Insights into the multistep transformation of MGUS to myeloma using microarray expression analysis

B-cell intrinsic RANK signaling cooperates with TCL1 to induce lineage-dependent B-cell transformation

B-cell malignancies, such as chronic lymphocytic leukemia (CLL) and multiple myeloma (MM), remain incurable, with MM particularly prone to relapse. Our study introduces a novel mouse model with active RANK signaling and the TCL1 oncogene, displaying both CLL and MM phenotypes. In younger mice, TCL1 and RANK expression expands CLL-like B1-lymphocytes, while MM originates from B2-cells, becoming predominant in later stages and leading to severe disease progression and mortality. The induced MM mimics human disease, exhibiting features like clonal plasma cell expansion, paraproteinemia, anemia, and kidney and bone failure, as well as critical immunosurveillance strategies that promote a tumor-supportive microenvironment. This research elucidates the differential impacts of RANK activation in B1- and B2-cells and underscores the distinct roles of single versus combined oncogenes in B-cell malignancies. We also demonstrate that human MM cells express RANK and that inhibiting RANK signaling can reduce MM progression in a xenotransplantation model. Our study provides a rationale for further investigating the effects of RANK signaling in B-cell transformation and the shaping of a tumor-promoting microenvironment.

MyeloDB: a multi-omics resource for multiple myeloma

Multiple myeloma (MM) is a common type of blood cancer affecting plasma cells originating from the lymphoid B-cell lineage. It accounts for about 10% of all hematological malignancies and can cause significant end-organ damage. The emergence of genomic technologies such as next-generation sequencing and gene expression analysis has opened new possibilities for early detection of multiple myeloma and identification of personalized treatment options. However, there remain significant challenges to overcome in MM research, including integrating multi-omics data, achieving a comprehensive understanding of the disease, and developing targeted therapies and biomarkers. The extensive data generated by these technologies presents another challenge for data analysis and interpretation. To bridge this gap, we have developed a multi-omics open-access database called MyeloDB. It includes gene expression profiling, high-throughput CRISPR-Cas9 screens, drug sensitivity resources profile, and biomarkers. MyeloDB contains 47 expression profiles, 3 methylation profiles comprising a total of 5630 patient samples and 25 biomarkers which were reported in previous studies. In addition to this, MyeloDB can provide significant insight of gene mutations in MM on drug sensitivity. Furthermore, users can download the datasets and conduct their own analyses. Utilizing this database, we have identified five novel genes, i.e., CBFB, MANF, MBNL1, SEPHS2, and UFM1 as potential drug targets for MM. We hope MyeloDB will serve as a comprehensive platform for researchers and foster novel discoveries in MM. MyeloDB Database URL: https://project.iith.ac.in/cgntlab/myelodb/ .

Single cell characterization of myeloma and its precursor conditions reveals transcriptional signatures of early tumorigenesis

Multiple myeloma is a plasma cell malignancy almost always preceded by precursor conditions, but low tumor burden of these early stages has hindered the study of their molecular programs through bulk sequencing technologies. Here, we generate and analyze single cell RNA-sequencing of plasma cells from 26 patients at varying disease stages and 9 healthy donors. In silico dissection and comparison of normal and transformed plasma cells from the same bone marrow biopsy enables discovery of patient-specific transcriptional changes. Using Non-Negative Matrix Factorization, we discover 15 gene expression signatures which represent transcriptional modules relevant to myeloma biology, and identify a signature that is uniformly lost in abnormal cells across disease stages. Finally, we demonstrate that tumors contain heterogeneous subpopulations expressing distinct transcriptional patterns. Our findings characterize transcriptomic alterations present at the earliest stages of myeloma, providing insight into the molecular underpinnings of disease initiation.

Looking into Endoplasmic Reticulum Stress: The Key to Drug-Resistance of Multiple Myeloma?

Multiple myeloma (MM) is the second most common hematologic malignancy, resulting from the clonal proliferation of malignant plasma cells within the bone marrow. Despite significant advances that have been made with novel drugs over the past two decades, MM patients often develop therapy resistance, especially to bortezomib, the first-in-class proteasome inhibitor that was approved for treatment of MM. As highly secretory monoclonal protein-producing cells, MM cells are characterized by uploaded endoplasmic reticulum stress (ERS), and rely heavily on the ERS response for survival. Great efforts have been made to illustrate how MM cells adapt to therapeutic stresses through modulating the ERS response. In this review, we summarize current knowledge on the mechanisms by which ERS response pathways influence MM cell fate and response to treatment. Moreover, based on promising results obtained in preclinical studies, we discuss the prospect of applying ERS modulators to overcome drug resistance in MM.

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

Although light-chain amyloidosis (AL) and multiple myeloma (MM) are characterized by tumor plasma cell (PC) expansion in bone marrow (BM), their clinical presentation differs. Previous attempts to identify unique pathogenic mechanisms behind such differences were unsuccessful, but there are no studies investigating the differentiation stage of tumor PCs in patients with AL and MM. We sought to define a transcriptional atlas of normal PC development (n=11) in secondary lymphoid organs (SLO), peripheral blood (PB) and BM for comparison with the transcriptional programs (TPs) of tumor PCs in AL (n=37), MM (n=46) and MGUS (n=6). Based on bulk and single-cell RNAseq, we observed thirteen TPs during transition of normal PCs throughout SLO, PB and BM; that CD39 outperforms CD19 to discriminate new-born from long-lived BM-PCs; that tumor PCs expressed the most advantageous TPs of normal PC differentiation; that AL shares greater similarity to SLO-PCs whereas MM is transcriptionally closer to PB-PCs and new-born BM-PCs; that AL and MM patients enriched in immature TPs had inferior survival; and that TPs related with protein N-linked glycosylation are upregulated in AL. Collectively, we provide a novel resource to understand normal PC development and the transcriptional reorganization of AL and other monoclonal gammopathies.

Activating KRAS, NRAS, and BRAF mutants enhance proteasome capacity and reduce endoplasmic reticulum stress in multiple myeloma

KRAS, NRAS, and BRAF mutations which activate p44/42 mitogen-activated protein kinase (MAPK) signaling are found in half of myeloma patients and contribute to proteasome inhibitor (PI) resistance, but the underlying mechanisms are not fully understood. We established myeloma cell lines expressing wild-type (WT), constitutively active (CA) (G12V/G13D/Q61H), or dominant-negative (DN) (S17N)-KRAS and -NRAS, or BRAF-V600E. Cells expressing CA mutants showed increased proteasome maturation protein (POMP) and nuclear factor (erythroid-derived 2)-like 2 (NRF2) expression. This correlated with an increase in catalytically active proteasome subunit β (PSMB)-8, PSMB9, and PSMB10, which occurred in an ETS transcription factor-dependent manner. Proteasome chymotrypsin-like, trypsin-like, and caspase-like activities were increased, and this enhanced capacity reduced PI sensitivity, while DN-KRAS and DN-NRAS did the opposite. Pharmacologic RAF or MAPK kinase (MEK) inhibitors decreased proteasome activity, and sensitized myeloma cells to PIs. CA-KRAS, CA-NRAS, and CA-BRAF down-regulated expression of endoplasmic reticulum (ER) stress proteins, and reduced unfolded protein response activation, while DN mutations increased both. Finally, a bortezomib (BTZ)/MEK inhibitor combination showed enhanced activity in vivo specifically in CA-NRAS models. Taken together, the data support the hypothesis that activating MAPK pathway mutations enhance PI resistance by increasing proteasome capacity, and provide a rationale for targeting such patients with PI/RAF or PI/MEK inhibitor combinations. Moreover, they argue these mutations promote myeloma survival by reducing cellular stress, thereby distancing plasma cells from the apoptotic threshold, potentially explaining their high frequency in myeloma.

