Relapsed Multiple Myeloma Patients Research Articles

Exposure-response relationships of venetoclax in combination with carfilzomib and dexamethasone in relapsed/refractory t(11;14) multiple myeloma patients.

Venetoclax is a first in class BCL-2 inhibitor, currently under investigation for the treatment of t(11;14) multiple myeloma (MM). The objective of this analysis was to characterize the exposure-efficacy and exposure-safety relationships of venetoclax when combined with carfilzomib and dexamethasone (VenKd) in t(11;14)-positive relapsed or refractory (R/R) MM patients from a phase 2 study. Fifty-seven patients receiving VenKd or Kd were included in the analysis. Efficacy endpoints included progression-free survival and clinical response rates of overall response, very good partial response or better and complete response or better. Grade ≥ 3 neutropenia, Grade ≥ 3 infections, Grade ≥ 3 treatment-emergent adverse events and any grade serious treatment-emergent adverse events were evaluated. The analysis demonstrated that adding venetoclax to Kd resulted in increased ORR, ≥VGPR and ≥ CR rates compared to the control arm. Within the venetoclax treatment arms (VenKd), no significant exposure-efficacy relationships were observed for ORR and ≥ VGPR rates. Higher ≥ CR rates trended with higher venetoclax exposures. While both 400mg and 800mg venetoclax in VenKd arms were generally tolerated, higher rates of Grade ≥ 3 neutropenia were observed with higher venetoclax exposures. Higher venetoclax exposures however were not associated with increased rates of Grade ≥ 3 treatment-emergent adverse events, Grade ≥ 3 infections, or serious treatment-emergent adverse events (any grade). These results confirm the benefit of adding venetoclax to carfilzomib and dexamethasone and support continued evaluation of venetoclax 400-800mg once daily in this combination in t(11;14)-positive R/R MM patients. NCT02899052 registered April 18, 2017.

Genomic and immune determinants of resistance to daratumumab-based therapy in relapsed refractory multiple myeloma

Targeted immunotherapy combinations, including the anti-CD38 monoclonal antibody (MoAb) daratumumab, have shown promising results in patients with relapsed/refractory multiple myeloma (RRMM), leading to a considerable increase in progression-free survival. However, a large fraction of patients inevitably relapse. To understand this, we investigated 32 relapsed MM patients treated with daratumumab, lenalidomide, and dexamethasone (Dara-Rd; NCT03848676). We conducted an integrated analysis using whole-genome sequencing (WGS) and flow cytometry in patients with RRMM. WGS before and after treatment pinpointed genomic drivers associated with early progression, including RPL5 loss, APOBEC mutagenesis, and gain of function structural variants involving MYC and chromothripsis. Flow cytometry on 202 blood samples, collected every 3 months until progression for 31 patients, revealed distinct immune changes significantly impacting clinical outcomes. Progressing patients exhibited significant depletion of CD38-positive NK cells, persistence of T-cell exhaustion, and reduced depletion of regulatory T cells over time. These findings underscore the influence of immune composition and daratumumab-induced immune changes in promoting MM resistance. Integrating genomics and flow cytometry unveiled associations between adverse genomic features and immune patterns. Overall, this study sheds light on the intricate interplay between genomic complexity and the immune microenvironment driving resistance to Dara-Rd in patients with RRMM.

Identification of clinical-biological features of newly diagnosed early relapse multiple myeloma patients eligible for autologous stem cell transplantation.

A portion of multiple myeloma (MM) patients relapse early or do not respond to first line treatment. Identification of possible clinical and or biological features of these patients remains an unmet medical need. In this study we assesed the predictive markers for early relapse MM, defined as a progressive disease that occurred within 18 months, from autologoust stem cell transplantation (ASCT) in MM patients who did not have primary refractory disease. 74 consecutive MM patients were included in the study that received intensive therapy with ASCT. The study was able to identify the main features of newly diagnosed ER MM patients eligible for ASCT identifying the IgA isotype and the R2-ISS score system as the main predictive prognostic factors for ER in this cohort of MM patients.

Elevated serum levels of soluble B-cell maturation antigen as a prognostic biomarker for multiple myeloma.

Serum B-cell maturation antigen (sBCMA) levels can serve as a sensitive biomarker in multiple myeloma (MM). In the research setting, sBCMA levels can be accurately detected by enzyme-linked immunosorbent assay (ELISA), but the approach has not been approved for clinical use. Here, we used a novel chemiluminescence method to assess sBCMA levels in 759 serum samples from 17 healthy donors and 443 patients with plasma cell (PC) diseases including AL amyloidosis, POEMS syndrome, and MM. Serum BCMA levels were elevated 16.1-fold in patients with newly diagnosed MM compared to healthy donors and rare PC diseases patients. Specifically, the sBCMA levels in patients with progressive disease were 64.6-fold higher than those who showed partial response or above to treatment. The sBCMA level also correlated negatively with the response depth of MM patients. In newly diagnosed and relapsed MM patients, survival was significantly longer among those subjects whose sBCMA levels are below the median levels compared with those above the median value. We optimized the accuracy of the survival prediction further by integrating sBCMA level into the Second Revised International Staging System (R2-ISS). Our findings provide evidence that the novel chemiluminescence method is sensitive and practical for measuring sBCMA levels in clinical samples and confirm that sBCMA might serve as an independent prognostic biomarker for MM.

Bone marrow stromal cells dictate lanosterol biosynthesis and ferroptosis of multiple myeloma

Ferroptosis has been demonstrated a promising way to counteract chemoresistance of multiple myeloma (MM), however, roles and mechanism of bone marrow stromal cells (BMSCs) in regulating ferroptosis of MM cells remain elusive. Here, we uncovered that MM cells were more susceptible to ferroptotic induction under the interaction of BMSCs using in vitro and in vivo models. Mechanistically, BMSCs elevated the iron level in MM cells, thereby activating the steroid biosynthesis pathway, especially the production of lanosterol, a major source of reactive oxygen species (ROS) in MM cells. We discovered that direct coupling of CD40 ligand and CD40 receptor constituted the key signaling pathway governing lanosterol biosynthesis, and disruption of CD40/CD40L interaction using an anti-CD40 neutralizing antibody or conditional depletion of Cd40l in BMSCs successfully eliminated the iron level and lanosterol production of MM cells localized in the Vk*MYC Vk12653 or NSG mouse models. Our study deciphers the mechanism of BMSCs dictating ferroptosis of MM cells and highlights the therapeutic potential of non-apoptosis strategies for managing refractory or relapsed MM patients.

