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Daratumumab, an anti-human CD38 monoclonal antibody, has become the standard of care in patients with systemic light-chain (AL) amyloidosis and multiple myeloma (MM). Herein, we report two cases of AL cardiac amyloidosis with MM who were treated with daratumumab, lenalidomide, and dexamethasone (DRd). Serial evaluation of cardiac biomarkers, echocardiography, and cardiac magnetic resonance imaging (CMR) were performed during 12 months of DRd treatment. A complete hematologic response was achieved three months after treatment initiation and sustained during the observation period. Twelve months after DRd treatment, we found improvements in levels (values for case 1 and case 2, respectively) of B-type natriuretic peptide (593.2 → 312.2 pg/mL and 202.4 → 104.3 pg/mL), N-terminal pro-brain natriuretic peptide (4005 → 1800 pg/mL and 2576 → 1170 pg/mL), high-sensitivity cardiac troponin T (0.156 → 0.072 ng/mL and 0.0678 → 0.0467 ng/mL), and global longitudinal strain (−6.8 → −10.4 % and −11.8 → −14.8 %). CMR revealed no noticeable changes in native T1 value or extracellular volume fraction. However, one case showed decreased native T2 value (61 → 55 ms). In conclusion, DRd treatment improved heart failure and cardiac function, relieved myocardial damage, and prevented amyloid deposition progression in the patients with AL cardiac amyloidosis. Cardiac biomarkers and imaging findings may be useful for monitoring the therapeutic effects of daratumumab-containing regimens. LEARNING OBJECTIVE: Daratumumab-containing regimens led to a rapid complete hematologic response, improvements in heart failure symptoms, cardiac function, and regression of myocardial damage in light-chain cardiac amyloidosis. This treatment prevents additional amyloid deposition and suppresses the direct cardiotoxic effects of amyloidogenic immunoglobulin light-chains. Serial assessments of cardiac biomarkers and imaging findings are useful for evaluating the therapeutic effect of daratumumab-containing regimens.

PURPOSE: To evaluate the diagnostic performance of myocardium-to-lumen R1 (1/T1) ratio on postcontrast T1 maps for the detection of cardiac amyloidosis in a large patient sample. MATERIALS AND METHODS: This retrospective study included consecutive patients who underwent MRI-derived extracellular volume fraction (MRI ECV) analysis between March 2017 and July 2021 because of known or suspected heart failure or cardiomyopathy. Pre- and postcontrast T1 maps were generated using the modified Look-Locker inversion recovery sequence. Diagnostic performances of MRI ECV and myocardium-to-lumen R1 ratio on postcontrast T1 maps (a simplified index not requiring a native T1 map and hematocrit level data) for detecting cardiac amyloidosis were evaluated using the area under the receiver operating characteristic curve (AUC), sensitivity, and specificity. RESULTS: Of 352 patients (mean age, 63 years ± 16 [SD]; 235 men), 136 had cardiac amyloidosis. MRI ECV showed 89.0% (121 of 136; 95% CI: 82%, 94%) sensitivity and 98.6% (213 of 216; 95% CI: 96%, 100%) specificity for helping detect cardiac amyloidosis (cutoff value of 40% [AUC, 0.99 {95% CI: 0.97, 1.00}; P < .001]). Postcontrast myocardium-to-lumen R1 ratio showed 92.6% (126 of 136; 95% CI: 89%, 96%) sensitivity and 93.1% (201 of 216; 95% CI: 89%, 96%) specificity (cutoff value of 0.84 [AUC, 0.98 {95% CI: 0.95, 0.99}; P < .001]). There was no evidence of a difference in AUCs for each parameter (P = .10). CONCLUSION: Postcontrast myocardium-to-lumen R1 ratio showed excellent diagnostic performance comparable to that of MRI ECV in the detection of cardiac amyloidosis. Keywords: MR Imaging, Cardiac, Heart, Cardiomyopathies Supplemental material is available for this article. © RSNA, 2023

Supplementary Table 1 listed the genes upregulated and downregulated after treatment with JQKD82 in MM1S cells for 48 h

Supplementary Figure S1 shows that higher KDM5A expression is associated with poor prognosis in MM.

The bone marrow (BM) microenvironment actively promotes multiple myeloma pathogenesis, and therapies targeting both cancer cells and the niche are highly effective. We were interested in identifying novel signaling pathways supporting multiple myeloma–BM cross-talk. Mutations in the transmembrane receptor Roundabout 1 (ROBO1) were recently identified in patients with multiple myeloma; however, their functional consequences are uncertain. Through protein structure–function studies, we discovered that ROBO1 is necessary for multiple myeloma adhesion to BM stromal and endothelial cells and that ROBO1 knockout (KO) compromises BM homing and engraftment in a disseminated mouse model. ROBO1 KO significantly decreases multiple myeloma proliferation in vitro and intra- and extramedullary tumor growth in vivo. Mechanistically, the ROBO1 C-terminus is cleaved in a ligand-independent fashion and is sufficient to promote multiple myeloma proliferation. Vice versa, mutants lacking the cytoplasmic domain, including the human-derived G674* truncation, act dominantly negative. Interactomic and RNA-sequencing studies suggest that ROBO1 may be involved in RNA processing, supporting further studies.Significance:ROBO1 is highly expressed in t(4;14) multiple myeloma and supports homing and dissemination to the BM niche. ROBO1 knockout causes reduced tumor growth in intramedullary and extramedullary myeloma animal models, while the ROBO1 C-terminus is cleaved in multiple fragments and it is necessary and sufficient to sustain myeloma proliferation.

