Genetic aberrations and survival in plasma cell leukemia

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.

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.

The genetic architecture of multiple myeloma

Multiple myeloma is a malignant proliferation of monoclonal plasma cells leading to clinical features that include hypercalcaemia, renal dysfunction, anaemia, and bone disease (frequently referred to by the acronym CRAB) which represent evidence of end organ failure. Recent evidence has revealed myeloma to be a highly heterogeneous disease composed of multiple molecularly-defined subtypes each with varying clinicopathological features and disease outcomes. The major division within myeloma is between hyperdiploid and nonhyperdiploid subtypes. In this division, hyperdiploid myeloma is characterised by trisomies of certain odd numbered chromosomes, namely, 3, 5, 7, 9, 11, 15, 19, and 21 whereas nonhyperdiploid myeloma is characterised by translocations of the immunoglobulin heavy chain alleles at chromosome 14q32 with various partner chromosomes, the most important of which being 4, 6, 11, 16, and 20. Hyperdiploid and nonhyperdiploid changes appear to represent early or even initiating mutagenic events that are subsequently followed by secondary aberrations including copy number abnormalities, additional translocations, mutations, and epigenetic modifications which lead to plasma cell immortalisation and disease progression. The following review provides a comprehensive coverage of the genetic and epigenetic events contributing to the initiation and progression of multiple myeloma and where possible these abnormalities have been linked to disease prognosis.

Treatment with bortezomib-based regimens improves overall response and predicts for survival in patients with primary or secondary plasma cell leukemia: Analysis of the Greek myeloma study group

Plasma cell leukemia (PCL) is a rare and aggressive plasma cell disorder, with poor outcome. Bortezomib-based regimens (BBR) are highly effective in myeloma, but there is limited information about their efficacy and safety in PCL. Thus, we retrospectively collected data from 42 consecutive PCL patients (25 with primary PCL-pPCL and 17 with secondary PCL-sPCL) to explore the role of BBR in this entity. BBR were administered in 29 of 42 patients, while 6 of 25 patients with pPCL underwent autologous transplantation. Objective response (≥partial response) was significantly higher in patients treated with BBR versus conventional therapies (69% vs. 30.8%, P = 0.04); 27.5% of patients treated with BBR achieved at least very good partial response (vgPR). The highest ORR was observed in pPCL patients treated with BBR (88.9%; ≥vgPR: 33.3%). In BBR-group, grade 3 of 4 hematological, neurological and renal toxicity and neutropenic infections were observed in 41.4%, 7%, 3.4%, and 31%, respectively. With a median follow-up of 51 months, median overall survival (OS) for patients treated with BBR versus conventional therapies was 13 versus 2 months (P < 0.007). Median OS of patients with pPCL and sPCL treated with BBR was 18 and 7 months, respectively (P < 0.001). In the multivariate analysis normal PLTs, treatment with BBR and high quality response were the only powerful predictors for survival. Our study carrying the longest reported median follow-up, demonstrated that treatment of PCL with BBR induces high response rates and prolongs survival over conventional therapies, regardless of additional autologous transplantation rescue or established high risk features, with manageable toxicity.

Two cases of nonsecretory multiple myeloma presenting as primary plasma cell leukemia

Plasma cell leukemia (PCL) is a rare variant of multiple myeloma (MM) with a poor prognosis. Nonsecretory myeloma is also a rare form of MM characterized by the absence of detectable M-protein in the serum and urine. This report describes two cases of nonsecretory PCL. The first patient was an 85-year-old man in whom the lack of monoclonal immunoglobulins made it difficult to make a diagnosis because the malignant cells showed an atypical morphology. He died of rapid disease progression before starting chemotherapy. The second patient was a 78-year-old woman whose tumor cells displayed a typical plasma cell morphology. She was successfully treated with bortezomib-containing chemotherapy.