RAB22A as a predictor of exosome secretion in the progression and relapse of multiple myeloma.

Multiple myeloma (MM) is an incurable malignant plasma cell disease. We explored the role of RAB22A in exosome secretion, epithelial-mesenchymal transition (EMT) and immune regulation. We obtained MM samples from Gene Expression Omnibus (GEO) data sets. We downloaded the "IOBR" package, and used the "PCA" and "ssGSEA" algorithms to calculate the EMT scores and exosome scores. The "CIBERSORT" package was used to analyze the infiltration of immune cells. We extracted the exosomes of mesenchymal stem cell (MSC) to verify the biological function of RAB22A. The expression level of RAB22A in smoldering multiple myeloma (SMM) and MM patients was significantly higher than that in normal people and monoclonal gammopathy of undetermined significance (MGUS) patients, and the expression level of RAB22A in relapse MM patients was significantly higher than that in newly diagnosed patients. The EMT scores and exosome scores of high RAB22A group were significantly higher than those of low RAB22A group, and the exosome scores of MSC in recurrent patients were significantly higher than those of newly diagnosed patients. In addition, the infiltration levels of monocyte, NK cells resting, eosinophils, T cells regulatory and T cells CD4 memory activated were positively correlated with RAB22A. After down-regulating the expression of RAB22A in MM-MSC, the secretion of exosomes decreased. Compared with the exosomes of MSC in si-RAB22A group, the exosomes in control group significantly promoted the proliferation of MM. RAB22A is a potential therapeutic target to improve the prognosis of MM, which is closely related to exosome secretion, EMT and immune cell infiltration.

Sensitivity, specificity, and accuracy of molecular profiling on circulating cell-free DNA in refractory or relapsed multiple myeloma patients, results of MM-EP1 study

As a promising alternative to bone marrow aspiration (BMA), mutational profiling on blood-derived circulating cell-free tumor DNA (cfDNA) is a harmless and simple technique to monitor molecular response and treatment resistance of patients with refractory/relapsed multiple myeloma (R/R MM). We evaluated the sensitivity and specificity of cfDNA compared to BMA CD138 positive myeloma plasma cells (PCs) in a series of 45 R/R MM patients using the 29-gene targeted panel (AmpliSeq) NGS. KRAS, NRAS, FAM46C, DIS3, and TP53 were the most frequently mutated genes. The average sensitivity and specificity of cfDNA detection were 65% and 97%, respectively. The concordance per gene between the two samples was good to excellent according to Cohen’s κ coefficients interpretation. An increased number of mutations detected in cfDNA were associated with a decreased overall survival. In conclusion, we demonstrated cfDNA NGS analysis feasibility and accuracy in R/R MM patients who may benefit from early phase clinical trial.

Multidimensional role of adapalene in regulating cell death in multiple myeloma.

Multiple myeloma (MM) remains a challenging condition to cure, with persistent drug resistance negating the benefits of treatment advancements. The unraveling complexities in programmed cell death (PCD), inclusive of apoptosis, autophagy, and ferroptosis, have highlighted novel therapeutic avenues. Our study focuses on deciphering how adapalene (ADA), a small molecule compound, accelerates the demise of MM cells via targeting their compensatory survival mechanisms. To assess the impact of ADA on MM, we employed flow cytometry and trypan blue exclusion assays to determine cell viabilities across MM cell lines and primary patient samples post-treatment. To delineate ADA's therapeutic targets and mechanisms, we conducted RNA sequencing (RNA-seq), gene set enrichment analysis (GSEA), molecular docking, and molecular dynamics simulations. We further designed pre-clinical trials emphasizing MM, exploring the efficacy of ADA as a standalone and in combination with bortezomib (BTZ). ADA elicited a dose-responsive induction of MM cell death. Building upon ADA's anti-MM capabilities as a single agent, we proposed that ADA-BTZ co-treatment might amplify this lethality. Indeed, ADA and BTZ together greatly potentiated MM cell death. ADA proved beneficial in restoring BTZ susceptibility in BTZ-resistant relapsed or refractory MM (RRMM) patient cells. Molecular simulations highlighted ADA's high affinity (-9.17kcal/mol) for CD138, with MM-GBSA revealing a binding free energy of -27.39kcal/mol. Detailed interaction analyses indicated hydrogen-bonding of ADA with CD138 at the Asp35 and Gln34 residues. Additionally, ADA emerged as a versatile instigator of both ferroptosis and apoptosis in MM cells. Furthermore, ADA disrupted activation of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway triggered by BTZ, fostering cell death in BTZ-resistant MM subsets. ADA demonstrates a comprehensive capability to orchestrate MM cell death, exerting pronounced anti-MM activity while disrupting NF-κB-related drug resistance. ADA sensitization of MM cells to BTZ unravels its potential as a novel therapeutic drug for MM management.

Bridging treatment prior to chimeric antigen receptor T-cell therapy in multiple myeloma.

Autologous patient-derived adoptive T-cell therapies have revolutionized the management of relapsed multiple myeloma (MM). However, the current manufacturing and quality control processes result in lengthy vein-to-vein time, making bridging therapy necessary for most patients. Yet the decision and choice of optimal bridging therapy are complex in the heavily pretreated relapsed MM patient. In this perspective piece, the authors provide their approach and considerations while selecting an optimal bridging regimen before autologous chimeric antigen receptor T-cell therapy.

