mutant HPC after treatment (6y rates of 85% and 83%, respectively; P =.65). Specific mutations in DNMT3A, TP53 and TET2 and were not associated with inferior OS. Conclusions: To our knowledge this is the first study analyzing the mutational landscape of purified HPC throughout lenalidomide based regimens in high risk smoldering MM as well as transplant eligible and ineligible active MM. Deep sequencing of CD34+ HPC uncovered that the frequency of mutations is similar between precursor and malignant disease, and that TP53 is amongst the top mutated genes. There was considerable volatility with presence of both transient and emerging mutations throughout treatment. Importantly, the detection of mutant HPC was associated with increased risk of SPM without differences in survival. Thus, this study supports the longitudinal screening of HPC for the identification of patients at risk of developing SPM.

Efficacy and Safety of Daratumumab (DARA) Monotherapy in Patients with Intermediate-Risk or High-Risk Smoldering Multiple Myeloma (SMM): Final Analysis of the Phase 2 Centaurus Study

Introduction: SMM is a precursor disorder to multiple myeloma (MM) (Rajkumar SV, et al. Blood. 2015;125[20]:3069-3075). Current guidelines for SMM recommend active monitoring, with treatment initiation only upon progression to MM. However, therapeutic intervention at the SMM stage may help delay the progression to MM (Lonial S, et al. J Clin Oncol. 2020;38[11]:1126-1137; Mateos MV, et al. ASH 2022. Abstract 118). DARA is a human IgGκ monoclonal antibody targeting CD38 with a direct on-tumor and immunomodulatory mechanism of action. Given the deep and durable responses and favorable safety profile of DARA monotherapy in patients (pts) with relapsed/refractory MM (Usmani SZ, et al. Blood. 2016;128[1]:37-44), we hypothesized that DARA could delay the progression of SMM to MM. In the primary analysis of the phase 2 CENTAURUS study (NCT02316106), after a 15.8-month median follow-up, DARA monotherapy showed activity and was well tolerated in pts with intermediate- or high-risk SMM (Landgren CO, et al. Leukemia. 2020;34[7]:1840-1852). Activity and tolerability of DARA monotherapy were also observed in CENTAURUS after an additional 10 months of median follow-up (Landgren CO, et al. ASH 2018. Abstract 1994). Here, we present the final analysis of the CENTAURUS study, with a median follow-up of 85.2 months (~7 years). Methods: Eligible pts had a diagnosis of intermediate-risk or high-risk SMM for <5 years. Pts were randomized (1:1:1) to receive 8-week cycles of DARA 16 mg/kg intravenously (IV) on 1 of 3 dosing schedules. In the Intense dosing arm, pts received DARA QW (Cycle 1), Q2W (Cycles 2-3), Q4W (Cycles 4-7), and Q8W (Cycles 8-20). In the Intermediate dosing arm, pts received DARA QW (Cycle 1) and Q8W (Cycles 2-20). In the Short dosing arm, pts received 1 cycle of DARA QW. For pts in the Intense and Intermediate arms, there was an option to extend treatment (Extension phase) with DARA IV or with subcutaneous DARA (DARA SC; DARA 1,800 mg co-formulated with recombinant human hyaluronidase PH20 [2,000 U/mL; Halozyme, Inc.]) Q8W after the end of Cycle 20 per investigator discretion if there was a positive benefit/risk ratio, no grade ≥3 treatment-related toxicity, and at least stable disease had been achieved. Rate of complete response or better (≥CR) was a primary endpoint. Secondary endpoints included overall response rate (ORR) and overall survival (OS). Results: A total of 123 pts (41 pts per arm) were randomized. Median (range) age was 61 (31-81) years. Median duration of study treatment overall during the study was 44.0 months in the Intense arm, 35.2 months in the Intermediate arm, and 1.6 months in the Short arm. A total of 36 pts (21 pts in the Intense arm and 15 pts in the Intermediate arm) continued to receive DARA Q8W in the Extension phase (Cycles 21+). During the Extension phase, median duration of study treatment was 45.2 months in the Intense arm and 46.1 months in the Intermediate arm ( Table 1). 16 pts in the Intense arm and 10 pts in the Intermediate arm switched from DARA IV to DARA SC during the Extension phase. Efficacy results are summarized in Table 2. At a median (range) follow-up of 85.2 (0-94.3) months, ORR and ≥CR rate were higher in the Intense and Intermediate arms than in the Short arm. In the Intense and Intermediate arms combined, the ≥CR rate was 8.5%. Median OS was not reached in any dosing arm; the 84-month OS rate was 81.3%, 89.5%, and 88.1% in the Intense, Intermediate, and Short arms, respectively. Safety results are summarized in Table 1. Grade 3/4 treatment-emergent adverse events (TEAEs) occurred in 65.9%, 41.5%, and 15.0% of pts in the Intense, Intermediate, and Short arms, respectively; grade 3/4 TEAEs were reasonably related to DARA in 12.2%, 2.4%, and 5.0% of pts, respectively. TEAEs that led to discontinuation of DARA occurred in 7.3%, 2.4%, and 5.0% of pts in the Intense, Intermediate, and Short arms, respectively. Conclusions: Findings from this final analysis of CENTAURUS continue to demonstrate the clinical activity of DARA monotherapy in pts with intermediate- or high-risk SMM after a median follow-up of ~7 years. A high proportion (44%) of pts in the Intense and Intermediate arms completed 20 cycles and remained on DARA monotherapy per investigator discretion, with a median duration of additional treatment of 46.0 months (~4 years) in the Extension phase. No new safety concerns were observed with extended follow-up.