GANT61 and Valproic Acid Synergistically Inhibited Multiple Myeloma Cell Proliferation via Hedgehog Signaling Pathway

Background

Multiple myeloma is featured by the proliferation of malignant plasma cell in bone marrow. We aimed to demonstrate the effects of valproic acid combined with GANT61 on multiple myeloma cell proliferation and clarify its mechanism.

Material/Methods

Multiple myeloma cells were exposed to valproic acid, GANT61, or the combination of valproic acid and GANT61, respectively. MTT assay was performed to detect the cell viability. Quantitative reverse transcriptase polymerase chain reaction and western blotting were used to detect mRNA and expression levels of proteins in Hedgehog signaling pathway. The Q-value of the combination regime was calculated to evaluate the drug combination effect.

Results

Both valproic acid and GANT61 alone inhibited multiple myeloma cell proliferation in a dose-dependent manner compared to the control. In the presence of GANT61 or not, valproic acid inhibited multiple myeloma cell proliferation in a time-dependent manner. These 2 drugs had a synergistic effect at valproic acid concentration of ≥4 mM. Expression analysis showed that valproic acid significantly inhibited the expression levels of PTCH1, GLI1, and HES-1. GANT61 enhanced the inhibition of Hedgehog signaling pathway mediated by valproic acid.

Conclusions

GANT61 and valproic acid inhibited multiple myeloma cell proliferation synergistically by inhibiting the Hedgehog signaling pathway. The present study may provide a combination regime for the therapy of multiple myeloma.

A multiple myeloma classification system that associates normal B-cell subset phenotypes with prognosis

Despite the recent progress in treatment of multiple myeloma (MM), it is still an incurable malignant disease, and we are therefore in need of new risk stratification tools that can help us to understand the disease and optimize therapy. Here we propose a new subtyping of myeloma plasma cells (PCs) from diagnostic samples, assigned by normal B-cell subset associated gene signatures (BAGS). For this purpose, we combined fluorescence-activated cell sorting and gene expression profiles from normal bone marrow (BM) Pre-BI, Pre-BII, immature, naïve, memory, and PC subsets to generate BAGS for assignment of normal BM subtypes in diagnostic samples. The impact of the subtypes was analyzed in 8 available data sets from 1772 patients' myeloma PC samples. The resulting tumor assignments in available clinical data sets exhibited similar BAGS subtype frequencies in 4 cohorts from de novo MM patients across 1296 individual cases. The BAGS subtypes were significantly associated with progression-free and overall survival in a meta-analysis of 916 patients from 3 prospective clinical trials. The major impact was observed within the Pre-BII and memory subtypes, which had a significantly inferior prognosis compared with other subtypes. A multiple Cox proportional hazard analysis documented that BAGS subtypes added significant, independent prognostic information to the translocations and cyclin D classification. BAGS subtype analysis of patient cases identified transcriptional differences, including a number of differentially spliced genes. We identified subtype differences in myeloma at diagnosis, with prognostic impact and predictive potential, supporting an acquired B-cell trait and phenotypic plasticity as a pathogenetic hallmark of MM.

Utility of Circulating Cell-Free RNA Analysis for the Characterization of Global Transcriptome Profiles of Multiple Myeloma Patients

In this study, we evaluated the utility of extracellular RNA (exRNA) derived from the plasma of multiple myeloma (MM) patients for whole transcriptome characterization. exRNA from 10 healthy controls (HC), five newly diagnosed (NDMM), and 12 relapsed and refractory (RRMM) MM patients were analyzed and compared. We showed that ~45% of the exRNA genes were protein-coding genes and ~85% of the identified genes were covered >70%. Compared to HC, we identified 632 differentially expressed genes (DEGs) in MM patients, of which 26 were common to NDMM and RRMM. We further identified 54 and 191 genes specific to NDMM and RRMM, respectively, and these included potential biomarkers such as LINC00863, MIR6754, CHRNE, ITPKA, and RGS18 in NDMM, and LINC00462, PPBP, RPL5, IER3, and MIR425 in RRMM, that were subsequently validated using droplet digital PCR. Moreover, single nucleotide polymorphisms and small indels were identified in the exRNA, including mucin family genes that demonstrated different rates of mutations between NDMM and RRMM. This is the first whole transcriptome study of exRNA in hematological malignancy and has provided the basis for the utilization of exRNA to enhance our understanding of the MM biology and to identify potential biomarkers relevant to the diagnosis and prognosis of MM patients.

Gene Co-expression Network and Copy Number Variation Analyses Identify Transcription Factors Associated With Multiple Myeloma Progression

Multiple myeloma (MM) has two clinical precursor stages of disease: monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM). However, the mechanism of progression is not well understood. Because gene co-expression network analysis is a well-known method for discovering new gene functions and regulatory relationships, we utilized this framework to conduct differential co-expression analysis to identify interesting transcription factors (TFs) in two publicly available datasets. We then used copy number variation (CNV) data from a third public dataset to validate these TFs. First, we identified co-expressed gene modules in two publicly available datasets each containing three conditions: normal, MGUS, and SMM. These modules were assessed for condition-specific gene expression, and then enrichment analysis was conducted on condition-specific modules to identify their biological function and upstream TFs. TFs were assessed for differential gene expression between normal and MM precursors, then validated with CNV analysis to identify candidate genes. Functional enrichment analysis reaffirmed known functional categories in MM pathology, the main one relating to immune function. Enrichment analysis revealed a handful of differentially expressed TFs between normal and either MGUS or SMM in gene expression and/or CNV. Overall, we identified four genes of interest (MAX, TCF4, ZNF148, and ZNF281) that aid in our understanding of MM initiation and progression.

Serum platelet factor 4 is a promising predictor in newly diagnosed patients with multiple myeloma treated with thalidomide and VAD regimens

OBJECTIVE

Frequent loss of expression of platelet factor 4 (PF4) in multiple myeloma (MM) was revealed in several previous researches. The predictive analysis of serum PF4 level in newly diagnosed MM has not been well elucidated. This study is to assess if serum PF4 could be a prognostic factor in predicting treatment response and survival of MM treated with thalidomide and VAD regimens.

METHODS

Sera of 122 MM were gained pre- and post-treatment of chemotherapy and oral thalidomide. Serological PF4 measurements were performed by ELISA. Kaplan-Meier method was employed for survival analysis. Log rank test was used significance analysis. Multivariate analysis of overall survival used Cox-regression.