Lysine demethylase 5A (KDM5A) is a negative regulator of histone H3 lysine 4 trimethy­lation (H3K4me3), a histone mark associated with activate gene transcription. We identify that KDM5A interacts with the P-TEFb complex and cooperates with MYC to control MYC-targeted genes in multiple myeloma cells. We develop a cell-permeable and selective KDM5 inhibitor, JQKD82, that increases H3K4me3 but paradoxically inhibits downstream MYC-driven transcriptional output in vitro and in vivo. Using genetic ablation together with our inhibitor, we establish that KDM5A supports MYC target gene transcription independent of MYC itself by supporting TFIIH (CDK7)- and P-TEFb (CDK9)–mediated phosphorylation of RNAPII. These data identify KDM5A as a unique vulnerability in multiple myeloma functioning through regulation of MYC target gene transcription and establish JQKD82 as a tool compound to block KDM5A function as a potential therapeutic strategy for multiple myeloma.Significance:We delineate the function of KDM5A in activating the MYC-driven transcriptional landscape. We develop a cell-permeable KDM5 inhibitor to define the activating role of KDM5A on MYC target gene expression and implicate the therapeutic potential of this compound in mouse models and multiple myeloma patient samples.See related video from the AACR Annual Meeting 2021: https://vimeo.com/554896826

Supplementary Figure 1 showing ROBO1 expression in primary MM cells versus normal donor bone marrow plasma cells via gene expression profiling and immunohistochemistry. Supplementary Figure 2 showing distribution of ROBO1 expression in the CoMMpass database; ROBO1 expression in CoMMpass database according to cytogenetics; ROBO1 expression in IFM170 database according to cytogenetics; ROBO1 expression in t(4;14) cell lines WT or KO for MMSET. Supplementary Figure 3 showing ROBO1 protein down regulation after ROBO1 knock down via shRNA. Supplementary Figure 4 showing effects of shRNA4- and shRNA-5 mediated ROBO1 KD on cell viability across a panel of MM cell lines with western confirming proper protein down regulation. Supplementary Figure 5 showing successful ROBO1 KO across several KMS11 monoclones, but not H929 monoclones. Supplementary Figure 6 showing expression of ROBO1 FL construct in polyclonally and monoclonally-transduced OPM2 cells. Supplementary Figure 7 showing expression of FL ROBO1 addback in distinct KMS11 ROBO1 KO monoclones. Supplementary Figure 8 showing radiographic images of WT versus KO ROBO1 mu-SCID mice. Supplementary Figure 9 showing adhesion defect in ROBO1 KO KMS11 cells that is fully rescued by FL ROBO1 addback. Supplementary Figure 10 showing Kaplan-Meier survival curve of disseminated mouse model injected with ROBO1 KO versus FL OPM2 cells. Supplementary Figure 11 showing cleaved cytosolic ROBO1 fragments in 293T cells transduced with FL ROBO1 tagged with C-LAP tag and in WT MM.1S cells. Supplementary Figure 12 showing interacting partners of ROBO1 cytosolic domain as deconvoluted via STRING database. Supplementary Figure 13 showing differentially expressed genes in ROBO1 WT versus KO plasmacytoma represented via Volcano plot. Supplementary Figure 14 showing gene set enrichment analysis of differentially expressed genes in ROBO1 WT versus KO plasmacytoma. Supplementary Figure 15 showing schema of patient-derived ROBO1 mutation and expression of G674 truncation in WT and KO ROBO1 OPM2 cells. Supplementary Table 1 showing clinical annotation of newly diagnosed MM parents used in Supplementary figure 1.

Supplementary Methods

Supplementary Methods, compound synthesis, Supplementary Materials and Supplementary References

Pyruvate dehydrogenase kinase 1 (PDK1) is a Ser/Thr kinase that inactivates mitochondrial pyruvate dehydrogenase (PDH), leading to switch of glucose metabolism from mitochondrial oxidation to aerobic glycolysis. We previously reported that PDK1 inhibition is a potent therapeutic strategy in multiple myeloma (MM). However, availability of PDK1 inhibitors, which are effective at low concentrations, are limited at present, making PDK1 inhibition difficult to apply in the clinic. In the present study, we examined the efficacy and mechanism of action of JX06, a novel PDK1 inhibitor, against MM cells. We confirmed that PDK1 is highly expressed in normal plasma cells and MM cells using publicly available gene expression datasets. JX06 suppressed cell growth and induced apoptosis against MM cells from approximately 0.5 μM JX06 treatment reduced PDH phosphorylation, suggesting that JX06 is indeed inhibiting PDK1. Intracellular metabolite analysis revealed that JX06 treatment reduced metabolites associated with glucose metabolism of MM cells. Additionally, JX06 in combination with a well-known proteasome inhibitor, bortezomib, significantly increased MM cell death, which raises the possibility of combination use of JX06 with proteasome inhibitors in the clinic. These findings demonstrate that PDK1 can be potentially targeted by JX06 in MM through glycolysis inhibition, leading to a novel therapeutic strategy in MM.

5TGM1 cells co-localized with platelets in femur of syngeneic murine model.

Purpose: Tumor cell–platelet interactions contribute to tumor progression and metastasis in solid tumors. However, the role of platelets in hematological malignancies is not clear. We investigated the association of platelet activation status with clinical stages in multiple myeloma (MM) patients and explored the role of platelets in MM progression.Experimental Design: Platelets were obtained from healthy donors and MM patients. We examined platelet activation status in MM patients by flow cytometry and transmission electron microscopy. We also observed the enriched pathways that are involved with platelet activation in RNA sequencing of platelets. MM cell lines were used to assess the effect of platelets on MM cell proliferation in vitro and their engraftment in vivo. RNA sequencing of MM cell lines was performed to explore molecular mechanisms underlying MM cell–platelet interaction and a CRISPR/Cas9 knockout approach was used for validation.Results: Platelets from MM patients were highly activated with disease progression. RNA sequencing of platelets revealed that genes involved in platelets were enriched in patients with smoldering MM (SMM) or MM. Platelets promoted MM cell proliferation in vitro and contributed to tumor engraftment in bone marrow in vivo. RNA sequencing revealed that IL-1β was upregulated in MM cell lines co-cultured with platelets, whereas IL-1β knockout in MM cell lines abrogated the effects of platelets on MM cell proliferation and engraftment in vivo.Conclusions: Platelets from MM patients were highly activated with disease progression. IL-1β is critical to platelet-mediated MM progression and might be a potential target for MM treatment. Clin Cancer Res; 24(10); 2430–9. ©2018 AACR.

