Prognostic factors and staging in multiple myeloma

Descriptive analysis and prognostic factors in cats with myeloma-related disorders: A multicenter retrospective study of 50 cases

BACKGROUND

Myeloma-related disorders (MRDs) are rare and poorly documented neoplasms of cats.

HYPOTHESIS/OBJECTIVES

To describe clinical, clinicopathologic, and imaging findings, response to treatment, and survival time and to identify factors associated with shorter outcomes in cats with MRD.

ANIMALS

Fifty cats with a diagnosis of MRD.

METHODS

Cats with paraproteinemia confirmed by serum protein electrophoresis (SPE) and either intramedullary plasmacytosis >10%, marked cytonuclear atypia with intramedullary plasmacytosis that ranged between 5% and 10%, or cytologically or histologically confirmed visceral infiltration were retrospectively included from several veterinary referral centers.

RESULTS

Bone marrow plasmacytosis and splenic or hepatic involvement were present in 17/27 cats (63%), 36/42 cats (86%), and 27/38 cats (71%), respectively. Anemia was reported in 33/49 cats (67%) and thrombocytopenia in 16/47 cats (34%). Some of the treatments that the cats received included melphalan and prednisolone (n = 19), cyclophosphamide and prednisolone (n = 10), chlorambucil and prednisolone (n = 4), prednisolone (n = 4), or other (n = 4). The overall response rates to melphalan, cyclophosphamide, and chlorambucil in combination with prednisolone were 87%, 90%, and 100%, respectively. Adverse events to melphalan or cyclophosphamide occurred in 65% and 23% of cats, respectively. Median survival time was 122 days (range, 0-1403) and was not significantly associated with chemotherapy protocol. Anemia (hazard ratio [HR], 3.1; 95% confidence interval [CI], 1.0-9.8) and thrombocytopenia (HR, 2.7; 95% CI, 1.2-6.0) were risk factors for shorter survival.

CONCLUSIONS AND CLINICAL IMPORTANCE

Our study confirmed the guarded prognosis of MRD in cats and identified risk factors for shorter survival times.

CD46-Targeted Theranostics for PET and 225Ac-Radiopharmaceutical Therapy of Multiple Myeloma

PURPOSE

Multiple myeloma is a plasma cell malignancy with an unmet clinical need for improved imaging methods and therapeutics. Recently, we identified CD46 as an overexpressed therapeutic target in multiple myeloma and developed the antibody YS5, which targets a cancer-specific epitope on this protein. We further developed the CD46-targeting PET probe [89Zr]Zr-DFO-YS5 for imaging and [225Ac]Ac-DOTA-YS5 for radiopharmaceutical therapy of prostate cancer. These prior studies suggested the feasibility of the CD46 antigen as a theranostic target in multiple myeloma. Herein, we validate [89Zr]Zr-DFO-YS5 for immunoPET imaging and [225Ac]Ac-DOTA-YS5 for radiopharmaceutical therapy of multiple myeloma in murine models.

EXPERIMENTAL DESIGN

In vitro saturation binding was performed using the CD46 expressing MM.1S multiple myeloma cell line. ImmunoPET imaging using [89Zr]Zr-DFO-YS5 was performed in immunodeficient (NSG) mice bearing subcutaneous and systemic multiple myeloma xenografts. For radioligand therapy, [225Ac]Ac-DOTA-YS5 was prepared, and both dose escalation and fractionated dose treatment studies were performed in mice bearing MM1.S-Luc systemic xenografts. Tumor burden was analyzed using BLI, and body weight and overall survival were recorded to assess antitumor effect and toxicity.