Ex-Vivo Testing Platform to Predict Clinical Response and Resistance to Proteosome Inhibitors, IMiDs and Daratumumab in Multiple Myeloma

Treatment of Multiple Myeloma (MM) relies on Standard of Care (SoC) schemes that include immunomodulatory drugs (IMiDs) and proteasome inhibitors (PIs) in combination with dexamethasone (Dexa). More recently, monoclonal antibodies such as Daratumumab (Dara) have become complementary therapeutic strategies to treat newly diagnosed and relapsed MM patients. Despite the multiple therapeutic schemes available, MM remains an incurable disease in which patients transit intermittent cycles of relapse and remission that ultimately lead to multi-drug resistance. It has therefore become clear that novel tools for personalized therapy selection are necessary to improve outcomes and reduce trial and error, particularly when selecting later lines of treatment. At OncoPrecision, we have developed a personalized ex-vivo platform that mimics the tumor microenvironment and promotes the survival of Patient-Derived Cells (PDCs), with the goal to predict the performance of the complete array of FDA-approved drugs, as well as experimental treatments, within 7 days. This technology, which we have named Patient Micro Avatars (PMAs), consists of the co-culture of PDCs with engineered neoplastic (System Control) and stromal (Tox Control) heterologous cells in combination with a multi-tagging approach coupled to high-throughput flow cytometry (Figure: Upper Panel). Our PMAs not only enable us to rank the activity of all approved treatments, but also unveil potential unspecific toxicities of novel treatments on non-tumoral cells, thus unlocking unique insights for early drug development programs. In this work, we introduce our PMA technology for MM by presenting differential response between patients in a Clinical Study performed in collaboration with two healthcare centers which, through approved IRBs, have provided MM patient samples from bone marrow aspiration. We present ex-vivo profiling results with a comprehensive MM drug matrix which includes SoC treatments used in several lines of therapy. We illustrate the potential of PMAs to identify differential activity from individual agents and synergistic drugs combinations in 13 patients (Figure: Lower Panel). By anticipating vulnerability/resistance to SoC treatments, our platform has the potential to become a first-in-class phenotypic biomarker to serve as a decision-support tool for Physicians to select optimal therapeutic regimes, as well as to elucidate valuable pre-clinical patient-derived insights for the development of innovative therapies for MM.

Identification of Clinical-Biological Features of Newly Diagnosed Early Relapse Multiple Myeloma Patients Eligible for Autologous Stem Cell Transplantation

Despite many therapeutics advances, Multiple Myeloma (MM) remains an incurable hematological malignancy with a cohort of patients who relapse early or does not respond to first-line therapy, including autologous stem cell transplantation (ASCT). The proportion of patients with early relapse is stable over time at about 30% and they have a median Overall Survival (OS) less than 3 years. Consequently, clinical and/or biological features that identify patient at high risk for early relapse at diagnosis represent a critical unmet medical need. With the aim of identify possible factors of early relapse (ER), we conducted a retrospective, observational, single center study on a cohort of 74 MM patients who received an upfront ASCT between 2011 and 2021 after a novel agent-based induction at the Hematological and BMT Unit of the University Hospital of Parma (Italy). The primary end point of the study was the assessment of possible predictive markers for ER, defined as progressive disease that occurred within 18 months from the time of ASCT. Clinical, biochemical and cytogenetics features of the cohort of MM patients were evaluated (Table 1). Definitions of response and progression were used according to the International Myeloma Working Group (IMWG) response criteria. All statistical analyses were done by SPSS Statistics. The characteristics of cohorts were summarized using the median value for continuous variates and the frequency for categorical ones. The Pearson chi-square test and Student t-test were used to identify differences between groups for categorical and continuous variables, respectively. Kaplan-Meier Curve with log-rank test were used to analyze survival data. The bivariate logistic analysis was conducted to recognize independent factors predicting ER, subsequently Cox regression analysis was performed to confirm the validity of multivariate analysis for survival data. The cohort characteristics were summarized in table 1. Among the 74 MM patients included in the study, a total of 19 patients (25.5) experienced ER, with mean time to relapse of 15.6 (18.0) months. Univariate statistical analysis identified as possible predictive markers for early relapse at diagnosis: IgA MM (p < 0.05), elevated serum LDH level (p < 0.05), C-CRAB criteria (p < 0.05), high risk cytogenetic aberrations (p < 0.05), stage R-ISS III (p < 0.001) and stage R2-ISS III or IV (p < 0.001). Multivariate statistical analysis confirmed IgA isotype (p < 0.05) and higher stage according to R2-ISS (p < 0.001) as effectively independent predictive risk factors for ER. Time-to-event analysis displayed a mean progression free survival (PFS) from transplant of 24.7 (16.0) months and 32.5 (19.0) months for those with IgA MM and stage R2-ISS III or IV, respectively. In the group of patients with IgA isotype the mean OS from transplant was 49.5 (30.0) months, while the mean OS from diagnosis was 58.0 (35.0) months without statistically significant differences compared to counterpart. In the group of patients with stage R2-ISS III or IV the mean OS from transplant was 48.2 (41.0) months, while the mean OS from diagnosis was 56.5 (49.0) months. Finally, in ER cohort the mean OS from diagnosis was 47.1 (35.0) in comparison with the 75.0 (71.0) months of non-ER cohort. In conclusion, this retrospective study was able to identify the main features of newly diagnosed early relapsed MM patients eligible to ASCT identifying the IgA isotype and the R2-ISS score system as the main predictive prognostic factors for early relapse in this cohort of patients.

Synergistic Effects of Type I PRMT1 and Type II PRMT5 Inhibitors Against Multiple Myeloma