RESULTS

Our data showed that the median serum PF4 concentration was negatively associated with MM response and a significant correlation between serum PF4 level and unfavorable clinical features (β2-microglobulin, ISS stage, del17p and creatinine). MM with lower serum PF4 concentration at diagnosis were prone to gain complete remission and very good partial remission after two courses of chemotherapy. Besides del17p, β2-microglobulin, treatment response, the low serum PF4 concentration was an independent variable associated with a poor overall survival by univariate analysis and multivariate analysis.

CONCLUSIONS

We speculate serum PF4 is a promising response and prognostic factor in newly diagnosed MM treated with thalidomide and VAD regimens.

Definition of a multiple myeloma progenitor population in mice driven by enforced expression of XBP1s

Multiple myeloma (MM) is an incurable plasma cell malignancy with frequent treatment failures and relapses, suggesting the existence of pathogenic myeloma stem/progenitor populations. However, the identity of MM stem cells remains elusive. We used a murine model of MM with transgenic overexpression of the unfolded protein response sensor X-box binding protein 1 (XBP1s) in the B cell compartment to define MM stem cells. We herein report that a post-germinal center, pre-plasma cell population significantly expands as MM develops. This population has the following characteristics: (a) cell surface phenotype of B220+CD19+IgM-IgD-CD138-CD80+sIgG-AA4.1+FSChi; (b) high expression levels of Pax5 and Bcl6 with intermediate levels of Blimp1 and XBP1s; (c) increased expression of aldehyde dehydrogenase, Notch1, and c-Kit; and (d) ability to efficiently reconstitute antibody-producing capacity in B cell-deficient mice in vivo. We thus have defined a plasma cell progenitor population that resembles myeloma stem cells in mice. These results provide potentially novel insights into MM stem cell biology and may contribute to the development of novel stem cell-targeted therapies for the eradication of MM.

Aberrant Wnt signaling in multiple myeloma: molecular mechanisms and targeting options

Aberrant activation of Wnt/β-catenin signaling plays a central role in the pathogenesis of a wide variety of malignancies and is typically caused by mutations in core Wnt pathway components driving constitutive, ligand-independent signaling. In multiple myelomas (MMs), however, these pathway intrinsic mutations are rare despite the fact that most tumors display aberrant Wnt pathway activity. Recent studies indicate that this activation is caused by genetic and epigenetic lesions of Wnt regulatory components, sensitizing MM cells to autocrine Wnt ligands and paracrine Wnts emanating from the bone marrow niche. These include deletion of the tumor suppressor CYLD, promotor methylation of the Wnt antagonists WIF1, DKK1, DKK3, and sFRP1, sFRP2, sFRP4, sFRP5, as well as overexpression of the co-transcriptional activator BCL9 and the R-spondin receptor LGR4. Furthermore, Wnt activity in MM is strongly promoted by interaction of both Wnts and R-spondins with syndecan-1 (CD138) on the MM cell-surface. Functionally, aberrant canonical Wnt signaling plays a dual role in the pathogenesis of MM: (I) it mediates proliferation, migration, and drug resistance of MM cells; (II) MM cells secrete Wnt antagonists that contribute to the development of osteolytic lesions by impairing osteoblast differentiation. As discussed in this review, these insights into the causes and consequences of aberrant Wnt signaling in MM will help to guide the development of targeting strategies. Importantly, since Wnt signaling in MM cells is largely ligand dependent, it can be targeted by drugs/antibodies that act upstream in the pathway, interfering with Wnt secretion, sequestering Wnts, or blocking Wnt (co)receptors.

Role of apurinic/apyrimidinic nucleases in the regulation of homologous recombination in myeloma: mechanisms and translational significance

We have previously reported that homologous recombination (HR) is dysregulated in multiple myeloma (MM) and contributes to genomic instability and development of drug resistance. We now demonstrate that base excision repair (BER) associated apurinic/apyrimidinic (AP) nucleases (APEX1 and APEX2) contribute to regulation of HR in MM cells. Transgenic as well as chemical inhibition of APEX1 and/or APEX2 inhibits HR activity in MM cells, whereas the overexpression of either nuclease in normal human cells, increases HR activity. Regulation of HR by AP nucleases could be attributed, at least in part, to their ability to regulate recombinase (RAD51) expression. We also show that both nucleases interact with major HR regulators and that APEX1 is involved in P73-mediated regulation of RAD51 expression in MM cells. Consistent with the role in HR, we also show that AP-knockdown or treatment with inhibitor of AP nuclease activity increases sensitivity of MM cells to melphalan and PARP inhibitor. Importantly, although inhibition of AP nuclease activity increases cytotoxicity, it reduces genomic instability caused by melphalan. In summary, we show that APEX1 and APEX2, major BER proteins, also contribute to regulation of HR in MM. These data provide basis for potential use of AP nuclease inhibitors in combination with chemotherapeutics such as melphalan for synergistic cytotoxicity in MM.

MALDI-TOF analysis of blood serum proteome can predict the presence of monoclonal gammopathy of undetermined significance

Monoclonal gammopathy of undetermined significance (MGUS) is a plasma cell dyscrasia that can progress to malignant multiple myeloma (MM). Specific molecular biomarkers to classify the MGUS status and discriminate the initial asymptomatic phase of MM have not been identified. We examined the serum peptidome profile of MGUS patients and healthy volunteers using MALDI-TOF mass spectrometry and developed a predictive model for classifying serum samples. The predictive model was built using a support vector machine (SVM) supervised learning method tuned by applying a 20-fold cross-validation scheme. Predicting class labels in a blinded test set containing randomly selected MGUS and healthy control serum samples validated the model. The generalization performance of the predictive model was evaluated by a double cross-validation method that showed 88% average model accuracy, 89% average sensitivity and 86% average specificity. Our model, which classifies unknown serum samples as belonging to either MGUS patients or healthy individuals, can be applied to clinical diagnosis.

From MGUS to Multiple Myeloma, a Paradigm for Clonal Evolution of Premalignant Cells

Multiple myeloma (MM) is a treatable, but incurable, malignancy of plasma cells (PC) in the bone marrow (BM). It represents the final stage in a continuum of PC dyscrasias and is consistently preceded by a premalignant phase termed monoclonal gammopathy of undetermined significance (MGUS). The existence of this well-defined premalignant phase provides the opportunity to study clonal evolution of a premalignant condition into overt cancer. Unraveling the mechanisms of malignant transformation of PC could enable early identification of MGUS patients at high risk of progression and may point to novel therapeutic targets, thereby possibly delaying or preventing malignant transformation. The MGUS-to-MM progression requires multiple genomic events and the establishment of a permissive BM microenvironment, although it is generally not clear if the various microenvironmental events are causes or consequences of disease progression. Advances in gene-sequencing techniques and the use of serial paired analyses have allowed for a more specific identification of driver lesions. The challenge in cancer biology is to identify and target those lesions that confer selective advantage and thereby drive evolution of a premalignant clone. Here, we review recent advances in the understanding of malignant transformation of MGUS to MM. Cancer Res; 78(10); 2449-56. ©2018 AACR.