Clinical information of patients with MGUS, SMM, or MM.

Recent investigations have improved our understanding of the molecular aberrations supporting Waldenström macroglobulinemia (WM) biology; however, whether the immune microenvironment contributes to WM pathogenesis remains unanswered. First, we showed how a transgenic murine model of human-like lymphoplasmacytic lymphoma/WM exhibits an increased number of regulatory T cells (Tregs) relative to control mice. These findings were translated into the WM clinical setting, in which the transcriptomic profiling of Tregs derived from patients with WM unveiled a peculiar WM-devoted messenger RNA signature, with significant enrichment for genes related to nuclear factor κB–mediated tumor necrosis factor α signaling, MAPK, and PI3K/AKT, which was paralleled by a different Treg functional phenotype. We demonstrated significantly higher Treg induction, expansion, and proliferation triggered by WM cells, compared with their normal cellular counterpart; with a more profound effect within the context of CXCR4C1013G-mutated WM cells. By investigating the B-cell–to–T-cell cross talk at single-cell level, we identified the CD40/CD40-ligand as a potentially relevant axis that supports WM cell–Tregs interaction. Our findings demonstrate the existence of a Treg-mediated immunosuppressive phenotype in WM, which can be therapeutically reversed by blocking the CD40L/CD40 axis to inhibit WM cell growth.

Background Large studies on the diagnostic performance of CT-derived myocardial extracellular volume fraction (ECV) for detecting cardiac amyloidosis are lacking. A simple and practical index as a surrogate for CT ECV would be clinically useful. Purpose To compare the diagnostic performances between CT-derived myocardial ECV and myocardium-to-lumen signal ratio for the detection of cardiac amyloidosis in a large patient sample. Materials and Methods This retrospective study included patients who underwent CT ECV analysis because of suspected heart failure or cardiomyopathy between January 2018 and July 2021. CT ECV was quantified using routine pre-transcatheter aortic valve replacement planning cardiac CT, pre-atrial fibrillation ablation planning cardiac CT, or coronary CT angiography with the addition of unenhanced and delayed phase cardiac CT scans. The diagnostic performances of CT ECV and myocardium-to-lumen signal ratio in delayed phase cardiac CT (a simplified index not requiring unenhanced CT and hematocrit) for detecting cardiac amyloidosis were evaluated using the area under the receiver operating characteristic curve (AUC), sensitivity, and specificity. Results Of 552 patients (mean age, 69 years ± 14 [SD]; 295 men), 41 had cardiac amyloidosis. The sensitivity of CT ECV for amyloidosis was 90% (37 of 41 patients [95% CI: 77, 97]), with a specificity of 92% (472 of 511 patients [95% CI: 90, 95]) and optimal ECV cutoff value of 37% (AUC, 0.97 [95% CI: 0.96, 0.99]). The sensitivity of myocardium-to-lumen signal ratio was 88% (36 of 41 patients [95% CI: 74, 96]), with a specificity of 92% (469 of 511 patients [95% CI: 89, 94]) and optimal myocardium-to-lumen signal ratio cutoff value of 0.87 (AUC, 0.96 [95% CI: 0.94, 0.97]

Recent advances in single-cell proteomics highlight the promise of sensitive analyses in limited cell populations. However, technical challenges remain for sample recovery, throughput, and versatility. Here, we first report a water droplet-in-oil digestion (WinO) method based on carboxyl-coated beads and phase transfer surfactants for proteomic analysis using limited sample amounts. This method was developed to minimize the contact area between the sample solution and the container to reduce the loss of proteins and peptides by adsorption. This method increased protein and peptide recovery 10-fold. The proteome profiles obtained from 100 cells using the WinO method highly correlated with those from 10,000 cells using the in-solution digestion method. We successfully applied the WinO method to single-cell proteomics and quantified 462 proteins. Using the WinO method, samples can be easily prepared in a multi-well plate, making it a widely applicable and suitable method for single-cell proteomics.

Multiple myeloma (MM) is still extremely difficult to cure, and new therapeutic drugs are needed. We recently found that integrin β7 is constitutively activated in MM cells, and chimeric antigen receptor (CAR) T cells targeting activated integrin β7 have a significant anti-MM effect. In this study, we performed flow cytometry analysis of the expression of activated integrin β7 in bone marrow cells from 137 symptomatic MM patients. In 60/137 (44%) MM patients, activated integrin β7 was detected in most MM cells (> 80% of MM cells were in the positive gate). Activated integrin β7 was highly expressed in MM cells even in heavily treated patients. It also showed high expression in many CD38lo/−CD138−CD19+B cells, which reportedly include clonotypic B cells, in the bone marrow of MM patients. Taken together, these results suggest that CAR T-cell therapy targeting activated integrin β7 has the potential to benefit many patients with relapsed or refractory MM.