Multiple myeloma (MM) is a plasma cell malignancy characterized by the extensive expansion of monoclonal aberrant plasma cells in the bone marrow and the second most prevalent hematological malignancies worldwide. Despite the promising outcomes of advanced therapies, relapsed/refractory (RR) diseases remain incurable, highlighting an unmet clinical need to identify novel therapeutic targets. An emerging field of investigation is the role of aberrant post-translational modifications in multiple myeloma pathology. Arginine methylation is one of the most predominant post-translational modifications in cells, catalyzed by protein arginine methyltransferases (PRMTs) that plays a crucial role in multiple cellular processes. Type I PRMTs catalyze mono- (MMA) and asymmetric demethylation (ADMA) of arginine; Type II PRMTs catalyze mono- and symmetric demethylation (SDMA) of arginine on proteins; Type III PRMT mediates MMA only. Aberrant expression of PRMTs is strongly associated with poor prognosis of solid cancers and hematologic malignancies. Recently, we identified PRMT1 as a novel therapeutic vulnerability in MM cells. Among PRMTs, PRMT1 is the highest expressed gene in MM cell lines and patient cells. The elevation of PRMT1 expression is strongly associated with relapsed/refractory patients and poor clinical outcomes. Deletion of PRMT1 and suppression of the PRMT1's enzymatic activity exhibited a strong anti-MM in vitro via suppressing cell cycle and elevating the apoptosis. We also found that inhibition of PRMT1 boosts the T cell activation in the co-culture setup, indicating a potential enhancement of immunotherapy. Using a subcutaneous xenograft model, we showed that suppressing PRTM1 in vivo by either genetic or pharmaceutical approaches robustly inhibits MM tumor growth and extends survival of tumor-bearing mice. Our findings demonstrated that PRMT1 is indispensable in MM. PRMT5, a PRMT type II, is prognostically relevant and a known druggable target in MM. PRMT1 and PRMT5 inversely regulate post-transcription and have been implicated in human cancers. Recent studies in solid tumor showed a strong anti-tumor effect in vivo using the combinational inhibition of PRMT1 and PRMT5. We hypothesize that PRMT1 and PRMT5 might have a complementary function in MM cells. The combinational inhibition PRMT1 and PRTM5 will exhibit a synergistic anti-MM effect. To address this hypothesis, we treated MM cell lines with two clinical trial inhibitors: GSK3368715 (GSK) and EPZ 015666 (EPZ), suppressing PRMT type I and type II inhibitor, respectively. We first performed dose-dependent cell viability inhibition and selected effective doses for drug combination treatments in three different MM cell lines. The combination of GSK and EPZ demonstrated a strong synergistic effect in suppressing the viability of MM cells. Using the SynergyFinder algorithm, we found that the synergistic indexes (>10, synergism) for 3 MM cell lines JJN3, MM1S, and KMS11 were 33.5, 32.8, and 14.3, respectively. We next assessed the effects of combined treatment on the cell cycle and apoptosis of MM cells. We found that combination of GSK and EPZ strikingly elevated the apoptosis and suppressed cell cycle of MM cell lines compared single treatment and untreated control. Intriguingly, the combination treatment of two inhibitors significantly decreased MMA, SDMA, and ADMA, suggesting a robust suppression of global arginine methylation. Of note, we found a similar anti-MM effect when treating bortezomib-resistant MM cells with GSK and EPZ, indicating that PRMT type I and type II inhibitors potentially have a substantial clinical impact on relapsed MM. Of note, the same dose of GSK and EPZ that exhibits the synergistic anti-MM effect, didn't suppress the viability of healthy peripheral blood cells. In summary, our preliminary data suggest that suppression of both PRMT type I and type II might provide a potential effective combination treatment for both newly diagnosed and relapsed MM patients. We're currently investigating the underling mechanisms of how PRMTs regulate MM pathology and validating the in vivo efficacy of combination treatment using patient-derived xenograft.

Daratumumab-Based Maintenance in Patients with Relapsed Multiple Myeloma after Salvage Autologous Hematopoietic Stem Cell Transplantation

Introduction: Maintenance therapy is considered standard of care after upfront autologous hematopoietic stem cell transplantation (auto-HCT) for patients with newly diagnosed multiple myeloma (MM). However, there is paucity of data on the use of maintenance after a salvage auto-HCT, whether first or second. Aim: We designed a clinical trial for relapsed MM patients who underwent salvage auto-HCT after disease relapse to receive post-transplant maintenance with daratumumab (dara), with the addition of pomalidomide (pom) in a later amendment. Methods: We hypothesized that maintenance therapy with dara +/- pom will improve the progression-free survival (PFS) after a salvage auto-HCT. Patients with prior exposure to dara or pom were included, but patients refractory to either drug were excluded. The trial was planned to enroll a total of 56 patients. Patients received dara SQ weekly for weeks 1-8, every 2 weeks for weeks 9-24, and monthly from week 25 until progression. Pom was given at 2 mg PO from day 1-21 every 28 days. Patients received herpes zoster prophylaxis for the duration of the trial. The primary endpoint of this phase II trial was PFS. Disease response was assessed according to the International Myeloma Working Group (IMWG) uniform response criteria. Minimal residual disease (MRD) was measured by multiparametric flow cytometry (10 -5) in the bone marrow at day 90-180 after transplant. Results: The trial was terminated due to poor accrual after 13/56 patients were enrolled between May 2019 and August 2022. Median age at salvage auto-HCT was 64 (range: 43-76) years, and 7 patients (54%) were male. Median prior lines of treatment was 2 (range: 2-4). Six patients (46%) had a prior auto-HCT, and 7 (54%) had a hematopoietic stem cell comorbidity index (HCT-CI) of >3. Median time from diagnosis to salvage auto-HCT was 58.3 (range 7.6-132) months. Five patients (38%) had high-risk cytogenetic abnormalities (1q+ in all 5). Eight (61%) patients received melphalan alone, 4 (31%) received busulfan/melphalan, and 1 (8%) received gemcitabine/busulfan/melphalan/panobinostat as their conditioning regimen (Table 1). Three patients (23%) started maintenance with dara alone, while the remaining 10 (77%) patients received dara + pom. At study entry, 6 patients (46%) had a complete response (CR), 4 (31%) in very good partial response (VGPR), 2 (15%) in partial response (PR), and 1 (8%) had stable disease (SD). At day 100 post maintenance, 9 (69%) were in CR, while 1 (8%) each had VGPR, PR, SD and progressive disease (PD), respectively. For the 12 patients that did not progress at day 100, best response to dara +/- pom maintenance was CR in 10 (83%), and VGPR and SD in 1 (8%) each. With a median follow up of 26.1 months (range: 14.2-37.7) from the start of maintenance, 3 patients had progressed but there are no deaths so far. Median PFS from the date of auto-HCT was not reached, and from start of maintenance 28.5 (95% CI 26.3-NA) months. 2-year PFS was 92% (Figure 1). Most common adverse events were neutropenia (n=11, 84%; none grade>3), grade 1-2 fatigue (n=6, 46%), and grade ≤3 bacterial infection, grade ≤3 viral infection, grade 1-2 diarrhea and grade 1 thrombocytopenia (n=5, 38% each). Conclusion: Maintenance therapy with dara, with or without pom, is safe and feasible after a salvage auto-HCT for MM, with 83% achieving a CR. After a median follow up exceeding 2 years, the median PFS was 28.5 months. The trial was terminated due to poor accrual.