RESULTS

[89Zr]Zr-DFO-YS5 demonstrated high affinity for CD46 expressing MM.1S multiple myeloma cells (Kd = 16.3 nmol/L). In vitro assays in multiple myeloma cell lines demonstrated high binding, and bioinformatics analysis of human multiple myeloma samples revealed high CD46 expression. [89Zr]Zr-DFO-YS5 PET/CT specifically detected multiple myeloma lesions in a variety of models, with low uptake in controls, including CD46 knockout (KO) mice or multiple myeloma mice using a nontargeted antibody. In the MM.1S systemic model, localization of uptake on PET imaging correlated well with the luciferase expression from tumor cells. A treatment study using [225Ac]Ac-DOTA-YS5 in the MM.1S systemic model demonstrated a clear tumor volume and survival benefit in the treated groups.

CONCLUSIONS

Our study showed that the CD46-targeted probe [89Zr]Zr-DFO-YS5 can successfully image CD46-expressing multiple myeloma xenografts in murine models, and [225Ac]Ac-DOTA-YS5 can effectively inhibit the growth of multiple myeloma. These results demonstrate that CD46 is a promising theranostic target for multiple myeloma, with the potential for clinical translation.

Hyperdiploid Multiple Myeloma with Novel Complex Structural Chromosome Abnormalities Associated with Poor Prognosis : A Rare Case Report

Hyperdiploid multiple myeloma (MM) is associated with better prognosis and non-hyperdiploid subtype is associated with variable to adverse prognosis based on the nature of karyotype abnormality.  Rarely exceptions to this hyperdiploid and non-hyperdiploid divisions do exist in a minority. We report an adult male MM patient who showed hyperdiploid karyotype with few novel complex abnormalities and who showed poor clinical outcome. Conventional cytogenetic analysis carried out in 22 GTG banded metaphases showed 53,Y,der(X)t(X;22)(q27;q11.2),+3,+5,+6,+9,+11,+15,der(17)ins(17;1;3)(q11.2;?;?),der(17)ins(17;1;3)(q11.2;?;?),+19,-22,+mar karyotype pattern in 15 metaphases whereas 7 metaphases showed 46,XY karyotype  pattern.  Interphase FISH revealed biallelic del(13q14) and del(17p13) but no translocations involving the 14q32 region. Through Spectral karyotyping FISH, the origin of complex abnormalities involving der(17) chromosome,  translocation t(X;22), and marker chromosome could be clearly delineated. Although the present case showed hyperdiploid karyotype, he showed an adverse prognosis probably due to the co-existence of high risk and complex abnormalities and expired 5 months after initial diagnosis despite standard treatment given.

Quantitative polymerase Chain reaction profiling of microRNAs in peripheral lymph-monocytes from MGUS subjects

Monoclonal gammopathy of undetermined significance (MGUS) is a pre-malignant abnormality of plasma cells, with increased serum levels of immunoglobulins. Patients with MGUS may evolve to multiple myeloma through a multistep process including deregulated gene expression. microRNAs are small non-coding RNA molecules involved in post-transcriptional regulation of crucial biological processes, such as morphogenesis, cell differentiation, apoptosis, and cancer. This study aimed to evaluate microRNA expression on peripheral lymph-monocytes from MGUS subjects compared with healthy controls using qPCR arrays. Blood samples were collected by venipuncture from fifteen, newly diagnosed MGUS patients and fifteen healthy subjects. A further group (validation group) of six newly diagnosed MGUS patients and five healthy control were enrolled for the validation of miRNAs and their mRNAs target. The study was conducted performing miProfile miRNA qPCR arrays, followed by validation of miRNAs and related mRNA targets through RT-qPCR. The functional interaction between microRNAs and target gene were obtained by Ingenuity Pathways Analysis (IPA). IPA network analysis identified only molecules and relationships experimentally observed in peripheral lymphomonocytes. The following miRNAs :133a-3p, 16-5p, 291-3p, 23a-3p, 205-5p, 17-5p, 7a-5p, 221-3p, 30c-5p, 126a-3p,155-5p, let-7a-5p and 26a-5p, involved in the regulation of genes with a role in lymphocyte homeostasis, cell proliferation, apoptosis, and multiple myeloma (MM) progression, were differently expressed in MGUS with respect to healthy subjects. This miRNA signature and its relative targets could be considered for the formulation of new therapeutic strategies in the prophylaxis or treatment of monoclonal gammopathies.