e20015 Background: The Phase 3 IKEMA study (NCT03275285) demonstrated that isatuximab (Isa) plus carfilzomib and dexamethasone (Kd) significantly improved progression-free survival (PFS) compared with Kd in patients (pts) with relapsed multiple myeloma (RMM) (hazard ratio [HR] 0.53; 99% confidence interval [CI] 0.32–0.89; P= 0.0007). We evaluated the efficacy and safety of Isa-Kd in the East Asian patients (19 Japanese, 27 Korean). Methods: RMM pts who received 1-3 prior lines of therapy were stratified to receive Isa-Kd or Kd. Isa-Kd arm received Isa (10 mg/kg intravenously) weekly for 4 weeks, then every 2 weeks. Both arms received K (20 mg/m2 days 1-2, 56 mg/m2 thereafter) twice-weekly for 3 of 4 weeks, and d (20 mg) twice-weekly. Treatment continued until disease progression or unacceptable adverse events (AE). The primary endpoint was prolongation of PFS. Key secondary endpoints included; very good partial response or better (≥VGPR), complete response (CR) rate and minimal residual disease negativity (MRD–) rate. Results: East Asian pts (25 Isa-Kd, 21 Kd) were randomized. Pt characteristics were similar in the East Asian subgroup compared with the intent to treat (ITT) population (N = 302). Median age (Isa-Kd 64.0 [range 45–83] years vs Kd 60.0 [range 33–73] years); median prior lines Isa-Kd 2.0 (range 1–3) vs Kd 1.0 (range 1–3); refractory to lenalidomide 16.0% Isa-Kd vs 47.6% Kd; refractory to PI 20.0% Isa-Kd vs 33.3% Kd; high-risk cytogenetics 48.0% Isa-Kd vs 42.9% Kd. After a median follow-up of 20.7 months, the addition of Isa to Kd improved ≥VGPR, CR and MRD– rates (Table). The HR 0.64 (95%CI: 0.231-1.764) for disease progression or death favored Isa-Kd. Grade ≥3 AEs were observed in 79.2% Isa-Kd vs 55.0% Kd pts, serious TEAEs in 45.8% Isa-Kd vs 50.0% Kd; TEAEs leading to treatment discontinuation were lower in the Isa-Kd group (4.2% Isa-Kd vs 10.0% Kd). Overall, 64.0% Isa-Kd vs 42.9% Kd pts were still receiving treatment. Conclusions: Efficacy and safety results of Isa-Kd in East Asian pts are consistent with the results of the overall IKEMA population, in which significantly better efficacy (PFS, CR, ≥VGPR and MRD– rate) was reported in favor of Isa-Kd without an increase in the number of patients with serious TEAEs or discontinuations. Isa-Kd is a potential treatment option for East Asian pts with RMM. Clinical trial information: NCT03275285. [Table: see text]

Recent advances in single-cell proteomics highlight the promise of sensitive analyses in limited cell populations. However, technical challenges remain for sample recovery, throughput, and versatility. Here, we first report a water droplet-in-oil digestion (WinO) method based on carboxyl-coated beads and phase transfer surfactants for proteomic analysis using limited sample amounts. This method was developed to minimize the contact area between the sample solution and the container to reduce the loss of proteins and peptides by adsorption. This method increased protein and peptide recovery 10-fold as well as the number of quantified transmembrane proteins compared to an in-solution digestion (ISD) method. The proteome profiles obtained from 100 cells using the WinO method highly correlated with those from 10000 cells using the ISD method. We successfully applied the WinO method to single-cell proteomics and quantified 462 proteins. Using the WinO method, samples can be easily prepared in a multi-well plate, making it a widely applicable and suitable method for single-cell proteomics.

(1) Background: multiple myeloma patients have benefited from bortezomib therapy, though it has often been discontinued owing to diarrhea. The objective of this study was to verify serum bortezomib concentration in the emergence of diarrhea. (2) Methods: this prospective, observational case-control, and monocentric study was performed with an approval by the Ethics Committee of Kumamoto University Hospital in 2015 (No. 1121) from February 2015 to April 2017. (3) Results: twenty-four patients with bortezomib therapy were recruited, eight patients (33.3%) developed diarrhea at day 3 as median. Median measured trough bortezomib concentration at 24 h after first or second dose for patients with or without diarrhea was 0.87 or 0.48 ng/mL, respectively (p = 0.04, Wilcoxon signed rank test). Receiver operation characteristic (ROC) analysis produced the cut-off concentration of 0.857 ng/mL (area under the ROC curve of 0.797, sensitivity of 0.625, specificity of 0.875). The survival curves between patients with and without diarrhea were similar (p = 0.667), those between patients with higher and lower concentration than median value (0.61 ng/mL) were also similar (p = 0.940). (4) Conclusions: this study indicated the possible involvement of serum bortezomib concentration in the emergence of diarrhea in bortezomib therapy in patients with multiple myeloma.

Lysine demethylase 5A (KDM5A) is a negative regulator of histone H3 lysine 4 trimethy­lation (H3K4me3), a histone mark associated with activate gene transcription. We identify that KDM5A interacts with the P-TEFb complex and cooperates with MYC to control MYC-targeted genes in multiple myeloma cells. We develop a cell-permeable and selective KDM5 inhibitor, JQKD82, that increases H3K4me3 but paradoxically inhibits downstream MYC-driven transcriptional output in vitro and in vivo. Using genetic ablation together with our inhibitor, we establish that KDM5A supports MYC target gene transcription independent of MYC itself by supporting TFIIH (CDK7)- and P-TEFb (CDK9)–mediated phosphorylation of RNAPII. These data identify KDM5A as a unique vulnerability in multiple myeloma functioning through regulation of MYC target gene transcription and establish JQKD82 as a tool compound to block KDM5A function as a potential therapeutic strategy for multiple myeloma. Significance: We delineate the function of KDM5A in activating the MYC-driven transcriptional landscape. We develop a cell-permeable KDM5 inhibitor to define the activating role of KDM5A on MYC target gene expression and implicate the therapeutic potential of this compound in mouse models and multiple myeloma patient samples. See related video from the AACR Annual Meeting 2021: https://vimeo.com/554896826