CD70/CD27 Signaling Promotes Expansion of Clonal Plasma Cells in Multiple Myeloma and Is a Promising Therapeutic Target in Advanced Disease

Introduction: Multiple Myeloma (MM) is a hematological malignancy characterized by the clonal expansion of malignant plasma cells within the bone marrow (BM). In the last decade, substantial advances in the treatment of MM patients have been made resulting in improved progression-free and overall survival rates. However, to date, MM remains incurable. CD70 and CD27 belong to the TNF receptor family. CD70 is the only known ligand for its receptor CD27. Physiologically, the CD70/CD27 interaction is involved in the regulation of immune cell expansion. However, numerous solid and hematological cancer types overexpress CD70. Aside, CD70 and CD27 co-expression has been described on leukemic stem cells (LSC) in acute myeloid leukemia patients where an autonomous signaling activation drives LSC self-renewal and expansion. While CD70/CD27 signaling plays a key role in the differentiation process of B lymphocytes into plasma cells, only little is known about its impact on myelomagenesis and MM progression. In this study, we analyzed the role of CD70/CD27 signaling in the pathogenesis of MM and studied the possibility to target CD70 by monoclonal antibodies to treat the disease. Materials and Methods: We evaluated CD70 and CD27 gene expression levels and its correlations with overall survival (OS), MM progression and high-risk molecular alterations using different databases (CoMMpass IA15, GSE6477). CD70 and CD27 protein expression patterns were analyzed in a newly established MM tissue microarray (TMA) and a collection of matched BM samples from initial and advanced disease stages (in collaboration with the Institutes of Pathology in Bern, Basel and Tübingen). To assess the functional role of CD70/CD27 signaling on MM initiation and expansion, we generated CD70 knock-out MM cell lines and newly established patient-derived xenografts (PDX) using CRISPR/Cas9 genome editing. CD70-expressing MM cell lines or patient-derived myeloma cells were grown in NOD/SCID (NSG) mice. Moreover, different monoclonal antibodies (Abs) and Ab-derivates were tested including a CD70 blocking antibody (αCD70) and an antibody-dependent cell-mediated cytotoxicity (ADCC) optimized antibody (cusatuzumab, ArgenX) that activates FcγR-expressing effector cells to assess the therapeutic potential of targeting CD70 in MM. Results: High CD70 gene expression levels correlate with increased MKI67 gene expression and elevated lactate dehydrogenase serum levels indicating a more rapid proliferation of CD70-expressing myeloma cells. In addition, high CD70 expression in MM patients correlated with shorter OS. Longitudinal analyses of CD70 gene expression in the precursor stages monoclonal gammopathy of undetermined significance and smoldering myeloma as well as MM and relapsed MM stages showed highest CD70 gene expression levels in relapsed MM patients. Assessment of the molecular background further revealed increased frequencies of the prognostically unfavorable genomic translocations t(4;14) and t(14;16), as well as gain/amplification of the chromosomal region 1q21 (1q+) in CD70 high expressing MM patients. In line with our previous findings, a TMA analysis of over 200 MM core biopsies as well as a longitudinal analysis of matched biopsies from patients at initial diagnosis and MM relapse indicated that CD70 was overexpressed in advanced disease. Functionally, we found that CD70/CD27 signaling promotes plasma cell survival inducing the expansion of MM cell lines and primary malignant plasma cells. CD70 blockade (αCD70) or CD70 knock-out (CD70 KO) resulted in a significant inhibition or complete abrogation of growth of a CD70-expressing MM patient-derived xenograft (PDX) (EMM01 CD70+) compared to controls (Figure 1). Interestingly, in vivo limiting dilution assays revealed that CD70+CD27+ double-positive myeloma subpopulations showed significantly higher cancer stem cell frequencies compared to CD70 negative fractions suggesting that CD70 expression might be related to an immature or stem-cell like phenotype. The ADCC-optimized CD70 specific antibody custatuzumab efficiently eliminated CD70-expressing MM cells in the presence of PBMC-derived natural killer (NK) cells in vitro and in a PDX model in vivo. Conclusion: Our results indicate that CD70-expressing MM cells have a stem-cell like phenotype and propagate the disease. Targeting CD70 is a promising new therapy especially in advanced disease.

Regulation of BCMA By the Ubiquitin Proteasome System Enables Optimization of BCMA-Targeting Therapies in Multiple Myeloma

Background: The exclusive expression of the B-cell maturation antigen (BCMA), in normal and malignant plasma cells, currently makes it a prominent target for immune cell therapies in multiple myeloma (MM) including chimeric antigen receptor T-cell (CART) and bi-specific T cell engaging antibody (BiTE) therapies. Despite initial high response rates, most patients eventually relapse highlighting the need to enhance therapy efficacy. Although loss of BCMA-antigen expression marks one reason for therapy failure, little is known about the mechanistic means of antigen escape. The ubiquitin proteasome system (UPS) controls abundance and protein degradation of about 80-90% of all cellular proteins. Protein degradation is initiated by substrate ubiquitination, which is orchestrated by the sequential action of enzymes whereby only E3-ligases possesses substrate specificity. Deubiquitinating enzymes (DUBs) can reverse substrate ubiquitination. Against this background, we raised the question whether BCMA antigen presentation, expression, and activity is regulated by the UPS and whether the UPS can be utilized to enhance BCMA directed CART therapies in MM. Methods: Protein turnover and regulation by the UPS was assayed using cycloheximide and proteasomal inhibitors (PI) followed by immunoblotting. Direct substrate ubiquitylation was confirmed by ubiquitylation assays based on immunoprecipitation and image-based analysis. Changes in antigen surface presentation were determined using FACS analysis. Changes in cellular signaling and downstream effects were assessed by immunoblotting and quantitative PCR (qPCR). Primary CD138 + cells were obtained from bone marrow aspirations followed by MACS ® cell separation. To assess the effect of PI on CART killing capacity, a classic co-culture was set up in vitro. Using a proximity-based protein purification method (TurboID), UPS-related interactors of BCMA were identified. Results: For the first time, we show that BCMA is a short-lived protein with a half-life of approximately 30 min in MM cells. Degradation of BCMA is abrogated upon PI treatment. Inhibition of γ-secretase, an established protease of the extracellular domain of BCMA does not impair BCMA turnover. Furthermore, we show that BCMA is indeed ubiquitylated in MM cells and that ubiquitylation is induced by the ligand APRIL. These results support the hypothesis that the UPS regulates BCMA abundance. In both MM cell line models and primary CD138 + MM cells of PI refractory/ relapsed MM (RRMM) patients, inhibition of the proteasome leads to a significant increase of BCMA on the cell surface without promoting oncogenic NF-κB signaling in MM cells. Subsequently, we show that the increase in BCMA surface expression upon PI treatment substantially increases the efficacy of BCMA directed CART cells in co-cultures with MM cells and primary CD138 + MM patient cells. Specific members of the UPS (E3 ligases and DUBs) identified from our proteome wide BCMA interactome analysis are currently being validated. Conclusion: Here we show, for the first time, that BCMA is ubiquitylated and degraded by the ubiquitin proteasome system in multiple myeloma. The increase in BCMA expression upon proteasomal inhibition enhanced efficacy of BCMA-targeting CART cells. These insights provide a rationale for combining BCMA CART cells with PI in patients with BCMA CART relapsed/refractory disease and persistence. The identification of BCMA-specific E3-ligases and DUBs may represent novel therapeutic targets to specifically prevent BCMA degradation and antigen escape.