Multiple myeloma with 1q21 amplification is highly sensitive to MCL-1 targeting

Prosurvival BCL-2 family proteins are potent inhibitors of apoptosis and often overexpressed in lymphoid malignancies. In multiple myeloma (MM), MCL-1 expression contributes to survival of malignant plasma cells, and overexpression correlates with poor prognosis. In this study, we investigated whether sensitivity to the novel MCL-1 inhibitor S63845 could be predicted using cytogenetics, focusing on amplification of 1q21, the chromosomal region that contains the MCL1 locus. In addition, we studied the relation of MCL-1 inhibitor sensitivity with other diagnostic characteristics and BCL-2 family protein expression. In 31 human myeloma cell lines and in bone marrow aspirates from 47 newly diagnosed MM patients, we measured the effect of S63845 alone, or combined with BCL-2 inhibitor ABT-199 (venetoclax), and BCL-XL inhibitor A-1155463 or A-1331852 on cell viability. We demonstrated for the first time that MM cells from patients with 1q21 amplification are significantly more sensitive to inhibition of MCL-1. We suggest that this increased sensitivity results from high relative MCL1 expression resulting from amplification of 1q21. Additionally, and partially independent from 1q21 status, high serum β2 microglobulin level and presence of renal insufficiency correlated with increased sensitivity to MCL-1 inhibitor treatment. Combining S63845 with other BH3 mimetics synergistically enhanced apoptosis compared with single inhibitors, and sensitivity to inhibitor combinations was found in a large proportion of MM insensitive to MCL-1 inhibition alone. Collectively, our data indicate that amplification of 1q21 identifies an MM subset highly sensitive to MCL-1 inhibitor treatment and can be used as a predictive marker to guide selection of therapy.

MiR-16 regulates crosstalk in NF-κB tolerogenic inflammatory signaling between myeloma cells and bone marrow macrophages

High levels of circulating miR-16 in the serum of multiple myeloma (MM) patients are independently associated with longer survival. Although the tumor suppressor function of intracellular miR-16 in MM plasma cells (PCs) has been elucidated, its extracellular role in maintaining a nonsupportive cancer microenvironment has not been fully explored. Here, we show that miR-16 is abundantly released by MM cells through extracellular vesicles (EVs) and that differences in its intracellular expression as associated with chromosome 13 deletion (Del13) are correlated to extracellular miR-16 levels. We also demonstrate that EVs isolated from MM patients and from the conditioned media of MM-PCs carrying Del13 more strongly differentiate circulating monocytes to M2-tumor supportive macrophages (TAMs), compared with MM-PCs without this chromosomal aberration. Mechanistically, our data show that miR-16 directly targets the IKKα/β complex of the NF-κB canonical pathway, which is critical not only in supporting MM cell growth, but also in polarizing macrophages toward an M2 phenotype. By using a miR-15a-16-1-KO mouse model, we found that loss of the miR-16 cluster supports polarization to M2 macrophages. Finally, we demonstrate the therapeutic benefit of miR-16 overexpression in potentiating the anti-MM activity by a proteasome inhibitor in the presence of MM-resident bone marrow TAM.

SLAMF receptors on normal and malignant B cells

The Signaling Lymphocyte Activation Molecule family (SLAMF) is a collection of nine surface receptors expressed mainly on hematopoietic cells, and was found to modulate the behavior of immune cells. SLAMF receptors are expressed on B cells in health and disease. Each SLAM receptor has a unique differential expression pattern during the development and activation of B cells. Furthermore, recent findings have revealed a principal role for this family of receptors in B cell malignancies, emphasizing their importance in the control of malignant cell survival, cell to cell communication within the tumor microenvironment, retention in the supporting niches and regulation of T cell anti-tumor response. This review summarizes the latest studies regarding SLAMF expression and behavior in B cells and in B cell pathologies, and discusses the therapeutic potential of these receptors.