Isolated and Dynamic Peripheral Blood Residual Disease Status Characterized By Mass Spectrometry Predicts Outcome in Patients with High Risk Smoldering Multiple Myeloma Treated in the GEM-CESAR Trial

Background: GEM-CESAR trial is a potentially curative strategy for high-risk smoldering multiple myeloma (HRsMM) patients (pts) in which the primary endpoint is the rate of minimal residual disease (MRD) negativity in the bone marrow (BM) assessed by next generation flow (NGF) after autologous stem cell transplantation (ASCT) and sustained 3 and 5 years afterwards. Here, we update the preliminary results presented at ASH2019 about the clinical value of quantitative immunoprecipitation mass spectrometry to assess treatment response in this group of patients. Methods: Pts received induction with six 4-week cycles of KRd (K: 36mg/m 2 twice weekly, R: lenalidomide 25mg po od days 1-21 and d: dexamethasone 40mg po weekly), high-dose melphalan followed by ASCT, consolidation with two further cycles of KRd and up to 2 years of maintenance with Rd (R: 10mg po od, d: 20mg po weekly). Peripheral blood Residual Disease(PRD) was analyzed post-ASCT and at treatment completion (after 2 years of maintenance) using Quantitative Immunoprecipitation Mass Spectrometry with anti IgG/A/M, total k and total l beads using the EXENT ® Solution (The Binding Site, part of Thermo Fisher Scientific). From the 90 pts enrolled in the trial, 61 were analyzed post-ASCT and 35 at the end of treatment. Isotype-matched immunoparesia (IMI) was also evaluated post-ASCT using the heavy/light chain pairs. Kaplan-Meier curves were plotted either from the specific time point investigated or from the last one if dynamics were analyzed. Results: First,PRD was analyzed post-ASCT and at treatment completion and deemed to be positive in 54% (33/61) and 20% (7/35) of patients, respectively. At both time points, PRD assessment discriminated two groups of patients with a very significantly different prognosis: median PFS in PRD+cases post-ASCT was 4.27 years vs not reached in PRD- cases (p=0.0071) (Fig 1A) and after 2 years of maintenance, the median PFS in PRD- cases was not reached vs 1.43 years in PRD+ cases (p=0.0011) (Fig 1B). Importantly, standard response criteria and, more specifically, the achievement of complete response (CR) or better, was not associated with disease outcome. And further, among samples in ³CR, PRD+ was also able to discriminate a group of patients with poorer outcome, with a median PFS of 4.42 years vs not reached in PRD- cases (p=0.0136) Interestingly, when we combined the analysis of the M-protein by mass spectrometry with the identification of severe isotype-matched suppression (uHLC < 50%), PRD+ patients post-ASCT could be further stratified in two subgroups with significantly different median PFS (not reached in those with no severe IMI vs 3.85 years in those with severe IMI, p=0.0384) (Fig 1C). A similar tendency was observed among PRD+cases after 2 years of maintenance (mPFS in those with no severe IMI of 2.5 years vs 9 months in those with severe IMI) although the difference did not reach statistical significance. Then, we analyzed PRD dynamics after ASCT and at the end of treatment. Sustained PRDnegativity during this period was observed in 12 pts (33.3%), and sustained positivity in 6 (16.6%). In 5 pts (13.8%) PRD converted from positive to negative, and in 1 (2.7%) from negative to positive. Whereas sustained PRD+ was associated with a very short median PFS of 1.66 years, patients with sustained PRD- or who converted from PRD+ to PRD- displayed a very favorable outcome with median PFS not reached and significantly different compared to the sustained PRD+ group (p<0,0001) (Fig 1D). Interestingly, the only patient that converted from PRD-to PRD+ had a very poor outcome with a mPFS 3.8 months. By contrast, sustained CR or better according to standard response criteria was not significantly associated with clinical outcome. Conclusion: In this cohort of high-risk smoldering MM patients treated intensively with a curative intention, whereas standard CR or better was not associated with clinical outcome, PRD status defined by mass-spectrometry segregated two groups of patients with different PFS at the 2 time points analyzed. Furthermore, this outcome was better predicted when PRD dynamics were analyzed and/or with the evaluation of severe IMI on PRD+ patients, highlighting once again the relevance of immune recovery as a determinant factor in the evolution of the disease.