The Spop/BRD4/c-Myc Axis Modulates IMiDs Sensitivity in Multiple Myeloma

The development of novel agents including immunomodulatory drugs (IMiDs) lenalidomide (Len) and pomalidomide (Pom) has led to improved patient outcomes in multiple myeloma (MM); however, MM patients inevitably experience relapse and drug resistance. The expression level of CRBN, CRBN-binding proteins, and CRL4 CRBN ubiquitin ligase is considered to be associated with IMiDs resistance. Clinical studies have shown that MM patients can exhibit IMiDs resistance even without CRBN abnormalities, suggesting the molecular mechanisms of intrinsic resistance to IMiDs are not fully understood. To delineate the molecular mechanisms underlying IMiDs resistance, we performed genome-wide knockout (KO) screening in IMiDs-sensitive MM cells. For in vitro work, we used the MM cell lines MM1S, and H929. We used sgRNA to KO SPOP and BRD4 in MM cells. After performing a CRISPR KO screen in MM cells, we discovered that in addition to CRBN and its associated genes, sgRNAs targeting SPOP (speckle-type POZ protein, a speckled zinc finger protein) were highly enriched after treatment with Poma. Importantly, SPOP KO MM cell lines acquired significant resistance to Pom and Len treatment. To examine whether SPOP KO-induced IMiDs resistance was CRBN-pathway dependent, we assessed CRBN and its downstream interacting protein levels. SPOP KO showed no effect on CRBN expression; moreover, IMiDs can still trigger IKZF1 and IKZF3 degradation, associated with the downregulation of IRF4, suggesting that SPOP mediates sensitivity to IMiDs in a mechanism independent of CRBN-IKZF1/3 axis.Compared to plasma cells from normal donors, we found that the expression levels of SPOP were significantly decreased in MGUS patients, smoldering myeloma patients, newly diagnosed MM patients, and refractory relapsed MM patients (p-values: 2.4e-2, 2.0e-4, 9.9e-3, 3.17e-6, respectively). SPOP is the adaptor protein of the Cullin3-RING ubiquitin ligase complex. Therefore, the function of SPOP is determined by the characteristics of the substrates it recruits. We performed immunoprecipitation with overexpressed SPOP in MM cells, followed by mass spectrometry analysis, and identified BRD4 as a candidate protein binding to SPOP in MM, which was confirmed by Co-IP. KO of SPOP led to an upregulation of BRD4 protein levels in MM cells. As a downstream regulator of BRD4, the oncogene c-Myc showed a significant increase in protein expression in IMiDs-resistant MM patients. Furthermore, the KO of SPOP notably enhanced c-Myc expression in MM cells, while the KO of BRD4 in SPOP KO MM cells decreaed c-Myc expression and restored MM cell sensitivity to IMiD treatment. These findings suggest that SPOP modulates c-Myc expression through BRD4 in a CRBN-IKZF1/3 independent manner, thereby mediating MM cell sensitivity to IMiDs. BRD4 plays a significant role in the development and progression of various tumors. The BRD4 inhibitor JQ1 has been shown to exhibit anti-tumor effects in multiple types of cancer. We found that combination treatment with JQ-1 and IMiDs reversed IMiDs resistance of SPOP KO MM cell lines and primary MM cells from relapsed patients. Our data show that SPOP is a CRBN-independent modulator of IMiDs sensitivity by regulating the BRD4/c-Myc axis and provides the preclinical rationale for combining IMiDs with BRD4 inhibitors to overcome IMiDs resistance and improve patient outcomes.