The role of Cancer/Testis Antigens in Multiple Myeloma pathogenesis and their application in disease monitoring and therapy

A unique group of genes, encoding tumour associated antigens, known as the Cancer/Testis Antigens (CTAs), have been explored as novel markers of disease progression and as targets of immunotherapy in several cancers, including the haematological malignancy Multiple Myeloma (MM). This review aims to update the knowledge of CTA involvement in MM pathogenesis and how their potential as biomarkers for disease monitoring and targets of immunotherapy has been explored in the MM disease arena. Despite the initial promise of these antigens, their use as immunotherapy targets has not been successful, yet with a greater understanding of their role in disease pathogenesis they may still have a significant role to play as biomarkers of disease and therapeutic targets.

Daratumumab induces CD38 internalization and impairs myeloma cell adhesion

Daratumumab (Dara), a human immunoglobulin G1 kappa (IgG1κ) monoclonal anti-CD38 antibody, has been approved by the U.S. Food and Drug Administration for the treatment of relapsed multiple myeloma (MM) as a single agent as well as in combination with immunomodulatory drugs (IMiDs) and proteasome inhibitors (PI). Although the scientific rationale behind the use of Dara in combination with IMiDs has been extensively explored, the molecular mechanisms underlying Dara-PI regimens have not yet been investigated. Here, we demonstrate that CD38 on the surface of MM cells is rapidly internalized after Dara treatment; we also show that Dara treatment impairs MM cell adhesion, an effect that can be rescued by using the endocytosis inhibitor Dynasore. Finally, we show that Dara potentiates bortezomib (BTZ) killing of MM cells in vitro and in vivo, independent of its function as an immune activator. In conclusion, our data show that Dara impairs MM cell adhesion, which results in an increased sensitivity of MM to proteasome inhibition.

Overcoming multiple myeloma drug resistance in the era of cancer 'omics'

Multiple myeloma (MM) is among the most compelling examples of cancer in which research has markedly improved the length and quality of lives of those afflicted. Research efforts have led to 18 newly approved treatments over the last 12 years, including seven in 2015. However, despite significant improvement in overall survival, MM remains incurable as most patients inevitably, yet unpredictably, develop refractory disease. Recent advances in high-throughput 'omics' techniques afford us an unprecedented opportunity to (1) understand drug resistance at the genomic, transcriptomic, and proteomic level; (2) discover novel diagnostic, prognostic, and therapeutic biomarkers; (3) develop novel therapeutic targets and rational drug combinations; and (4) optimize risk-adapted strategies to circumvent drug resistance, thus bringing us closer to a cure for MM. In this review, we provide an overview of 'omics' technologies in MM biomarker and drug discovery, highlighting recent insights into MM drug resistance gleaned from the use of 'omics' techniques. Moving from the bench to bedside, we also highlight future trends in MM, with a focus on the potential use of 'omics' technologies as diagnostic, prognostic, or response/relapse monitoring tools to guide therapeutic decisions anchored upon highly individualized, targeted, durable, and rationally informed combination therapies with curative potential.

HDAC inhibitor AR-42 decreases CD44 expression and sensitizes myeloma cells to lenalidomide