Active enhancer and chromatin accessibility landscapes chart the regulatory network of primary multiple myeloma

Multiple myeloma (MM) is an aggressive cancer that originates from antibody-secreting plasma cells. Although genetically and transcriptionally well characterized, the aberrant gene regulatory networks that underpin this disease remain poorly understood. Here, we mapped regulatory elements, open chromatin, and transcription factor (TF) footprints in primary MM cells. In comparison with normal antibody-secreting cells, MM cells displayed consistent changes in enhancer activity that are connected to superenhancer (SE)-mediated deregulation of TF genes. MM cells also displayed widespread decompaction of heterochromatin that was associated with activation of regulatory elements and in a major subset of patients' deregulation of the cyclic adenosine monophosphate pathway. Finally, building SE-associated TF-based regulatory networks allowed identification of several novel TFs that are central to MM biology. Taken together, these findings significantly add to our understanding of the aberrant gene regulatory network that underpins MM.

Proposed Terminology and Classification of Pre-Malignant Neoplastic Conditions: A Consensus Proposal

Cancer evolution is a step-wise non-linear process that may start early in life or later in adulthood, and includes pre-malignant (indolent) and malignant phases. Early somatic changes may not be detectable or are found by chance in apparently healthy individuals. The same lesions may be detected in pre-malignant clonal conditions. In some patients, these lesions may never become relevant clinically whereas in others, they act together with additional pro-oncogenic hits and thereby contribute to the formation of an overt malignancy. Although some pre-malignant stages of a malignancy have been characterized, no global system to define and to classify these conditions is available. To discuss open issues related to pre-malignant phases of neoplastic disorders, a working conference was organized in Vienna in August 2015. The outcomes of this conference are summarized herein and include a basic proposal for a nomenclature and classification of pre-malignant conditions. This proposal should assist in the communication among patients, physicians and scientists, which is critical as genome-sequencing will soon be offered widely for early cancer-detection.

Long non-coding RNA MALAT1 is an inducible stress response gene associated with extramedullary spread and poor prognosis of multiple myeloma

Extramedullary myeloma (EMM) occurs when myeloma develops outside the bone marrow; it often develops after chemotherapy and is associated with the acquisition of chemo-resistance and a fatal course. The mechanisms underlying extramedullary spread have not yet been fully elucidated. MALAT1 is a highly abundantly and ubiquitously expressed long non-coding RNA that plays important roles in cancer metastasis. The aims of this study were to clarify the association of MALAT1 with EMM and to elucidate the underlying mechanism of EMM formation under chemotherapeutic pressure. MALAT1 expression was significantly higher in multiple myeloma (MM) than in monoclonal gammopathy of undetermined significance. Furthermore, MALAT1 expression was markedly higher in EMM compared with that in corresponding intramedullary myeloma cells. A higher MALAT1 level was associated with shorter overall and progression-free survival. MALAT1 expression level was positively correlated with expression of HSP90AA1, HSP90AB1 and HSP90B1 but not with TP53 expression. MALAT1 was significantly upregulated by bortezomib and doxorubicin. Considering the known functions of MALAT1, our results suggest that it acts as a stress response gene that is upregulated by chemotherapy, thereby linking chemotherapy to EMM formation. Elucidating the biological implication of long non-coding RNA contributes to deeper understanding concerning the pathogenesis and investigation of novel therapeutic targets for MM.

Cooperative Targets of Combined mTOR/HDAC Inhibition Promote MYC Degradation

Cancer treatments often require combinations of molecularly targeted agents to be effective. mTORi (rapamycin) and HDACi (MS-275/entinostat) inhibitors have been shown to be effective in limiting tumor growth, and here we define part of the cooperative action of this drug combination. More than 60 human cancer cell lines responded synergistically (CI<1) when treated with this drug combination compared with single agents. In addition, a breast cancer patient-derived xenograft, and a BCL-XL plasmacytoma mouse model both showed enhanced responses to the combination compared with single agents. Mice bearing plasma cell tumors lived an average of 70 days longer on combination treatment compared with single agents. A set of 37 genes cooperatively affected (34 downregulated; 3 upregulated) by the combination responded pharmacodynamically in human myeloma cell lines, xenografts, and a P493 model, and were both enriched in tumors, and correlated with prognostic markers in myeloma patient datasets. Genes downregulated by the combination were overexpressed in several untreated cancers (breast, lung, colon, sarcoma, head and neck, myeloma) compared with normal tissues. The MYC/E2F axis, identified by upstream regulator analyses and validated by immunoblots, was significantly inhibited by the drug combination in several myeloma cell lines. Furthermore, 88% of the 34 genes downregulated have MYC-binding sites in their promoters, and the drug combination cooperatively reduced MYC half-life by 55% and increased degradation. Cells with MYC mutations were refractory to the combination. Thus, integrative approaches to understand drug synergy identified a clinically actionable strategy to inhibit MYC/E2F activity and tumor cell growth in vivoMol Cancer Ther; 16(9); 2008-21. ©2017 AACR.

The Role of Intracellular Signaling Pathways in the Pathogenesis of Multiple Myeloma and Novel Therapeutic Approaches

The introduction of novel agents, such as bortezomib, thalidomide, and lenalidomide, into daily practice has dramatically improved clinical outcomes and prolonged survival of patients with multiple myeloma (MM). However, despite these advanced clinical benefits, MM remains an incurable hematological malignancy. Therefore, development of new agents and novel therapeutic strategies is urgently needed. Recent advances toward understanding the mechanism of myeloma cell growth and drug resistance in the bone marrow milieu have provided clues for the development of next-generation agents aimed at improving patient outcomes. In this review article, we discuss new possible agents for the treatment of MM based on recent advances in the understanding of signaling pathways in myeloma cells.

Next-Generation Sequencing Informing Therapeutic Decisions and Personalized Approaches

Multiple myeloma is a heterogeneous disease featured by different molecular subtypes. In the last decade, new therapeutics including second- and third-generation proteasome inhibitors and immunomodulatory agents, monoclonal antibodies, and other novel targeted agents have completely transformed the outcome of the disease. The task ahead is to develop strategies to identify effective combinations and sequences of agents that can exploit the genetic make-up of myeloma cells to improve efficacy. Moreover, a subgroup of high-risk patients who experience early disease relapse and shorter survival also requires early identification and specific intervention. Next-generation sequencing (NGS) technologies now allow us to accomplish some of these goals. As described here, besides improving our understanding of the disease, it is beginning to influence our clinical decisions and therapeutic choices. In this article, we describe the current state-of-the-art role of NGS in myeloma from identifying high-risk disease, to drug selection, and, ultimately, to guide personalized therapy.