Salvage Transplant Versus CAR-T Cell Therapy for Relapsed Multiple Myeloma

Background: Ide-cel and cilta-cel received regulatory approval for the treatment of patients with relapsed or refractory multiple myeloma (MM) after ≥4 prior lines of therapy, and almost all eligible patients in the US and Europe have previously received at least one autologous hematopoietic cell transplant (autoHCT). Even for those who received upfront autoHCT, salvage transplant (either second autoHCT or allogeneic HCT) for patients with relapsed MM was shown to be effective and feasible. Therefore, comparing CAR-T cell therapy with salvage transplant could facilitate future selection of patients with relapsed MM, as eligibility for transplant (especially allogeneic HCT) differs significantly from that of CAR-T. Methods: We leveraged a large European dataset to identify relapsed MM patients who received either salvage autoHCT, allogeneic HCT, or CAR-T cell therapy. To minimize selection bias, we only included patients who received salvage treatment from 2018 onwards and who had documented time of relapse. Furthermore, to control for differences in patient characteristics, we applied propensity score (PS) matching for the comparison: CAR-T versus auto HCT and versus allogeneic HCT. We performed individual matching with the “nearest neighbour” method, using a caliper=0.2. The model for PS estimation included patient sex, MM classification at diagnosis, previous transplant history (single or tandem auto), interval between upfront transplant and relapse and between relapse and CAR-T/salvage transplant, age, performance status and disease status at CAR-T/salvage transplant. Endpoints of matched groups were compared by Log-Rank test or Gray test stratified on the pair. Primary endpoint was progression-free survival (PFS) at 1 year with 95% confidence interval (CI). Secondary endpoints constituted non-relapse mortality, incidence of relapse, and overall survival (OS). Results: We included 4292 patients, of whom 3858 received salvage autoHCT, 371 allogeneic HCT, and 63 CAR-T cell therapy (60% ide-cel, 33% cilta-cel, 7% other investigational). Median age at time of salvage treatment was 62 years for autoHCT, 54 years for allogeneic HCT, and 61 years for CAR-T cell therapy (P<0.001). More than 60% of patients were male in all groups, and IgG subtype of MM was present in 52% of autoHCT, 48% of allogeneic HCT, and 44% of CAR-T cell therapy. More patients receiving CAR-T cell therapy had a Karnofsky performance status <80% (41%) versus 32% of autoHCT and 29% of allogeneic HCT. In terms of response, complete response to treatment was observed in 40% for autoHCT, 63% for allogeneic HCT, and 44% for CAR-T cell therapy. Partial remission or very good partial remission was achieved 11%, 9%, and 35%, respectively (P<0.001). Median follow-up was 16.7 months for the entire cohort. The PS method could successfully match almost all patients for the comparison of CAR-T cell therapy versus salvage autoHCT (59 patient, respectively). The 1-year PFS for CAR-T cell therapy versus autoHCT was 68% (95% CI, 56-80%) versus 44% (95% CI, 28-59%; P=0.048; Figure 1). The 1-year non-relapse mortality was 9% (95% CI, 2-17%) versus 0% (P=0.31). Cumulative incidence of relapse at 1 year was 23% versus 57% (P=0.028), and 1-year overall survival was 81% versus 68% (P=0.059). The PS method matched 33 patients for the comparison of CAR-T cell therapy versus salvage allogeneic HCT. The 1-year PFS was 72% (95% CI, 56-88%) versus 39% (95% CI, 18-60%; P=0.346). Non-relapse mortality at 1-year was 13% (95% CI, 1-25%) versus 23% (95% CI, 7-43%; P=0.257). The 1-year cumulative incidence of relapse was 15% versus 36% (P=0.763), and the 1-year overall survival was 84% (95% CI, 71-97%) versus 60% (95% CI, 39-81%; P=0.083). Conclusion: This multicenter retrospective study compared CAR-T cell therapy with salvage transplantation strategies for relapsed MM. CAR- T cell therapy appeared to improve outcomes, especially in comparison with salvage autoHCT. The higher absolute rates of non-relapse mortality observed with CAR-T cell therapy may not counterbalance overall beneficial results, and rather highlights the need for careful selection of patients. Longer follow-up will be needed for definitive results.

RAB22A As a Predictor of Exosome Secretion in the Progression and Relapse of Multiple Myeloma

Background: Multiple myeloma（MM）is an incurable malignant plasma cell disease in the blood system. After remission, patients will still have multiple recurrences, and the remission time after each recurrence will gradually become shorter. RAB22A is a member of RAS oncogene family, and there is no relevant research in MM at present. In this study, we explored the role of RAB22A in exosome secretion, Epithelial-mesenchymal transition（EMT）and immune regulation. Methods: We obtained MM samples from GEO data sets (GSE5900, GSE4581 and GSE146649), and analyzed the difference of expression of RAB22A. We downloaded the “IOBR” package, and used the “PCA” and “ssGSEA” algorithms to calculate the EMT scores and exosome scores of the high/low RAB22A expression groups. The “CIBERSORT” package was used to analyze the infiltration of immune cells. RT-PCR and Western-blot were used to verify the expression level of RAB22A in normal people and MM patients. After regulating the expression of RAB22A, the exosomes of MSC were collected for immunofluorescence staining and CCK-8 experiment. Results: The expression level of RAB22A in SMM and MM patients was significantly higher than that in normal people and MGUS patients, and the expression level of RAB22A in relapse MM patients was significantly higher than that in newly diagnosed patients. We calculated the EMT score and exosomes score by “IOBR” package. The results showed that the EMT score and exosomes score of high RAB22A group were significantly higher than those of low RAB22A group, and the exosomes score of MSC in recurrent patients was significantly higher than that of newly diagnosed patients. In addition, the infiltration levels of Monocyte, NK cells resting, Eosinophils, T cells regulatory (Treg) and T cells CD4 memory activated were positively correlated with RAB22A, while plasma cells and T cells gamma delta were negatively correlated with RAB22A. The expression levels of m6A genes (METTL14, VIRMA, RBM15 and FMR1) in the high RAB22A group were significantly higher than those in the low RAB22A group. We constructed a nomogram based on m6A genes significantly related to RAB22A to predict the risk value of high RAB22A expression, and the calibration curve showed that the nomogram had good prediction ability. We screened sensitive drugs according to the difference of IC50 values between high and low RAB22A groups, and found that cisplatin, Doxorubicin and bcl-2 inhibitors had higher sensitivity in low RAB22A group. Finally, we verified the above results in the samples of our center. The results showed that the expression level of RAB22A in MM patients was significantly higher than that of donors. After down-regulating the expression of RAB22A in MM-MSC, the secretion of exosomes decreased（Figure 1). Down-regulation of RAB22A reduced the proliferation of MM cells, and the addition of exosomes of MM-MSC partially reversed this effect. Conclusion: RAB22A is a potential therapeutic target to improve the prognosis of MM, which is closely related to exosome secretion, EMT and immune cell infiltration.

Heme Attenuates T Cell Exhaustion and Drives Effector Function: Implications for Immune and Adoptive T Cell Therapy