The bone marrow (BM) microenvironment actively promotes multiple myeloma pathogenesis, and therapies targeting both cancer cells and the niche are highly effective. We were interested in identifying novel signaling pathways supporting multiple myeloma–BM cross-talk. Mutations in the transmembrane receptor Roundabout 1 (ROBO1) were recently identified in patients with multiple myeloma; however, their functional consequences are uncertain. Through protein structure–function studies, we discovered that ROBO1 is necessary for multiple myeloma adhesion to BM stromal and endothelial cells and that ROBO1 knockout (KO) compromises BM homing and engraftment in a disseminated mouse model. ROBO1 KO significantly decreases multiple myeloma proliferation in vitro and intra- and extramedullary tumor growth in vivo. Mechanistically, the ROBO1 C-terminus is cleaved in a ligand-independent fashion and is sufficient to promote multiple myeloma proliferation. Vice versa, mutants lacking the cytoplasmic domain, including the human-derived G674* truncation, act dominantly negative. Interactomic and RNA-sequencing studies suggest that ROBO1 may be involved in RNA processing, supporting further studies. Significance: ROBO1 is highly expressed in t(4;14) multiple myeloma and supports homing and dissemination to the BM niche. ROBO1 knockout causes reduced tumor growth in intramedullary and extramedullary myeloma animal models, while the ROBO1 C-terminus is cleaved in multiple fragments and it is necessary and sufficient to sustain myeloma proliferation.

Regulatory T cells (Tregs) are a subset of CD4+ T lymphocytes that suppress the functions of antigen-presenting cells and effector T cells, characterized by the expression of transcription factor forkhead box P3 (FOXP3). Recent studies have reported an increase in the number of Tregs in the bone marrow (BM) of multiple myeloma (MM) patients. However, the role and mechanisms of Treg accumulation in the BM of MM patients remain debatable. Here, we present our data demonstrating the significance of Tregs in the context of MM disease progression. Using the transplantable MM mouse model, we observed a significant increase in Tregs in the BM of MM-injected mice from the early disease stage. We observed extended survival in MM-injected mice with Treg depletion than in mice without Treg depletion, demonstrating direct in vivo evidence that Tregs enhance disease progression in MM. It is noteworthy that type 1 interferon (IFN) signaling is activated in MM-associated Tregs. By using type 1 IFN receptor blocking antibody treatment and type 1 IFN receptor knockout Tregs, we demonstrated a significant decrease in MM-associated Treg proliferation, which was associated with longer survival in MM-injected mice. Thus, we have demonstrated that Tregs play a significant role in MM progression; the function and homeostasis of Tregs are regulated by type 1 IFN secreted in the BM microenvironment.

Clonal evolution drives tumor progression, dissemination, and relapse in multiple myeloma (MM), with most patients dying of relapsed disease. This multistage process requires tumor cells to enter the circulation, extravasate, and colonize distant bone marrow (BM) sites. Here, we developed a fluorescent or DNA-barcode clone-tracking system on MM PrEDiCT (progression through evolution and dissemination of clonal tumor cells) xenograft mouse model to study clonal behavior within the BM microenvironment. We showed that only the few clones that successfully adapt to the BM microenvironment can enter the circulation and colonize distant BM sites. RNA sequencing of primary and distant-site MM tumor cells revealed a progression signature sequentially activated along human MM progression and significantly associated with overall survival when evaluated against patient data sets. A total of 28 genes were then computationally predicted to be master regulators (MRs) of MM progression. HMGA1 and PA2G4 were validated in vivo using CRISPR-Cas9 in the PrEDiCT model and were shown to be significantly depleted in distant BM sites, indicating their role in MM progression and dissemination. Loss of HMGA1 and PA2G4 also compromised the proliferation, migration, and adhesion abilities of MM cells in vitro. Overall, our model successfully recapitulates key characteristics of human MM disease progression and identified potential new therapeutic targets for MM.

We report the case of a 79-year-old man with chronic lymphocytic leukemia (CLL) with IgM-kappa type monoclonal gammopathy according to immunophenotypes and a negative result for MYD88 L265P mutation of leukemic cells. Abnormal lymphocytes and IgM increased under observation, and he experienced paresthesia. The diagnosis of IgM-type M protein associated peripheral neuropathy was confirmed by nerve conduction test, and negativity of myelin-associated glycoprotein and glycolipid antibodies. He was placed on intravenous immunoglobulin (IVIg) in combination with ibrutinib. His symptoms dramatically subsided and did not recur. Treatment with IVIg and ibrutinib may be useful for the rare complication of peripheral neuropathy with CLL.

Summary Background Isatuximab is an anti-CD38 monoclonal antibody approved in combination with pomalidomide–dexamethasone and carfilzomib–dexamethasone for relapsed or refractory multiple myeloma. This phase 3, open-label study compared the efficacy of isatuximab plus carfilzomib–dexamethasone versus carfilzomib–dexamethasone in patients with relapsed multiple myeloma. Methods This was a prospective, randomised, open-label, parallel-group, phase 3 study done at 69 study centres in 16 countries across North America, South America, Europe, and the Asia-Pacific region. Patients with relapsed or refractory multiple myeloma aged at least 18 years who had received one to three previous lines of therapy and had measurable serum or urine M-protein were eligible. Patients were randomly assigned (3:2) to isatuximab plus carfilzomib–dexamethasone (isatuximab group) or carfilzomib–dexamethasone (control group). Patients in the isatuximab group received isatuximab 10 mg/kg intravenously weekly for the first 4 weeks, then every 2 weeks. Both groups received the approved schedule of intravenous carfilzomib and oral or intravenous dexamethasone. Treatment continued until progression or unacceptable toxicity. The primary endpoint was progression-free survival and was assessed in the intention-to-treat population according to assigned treatment. Safety was assessed in all patients who received at least one dose according to treatment received. The study is registered at ClinicalTrials.gov, NCT03275285. Findings Between Nov 15, 2017, and March 21, 2019, 302 patients with a median of two previous lines of therapy were enrolled. 179 were randomly assigned to the isatuximab group and 123 to the control group. Median progression-free survival was not reached in the isatuximab group compared with 19·15 months (95% CI 15·77–not reached) in the control group, with a hazard ratio of 0·53 (99% CI 0·32–0·89; one-sided p=0·0007). Treatment-emergent adverse events (TEAEs) of grade 3 or worse occurred in 136 (77%) of 177 patients in the isatuximab group versus 82 (67%) of 122 in the control group, serious TEAEs occurred in 105 (59%) versus 70 (57%) patients, and TEAEs led to discontinuation in 15 (8%) versus 17 (14%) patients. Fatal TEAEs during study treatment occurred in six (3%) versus four (3%) patients. Interpretation The addition of isatuximab to carfilzomib–dexamethasone significantly improves progression-free survival and depth of response in patients with relapsed multiple myeloma, representing a new standard of care for this patient population. Funding Sanofi. Video Abstract Video abstractYouTube link: https://youtu.be/5kXtQQlzRh4