IL21R expressing CD14+CD16+ monocytes expand in multiple myeloma patients leading to increased osteoclasts

Bone marrow monocytes are primarily committed to osteoclast formation. It is, however, unknown whether potential primary alterations are specifically present in bone marrow monocytes from patients with multiple myeloma, smoldering myeloma or monoclonal gammopathy of undetermined significance. We analyzed the immunophenotypic and transcriptional profiles of bone marrow CD14⁺ monocytes in a cohort of patients with different types of monoclonal gammopathies to identify alterations involved in myeloma-enhanced osteoclastogenesis. The number of bone marrow CD14⁺CD16⁺ cells was higher in patients with active myeloma than in those with smoldering myeloma or monoclonal gammopathy of undetermined significance. Interestingly, sorted bone marrow CD14⁺CD16⁺ cells from myeloma patients were more pro-osteoclastogenic than CD14⁺CD16-cells in cultures ex vivo. Moreover, transcriptional analysis demonstrated that bone marrow CD14⁺ cells from patients with multiple myeloma (but neither monoclonal gammopathy of undetermined significance nor smoldering myeloma) significantly upregulated genes involved in osteoclast formation, including IL21R. IL21R mRNA over-expression by bone marrow CD14⁺ cells was independent of the presence of interleukin-21. Consistently, interleukin-21 production by T cells as well as levels of interleukin-21 in the bone marrow were not significantly different among monoclonal gammopathies. Thereafter, we showed that IL21R over-expression in CD14⁺ cells increased osteoclast formation. Consistently, interleukin-21 receptor signaling inhibition by Janex 1 suppressed osteoclast differentiation from bone marrow CD14⁺ cells of myeloma patients. Our results indicate that bone marrow monocytes from multiple myeloma patients show distinct features compared to those from patients with indolent monoclonal gammopathies, supporting the role of IL21R over-expression by bone marrow CD14⁺ cells in enhanced osteoclast formation.

Progress and Paradigms in Multiple Myeloma

Remarkable progress has been achieved in multiple myeloma, and patient median survival has been extended 3- to 4-fold. Specifically, there have been 18 newly approved treatments for multiple myeloma in the past 12 years, including seven in 2015, and the treatment paradigm and patient outcome have been transformed. The definition of patients benefitting from these therapies has been broadened. Response criteria now include minimal residual disease (MRD), assessed in bone marrow by multicolor flow cytometry or sequencing, and by imaging for extramedullary disease. Initial therapy for transplant candidates is a triplet incorporating novel therapies-that is, lenalidomide, bortezomib, and dexamethasone or cyclophosphamide, bortezomib, and dexamethasone. Lenalidomide maintenance until progression can prolong progression-free and overall survival in standard-risk multiple myeloma, with incorporation of proteasome inhibitor for high-risk disease. Studies are evaluating the value of early versus late transplant and MRD as a therapeutic goal to inform therapy. In nontransplant patients, triplet therapies are also preferred, with doublet therapy reserved for frail patients, and maintenance as described above. The availability of second-generation proteasome inhibitors (carfilzomib and ixazomib), immunomodulatory drugs (pomalidomide), histone deacetylase inhibitors (panobinostat), and monoclonal antibodies (elotuzumab and daratumumab) allows for effective combination therapies of relapsed disease as well. Finally, novel therapies targeting protein degradation, restoring autologous memory anti-multiple myeloma immunity, and exploiting genetic vulnerabilities show promise to improve patient outcome even further. Clin Cancer Res; 22(22); 5419-27. ©2016 AACR SEE ALL ARTICLES IN THIS CCR FOCUS SECTION, "MULTIPLE MYELOMA MULTIPLYING THERAPIES".

A novel alkylating agent Melflufen induces irreversible DNA damage and cytotoxicity in multiple myeloma cells

Our prior study utilized both in vitro and in vivo multiple myeloma (MM) xenograft models to show that a novel alkylator melphalan-flufenamide (Melflufen) is a more potent anti-MM agent than melphalan and overcomes conventional drug resistance. Here we examined whether this potent anti-MM activity of melflufen versus melphalan is due to their differential effect on DNA damage and repair signalling pathways via γ-H2AX/ATR/CHK1/Ku80. Melflufen-induced apoptosis was associated with dose- and time-dependent rapid phosphorylation of γ-H2AX. Melflufen induces γ-H2AX, ATR, and CHK1 as early as after 2 h exposure in both melphalan-sensitive and -resistant cells. However, melphalan induces γ-H2AX in melphalan-sensitive cells at 6 h and 24 h; no γ-H2AX induction was observed in melphalan-resistant cells even after 24 h exposure. Similar kinetics was observed for ATR and CHK1 in meflufen- versus melphalan-treated cells. DNA repair is linked to melphalan-resistance; and importantly, we found that melphalan, but not melflufen, upregulates Ku80 that repairs DNA double-strand breaks. Washout experiments showed that a brief (2 h) exposure of MM cells to melflufen is sufficient to initiate an irreversible DNA damage and cytotoxicity. Our data therefore suggest that melflufen triggers a rapid, robust, and an irreversible DNA damage which may account for its ability to overcome melphalan-resistance in MM cells.

BCL-B (BCL2L10) is overexpressed in patients suffering from multiple myeloma (MM) and drives an MM-like disease in transgenic mice

Luciano et al. generate transgenic mice expressing the Bcl-B gene under the control of the VH promoter and Eµ enhancer and show that these mice recapitulate the characteristic features of human MM.

Multiple myeloma (MM) evolves from a premalignant condition known as monoclonal gammopathy of undetermined significance (MGUS). However, the factors underlying the malignant transformation of plasmocytes in MM are not fully characterized. We report here that Eµ-directed expression of the antiapoptotic Bcl-B protein in mice drives an MM phenotype that reproduces accurately the human disease. Indeed, with age, Eµ-bcl-b transgenic mice develop the characteristic features of human MM, including bone malignant plasma cell infiltration, a monoclonal immunoglobulin peak, immunoglobulin deposit in renal tubules, and highly characteristic bone lytic lesions. In addition, the tumors are serially transplantable in irradiated wild-type mice, underlying the tumoral origin of the disease. Eµ-bcl-b plasmocytes show increased expression of a panel of genes known to be dysregulated in human MM pathogenesis. Treatment of Eµ-bcl-b mice with drugs currently used to treat patients such as melphalan and VELCADE efficiently kills malignant plasmocytes in vivo. Finally, we find that Bcl-B is overexpressed in plasmocytes from MM patients but neither in MGUS patients nor in healthy individuals, suggesting that Bcl-B may drive MM. These findings suggest that Bcl-B could be an important factor in MM disease and pinpoint Eµ-bcl-b mice as a pertinent model to validate new therapies in MM.

IRE1α-XBP1 signaling pathway, a potential therapeutic target in multiple myeloma

Multiple myeloma (MM), which arises from the uncontrolled proliferation of malignant plasma cells, is the second most commonly diagnosed hematologic malignancy in the United States. Despite the development and application of novel drugs and autologous stem cell transplantation (ASCT), MM remains an incurable disease and patients become more prone to MM relapse and drug resistance. It is extremely urgent to find novel targeted therapy for MM. To date, the classic signaling pathways underlying MM have included the RAS/RAF/MEK/ERK pathway, the JAK-STAT3 pathway, the PI3K/Akt pathway and the NF-KB pathway. The IRE1α-XBP1 signaling pathway is currently emerging as an important pathway involved in the development of MM. Moreover, it is closely associated with the effect of MM treatment and its prognosis. All these findings indicate that the IRE1α-XBP1 pathway can be a potential treatment target. Herein, we investigate the relationship between the IRE1α-XBP1 pathway and MM and discuss the functions of IRE1α-XBP1-targeted drugs in the treatment of MM.

Phenotypic, transcriptomic, and genomic features of clonal plasma cells in light-chain amyloidosis

Clonal PCs in AL have similar phenotypic and CNA profiles as those in MM, but their transcriptome is similar to that of normal PCs. First-ever WES in AL amyloidosis reveals potential lack of a unifying mutation.