Multiple myeloma (MM) is a hematological malignancy of plasma cells in the bone marrow. Despite multiple treatment options, MM is inevitably associated with drug resistance and poor outcomes. Histone deacetylase inhibitors (HDACi's) are promising novel chemotherapeutics undergoing evaluation in clinical trials for the potential treatment of patients with MM. Although in preclinical studies HDACi's have proven anti-myeloma activity, but in the clinic single-agent HDACi treatments have been limited due to low tolerability. Improved clinical outcomes were reported only when HDACi's were combined with other drugs. Here, we show that a novel pan-HDACi AR-42 downregulates CD44, a glycoprotein that has been associated with lenalidomide and dexamethasone resistance in myeloma both in vitro and in vivo. We also show that this CD44 downregulation is in part mediated by miR-9–5p, targeting insulin-like growth factor 2 mRNA binding protein 3 (IGF2BP3), which directly binds to CD44 mRNA and increases its stability. Importantly, we also demonstrate that AR-42 enhances anti-myeloma activity of lenalidomide in primary MM cells isolated from lenalidomide resistant patients and in in vivo MM mouse model. Thus, our findings shed light on potential novel combinatorial therapeutic approaches modulating CD44 expression, which may help overcome lenalidomide resistance in myeloma patients.

MR imaging and PET/CT in diagnosis and management of multiple myeloma

Multiple myeloma is a common hematologic malignancy among the elderly population. Although there have been many advances in treatment over the past few decades, the overall prognosis for the disease remains poor. Conventional radiography has long been the standard of reference for the imaging of multiple myeloma. However, 10%-20% of patients with multiple myeloma do not have evidence of disease at conventional radiography. There is a growing body of evidence supporting use of magnetic resonance (MR) imaging and 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET)/computed tomography (CT) in diagnosis and management of multiple myeloma. MR imaging is useful in detection of bone marrow infiltration, a finding often missed at conventional radiography. FDG PET/CT is especially sensitive for the detection of extramedullary disease and can help detect the metabolically active lesions that often precede evidence of osseous destruction at conventional radiography. MR imaging and FDG PET/CT are useful tools that can provide essential information for diagnosis and management of patients with multiple myeloma. Both modalities allow accurate localization of disease after chemotherapy or autologous stem cell transplantation and can provide important prognostic information that can influence further clinical decision making regarding therapy, particularly when tumor serum markers may be a less reliable indicator of disease burden after repeated treatments.

Multiple myeloma international staging system: "staging" or simply "aging" system?

Because of the wide variation in multiple myeloma (MM) survival, numerous studies have focused over the past 40 years on the biological and cytogenetic prognostic values in MM patients. Since 2005, the MM International Staging System (ISS) has recognized the combination of beta-2 microglobulin (β2M) with serum albumin (SA) concentrations as the most simple and potent combination to determine the prognosis in MM patients. Curiously, the reasons for the efficiency of the combination of β2M with SA remain not clear-cut. In 2007, Fonseca and San Miguel (Prognostic factors and staging in multiple myeloma. Hematol Oncol Clin North Am 2007; 21:1115-40) underlined that cytogenetic assessment might also be useful for evaluating MM prognosis. Furthermore, new perspectives recently appeared with the genomic approach. Here, we (1) question the specific rationale for β2M and SA as prognostic markers in MM, (2) emphasize the well-documented prognostic implications of β2M and SA as potent biomarkers of comorbidity in older adults, and (3) conclude that the current MM-ISS is rather a staging system for age-related comorbidity burden (ie, aging system) than a specific MM staging system, and should not be used alone. Thus, we suggest that: (1) cytogenetics with the superscript MM-ISS could be the standard method; (2) some factors discovered using genomics could reflect the comorbidity burden and the intrinsic malignancy of MM clone, and thus needs more investigation; and (3) while waiting for standard genomic classification.

