Molecular Pathogenesis of Multiple Myeloma

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.

Chromosome 8q24.1/c-MYC abnormality: a marker for high-risk myeloma

The proto-oncogene c-MYC is rearranged in about 15% of patients with multiple myeloma (MM). We identified 23 patients with MM and c-MYC. Primary objectives were to describe the clinical characteristics, response to therapy, progression-free survival and overall survival (OS). Twelve out of twenty-three patients presented with or progressed to either plasma cell leukemia (PCL) and/or extramedullary disease (EMD). Induction therapy consisted of an immunomodulatory, proteasome inhibitor-based or conventional chemotherapy regimen. Fifteen patients achieved a partial response and three achieved a very good partial response. Sixteen patients received an autologous and one patient an allogeneic hematopoietic stem cell transplant. Median OS from diagnosis was 20.2 months. Patients with PCL or EMD had significantly shorter OS (15.5 vs. 40.4 months, p = 0.0005). This is the first report describing the clinical characteristics of patients with MM and c-MYC. These abnormalities are associated with an aggressive form of MM, high incidence of PCL/EMD and short OS.

High prevalence of immunoglobulin light chain gene aberrations as revealed by FISH in multiple myeloma and MGUS

Multiple myeloma (MM) is a malignant B-cell neoplasm characterized by an uncontrolled proliferation of aberrant plasma cells in the bone marrow. Chromosome aberrations in MM are complex and represent a hallmark of the disease, involving many chromosomes that are altered both numerically and structurally. Nearly half of the cases are nonhyperdiploid and show IGH translocations with the following partner genes: CCND1, FGFR3 and MMSET, MAF, MAFB, and CCND3. The remaining 50% are grouped into a hyperdiploid group that is characterized by multiple trisomies involving chromosomes 3, 5, 7, 9, 11, 15, 19, and 21. In this study, we analyzed the immunoglobulin light chain kappa (IGK, 2p12) and lambda (IGL, 22q11) loci in 150 cases, mostly with MM but in a few cases monoclonal gammopathy of undetermined significance (MGUS), without IGH translocations. We identified aberrations in 27% (= 40 patients) including rearrangements (12%), gains (12%), and deletions (4.6%). In 6 of 18 patients with IGK or/and IGL rearrangements, we detected a MYC rearrangement which suggests that MYC is the translocation partner in the majority of these cases.

Identification of novel pathogenic copy number aberrations in multiple myeloma: the Malaysian context

Background

Multiple myeloma is an incurable disease. Little is known about the genetic and molecular mechanisms governing the pathogenesis of multiple myeloma. The risk of multiple myeloma predispositions varies among different ethnicities. More than 50% of myeloma cases showed normal karyotypes with conventional cytogenetic analysis due to the low mitotic activity and content of plasma cells in the bone marrow. In the present study, high resolution array comparative genomic hybridization technique was used to identify copy number aberrations in 63 multiple myeloma patients of Malaysia.

Results

Copy number aberrations were identified in 100% of patients analyzed (n = 63). Common chromosomal gains were detected at regions 1q, 2q, 3p, 3q, 4q, 5q, 6q, 8q, 9q, 10q, 11q, 13q, 14q, 15q, 21q and Xq while common chromosomal losses were identified at regions 3q and 14q. There were a total of 25 and 5 genes localized within the regions of copy number gains and losses, respectively (>30% penetrance). The LYST, CLK1, ACSL1 and NFKBIA are genes localized within the copy number aberration regions and they represent novel information that has never been previously described in multiple myeloma patients.

Conclusions

In general, due to the differences in genetic background, dietary and lifestyle practices of Malaysian compared to the Caucasian population, these chromosomal alterations might be unique for Asian MM patients. Genes identified in this study could be potential molecular therapeutic targets for the treatment and management of patients with multiple myeloma.