Circulating Tumor Cells By Next Generation Flow Cytometry May be a New Prognostic Biomarkers Among Patients with Asymptomatic Monoclonal Gammopathies

Monoclonal gammopathy of undetermined significance (MGUS) and asymptomatic (smoldering) multiple myeloma (sMM) precede symptomatic myeloma (MM) but are characterized by significant heterogeneity in terms of biological characteristics and clinical course. Currently no single molecular or clinical feature can identify patients (pts) who should be treated immediately or for which treatment should be prioritized over watchful wait. Circulating tumor cells (CTCs - clonal plasma cells) are frequent in pts with symptomatic MM and have prognostic significance, independently of other disease and patient characteristics. The use of next generation flow cytometry (NGF) is an accurate method to assess CTCs and provides a non-invasive tool to assess tumor cells. Few studies have addressed the prognostic significance of CTCs detected by NGF as a potential prognostic biomarker in SMM. Herein, we report our initial results from the prospective evaluation of pts with asymptomatic plasma cell dyscrasias with NGF to determine baseline CTC values. We prospectively analyzed the data and outcomes of 189 consecutive pts with asymptomatic monoclonal gammopathies (MGUS or SMM by IMWG criteria), diagnosed and followed in the Department of Clinical Therapeutics, Athens, which were evaluated prospectively for the detection of CTCs at the time of initial diagnosis. CTCs were assessed in peripheral blood (PB) according to the EuroFlow guidelines, using two independent 8-color panels, both containing CD19-PC7, CD27-BV510, CD38-FITC, CD45-PerCPCy5.5, CD56-PE, CD138-BV421, and additionally CD117-APC and CD81-APCC750 only in the surface tube or CyIgκ-APC and CyIgλ-APCC750 only in the intracytoplasmic tube. A median number of 5 million events (range 3.9x106-6.1x106) were acquired for each tube and median LOD was 2.3x10-6 (range 2x10-6- 3.1x10-6). The median age of the cohort's pts was 65 years (range 28-87) and 59% were females; 47% had non-IgM MGUS and 53% had a diagnosis of SMM. The isotype was IgG in 85% and 74%, IgA in 10% and 22% and light chain only in 2% and 4% in MGUS and SMM pts respectively. Among MGUS pts, 50% had abnormal FLC ratio and the median M-spike was 0.54 gr/dl (range: 0-1.96). For pts with SMM, 58% had abnormal FLC ratio, 16% had FLC ratio >20, 13% had M-spike >2 gr/dl and 31% had BM plasma cell infiltration >20%.Per IMWGs 20/2/20, 55% were low risk (no risk factors), 33% intermediate risk (one risk factor) and12% were high risk (2-3 risk factors). Cytogenetics were available in 60 pts (19 MGUS and 41 SMM): t(4;14) was present in 10% of SMM, t(11;14) in 22% of SMM and MGUS, t(14;16) in 8% if SMM, +1q21 in 31% of SMM and 6% of MGUS, del17p in 2% of SMM and 5% of MGUS (one patient each) and del13q in 29% of SMM and 17% of MGUS. Clonal plasma cells (CTCs) were detectable in 33% of patient in the cohort: in 17% of MGUS and in 42% of SMM pts. Among those with detectable CTCs, median level was 0.004% (range 0.0002% to 0.22%) and did not differ among MGUs and SMM pts. Among pts with low-risk SMM, 31% had detectable CTCs (median 0.0065%) vs 45% of pts with intermediate/high risk (median 0.0022%) (p=0.066). The median follow-up of the whole cohort is 18 months; until the data cutoff date 13pts have progressed (all with SMM); the 2-year progression rate 7%,29% and 46% for low, intermediate and high risk SMM (p=0.032) The presence of CTCs was associated with a higher risk of progression to symptomatic MM among all pts in the cohort (HR: 4; 95% CI 1.1-14.7, p=0.024); among SMM pts there was a trend for shorter time to progression but did not reach statistical significance probably due to relatively short follow up and small numbers. We also evaluated 0.015% as a CTCs cutoff(identified previously by Termini et al) but only 10pts had CTCs above this level and did not reach statistical significance. Adjusted for IMWG 20/2/20 risk score, the presence of CTCs was associated with a trend towards statistical significance (HR: 3, 95% 0.97-11.9, p=0.104). In conclusion, CTCs are detectable in about 33% of pts with asymptomatic monoclonal gammopathies, both in MGUS (in 17%) and more frequently in SMM (in 42%) pts. Their presence is associated with a trend towards increased risk of progression to symptomatic disease for SMM, but needs longer follow up to identify the role of CTCs in MGUS and the additive information over available risk stratification tools, which could provide an non-invasive, easy-to-follow longitudinally biomarker.