Unrelated donor allogeneic hematopoietic cell transplantation is underused as a curative therapy in eligible patients from the United States

Allogeneic hematopoietic cell transplantation (alloHCT) is a curative therapy for hematologic disorders including acute lymphoblastic and myeloid leukemia, chronic lymphocytic and myeloid leukemia, Hodgkin's and non-Hodgkin lymphoma, multiple myeloma, and myelodysplastic syndrome. To determine the utilization of alloHCT from unrelated donors (URDs) in the United States, we calculated the number of patients diagnosed with hematologic disorders age 20 to 74 years based on 2004 to 2008 Surveillance, Epidemiology and End Results and 2007 US Census data, estimated the percentage of patients who would be eligible for URD alloHCT after discounting the mortality rate during induction therapy and the rate of severe comorbidities, and compared these with the actual 2007 alloHCTs facilitated by the National Marrow Donor Program. We found that the number of URD alloHCT as a percentage of the estimated potential transplantations ranged from 11% for multiple myeloma to 54% for chronic myeloid leukemia, with an average percentage of 26% for all the disorders considered. In an analysis stratified by age groups (20 to 44, 45 to 64, and 65 to 74 years), the utilization of URD alloHCT was higher in younger patients than in older patients for all disorders. Of acute lymphoblastic and myeloid leukemia patients, approximately 66% underwent URD alloHCT later in the course of their disease (in second or greater complete remission). URD alloHCT is likely underused for potentially curable hematologic disorders, particularly in older patients. Understanding the reasons for low use of alloHCT may lead to strategies to expand the use of this curative therapy for more patients with hematologic disorders.

Correlation between eight-gene expression profiling and response to therapy of newly diagnosed multiple myeloma patients treated with thalidomide-dexamethasone incorporated into double autologous transplantation

We performed a molecular study aimed at identifying a gene expression profile (GEP) signature predictive of attainment of at least near complete response (CR) to thalidomide-dexamethasone (TD) as induction regimen in preparation for double autologous stem cell transplantation in 112 younger patients with newly diagnosed multiple myeloma. A GEP supervised analysis was performed on a training set of 32 patients, allowing to identify 157 probe sets differentially expressed in patients with CR versus those failing CR to TD. We then generated an eight-gene GEP signature whose performance was subsequently validated in a training set of 80 patients. A correct prediction of response to TD was found in 71 % of the cases analyzed. The eight genes were downregulated in patients who achieved CR to TD. Comparisons between post-autotransplantation outcomes of the 44 non-CR-predicted patients and of the 36 CR-predicted patients showed that this latter subgroup had a statistically significant benefit in terms of higher rate of CR after autotransplant(s) and longer time to progression, event-free survival, and overall survival. These results can be an important first step to identify at diagnosis those patients who will respond more favourably to a particular treatment strategy.

Microcalorimetry of blood serum proteome: a modified interaction network in the multiple myeloma case

Hereby we report on a novel approach in the study of multiple myeloma (MM), namely, differential scanning calorimetry (DSC) combined with serum protein electrophoresis. Distinct thermodynamic signatures describe the DSC thermograms of MM blood sera, in contrast to the unique profile found for healthy individuals. The thermal behavior of MM sera reflects a complex interplay between the serum concentration and isotype of the M protein and of albumin, and modified ligand- and/or protein-protein interactions, resulting in stabilization of globulins and at least a fraction of albumin. In all MM cases the 85 °C, transferrin-assigned transition is missing. A distinct feature of IgG isotype (κ and λ) DSC profiles only is the presence of a transition at 82 °C. A DSC-based classification of MM depicts two sets of melting patterns (MMt2 and MMt3 with two or three successive thermal transitions), and subsets within each set (MMt2(i) or MMt3(i), the subscript i = 1, 2 or 3 denotes the main transition being one of the three transitions). The results demonstrate the potential of DSC to monitor MM-related modifications of the serum proteome, even at low M protein concentrations, Bence Jones and importantly nonsecretory multiple myeloma cases, and prove DSC as a versatile tool for oncohematology.