Introduction: Though frontline agents have been effective in multiple myeloma (MM) therapy, a significant proportion of MM patients relapse and succumb to refractory disease. B-cell maturation antigen (BCMA)-directed chimeric antigen receptor (CAR) T therapy represents an exciting novel therapeutic strategy for MM but still suffers from limited in vivo T cell expansion and CAR T cytotoxicity. Altering the CAR T manufacturing process to produce CAR T cells with less exhausted phenotypes and robust killing is an active area of research. Mitochondrial function and energetics play a central role in regulating T cell fate and function, and heme (iron-protoporphyrin IX) is critical for maintaining electron transport chain activity and oxidative phosphorylation. Heme can be sourced from the extracellular milieu, diet, or intrinsic heme biosynthesis and has a multitude of cellular functions throughserving as a cofactor for enzymatic and metabolic reactions. Additionally, heme is catabolized by heme oxygenase 1, producing the antioxidants biliverdin and bilirubin critical to preserving cellular redox homeostasis. In the present study, we investigate the effects of heme on CAR T cell efficacy. Our results suggest that heme supplementation during ex vivo CAR T manufacturing or supplementation during CAR T-tumor cell engagement can lead to decreased T cell exhaustion and increased tumor killing. Methods: Human healthy donor and MM patient T cells were activated and expanded with α-CD3/CD28 and IL-2 for 7 days +/- hemin, after which immunostaining and metabolic assays were conducted. For CAR T manufacture, T cells were transduced with CAR construct starting on day 3 and were co-cultured with antigen-expressing tumor cells in vitro on day 7-8. Cytotoxicity and cytokine production were assayed after 24 hours of co-culture. Results: In a dose-dependent manner, heme supplementation significantly decreases proportions of LAG3 + and TIM3 + and decreases proportions of CD62L + and TCF1 + cells in both CD4 + and CD8 + subsets isolated from healthy donor and MM patient peripheral blood. Supportive of these observations, inhibition of de novo heme biosynthesis leads to the opposite effect with an increase in proportions of PD1 +, LAG3 +, TIM3 +, and CD62-L + cells. CAR T cells manufactured with heme (heme-CAR T cells) have significantly reduced terminally exhausted phenotypes (PD1 +/LAG3 +/TIM3 +) and increased enrichment of effector memory cells (CD62L -CD45RA -) in both CD4 + and CD8 + subsets. Inquiry of cellular energetics of heme supplemented CAR T cells reveals reduced reactive oxygen species (ROS) and increased mitochondrial membrane potential, consistent with previous reports showing increased membrane potential in effector T cells for greater production of cytokines such as IL-17A, IL-17F, and IFNγ. In co-culture with tumor cells in vitro, heme-CAR T cells have higher tumor-specific lysis and production of TNFα and IL-2. CAR T-tumor cell engagement in the presence of heme resulted in significantly decreased proportions of exhausted CAR T cells and increased production of TNFα. Heme also increases BCMA surface expression in several MM cell lines, highlighting a viable strategy for enhancing BCMA CAR T engagement with MM. Lastly, MM patient bone marrow-localized T cells demonstrate significantly decreased terminally exhausted phenotypes and increased differentiation into effector subsets when expanded with heme. Conclusion: We show that heme increases effector T and CAR T cell function and decreases T cell exhaustion. Increased cytotoxicity of heme-supplemented CAR T cells was associated with reduced ROS and increased membrane potential. Ongoing in vivo studies aim to characterize the efficacy of heme-supplemented CAR T cells in MM xenograft models. Our studies have broader implications for investigating heme supplementation in ex vivo CAR T manufacturing for a wide range of hematological cancers and underscore the need for further investigation of heme uptake and metabolism for strategic enhancement of T-cell based immunotherapies.

Real-World Treatment Patterns and Clinical Outcomes Among Triple-Class Exposed and B-Cell Maturation Antigen (BCMA) Exposed Multiple Myeloma Patients

Introduction: Despite the development of advanced treatment options, multiple myeloma (MM) remains an incurable disease. Most MM patients relapse and require further treatments. B-cell maturation antigen (BCMA) targeted immunotherapy is a novel MM therapy class that is now available to heavily pre-treated relapse/refractory MM (R/R MM) patients, who were triple class exposed (TCE) to proteasome inhibitors (PIs), immunomodulatory drugs (IMiDs), and anti-CD38 monoclonal antibodies. As BCMA therapies continue to be further utilized and become an integral part of MM treatment, the proportion of TCE patients who are also BCMA exposed (TCE+BCMA exposed) is expected to grow. However, the clinical outcomes of TCE+BCMA exposed RRMM patients have not been previously assessed. The objective of this study was to evaluate the real-world outcomes of TCE+BCMA exposed MM patients who started a subsequent LOT, describing their characteristics, treatment patterns, and clinical outcomes. Subgroups of penta-drug exposed (at least two PIs, at least two IMiDs, and at least one anti-CD38) patients, as well as White and African American patients were also evaluated as penta-drug exposure status and race were known to impact clinical outcomes. Methods: Adult patients with MM who were TCE+BCMA exposed and started a subsequent LOT starting from July 03, 2019 (when additional new treatment options became available) were selected from the Komodo Healthcare Map (a US claims dataset) and were followed until the earliest of death, last claim, or end of study period (December 31, 2022). Index date was defined as the start date of the subsequent LOT following TCE and BCMA exposure. Descriptive statistics were provided for patient characteristics and treatment patterns. Clinical outcomes including time to treatment discontinuation or death (TTD) and time to next treatment or death (TTNT) were estimated using the Kaplan-Meier method. Results: A total of 344 TCE+BCMA exposed patients, who received the next LOT were included in the study, including 152 (44.2%) patients who were penta-drug exposed before index, 57 (16.6%) African American, and 185 (53.8%) White patients. Key baseline demographic characteristics and treatment history for the overall group and the three subgroups are listed in Table 1. The mean (SD) and median number of prior LOTs for the overall group before index date were 5.7 (1.7) and 6.0, respectively. The most prevalent prior treatments before the index date for the overall group were daratumumab (99.1%), belantamab mafadotin (91.9%), pomalidomide (84.3%), carfilzomib (83.1 %), bortezomib (76.2%) and lenalidomide (72.1%). Excluding corticosteroids, the most frequently used index treatments (i.e., treatment used post TCE+BCMA exposure) were carfilzomib- (21.9%), bortezomib- (20.8%), pomalidomide- (18.3%), and belantamab mafadotin- (18.3%) based regimens. The median (95% confidence interval [CI]) TTD was 3.7 (3.3, 4.4) months, and the median (95% CI) TTNT was 6.4 (5.5, 7.6) months. TTD and TTNT estimates for the three subgroups are listed in Table 2. Conclusions: To our knowledge, this is the first real-world study of treatment patterns and outcomes for TCE+BCMA exposed MM patients who started a subsequent LOT. The findings showed that this group of heavily pretreated MM patients were often retreated with the same therapies or therapies in the same classes, as they have limited effective treatment options. TCE+BCMA exposed patients exhibited poor clinical outcomes, as demonstrated by the rapid treatment discontinuation and moving on to the next treatment shortly after initial treatment. Many patients were already penta-drug exposed, and they appear to have worse clinical outcomes than the overall patient group. A shorter TTD was observed, and a trend for shorter TTNT was observed among African American patients than White patients. The findings highlight the continued need for effective treatments for heavily treated MM patients and particularly those with poor outcomes.