Single-Cell RNA Sequencing of Circulating Tumor Cells in Precursor Myeloma Patients Reveals Mechanisms of Disease Dissemination

Introduction Multiple Myeloma (MM) is preceded by the precursors Monoclonal Gammopathy of Undetermined Significance (MGUS) and Smoldering Multiple Myeloma (SMM), where some patients with precursor disease progress to active MM faster than others. BM biopsies are useful to monitor disease progression, however, they cannot be repeated often for continuous monitoring of tumor burden especially in the precursor disease management setting. Numerous studies have identified circulating tumor cell (CTC) levels in peripheral blood (PB) are a powerful biomarker of disease aggressiveness; CTC levels have associated with disease stage, PFS and OS in various trials and even outperformed BM to assess tumor burden in the SMM setting. Genomic profiling also demonstrated CTCs harbor the same copy number abnormalities, translocations and mutations as BM tumor cells, and CTCs can be serially monitored to detect the emergence of high-risk subclones in the blood. Further investigations of the molecular profile of both normal plasma cells (NPCs) and CTCs are needed to improve our understanding of myeloma pathogenesis and mechanisms of CTC dissemination across the MM disease continuum. Methods A cohort of 309 samples including CD138-enriched paired PB and BM aspirates and matched CD138- BM aspirates were collected from 103 individuals, including patients with MGUS (n=11), SMM (n=46), NDMM (n=17) and healthy donors (n=29). Malignant PCs from BM and PB underwent 5' single-cell RNA sequencing (scRNA-seq) and single-cell B-cell receptor sequencing (scBCR-seq) (10x Genomics), and CD138- BM immune cells underwent 5' scRNA-seq and single-cell T-cell receptor sequencing (scTCR-seq) to study immune alterations related the tumors' ability to circulate. To differentiate malignant from normal PCs, we used clonal V(D)J rearrangements. Differential expression (DE) and composition analyses were conducted using Wilcoxon's rank-sum tests. Results We successfully captured and profiled 774,647 BM tumor cells and 93,878 CTCs from the PB. The percent malignant plasma cells within the PB increased with disease stage, where NDMM patients had significantly more CTCs compared to MGUS patients (p=0.017) and low-risk SMM patients (p=0.0052). A median of 13.51%, 15.53%, and 18.34% CTCs were present from low (n=20), intermediate (n=10), and high-risk (n=16) SMM patients as defined by the International Myeloma Working Group's 2/20/20 criteria, suggesting sequencing-based CTC enumeration captures prognostically relevant differences in tumor burden. High expression of driver genes upregulated in patients with translocations, including CCND1, NSD2, and MAF, were detected in both BM tumor cells and CTCs in patients with t(11;14), t(4;14), and t(14;16) as identified by fluorescence in situ hybridization (FISH). In 5 patients with normal or inconclusive FISH results, we observed high levels of CCND2 and MAF in both BM and CTCs, indicating scRNA-seq can detect missed prognostically relevant cytogenetic abnormalities. A cytogenetic classifier model was developed to determine the accuracy of translocation calling using minimal numbers of CTCs, where the classifier's performance was able to consistently identify translocations downsampled to 50 CTCs. DE analysis of CTCs vs. BM tumor cells highlighted transcriptional similarity between BM and CTCs, validating their utility as a surrogate for analyzing BM tumor cells. DE analysis also revealed 8 genes significantly upregulated and 3 genes significantly downregulated in CTCs compared to BM tumor cells, providing novel insights into genes involved in PC circulatory potential. Pathway enrichment analysis revealed genes upregulated in CTCs were associated with epithelial mesenchymal transition, interferon response, and inflammation, consistent with CTC studies on MM patients, suggesting these pathways are dysregulated earlier in the disease continuum. Conclusions In the largest scRNA-seq study on CTCs to date, we demonstrate the utility of CTC-based molecular profiling for prognostication of patients with early-stage disease and provide novel insights into PC circulatory potential. Additional analyses are ongoing to gain further insight into intra-patient CTC heterogeneity and define high-risk disease CTC signatures that emerge throughout the MM disease continuum.