Immunomodulation as a therapeutic strategy in the treatment of multiple myeloma

Growth and survival of multiple myeloma (MM) cells depend on intrinsic, cell-autonomous parameters, such as the genetic lesions harboured by the MM cells, as well as extracellular, cell-non-autonomous factors, including the interaction between MM cells and bone-marrow stromal cells and the suppression of the host's anticancer immune responses. Thalidomide and the immunomodulatory agents lenalidomide and pomalidomide have pleiotropic effects on MM cells and their microenvironment, including promotion of direct mechanisms of MM-cell apoptosis, as well as indirect mechanisms mediated by perturbation of cell adhesion, modulation of cytokine production, and inhibition of tumor-associated angiogenesis. The immunomodulatory properties of these agents are mediated by effects on T-cell proliferation and function, stimulation of natural killer cells, and inhibition of regulatory T cells. Thalidomide and lenalidomide have established roles in the treatment of patients with newly diagnosed MM and those with relapsed/refractory disease. Pomalidomide is currently being evaluated in clinical trials, and preliminary clinical data suggest that it is active in patients with MM that is refractory to lenalidomide and bortezomib treatment. This article provides an overview of the current and potential future roles of immunomodulation in the management of MM, and how improved anticancer immune responses may improve treatment outcomes.

TRIM13 (RFP2) downregulation decreases tumour cell growth in multiple myeloma through inhibition of NF Kappa B pathway and proteasome activity

Multiple myeloma (MM) is an incurable neoplasm caused by proliferation of malignant plasma cells in the bone marrow (BM). MM is characterized frequently by a complete or partial deletion of chromosome 13q14, seen in more than 50% of patients at diagnosis. Within this deleted region the tripartite motif containing 13 (TRIM13, also termed RFP2) gene product has been proposed to be a tumour suppressor gene (TSG). Here, we show that low expression levels of TRIM13 in MM are associated with chromosome 13q deletion and poor clinical outcome. We present a functional analysis of TRIM13 using a loss-of-function approach, and demonstrate that TRIM13 downregulation decreases tumour cell survival as well as cell cycle progression and proliferation of MM cells. In addition, we provide evidence for the involvement of TRIM13 downregulation in inhibiting the NF kappa B pathway and the activity of the 20S proteasome. Although this data does not support a role of TRIM13 as a TSG, it substantiates important roles of TRIM13 in MM tumour survival and proliferation, underscoring its potential role as a novel target for therapeutic intervention.

Conventional and molecular cytogenetic analyses in Turkish patients with multiple myeloma

OBJECTIVE

Multiple myeloma (MM) is characterized by the accumulation and proliferation of malignant plasma cells, secreting monoclonal immunoglobulins and genetic abnormalities in MM have implications for disease progression and survival. In the present study, we investigated the frequency of chromosomal abnormalities (CA) in Turkish patients with MM, using interphase FISH and CC and evaluated the relationship between the rearrangements detected, prognosis and stage of disease.

MATERIAL AND METHODS

We performed conventional cytogenetic and FISH studies in 50 patients to detect chromosome anomalies associated with MM. FISH probes were used to detect 13q14, 13q34, 17p13 deletions, IGH rearrangements, and monosomy and/or trisomy of chromosomes 5, 9, and 15.

RESULTS

CC studies could be performed in 32 of 50 cases and five patients (15.6%) showed chromosomal aberrations while 27 (84.3%) had normal karyotypes. By FISH, eighteen percent (9/50) of cases were found to be normal for all parameters evaluated. Eighty-two percent (41/50) of the patients were positive for at least one abnormality. Chromosome 13 anomalies were detected in 54% (27/50) of cases. The second most common aberration observed is chromosome 15 aberrations (50%).

CONCLUSION

Median survival rate was shorter in patients with one of the abnormalities including chromosome 13 aberrations, IGH rearrangements or P53 deletions. Chromosome 15 aberrations were significantly higher in patients with stage III disease (p=0.02). We conclude that FISH studies should be performed in conjunction with conventional cytogenetic analysis for prognosis in multiple myeloma patients.

Multiple myeloma: current perspectives

Multiple myeloma (MM) is a malignancy of terminally differentiated plasma cells characterized by complex genetic aberrations and heterogeneous outcomes. Over the past 25 years, cytogenetic analysis has played a key role in the diagnosis and management of MM. This article reviews the conventional cytogenetics, molecular cytogenetics, and genomic diagnostics of MM and highlights a few recent clinical trials that demonstrate the impact of genetic risk stratification on the treatment of this plasma cell malignancy.