Opposite activation of the Hedgehog pathway in CD138+ plasma cells and CD138-CD19+ B cells identifies two subgroups of patients with multiple myeloma and different prognosis

Hyperactivation of the Hedgehog (Hh) pathway, which controls refueling of multiple myeloma (MM) clones, might be critical to disease recurrence. Although several studies suggest the Hh pathway is activated in CD138- immature cells, differentiated CD138+ plasma cells might also be able to self-renew by producing themselves the Hh ligands. We studied the gene expression profiles of 126 newly diagnosed MM patients analyzed in both the CD138+ plasma cell fraction and CD138-CD19+ B-cell compartment. Results demonstrated that an Hh-gene signature was able to cluster patients in two subgroups characterized by the opposite Hh pathway expression in mature plasma cells and their precursors. Strikingly, patients characterized by Hh hyperactivation in plasma cells, but not in their B cells, displayed high genomic instability and an unfavorable outcome in terms of shorter progression-free survival (hazard ratio: 1.92; 95% confidence interval: 1.19-3.07) and overall survival (hazard ratio: 2.61; 95% confidence interval: 1.26-5.38). These results suggest that the mechanisms triggered by the Hh pathway ultimately led to identify a more indolent vs a more aggressive biological and clinical subtype of MM. Therefore, patient stratification according to their molecular background might help the fine-tuning of future clinical and therapeutic studies.

Immune responses in multiple myeloma: role of the natural immune surveillance and potential of immunotherapies

Multiple myeloma (MM) is a tumor of terminally differentiated B cells that arises in the bone marrow. Immune interactions appear as key determinants of MM progression. While myeloid cells foster myeloma-promoting inflammation, Natural Killer cells and T lymphocytes mediate protective anti-myeloma responses. The profound immune deregulation occurring in MM patients may be involved in the transition from a premalignant to a malignant stage of the disease. In the last decades, the advent of stem cell transplantation and new therapeutic agents including proteasome inhibitors and immunoregulatory drugs has dramatically improved patient outcomes, suggesting potentially key roles for innate and adaptive immunity in disease control. Nevertheless, MM remains largely incurable for the vast majority of patients. A better understanding of the complex interplay between myeloma cells and their immune environment should pave the way for designing better immunotherapies with the potential of very long term disease control. Here, we review the immunological microenvironment in myeloma. We discuss the role of naturally arising anti-myeloma immune responses and their potential corruption in MM patients. Finally, we detail the numerous promising immune-targeting strategies approved or in clinical trials for the treatment of MM.

Heterogeneous chromosome 12p deletion is an independent adverse prognostic factor and resistant to bortezomib-based therapy in multiple myeloma

The deletion of 12p (del(12p)) has been described as a novel negative prognostic marker in multiple myeloma (MM) and has gained increasing attention in recent years. However, its impact on MM is still controversial. In this study, we comprehensively evaluated the clinical impact of 12p13 deletion using fluorescence in situ hybridization (FISH) on 275 newly diagnosed MM cases treated in a prospective, non-randomized clinical trial (BDH 2008/02). The results showed that deletion of 12p13 was detected in 10.5% of newly diagnosed cases and associated with multiple indicators for high tumor burden including ISS III, BM plasmacytosis larger than 50%, and renal lesion. Moreover, the cases with 12p13 deletion typically had higher incidence of del(17p), IGH translocation and t(4;14). Patients with del(12p) conferred significantly adverse prognosis for PFS and OS, even in patients subjected to bortezomib-based therapy. When adjusted to the established prognostic variables including del(13q), del(17p), t(4;14), amp(1q21), ISS stage and LDH, del(12p13) remained the powerful independent adverse factor for PFS (P = 0.007) and OS (P = 0.032). In addition, del(12p13) combined with high β2-MG, high LDH and bone lesion can further identify subpopulations with high-risk features. Our results strongly supported that del(12p13) can be used as a valuable prognostic marker in MM.

Multiple myeloma: is it time for biomarker-driven therapy?

Remarkable strides have been made in understanding the molecular mechanisms by which multiple myeloma develops, leading to more sophisticated classification that incorporates not only the traditional diagnostic criteria, but also immunophenotype, genetic, and molecular features. However, even with this added information, considerable heterogeneity in clinical outcomes exists within the identified subtypes. The present paradigm for myeloma treatment is built on the basic step of defining transplant eligibility versus noneligibility, as determined by age, performance status, and cumulative burden of comorbidities. An incredibly complex heterogeneous disease is, therefore, treated in a generalized way with the result that large interpatient variability exists in the outcome. As antimyeloma therapeutics continue to expand it is becoming even more crucial to personalize treatment approaches that provide the most value to a specific patient. Development of biomarkers, either individually or as larger sets or patterns and ranging from analysis of blood or bone marrow to biomedical imaging, is a major focus in the field. Biomarkers such as involved serum free light chain ratio and MRI focal lesions have been implemented in the new definition of multiple myeloma and guide clinicians to initiate treatment in otherwise asymptomatic individuals. Currently, however, there is not enough evidence to support intensifying the treatment for high-risk disease or reducing the treatment for low-risk disease. Minimal residual disease-negative status is an important biomarker that holds promise for monitoring the effectiveness of response-adapted strategies. This article sheds light on the forward landscape and rear-mirror view of biomarkers in myeloma.

Role of NSC319726 in ovarian cancer based on the bioinformatics analyses

Aim

This study aimed to explore the molecular mechanisms of NSC319726 in ovarian cancer by bioinformatics analyses.

Methods

Gene expression profile GSE35972 was downloaded from the Gene Expression Omnibus database. The data set contains six samples, including three samples of TOV112D cells untreated and three samples of TOV112D cells treated with NSC319726. The differentially expressed genes (DEGs) between untreated and treated samples were analyzed using the limma package. Kyoto Encyclopedia of Genes and Genomes pathway analysis was performed using the signaling pathway impact analysis package, followed by the functional annotation of DEGs and protein–protein interaction network construction. Finally, the subnetwork was identified, and Gene Ontology functional enrichment analysis was performed on the DEGs enriched in the subnetwork.

Results

A total of 120 upregulated and 126 downregulated DEGs were identified. Six Kyoto Encyclopedia of Genes and Genomes pathways were significantly perturbed by DEGs, and the pathway of oocyte meiosis was identified as the most perturbed one. Oocyte meiosis was enriched by eight downregulated DEGs, such as ribosomal protein S6 kinase, 90 kDa, and polypeptide 6 (RPS6KA6). After functional annotation, eight transcription factors were upregulated (such as B-cell CLL/lymphoma 6 [BCL6]), and three transcription factors were downregulated. Seven tumor suppressor genes, such as forkhead box O3 (FOXO3), were upregulated. Additionally, in the protein–protein interaction network and subnetwork, cyclin B1 (CCNB1) and cell division cycle 20 (CDC20) were hub genes, which were also involved in the functions related to mitotic cell cycle.

Conclusion

NSC319726 may play an efficient role against ovarian cancer via targeting genes, such as RPS6KA6, BCL6, FOXO3, CCNB1, and CDC20, which are involved in oocyte meiosis pathway.