The 3D- Telomere Profiling Assay Identifies High Risk Smoldering Multiple Myeloma Patients with High Precision

Smoldering multiple myeloma (SMM) is an asymptomatic precursor stage of multiple myeloma (MM). According to the international Myeloma Working Group data (Blood Cancer J. 2020 Oct 16;10(10):102) the probability of progression to MM is 22% at 2 years, and 42% and 64% at 5 and 10 years, respectively. Thus, identification of patients with high risk of early progression to MM is crucial for optimal treatment management. Genomic instability is a sensitive indicator of disease progression in cancer. Telomere dysfunction is an early event in genomic instability. The 3-dimensional (3D) spatial profiling of telomeres using TeloView technology allows for quantification of telomere dysfunction and was shown to be instrumental in risk stratification of cancer patients generally, but particularly in selected hematological malignancies. Importantly, the utility of the 3D-telomere profiling was recently demonstrated in 2 clinical studies validating the utility of 3D telomere profiling as a structural biomarker to identify high risk SMM patients. The two studies achieved accuracy of >80% and specificity and sensitivity of over 80% & 76% respectively in a training dataset study followed by a blind validation (Kumar S.et al 2023. J Clin Oncol). To present the 3D telomere profiling assay as a reliable prognostic tool in the clinic, capable to precisely identify high risk SMM patients, it is important to demonstrate the repeatability and accuracy of the assay. In this study, we conducted a retrospective analytical validation including samples of 20 SMM patients with known progression outcome. The samples of each patient were blindly processed in triplets using the 3D-telomere assay, followed by the TeloView analysis. To eliminate any validation-bias the validation was conducted with uncontrolled variables. Samples were processed blindly by different operators on different dates using different instrumentation. We interrogated the repeatability and precision of the results of each patient analyzed on 2 levels. First, we calculated coefficient of variation (CV) of telomere predictors of each patient across the three runs; and secondly, we interrogated the repeatability of patient outcome using the scoring model developed and validated in (Kumar et al. 2023, J Clin Oncol) across the three runs of each patient. We set the acceptable concordance to 80% for CVs (CV <20%) and the acceptable repeatability of patient-outcome as predicted by the scoring model to 80% of the patients included in the study. We report CVs across all the telomere predictors, across the 3 runs of all patients ranging between 2.3 - 17.8. Furthermore, patient outcome as high/low risk of progression was consistent in 17 out of the 20 patients in all 3 runs (85%). The results of this study demonstrate the 3D-telomere profiling as an accurate and prognostic structural biomarker. The assay shows high level of precision, repeatability, and reliability, and presents a viable solution to accurately identify high risk SMM patients. This will potentially allow the treating physicians to make confident treatment decisions for high risk SMM patients based on the results of the 3D Telomere profiling assay.