Soft-Tissue Plasmacytomas in Multiple Myeloma: Incidence, Mechanisms of Extramedullary Spread, and Treatment Approach

We provide an overview on soft-tissue extramedullary plasmacytomas (EMPs) in multiple myeloma (MM). We reviewed the incidence of EMPs in MM, myeloma bone marrow homing, possible mechanisms of extramedullary spread, and prognosis and response to therapy. The incidence of EMPs is 7% to 18% at MM diagnosis and up to 20% at relapse. The current notion that EMPs are more frequent after treatment with novel agents remains to be proven, especially considering that different patterns of disease recurrence can emerge as patients live longer in the era of novel drugs. Bone marrow genetic abnormalities are not associated with extramedullary spread per se, which also suggests that microenvironmental interactions are key. Possible mechanisms of extramedullary spread include decreased adhesion molecule expression and downregulation of chemokine receptors. EMPs usually show plasmablastic morphology with negative CD56 expression. High-dose therapy with autologous stem-cell transplantation (ASCT) can overcome the negative prognostic impact of extramedullary disease in younger selected patients. EMPs do not typically respond to thalidomide alone, but in contrast, responses to bortezomib have been reported. The incidence of EMPs in patients with MM is high and is associated with poor outcome in patients treated conventionally. A potential first-line treatment option seems to be a bortezomib-containing regimen followed by ASCT, whenever possible. Experimental studies on the mechanisms of myeloma cell adhesion, myeloma growth at extramedullary sites, and drug sensitivity are priorities for this area of continuing therapeutic challenge.

Dominant genetic aberrations and coexistent EBV infection in HIV-related oral plasmablastic lymphomas

We present common cytogenetic features in the largest cohort of plasmablastic lymphoma (PBL) of the oral cavity published to date. This cohort included 45 patients, 32 of whom had a known HIV status, of which 31 were HIV positive. Ninety eight per cent of all PBL cases were known to be EBV positive. In line with previous studies, we found that rearrangements of the MYC gene was the most common genetic abnormality seen in 60% of cases with the immunoglobulin heavy chain (IGH) locus as a partner in 51% of cases. Additional complex genetic aberrations were frequent, in particular, an increased copy number of the CCND1 gene was seen in 41% of cases with true amplification of CCND1 in 15% of cases. Aneuploidy was also observed for the BCL6 gene in 28% of cases. Interestingly, rearrangements of both IGH genes were detected in 16% of cases with t(14;18) and t(11;14) respectively involved in conjunction with a t(8;14) in two cases. These bi-allelic IGH rearrangements have not been described before in oral PBL. Our results reinforce the notion that EBV infection and MYC rearrangements are important events in the pathogenesis of oral PBL. The genetic diversity and complexity observed in these cases, underlines the importance to genetically characterise PBL patients at presentation as this may inform the choice of more effective treatment modalities.

The prognostic significance of cytogenetics and molecular profiling in multiple myeloma

Multiple myeloma (MM) is a plasma cell malignancy characterized by very complex cytogenetic and molecular genetic aberrations. In newly diagnosed symptomatic patients, the modal chromosome number is usually either hyperdiploid with multiple trisomies or hypodiploid with one of several types of immunoglobulin heavy chain (Ig) translocations. The chromosome ploidy status and Ig rearrangements are two genetic criteria that are used to help stratify patients into prognostic groups based on the findings of conventional cytogenetics and fluorescence in situ hybridization (FISH). In general, the hypodiploid group with t(4;14)(p16;q32) or t(14;16)(q32;q23) is considered a high-risk group, while the hyperdiploid patients with t(11;14)(q13;q32) are considered a better prognostic group. As the disease progresses, it becomes more proliferative and develops a number of secondary chromosome aberrations. These secondary aberrations commonly involve MYC rearrangements, del(13q), del(17p), and the deletion of 1p and/or amplification of 1q. Of the secondary aberrations, del(17p) is consistently associated with poor prognosis. All of these cytogenetic aberrations and many additional ones are now identified by means of high resolution molecular profiling. Gene expression profiling (GEP), array comparative genomic hybridization (aCGH), and single-nucleotide polymorphism (SNP) arrays have been able to identify novel genetic aberration patterns that have previously gone unrecognized. With the integration of data from these profiling techniques, new subclassifications of MM have been proposed which define distinct molecular genetic subgroups. In this review, the findings from conventional cytogenetics, interphase FISH, GEP, aCGH, and SNP profiles are described to provide the conceptual framework for defining the emerging molecular genetic subgroups with prognostic significance.