Myeloma bone disease is a devastating complication of multiple myeloma (MM) and is caused by dysregulation of bone remodeling processes in the bone marrow microenvironment. Previous studies showed that microRNA-138 (miR-138) is a negative regulator of osteogenic differentiation of mesenchymal stromal cells (MSCs) and that inhibiting its function enhances bone formation in vitro. In this study, we explored the role of miR-138 in myeloma bone disease and evaluated the potential of systemically delivered locked nucleic acid (LNA)-modified anti-miR-138 oligonucleotides in suppressing myeloma bone disease. We showed that expression of miR-138 was significantly increased in MSCs from MM patients (MM-MSCs) and myeloma cells compared to those from healthy subjects. Furthermore, inhibition of miR-138 resulted in enhanced osteogenic differentiation of MM-MSCs in vitro and increased the number of endosteal osteoblastic lineage cells (OBCs) and bone formation rate in mouse models of myeloma bone disease. RNA sequencing of the OBCs identified TRPS1 and SULF2 as potential miR-138 targets that were de-repressed in anti-miR-138-treated mice. In summary, these data indicate that inhibition of miR-138 enhances bone formation in MM and that pharmacological inhibition of miR-138 could represent a new therapeutic strategy for treatment of myeloma bone disease.

Purpose: Tumor cell–platelet interactions contribute to tumor progression and metastasis in solid tumors. However, the role of platelets in hematological malignancies is not clear. We investigated the association of platelet activation status with clinical stages in multiple myeloma (MM) patients and explored the role of platelets in MM progression. Experimental Design: Platelets were obtained from healthy donors and MM patients. We examined platelet activation status in MM patients by flow cytometry and transmission electron microscopy. We also observed the enriched pathways that are involved with platelet activation in RNA sequencing of platelets. MM cell lines were used to assess the effect of platelets on MM cell proliferation in vitro and their engraftment in vivo. RNA sequencing of MM cell lines was performed to explore molecular mechanisms underlying MM cell–platelet interaction and a CRISPR/Cas9 knockout approach was used for validation. Results: Platelets from MM patients were highly activated with disease progression. RNA sequencing of platelets revealed that genes involved in platelets were enriched in patients with smoldering MM (SMM) or MM. Platelets promoted MM cell proliferation in vitro and contributed to tumor engraftment in bone marrow in vivo. RNA sequencing revealed that IL-1β was upregulated in MM cell lines co-cultured with platelets, whereas IL-1β knockout in MM cell lines abrogated the effects of platelets on MM cell proliferation and engraftment in vivo. Conclusions: Platelets from MM patients were highly activated with disease progression. IL-1β is critical to platelet-mediated MM progression and might be a potential target for MM treatment. Clin Cancer Res; 24(10); 2430–9. ©2018 AACR.

Hypoxia serves a crucial role in the development of drug resistance in various cancer cells. Therefore, many attempts targeting hypoxia are underway to overcome the drug resistance mediated by hypoxia. This strategy is useful for multiple myeloma (MM) cells, as MM cells reside within the bone marrow, where oxygen concentrations are relatively low. A natural compound library was screened to identify compounds exerting cytotoxicity in MM cells under hypoxic conditions. Bufalin exhibited marked cytotoxicity to MM cells under normoxic and hypoxic conditions. No significant toxicity was observed in lymphocytes obtained from healthy donors. Under normoxic conditions, bufalin induced a DNA double strand break (DSB) response, ROS induction and apoptosis within 24 with a rapid response compared with melphalan. Interestingly, the bufalin-induced DSB response was not impaired by low oxygen concentrations while the DSB response by melphalan was reduced. Furthermore, treatment with bufalin abolished HIF-1α expression under hypoxia, suggesting that bufalin exerts cytotoxicity under hypoxia by regulating HIF-1α. These results indicate that bufalin induces apoptosis in MM cells through DSB under hypoxic conditions by inhibiting HIF-1α, suggesting that bufalin could be useful for eradication of drug-resistant MM cells in the hypoxic microenvironment.