Trial in Progress: A Phase 2 Study of Linvoseltamab for the Treatment of High-Risk Smoldering Multiple Myeloma (LINKER-SMM1)

Background and Significance Smoldering multiple myeloma (SMM) is an asymptomatic clonal plasma cell disorder that precedes the development of multiple myeloma (MM). Traditionally, patients with SMM have undergone observation until progression to MM, but this paradigm can result in poor outcomes for some patients. Phase 3 clinical trials have demonstrated that early treatment with lenalidomide with or without dexamethasone can delay the development of end-organ damage and improve overall survival among SMM patients with high-risk features. Linvoseltamab (REGN5458) is a fully human B-cell maturation antigen (BCMA)×CD3 bispecific antibody that targets BCMA on plasma cells and CD3 on T cells, resulting in targeted T-cell-mediated cytotoxicity. In the Phase 1/2 LINKER-MM1 study, linvoseltamab alone induced deep and durable responses with a generally manageable safety profile in patients with relapsed/refractory MM (Lee et al. EHA. 2023). These data highlight the potential of novel immunotherapies with promising single-agent activity to be attractive therapeutics for early intervention to prevent progression to MM. Study Design and Methods LINKER-SMM1 is an open-label, Phase 2 study (NCT05955508) designed to evaluate the safety and efficacy of linvoseltamab monotherapy in adult participants with SMM who are at a high risk of progression to MM. High-risk criteria include having both ≥95% clonal plasma cells in the bone marrow (BM) and immunoparesis and/or ≥2 of the following: serum M-protein >2 g/dL, free light chain ratio >20, and BM plasma cells >20%. Participants must have a confirmed diagnosis of SMM within 5 years of enrollment, Eastern Cooperative Oncology Group performance status ≤1, and adequate organ function to be eligible. Participants will be excluded from enrollment if they have myeloma-defining events, uncontrolled infection, history of allogeneic stem cell transplantation, or received prior treatment for SMM. The study will take place at approximately 15 sites in Spain and will include two parts: Part 1 (safety run-in) to evaluate the preliminary safety and tolerability of linvoseltamab and Part 2 (expansion) to evaluate the clinical activity of the selected dosing regimen. In Part 1, at least 6 participants will receive linvoseltamab starting with a step-up schedule before reaching the full dose. All subsequent treatment with full-dose linvoseltamab will be given over 28-day cycles until completion of 24 cycles or occurrence of a protocol-defined reason for discontinuation. Assuming that initial safety is shown to be acceptable, an additional 34 participants will be enrolled in Part 2 according to the dosing regimen established in Part 1. Post-treatment safety monitoring will continue for up to 90 days after the last dose of linvoseltamab, and participants with an ongoing response will continue routine efficacy assessments until confirmed biochemical progression, start of non-protocol cancer therapy, or death. Long-term follow-up will continue for up to 5 years after the last dose of linvoseltamab. The primary endpoints in Part 1 are frequency of adverse events (AEs) of special interest, including grade ≥2 cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome, and frequency and severity of treatment-emergent AEs. In Part 2, the primary endpoints are complete response (assessed by International Myeloma Working Group criteria) and minimal residual disease (MRD) negativity (10 -5 sensitivity) after 12 and 24 months of treatment. Secondary endpoints include cumulative safety, overall response rate, duration of response, sustained MRD negativity, biochemical and clinical progression-free survival (PFS), time to myeloma-defining event, time to initiation of first-line treatment for MM, and overall survival as well as immunogenicity and serum concentration of linvoseltamab over time. Exploratory endpoints include PFS after the start of first-line treatment for MM, adequacy of stem cell collection, patient-reported outcomes, and various biomarker changes. As this is a proof-of-concept study, results will be analyzed using descriptive statistics and no formal hypothesis testing is planned. Study accrual is planned to begin in Q4 2023.