Genetic markers used for risk stratification in multiple myeloma

While no specific genetic markers are required in the diagnosis of multiple myeloma (MM), multiple genetic abnormalities and gene signatures are used in disease prognostication and risk stratification. This is particularly important for the adequate identification of the high-risk MM group, which does not benefit from any of the current therapies, and novel approaches need to be proposed. Fluorescence in situ hybridization (FISH) has been employed for establishing risk-based stratification and still remains the most used genetic technique in the clinical routine. The incorporation of gene expression profiling (GEP) in the study of MM has shown to be a very powerful test in the patient stratification, but its incorporation in clinical routine depends on some technical and logistic resolutions. Thus, FISH still remains the gold standard test for detecting genomic abnormalities and outcome discrimination in MM.

Risk stratification in the era of novel therapies

Multiple myeloma (MM) is an heterogeneous disease and this concept, together with the recent discovery of new drugs with novel mechanisms of action, will lead to the design of individualized treatments. The term "high-risk MM" includes those patients with at least one of the following features: deletion of 17p or t(4;14) or t(14;16), detected by fluorescence in situ hybridization analysis; deletion of 13q detected by conventional cytogenetics; or hypodiploidy or complex karyotype. In addition, patients with high proliferative activity of plasma cells (> or = 3%) measured by the PC labeling index or S-phase by flow cytometry as well as those with a poor response to induction therapy are also high risk. The definition of high-risk MM has been based on patients treated with conventional drugs with or without autologous transplant. However, current data suggest that novel agents can overcome the initial adverse prognosis of deletion 13q and t(4;14) but probably not that of 17p deletion, at least when using immunomodulatory drugs. Nevertheless, the number of patients analyzed is rather limited and, more important, time to progression is only available in a small number of studies. On the basis of these data, it is probably premature to mandate specific therapies on the basis of cytogenetic abnormalities. Moreover, it is possible that the more intensive therapies selected for high-risk patients may be of even greater benefit to standard-risk cases. Accordingly, at present, although we discourage treatment of high-risk patients with conventional schedules, we recommend to include them in large cooperative trials based on novel agents and performing a comprehensive genetic analysis up-front, so that the patients benefiting most from each treatment can subsequently be identified.

Transcription factor MIST1 in terminal differentiation of mouse and human plasma cells

Despite their divergent developmental ancestry, plasma cells and gastric zymogenic (chief) cells share a common function: high-capacity secretion of protein. Here we show that both cell lineages share increased expression of a cassette of 269 genes, most of which regulate endoplasmic reticulum (ER) and Golgi function, and they both induce expression of the transcription factors X-box binding protein 1 (Xbp1) and Mist1 during terminal differentiation. XBP1 is known to augment plasma cell function by establishing rough ER, and MIST1 regulates secretory vesicle trafficking in zymogenic cells. We examined morphology and function of plasma cells in wild-type and Mist1(-/-) mice and found subtle differences in ER structure but no overall defect in plasma cell function, suggesting that Mist1 may function redundantly in plasma cells. We next reasoned that MIST1 might be useful as a novel and reliable marker of plasma cells. We found that MIST1 specifically labeled normal plasma cells in mouse and human tissues, and, moreover, its expression was also characteristic of plasma cell differentiation in a cohort of 12 human plasma cell neoplasms. Overall, our results show that MIST1 is enriched upon plasma cell differentiation as a part of a genetic program facilitating secretory cell function and also that MIST1 is a novel marker of normal and neoplastic plasma cells in mouse and human tissues.