Introduction. Anti-CD38 monoclonal antibodies, such as daratumumab and isatuximab, which exerts therapeutic effect against multiple myeloma (MM) cells through direct cell damage, antibody dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC), has shown its high efficacy in clinical practice. However, the role of CD38 in MM cell biology is still unclear. CD38 is known as a major nicotinamide adenine dinucleotide (NAD +) glycohydrase (NADase) in mammalian tissues, which regulate cellular levels of NAD +. In the present study, we compared metabolic and proteomic profile between CD38 positive and negative MM cell lines to analyze the biological significance of CD38 in MM cells. Additionally, we performed CD38 enzyme activity inhibition on MM cells using 78c, a NADase enzyme inhibitor of CD38, in order to study the role of CD38 NADase activity in MM cell survival. Materials and methods. MM cell lines harboring CD38 positive and negative fractions (KMS-12BM, KMS-11) were sorted according to CD38 expression. Intracellular NAD+ and NADH concentrations between CD38 positive and negative cells were analyzed using NAD/NADH Assay kit. CD38 positive and negative MM cells were subjected to metabolome and proteome analysis using Shimadzu TQ8050 GC-MS/MS and TripleTOF 5600 respectively. Metabolites and proteins significantly enriched in CD38 negative MM cells were analyzed using MetaboAnalyst and Metascape. Cell cycle status between CD38 positive and negative cells were determined by flow cytometry after staining by BRDU and 7AAD. CD38 positive MM cell lines (NCI-H929 and KMS-12PE) and patient derived bone marrow cells were treated with 78c, a CD38 NADase inhibitor, in vitro. MM cell viability were determined by flow cytometry post Annexin V and PI staining. Differences in metabolites between 78c treated and control MM cell lines were also analyzed using Shimadzu TQ8050 GC-MS/MS. Results. Higher NAD+ and NAD+/NADH ratio was observed in CD38 negative fraction of MM cell lines compared to their CD38 positive counterparts, demonstrating that cell surface CD38 expression influences intracellular NAD+ concentration. Both metabolome and proteome analysis revealed that CD38 negative cells tend to have higher glycolytic activity compared to CD38 positive cells. Significant suppression of cell cycle, accompanying G0/G1 phase arrest, was observed in CD38 negative MM cells, indicating that metabolic shift in CD38 negative MM cells may lead to change in cell proliferation. Marked increase of NAD+/NADH ratio was observed in 78c treated MM cell lines compared to control, proving that CD38 NADase inhibiton indeed affects intracellular NAD+ concentration in MM cells. 78c was capable of inducing cell death in MM cell lines and patient derived MM cells, accompanying cell cycle arrest. Metabolites significantly upregulated in 78c treated MM cells compared to control were associated with glycolysis, demonstrating that CD38 NADase activity has a significant effect on MM cell metabolism. Conclusions. CD38 is the major NADase in mammalian tissues, involved in catabolism of NAD +. Although CD38 is highly expressed in normal plasma cells and MM cells, its role in MM cell biology has not been studied in detail. By comparing CD38 positive and negative cells and using CD38 NADase inhibitor, we showed for the first time that CD38 on MM cells decrease intracellular NAD+, reduces intracellular glycolysis and as a result, has an influence on cell cycle. The present study sheds light on the significance of CD38 enzyme activity in MM cell biology and may also contribute to understanding the mechanism of resistance to CD38 targeted therapy. Disclosures Kawano: Janssen Pharmaceuticals: Honoraria; Ono pharmaceutical: Honoraria; Sanofi: Honoraria; Bristol Myers Squibb: Honoraria; Takeda Pharmaceuticals: Honoraria.

The tumor suppressors B-lymphocyte-induced maturation protein-1 (BLIMP-1) and p53 play a crucial role in B-cell lymphomas, and their inactivation contributes to the pathogenesis of a wide spectrum of lymphoid malignancies, including diffuse large B-cell lymphomas (DLBCLs). Patients with activated B-cell-like (ABC) DLBCL may present with loss of BLIMP-1, c-Myc over-expression, decreased p53, and poor prognosis. Nevertheless, there is a lack of in vivo models recapitulating the biology of high-grade ABC DLBCL. We therefore aimed to develop an in vivo model aiming to recapitulate the phenotype observed in this cohort of patients. A Cre-Lox approach was used to achieve inactivation of both p53 and BLIMP-1 in murine B-cells. Contextual ablation of BLIMP-1 and p53 led to development of IgM-positive B-cell lymphoma with an aggressive phenotype, supported by c-Myc up-regulation, and accumulation of somatic mutations, as demonstrated by whole exome sequencing. Sensitivity of B-tumor cells to BTK inhibition was demonstrated. This model mirrors what reported in patients with ABC DLBLC, and therefore represents a novel model for studying the biology of ABC-DLBCL harboring the dual loss of BLIMP-1/p53 and c-Myc over-expression.

Late gadolinium enhancement imaging by cardiac magnetic resonance imaging (CMR) is the most reliable method for identifying cardiac involvement in patients with amyloidosis, and myocardial T1 mapping is a novel CMR technique that enables the noninvasive detection and quantification of myocardial amyloid burden. Although, base-to-apex gradient patterns of impairment in patients with cardiac amyloidosis have been reported on myocardial strain analysis using echocardiography, we could not find any other reports to demonstrate that myocardial T1 mapping on CMR can clearly identify a base-to-apex gradient pattern of cardiac impairment in a patient with cardiac amyloidosis. Keywords: Cardiac amyloidosis, Myocardial T1 mapping, Myocardial extracellular volume, Base-to-apex gradient

Coagulation factor XIII is a fibrin-stabilizing factor that leads to the crosslinking of fibrin when activated by thrombin. Acquired factor XIII inhibitor is caused when antibodies are generated against factor XIII, reducing its activity. Here we report a case of acquired factor XIII inhibitor. Although prednisolone was administered, factor XIII activity was not recovered. Interestingly, the activity normalized following the onset of multiple myeloma. The presence of inhibitors was evaluated in the patient's plasma by absorption tests and enzyme-linked immunosorbent assay. Immunoglobulin G inhibitors of factor XIII were present at admission, but later decreased with the onset of the IgA-λ-type myeloma. Thus, it is possible that the level of factor XIII inhibitors and polyclonal immunoglobulins could have been suppressed by the progression of myeloma, resulting in the normalization of factor XIII activity.

Multiple myeloma is a plasma cell malignancy evolving in the bone marrow and leading to end organ damage such as bone lesions, cytopenias, and kidney failure. This review delineates recent advances in the molecular mechanisms leading to tumor progression in multiple myeloma. Two different aspects enable tumor expansion: cell autonomous through genomic alterations in the tumor clone and noncell autonomous deregulations in the bone marrow tumor microenvironment. These alterations provide the framework for the continuous progression of multiple myeloma from early precursor conditions such as monoclonal gammopathy of undetermined significance and smoldering multiple myeloma to overt multiple myeloma.In this review, we discuss recent findings in the genomic alterations that occur in the tumor clone such as somatic genomic mutations, copy number variation and chromosomal translocation, and delineate noncell autonomous deregulations in which tumor cells take advantage of a permissive microenvironment to further proliferate. The latter compartment includes interaction with bone marrow stromal cells, osteoblasts, osteoclasts, and immune escape.Understanding the mechanisms that lead tumor progression from early stages to overt multiple myeloma could guide to more effective therapies and therefore prevent disease progression.