Cell Free MYC DNA Copy Number Identifies High-Risk Smouldering Myeloma and Newly Diagnosed Multiple Myeloma

Introduction Smouldering multiple myeloma (SMM) is a heterogenous condition, with some patients progressing rapidly (high-risk) while others have MGUS-like disease (low-risk). The International Myeloma Working Group's (IMWG) 2/20/20 risk score predicts 2-year progression, but despite these improvements in risk-stratification, identification of patients requiring early intervention remains elusive. For newly diagnosed multiple myeloma (NDMM), survival varies, and current risk-stratification falls short for poor responders to standard first-line therapy (high-risk). MYC is a potent oncogene implicated in the initiation, maintenance, and progression of various malignancies. MYC overexpression on immunohistochemistry predicts poor clinical outcome in MM 1, implicating MYC overexpression in aggressive disease kinetics in MM. We hypothesised that MYC copy number could improve identification of high-risk SMM and ND MM. In this study, we developed a minimally invasive liquid biopsy approach to characterise the expression of MYC copy number in circulating cell-free DNA (cfDNA) on a unique cohort of peripheral blood samples obtained from the national liquid biopsy biobank, the M1000 that is linked to our clinical registry, the Myeloma and Related Diseases Registry (MRDR). Methods We obtained plasma samples from 64 SMM and 149 ND MM patients from the M1000. cfDNA was extracted from 1mL of plasma collected in Streck™ tubes using QIAamp Circulating Nucleic Acid Kit (QIAGEN) according to manufacturer instructions. Equal amount of cfDNA (5 uL), run in duplicates, from each patient was utilised for copy number assessment developed using the Biorad QX200 Digital Droplet TM PCR. The copy number of MYC was calculated by comparing the number of molecules (using a ratio of positive to negative droplets) to the number of molecules arising from the reference (RPP30) genomic locus using the QuantaSoft TM Analysis Pro Software (Biorad). MYC copy number were correlated with clinical data from MRDR on progression in SMM and overall survival (OS) in NDMM. We use median copy number as cut off to categorise high and low MYC. Results We were able to extract cfDNA from 1 ml of plasma samples from both SMM and NDMM patients, with the median amount being 35.11 ng (11.9 ng - 107.78ng) and 50.26 ng (5.85 ng - 243.45 ng), respectively. The median MYC copy number levels were 1.883 in SMM and 1.860 for NDMM. Within 36 months follow up in the SMM cohort, 18 patients progressed to MM with median time to progression of 14 months (2- 36 months, Figure 1). High MYC copy number (>1.9) at diagnosis was predictive of disease progression with hazard ratio of 5.27 (95% CI 1.99 -14; P = 0.0015). When combined with the 20/20/20 risk stratification model 3, MYC copy number improved the reliability of this score. In the NDMM cohort, median OS for the cohort was not reached at 36 months follow up. Patients with high MYC copy number (>1.9) at diagnosis had shorter OS at 36 months compared to those with low MYC copy number at 36 months (66.05% vs 82.02%. P=0.0012, Figure 2). Conclusion Our study demonstrates a significant association between MYC copy number, assessed via plasma cfDNA, and the risk of progression in patients with SMM. Additionally, in NDMM, MYC copy number at diagnosis directly correlates with OS. These findings require further investigation and validation in a larger cohort of M1000 samples, as they have the potential to introduce a minimally-invasive risk stratification methodology to identify high-risk patients and the introduction of MYC targeted therapies in patients with high MYC copy number.

Clinical characteristics and outcomes in risk-stratified patients with smoldering multiple myeloma: data from the Czech Republic Registry of Monoclonal Gammopathies

Smoldering multiple myeloma (SMM) is an asymptomatic precursor to active multiple myeloma (MM). The aim of this study was to report clinical characteristics and outcomes of patients with SMM stratified based on their risk of progression to MM using the Mayo 20/2/20 criteria. Data were leveraged from the Czech Myeloma Group Registry of Monoclonal Gammopathies (RMG). Key outcomes included progression-free survival from SMM diagnosis to active MM diagnosis or death (PFS), progression-free survival from SMM diagnosis to progression on first line (1 L) MM treatment or death (PFS2), and overall survival (OS). Of 498 patients, 174 (34.9%) were classified as high risk and 324 (65.1%) as non–high risk. Median follow-up was approximately 65 months. During follow-up, more patients in the high-risk vs non–high-risk group received 1 L MM treatment (76.4% vs 46.6%, p < 0.001). PFS, PFS2, and OS were significantly shorter in high-risk vs non–high-risk patients (13.2 vs 56.6 months, p < 0.001; 49.9 vs 84.9 months, p < 0.001; 93.2 vs 131.1 months, p = 0.012, respectively). The results of this study add to the growing body of evidence that patients with high-risk vs non–high-risk SMM have significantly worse outcomes, including OS.