Primary myeloma interaction and growth in coculture with healthy donor hematopoietic bone marrow

Background

Human primary myeloma (MM) cells do not survive in culture; current in vitro and in vivo systems for growing these cells are limited to coculture with a specific bone marrow (BM) cell type or growth in an immunodeficient animal model. The purpose of the study is to establish an interactive healthy donor whole BM based culture system capable of maintaining prolonged survival of primary MM cells. This normal BM (NBM) coculture system is different from using autologous BM that is already affected by the disease.

Methods

Whole BM from healthy donors was cultured in medium supplemented with BM serum from MM patients for 7 days, followed by 7 days of coculture with CD138-selected primary MM cells or MM cell lines. MM cells in the coculture were quantified using flow cytometry or bioluminescence of luciferase-expressing MM cells. T-cell cytokine array and proteomics were performed to identify secreted factors.

Results

NBM is composed of adherent and nonadherent compartments containing typical hematopoietic and mesenchymal cells. MM cells, or a subset of MM cells, from all examined cases survived and grew in this system, regardless of the MM cells’ molecular risk or subtype, and growth was comparable to coculture with individual stromal cell types. Adherent and nonadherent compartments supported MM growth, and this support required patient serum for optimal growth. Increased levels of MM growth factors IL-6 and IL-10 along with MM clinical markers B2M and LDHA were detected in supernatants from the NBM coculture than from the BM cultured alone. Levels of extracellular matrix factors (e.g., MMP1, HMCN1, COL3A1, ACAN) and immunomodulatory factors (e.g., IFI16, LILRB4, PTPN6, AZGP1) were changed in the coculture system. The NBM system protected MM cells from dexamethasone but not bortezomib, and effects of lenalidomide varied.

Conclusions

The NBM system demonstrates the ability of primary MM plasma cells to interact with and to survive in coculture with healthy adult BM. This model is suitable for studying MM-microenvironment interactions, particularly at the early stage of engagement in new BM niches, and for characterizing MM cell subpopulations capable of long-term survival through secretion of extracellular matrix and immune-related factors.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1892-7) contains supplementary material, which is available to authorized users.

Synergistic anti-myeloma activity of the proteasome inhibitor marizomib and the IMiD immunomodulatory drug pomalidomide

The proteasome inhibitor bortezomib is an effective therapy for the treatment of relapsed and refractory multiple myeloma (RRMM); however, prolonged treatment can be associated with toxicity, peripheral neuropathy and drug resistance. Our earlier studies showed that the novel proteasome inhibitor marizomib is distinct from bortezomib in its chemical structure, mechanisms of action and effects on proteasomal activities, and that it can overcome bortezomib resistance. Pomalidomide, like lenalidomide, has potent immunomodulatory activity and has been approved by the US Food and Drug Administration for the treatment of RRMM. Here, we demonstrate that combining low concentrations of marizomib with pomalidomide induces synergistic anti-MM activity. Marizomib plus pomalidomide-induced apoptosis is associated with: (i) activation of caspase-8, caspase-9, caspase-3 and PARP cleavage, (ii) downregulation of cereblon (CRBN), IRF4, MYC and MCL1, and (iii) suppression of chymotrypsin-like, caspase-like, and trypsin-like proteasome activities. CRBN-siRNA attenuates marizomib plus pomalidomide-induced MM cells death. Furthermore, marizomib plus pomalidomide inhibits the migration of MM cells and tumour-associated angiogenesis, as well as overcomes cytoprotective effects of bone marrow microenvironment. In human MM xenograft model studies, the combination of marizomib and pomalidomide is well tolerated, inhibits tumour growth and prolongs survival. These preclinical studies provide the rationale for on-going clinical trials of combined marizomib and pomalidomide to improve outcome in patients with RRMM.

Whole Genome Sequence of Multiple Myeloma-Prone C57BL/KaLwRij Mouse Strain Suggests the Origin of Disease Involves Multiple Cell Types

Monoclonal gammopathy of undetermined significance (MGUS) is the requisite precursor to multiple myeloma (MM), a malignancy of antibody-producing plasma B-cells. The genetic basis of MGUS and its progression to MM remains poorly understood. C57BL/KaLwRij (KaLwRij) is a spontaneously-derived inbred mouse strain with a high frequency of benign idiopathic paraproteinemia (BIP), a phenotype with similarities to MGUS including progression to MM. Using mouse haplotype analysis, human MM SNP array data, and whole exome and whole genome sequencing of KaLwRij mice, we identified novel KaLwRij gene variants, including deletion of Samsn1 and deleterious point mutations in Tnfrsf22 and Tnfrsf23. These variants significantly affected multiple cell types implicated in MM pathogenesis including B-cells, macrophages, and bone marrow stromal cells. These data demonstrate that multiple cell types contribute to MM development prior to the acquisition of somatic driver mutations in KaLwRij mice, and suggest that MM may an inherently non-cell autonomous malignancy.

Genomic heterogeneity in multiple myeloma

Multiple myeloma (MM) is an incurable malignancy in majority of patients characterized by clonal proliferation of plasma cells. To date, treatment is established based on general conditions and age of patients. However, MM is a heterogeneous disease, featured by various subtypes and different outcomes. Thus, the understanding of MM biology is currently a major challenge to eventually cure the disease. During the last decade, karyotype studies and gene expression profiling have identified robust prognostic markers as well as a widespread genomic landscape. More recently, studies of epigenetic, transcriptional modifications and next generation sequencing have allowed characterization of critical genes and pathways, clonal heterogeneity and mutational profiles involved in myelomagenesis. Altogether, these findings constitute important tools to develop new targeted and personalized therapies in MM.

Lenalidomide Polarizes Th1-specific Anti-tumor Immune Response and Expands XBP1 Antigen-Specific Central Memory CD3+CD8+ T cells against Various Solid Tumors

Introduction

Effective combination immunotherapeutic strategies may be required to enhance effector cells’ anti-tumor activities and improve clinical outcomes.

Methods

XBP1 antigen-specific cytotoxic T lymphocytes (XBP1-CTL) generated using immunogenic heteroclitic XBP1 US184-192 (YISPWILAV) and XBP1 SP367-375 (YLFPQLISV) peptides or various solid tumor cells over-expressing XBP1 target antigen were evaluated, either alone or in combination with lenalidomide, for phenotype and immune functional activity.

Results

Lenalidomide treatment of XBP1-CTL increased the proportion of CD45RO⁺ memory CD3+CD8+ T cells, but not the total CD3⁺CD8⁺ T cells. Lenalidomide upregulated critical T cell activation markers and costimulatory molecules (CD28, CD38, CD40L, CD69, ICOS), especially within the central memory CTL subset of XBP1-CTL, while decreasing TCRαβ and T cell checkpoint blockade (CTLA-4, PD-1). Lenalidomide increased the anti-tumor activities of XBP1-CTL memory subsets, which were associated with expression of Th1 transcriptional regulators (T-bet, Eomes) and Akt activation, thereby resulting in enhanced IFN-γ production, granzyme B upregulation and specific CD28/CD38-positive and CTLA-4/PD-1-negative cell proliferation.

Conclusions

These studies suggest the potential benefit of lenalidomide treatment to boost anti-tumor activities of XBP1-specific CTL against a variety of solid tumors and enhance response to an XBP1-directing cancer vaccine regime.