The role of endothelial progenitor cell (EPC)-mediated vasculogenesis in hematological malignancies is not well explored. Here, we showed that EPCs are mobilized from the bone marrow (BM) to the peripheral blood at early stages of multiple myeloma (MM); and recruited to MM cell-colonized BM niches. Using EPC-defective ID1+/- ID3-/- mice, we found that MM tumor progression is dependent on EPC trafficking. By performing RNA-sequencing studies, we confirmed that endothelial cells can enhance proliferation and favor cell-cycle progression only in MM clones that are smoldering-like and have dependency on endothelial cells for tumor growth. We further confirmed that angiogenic dependency occurs early and not late during tumor progression in MM. By using a VEGFR2 antibody with anti-vasculogenic activity, we demonstrated that early targeting of EPCs delays tumor progression, while using the same agent at late stages of tumor progression is ineffective. Thus, although there is significant angiogenesis in myeloma, the dependency of the tumor cells on EPCs and vasculogenesis may actually precede this step. Manipulating vasculogenesis at an early stage of disease may be examined in clinical trials in patients with smoldering MM, and other hematological malignancies with precursor conditions.

Citron Rho-interacting serine/threonine kinase (CIT) is a serine/threonine kinase that acts as a key component of the midbody and is essential for cytokinesis. CIT has been reported to be highly expressed in some tumor tissues and to play a role in cancer proliferation; however, the significance of CIT has not been investigated in multiple myeloma (MM). Here, we identified, by protein microarray and immunohistochemistry, that CIT is 1 of the upregulated proteins in the plasma cells of MM patients compared with healthy controls. Analysis of a gene expression profile data set showed that MM patients with high CIT gene expression had significantly worse overall survival compared with MM patients with low CIT gene expression. CIT silencing in MM cell lines induced cytokinesis failure and resulted in decreased MM cell proliferation in vitro and in vivo. TP53 expression was found to be an independent predictor of CIT dependency, with low-TP53 cell lines exhibiting a strong dependency on CIT. This study provides the rationale for CIT being a potential therapeutic target in MM in future trials.

The sialic glycoprotein, MUC1, is known to be involved in the pathogenesis of various types of cancers. KL-6 is one of the surface antigens of MUC1 and also a marker of interstitial pneumonitis. A fraction of patients with myeloma (3.9%) have elevated serum KL-6 levels without any evidence of interstitial pneumonitis and their myeloma cells have high MUC1 expression. We established a myeloma cell line designated EMM1 from a patient with multiple myeloma accompanied with elevated serum KL-6. EMM1 cells expressed high levels of MUC1 compared with other myeloma cell lines. Knockdown of MUC1 in EMM1 cells induced cell cycle arrest during S phase and apoptosis, suggesting that the MUC1 expression is involved in accelerated growth of EMM1 cells. RNA-seq analysis suggests that MUC1 expression activates k-ras and TNFα-induced NFκB pathways in EMM1 cells. We injected EMM1 cells subcutaneously into Rag2-/-Jak3-/- Balb/c mice to establish a mouse xenograft model. These mice had aggressive tumor growth that was accompanied by high serum KL-6 levels. In addition, MUC1 knockdown in EMM1 cells led to inhibited tumor growth. These findings demonstrate that MUC1 serves as a potential target for developing drugs for treatment of patients with KL-6+ myeloma, and EMM1 cells and EMM1-engrafted mice are useful tools for the development of such novel agents.

A 76-year-old woman presented to our hospital with leukocytosis and abnormal lymphocytes. M protein of the immunoglobulin G (IgG) type was detected using immunoelectrophoresis. A bone marrow biopsy revealed infiltration of small mature lymphocytes, lymphoplasmacytoid cells with Dutcher bodies, grape cells, and Russell bodies. The MYD88 L265P mutation was detected in the abnormal peripheral lymphocytes, and a diagnosis of lymphoplasmacytoid lymphoma was established. MYD88 L265P mutation analysis is useful for making a diagnosis of non-IgM lymphoplasmacytoid lymphoma because it enables the differentiation from other low-grade B-cell malignancies.

Despite significant advances in the treatment of multiple myeloma (MM), most patients succumb to disease progression. One of the major immunosuppressive mechanisms that is believed to play a role in myeloma progression is the expansion of regulatory T cells (Tregs). In this study, we demonstrate that myeloma cells drive Treg expansion and activation by secreting type 1 interferon (IFN). Blocking IFN α and β receptor 1 (IFNAR1) on Tregs significantly decreases both myeloma-associated Treg immunosuppressive function and myeloma progression. Using syngeneic transplantable murine myeloma models and bone marrow (BM) aspirates of MM patients, we found that Tregs were expanded and activated in the BM microenvironment at early stages of myeloma development. Selective depletion of Tregs led to a complete remission and prolonged survival in mice injected with myeloma cells. Further analysis of the interaction between myeloma cells and Tregs using gene sequencing and enrichment analysis uncovered a feedback loop, wherein myeloma-cell-secreted type 1 IFN induced proliferation and expansion of Tregs. By using IFNAR1-blocking antibody treatment and IFNAR1-knockout Tregs, we demonstrated a significant decrease in myeloma-associated Treg proliferation, which was associated with longer survival of myeloma-injected mice. Our results thus suggest that blocking type 1 IFN signaling represents a potential strategy to target immunosuppressive Treg function in MM.