A first case report of using chimeric antigen receptor T-cell immunotherapy to treat high-risk smoldering multiple myeloma.

A first case report of using chimeric antigen receptor T-cell immunotherapy to treat high-risk smoldering multiple myeloma.

ISAMAR: Multicenter phase II single arm trial of isatuximab (ISA) with/without lenalidomide (LEN) in pts with high risk smoldering multiple myeloma (HRSMM).

8046 Background: HRSMM patients (pts) have a median time to progression of &lt; 2 years. ISA is a monoclonal antibody that binds to highly expressed CD38 on myeloma cells and is approved in RRMM. We designed a phase II study to test the efficacy of ISA +/- LEN in HRSMM (NCT02960555). Methods: The primary endpoint of the study was the overall response rate (ORR) after 6 months of ISA 20 mg/kg IV days 1, 8, 15, 22 cycle 1; days 1, 15 cycles 2-6; day 1 cycles 7-30 monotherapy (stage 1, n = 25) or with LEN 25 mg po daily on days 1-21 every 28 days, cycles 1-6 (stage 2, n = 36). Secondary endpoints are progression free survival (PFS), overall survival (OS) while exploratory endpoints included quality of life (QoL), flow and sequencing. Results: 61 HRSMM pts (+immunoparesis and ≥95%abnormal plasma cells in bone marrow) (stage 1 n = 25; stage 2 n = 36) were accrued 02/2017-10/2022. The study met its primary endpoint of ORR ≥ 70% after 6 cycles of therapy [Stage 2 ORR (89%) = VGPR 9 (25%), PR 23 (64%), MR 3(8%), PD 1(3%)]. Median time to response was 1 cycle. In stage 2, 17/36 (47%) patients had grade 3 treatment related adverse events (AEs): 1 pt related to ISA (myalgia, 3%) and 16 pts related to LEN (44%) [ANC decrease (36%), skin rash (8%), ALC decrease (11%), WBC decrease (8%), fatigue (6%)] and 1/36 pts a grade 4 (related to LEN) [ANC decrease 3%]. Most common grade 1-2 AEs: WBC decrease (53%), ANC decrease (56%), skin rash (28%), fatigue (39%), ALC decrease (42%), thrombocytopenia (28%), diarrhea (39%), constipation (28%). There were no grade 5 AEs. No patients discontinued treatment due to AEs. There were 3 deaths in stage 1 unrelated to therapy: 1 patient progressed to and died while on systemic AL amyloidosis therapy, one patient (with COPD) died of COVID19 while in sustained PR, one heavy smoker died of squamous cell cancer of the tongue. Pre- and post- treatment BM flow showed that ISA/LEN increased CD4+/CD8+ and effector memory cytotoxic T cells. QoL measures (n = 32; 15 in stage 1, 17 in stage 2 and 21 with both BL/after 6 months data) showed that ISA+/- LEN resulted in decreased cancer worry/anxiety and improved future perspective at 6 months compared to BL in both stages. QoL was favorable and conserved throughout treatment, suggesting minimal effects of treatment on patient assessment of well-being. For stage 1, median PFS was 49.3 months (95% CI:40.8~NA months); median OS not reached at a median f/u of 49 months (range 6.3-68 months). Stage 2 median PFS/OS is not reached. Conclusions: ISA/LEN results in high ORR without decrease in patient well-being. ISA monotherapy also results in prolonged PFS when compared to historical data. ISA/LEN therapy remodels the BM TME with increase in memory cytotoxic T cells. The results of this study give rationale for the ongoing phase 3 ITHACA evaluating ISA +/- LEN/DEX with the potential to change the standard of care in HRSMM (NCT04270409). RO and OL have equal contribution. Clinical trial information: NCT02960555 .