MicroRNAs regulate critical genes associated with multiple myeloma pathogenesis

Progress in understanding the biology of multiple myeloma (MM), a plasma cell malignancy, has been slow. The discovery of microRNAs (miRNAs), a class of small noncoding RNAs targeting multiple mRNAs, has revealed a new level of gene expression regulation. To determine whether miRNAs play a role in the malignant transformation of plasma cells (PCs), we have used both miRNA microarrays and quantitative real time PCR to profile miRNA expression in MM-derived cell lines (n = 49) and CD138+ bone marrow PCs from subjects with MM (n = 16), monoclonal gammopathy of undetermined significance (MGUS) (n = 6), and normal donors (n = 6). We identified overexpression of miR-21, miR-106b approximately 25 cluster, miR-181a and b in MM and MGUS samples with respect to healthy PCs. Selective up-regulation of miR-32 and miR-17 approximately 92 cluster was identified in MM subjects and cell lines but not in MGUS subjects or healthy PCs. Furthermore, two miRNAs, miR-19a and 19b, that are part of the miR-17 approximately 92 cluster, were shown to down regulate expression of SOCS-1, a gene frequently silenced in MM that plays a critical role as inhibitor of IL-6 growth signaling. We also identified p300-CBP-associated factor, a gene involved in p53 regulation, as a bona fide target of the miR106b approximately 25 cluster, miR-181a and b, and miR-32. Xenograft studies using human MM cell lines treated with miR-19a and b, and miR-181a and b antagonists resulted in significant suppression of tumor growth in nude mice. In summary, we have described a MM miRNA signature, which includes miRNAs that modulate the expression of proteins critical to myeloma pathogenesis.

Multiple myeloma and immunosecretory disorders: an update

The immunosecretory disorders are a diverse group of diseases associated with proliferation of an abnormal clone of immunoglobulin (Ig)-synthesizing, terminally differentiated B cells. These disorders include multiple myeloma (MM) and its variants, plasmacytoma, Waldenstrom macroglobulinemia, monoclonal gammopathy of undetermined significance, and monoclonal Ig deposition diseases, the latter including primary amyloidosis and nonamyloidotic types. These disorders are histologically composed of plasma cells, or plasmacytoid cells which produce Ig that is synthesized and usually secreted and can be deposited in some diseases. The Ig can be complete or can be composed of either heavy or light chains and is termed M-(monoclonal) protein. In MM, this proliferation overwhelms the normal cellular counterparts that synthesize and secrete appropriate levels of Ig. Immunosecretory disorders have been classified in multiple schemes, mostly morphologic, to such a degree that the classification of these entities has become a challenge to pathologists. The World Health Organization classification in 2001 was helpful because it provided specific clinicopathologic criteria for diagnosis. However, terms such as "progressive" disease were not well defined. In 2003, the International Myeloma Group defined MM as a disease with related organ and tissue injury, serving to better explain progressive in terms of deterioration of organ (renal, bone, and bone marrow) function over time. Therefore, modern classification of immunosecretory diseases is based on integration of clinical, morphologic, laboratory, radiographic, and biologic (including molecular) parameters, which we review here.

Incorporation of the bone marker carboxy-terminal telopeptide of type-1 collagen improves prognostic information of the International Staging System in newly diagnosed symptomatic multiple myeloma

Several prognostic markers, including parameters of tumor burden and cytogenetics, were adopted to identify high-risk patients in multiple myeloma (MM). Recently, the International Staging System (ISS), including beta2-microglobulin (beta2M) and albumin, was introduced for patients with symptomatic MM. As bone disease is a hallmark of MM, we investigated the prognostic impact of the bone resorption marker carboxy-terminal telopeptide of type-1 collagen (ICTP) in combination with ISS, beta2M, albumin, deletion of chromosome 13 and high-dose therapy (HDT) in 100 patients with newly diagnosed symptomatic MM. beta2M alone, albumin alone, ISS, HDT, del(13q14) and ICTP were significant prognostic factors for overall survival (OS). In a multivariate analysis, ICTP was the most powerful prognostic factor (log-rank P<0.001, hazard ratio: ninefold increase). ICTP clearly separated two subgroups with a good and a worse prognosis within each of the three ISS stages (ISS I: P=0.027, ISS II: P=0.022, ISS III: P=0.013). Incorporation of ICTP in a combined ICTP-ISS score significantly (P<0.001) separated four risk groups with a 5-year OS rate of 95, 64, 46 and 22%, [corrected] respectively. These data demonstrate for the first time that the inclusion of the collagen-I degradation product ICTP, as a biomarker of bone resorption, adds to the prognostic value of ISS.