Lenalidomide in multiple myeloma: current role and future directions

IMPORTANCE OF THE FIELD

Lenalidomide and other new agents are improving survival of multiple myeloma patients. This review describes current data on lenalidomide in myeloma and how the unique properties of lenalidomide may lend its use in new settings, such as maintenance and preventive therapy.

AREAS COVERED IN THIS REVIEW

This review covers the activity of lenalidomide in multiple myeloma, efficacy in both newly diagnosed and relapsed/refractory patients, how to manage effectively common adverse events observed with lenalidomide, and its potential use in new settings based on clinical trials published up to 2009.

WHAT THE READER WILL GAIN

This review describes the mechanism of action of lenalidomide in myeloma which provides the basis for its clinical use in newly diagnosed, relapsed/refractory, and high-risk smoldering myeloma in combination with other agents. Strategies to reduce or effectively manage myelosuppression and thromboembolic events, the main adverse events associated with lenalidomide plus dexamethasone therapy, are also described.

TAKE HOME MESSAGE

Lenalidomide is an oral immunomodulatory drug that is highly effective in treating multiple myeloma, has a favorable safety profile and is now being evaluated as maintenance therapy, preventive therapy and in combination with other new agents.

Moving toward individualized cancer therapies

In vivo analysis of the gene expression profiles of cancer cells before and after treatment in patients may define mechanisms of sensitivity and resistance to specific drugs and ultimately allow for the selection of optimal individualized therapy to improve outcome in cancer.

Familial multiple myeloma associated with disorders of chronic inflammation: first report from Turkey

Multiple myeloma (MM) is a malignancy arising from mature plasma cells in the bone marrow and usually presents with bone destruction, hypercalcemia, anemia, renal damage, and increased susceptibility to infection. The etiology of MM is unknown, with no established lifestyle, occupational, or environmental risk factors. Because MM is an uncommon disease, etiologic assessments can be difficult. It has been reported to be in association with sarcoidosis, and in a few cases, rheumatoid arthritis. Familial type of MM with an autosomal dominant heredity pattern has also been reported. The genetic loci affected in these cases are still unknown. Herein we present a family with 3 affected cases in an autosomal dominant inheritance pattern. The first case was a man diagnosed to have immunoglobulin (Ig)A-type myeloma at the age of 50. The history revealed 2 more cases in the family: an uncle diagnosed to have unsecretory-type myeloma at the age of 76 and a cousin (the daughter of the affected uncle) who was diagnosed at the age of 48 years to have IgG-type myeloma and did not respond to therapy. This patient also had a history of sarcoidosis preceding the diagnosis of myeloma. All other affected family members had been treated for dental-oral infection (including chronic gingivitis) for 3 and 4 years before the diagnosis of myeloma. Karyotype analysis revealed pseudohypodiploidy and deletion of chromosome 13q in only the patient with coexisting sarcoidosis. To our knowledge, this is the first report on familial myeloma from Turkey. This family enhances the role of hereditary factors and chronic inflammation in the etiology of MM.

Biologic and genetic characterization of the novel amyloidogenic lambda light chain-secreting human cell lines, ALMC-1 and ALMC-2

Primary systemic amyloidosis (AL) is a rare monoclonal plasma cell (PC) disorder characterized by the deposition of misfolded immunoglobulin (Ig) light chains (LC) in vital organs throughout the body. To our knowledge, no cell lines have ever been established from AL patients. Here we describe the establishment of the ALMC-1 and ALMC-2 cell lines from an AL patient. Both cell lines exhibit a PC phenotype and display cytokine-dependent growth. Using a comprehensive genetic approach, we established the genetic relationship between the cell lines and the primary patient cells, and we were also able to identify new genetic changes accompanying tumor progression that may explain the natural history of this patient's disease. Importantly, we demonstrate that free lambda LC secreted by both cell lines contained a beta structure and formed amyloid fibrils. Despite absolute Ig LC variable gene sequence identity, the proteins show differences in amyloid formation kinetics that are abolished by the presence of Na(2)SO(4). The formation of amyloid fibrils from these naturally secreting human LC cell lines is unprecedented. Moreover, these cell lines will provide an invaluable tool to better understand AL, from the combined perspectives of amyloidogenic protein structure and amyloid formation, genetics, and cell biology.