SAMSN1 is a tumor suppressor gene in multiple myeloma

Multiple myeloma (MM), a hematological malignancy characterized by the clonal growth of malignant plasma cells (PCs) in the bone marrow, is preceded by the benign asymptomatic condition, monoclonal gammopathy of undetermined significance (MGUS). Several genetic abnormalities have been identified as critical for the development of MM; however, a number of these abnormalities are also found in patients with MGUS, indicating that there are other, as yet unidentified, factors that contribute to the onset of MM disease. In this study, we identify a Samsn1 gene deletion in the 5TGM1/C57BL/KaLwRij murine model of myeloma. In addition, SAMSN1 expression is reduced in the malignant CD138 + PCs of patients with MM and this reduced expression correlates to total PC burden. We identify promoter methylation as a potential mechanism through which SAMSN1 expression is modulated in human myeloma cell lines. Notably, re-expression of Samsn1 in the 5TGM1 murine PC line resulted in complete inhibition of MM disease development in vivo and decreased proliferation in stromal cell–PC co-cultures in vitro. This is the first study to identify deletion of a key gene in the C57BL/KaLwRij mice that also displays reduced gene expression in patients with MM and is therefore likely to play an integral role in MM disease development.

The cellular origin and malignant transformation of Waldenström macroglobulinemia

Benign (ie, IgM MGUS and smoldering WM) clonal B cells already harbor the phenotypic and molecular signatures of the malignant WM clone. Multistep transformation from benign (ie, IgM MGUS and smoldering WM) to malignant WM may require specific copy number abnormalities.

Heteroclitic XBP1 peptides evoke tumor-specific memory cytotoxic T lymphocytes against breast cancer, colon cancer, and pancreatic cancer cells

XBP1 is a critical transcriptional activator of the unfolded protein response (UPR), which increases tumor cell survival under prolonged endoplasmic reticulum (ER) stress and hypoxic conditions.This study was designed to evaluate the immunogenicity of heteroclitic XBP1 unspliced (US)_184-192 (YISPWILAV) and heteroclictic XBP1 spliced (SP)_367-375 (YLFPQLISV) HLA-A2 peptides, and to characterize the specific activities of XBP1 peptides-specific cytotoxic T lymphocytes (XBP1-CTL) against breast cancer, colon cancer, and pancreatic cancer cells.The XBP1-CTL had upregulated expression of critical T cell markers and displayed HLA-A2-restricted and antigen-specific activities against breast cancer, colon cancer and pancreatic cancer cells. XBP1-CTL were enriched withCD45RO⁺ memory CTL, which showed high expression of critical T cell markers (CD28, ICOS, CD69, CD40L), cell proliferation and antitumor activities as compared to CD45RO^- non-memory CTL. The effector memory (EM: CD45RO⁺CCR7^-) subset had the highest level of cell proliferation while the central memory (CM: CD45RO⁺CCR7⁺) subset demonstrated enhanced functional activities (CD107a degranulation, IFNγ/IL-2 production) upon recognition of the respective tumor cells. Furthermore, both the EM and CM XBP1-CTL subsets expressed high levels of Th1 transcription regulators Tbet and Eomes. The highest frequencies of IFNγ or granzyme B producing cells were detected within CM XBP1-CTL subset that were either Tbet⁺ or Eomes⁺ in responding to the tumor cells.These results demonstrate the immunotherapeutic potential of a cocktail of immunogenic HLA-A2 specific heteroclitic XBP1 US_184-192 and heteroclictic XBP1 SP_367-375 peptides to induce CD3⁺CD8⁺ CTL enriched for CM and EM cells with specific antitumor activities against a variety of solid tumors.

Panobinostat: a review of trial results and future prospects in multiple myeloma

Multiple myeloma is an incurable often devastating disease that is responsible for 1-2% of all cancers. Multiple myeloma is the second most common hematologic malignancy. Over the past two decades, advances in therapy have doubled life expectancy. Unfortunately, all patients ultimately relapse. Novel agents (immunomodulatory drugs and proteasome inhibitors) have changed the outlook for patients, but further breakthroughs are needed. Epigenetic treatments offer potential for advancing therapy by modifying oncogene responses. The acetylation status of various proteins can affect the availability of chromatin for transcription. This response may be modulated epigenetically to advantage using histone deacetylase inhibitors like panobinostat.

T cell-based targeted immunotherapies for patients with multiple myeloma

Despite high-dose chemotherapy followed by autologs stem-cell transplantation as well as novel therapeutic agents, multiple myeloma (MM) remains incurable. Following the general trend towards personalized therapy, targeted immunotherapy as a new approach in the therapy of MM has emerged. Better progression-free survival and overall survival after tandem autologs/allogeneic stem cell transplantation suggest a graft versus myeloma effect strongly supporting the usefulness of immunological therapies for MM patients. How to induce a powerful antimyeloma effect is the key issue in this field. Pivotal is the definition of appropriate tumor antigen targets and effective methods for expansion of T cells with clinical activity. Besides a comprehensive list of tumor antigens for T cell-based approaches, eight promising antigens, CS1, Dickkopf-1, HM1.24, Human telomerase reverse transcriptase, MAGE-A3, New York Esophageal-1, Receptor of hyaluronic acid mediated motility and Wilms' tumor gene 1, are described in detail to provide a background for potential clinical use. Results from both closed and on-going clinical trials are summarized in this review. On the basis of the preclinical and clinical data, we elaborate on three encouraging therapeutic options, vaccine-enhanced donor lymphocyte infusion, chimeric antigen receptors-transfected T cells as well as vaccines with multiple antigen peptides, to pave the way towards clinically significant immune responses against MM.

Novel targeted agents in the treatment of multiple myeloma

New, next-generation targeted treatment strategies are required to improve outcomes in patients with multiple myeloma (MM). Monoclonal antibodies, cell signaling inhibitors, and selective therapies targeting the bone marrow microenvironment have demonstrated encouraging results with generally manageable toxicity in therapeutic trials of patients with relapsed and refractory disease, each critically informed by preclinical studies. A combination approach of these newer agents with immunomodulators and/or proteasome inhibitors as part of a treatment platform seems to improve the efficacy of anti-MM regimens, even in heavily pretreated patients. Future studies are required to better understand the complex mechanisms of drug resistance in MM.

MicroRNA: important player in the pathobiology of multiple myeloma

Recent studies have revealed a pivotal role played by a class of small, noncoding RNAs, microRNA (miRNA), in multiple myeloma (MM), a plasma cell (PC) malignancy causing significant morbidity and mortality. Deregulated miRNA expression in patient's PCs and plasma has been associated with tumor progression, molecular subtypes, clinical staging, prognosis, and drug response in MM. A number of important oncogenic and tumor suppressor miRNAs have been discovered to regulate important genes and pathways such as p53 and IL6-JAK-STAT signaling. miRNAs may also form complex regulatory circuitry with genetic and epigenetic machineries, the deregulation of which could lead to malignant transformation and progression. The translational potential of miRNAs in the clinic is being increasingly recognized that they could represent novel biomarkers and therapeutic targets. This review comprehensively summarizes current progress in delineating the roles of miRNAs in MM pathobiology and management.