Decoding the pathophysiology and the genetics of multiple myeloma to identify new therapeutic targets

In recent years, significant progress has been achieved in the characterization of the transcriptional profiles, gene mutations and structural chromosomal lesions in myeloma cells. These studies have identified many candidate therapeutic targets, which are recurrently deregulated in myeloma cells. However, these targets do not appear, at least individually, to represent universal driver(s) of this disease. Furthermore, evaluation of these recurrent lesions does not suggest that they converge to a single molecular pathway. Detailed integration of molecular and functional data for these candidate targets and pathways will hopefully dissect which of them play more critical roles for each of the different individual molecular defined subtypes of this disease. This review focuses on how recent updates in our understanding of myeloma pathogenesis and molecular characterization may impact ongoing and future efforts to develop new therapeutics for this disease.

Survival of >20 years in a myeloma patient with an unusual combination of t(14;16) and hyperdiploidy: A case report

The current case report presents the prolonged survival of >20 years in a myeloma patient with secondary plasma cell leukemia and myelomatous pleural effusion. FISH on marrow plasma cells showed hyperdiploidy and concomitant t(14;16) and karyotypes predicting superior and short survival. The possibility of primary hyperdiploidy with t(14;16) as a secondary event has been discussed.

Plasma cell leukaemia and HIV co-infection: profile of patients and experience at Universitas Academic Hospital in Bloemfontein, South Africa

Plasma cell leukaemia (PCL) is a rare condition with high mortality. HIV-positive patients have a propensity to develop malignancy; however, the occurrence of PCL with HIV infection in South Africa has not been documented. We describe patients with PCL in Universitas Hospital in Bloemfontein, South Africa, and report two new cases of HIV infection concurrent with PCL. A retrospective case series of PCL patients (2006-2012) seen at our Clinical Haematology unit is reported. Patient files were used to obtain information. The median age of patients (n = 9) was 51 years, and 66.7 % of cases were of African ethnicity. The condition was equally distributed between genders. Two patients were HIV positive. Both received combination antiretroviral therapy. The diagnosis of PCL was usually made as an incidental finding, subsequently confirmed on bone marrow aspirate and trephine. Deranged haematological and biochemical parameters, including severe anaemia, hypoalbuminaemia, and hyper-cellular bone marrow, were observed. Only one patient improved markedly on treatment, and remains alive at the time of writing. PCL shows poor response to treatment and predominates among Africans. The small sample size made it difficult to determine whether co-infection with HIV was a coincidental finding or the two diseases are pathophysiologically linked.

Transient Plasmacytosis With Trisomy of Chromosome 8 in a Patient With Multiple Myeloma: A Case Report

A 96-year-old woman with a 5-year history of multiple myeloma was admitted to our hospital because of increasing fatigue and fever. Bone marrow plasma cell analysis showed t(11;14), del(13q), and del(17p13). Her condition deteriorated, and she developed plasmacytosis resembling plasma cell leukemia. Chromosome analysis showed trisomy of chromosome 8 in the circulating plasma cells. The plasmacytosis resolved spontaneously without chemotherapy after about 5 weeks, and the trisomy became undetectable. The findings suggest that trisomy 8 might have contributed to the transient plasmacytosis, and that chromosome 8 carries genes associated with plasma cell proliferation, maturation, and apoptosis.

Biclonal light chain gammopathy with aberrant CD33 expression in secondary plasma cell leukemia

Plasma cell leukemia is a rare neoplastic proliferation of circulating plasma cells. Clonal proliferations of plasma cells, such as in plasma cell leukemia or plasma cell myeloma, are typically characterized by production of a monoclonal heavy and/or light chain immunoglobulin. We present a case of a secondary plasma cell leukemia arising from plasma cell myeloma with dual expression of lambda and kappa light chains along with aberrant expression of CD33, CD20, and dim CD56. This case emphasizes the importance of recognizing aberrant immunophenotypes in plasma cell leukemias and represents the first reported case of biclonal light chain expression in a secondary plasma cell leukemia.

Biological and clinical relevance of miRNA expression signatures in primary plasma cell leukemia

PURPOSE

Primary plasma cell leukemia (pPCL) is a rare and very aggressive form of plasma cell dyscrasia. To date, no information on microRNA (miRNA) expression in pPCL has been reported. This study aimed at investigating the involvement of miRNAs in pPCL and their possible relationship with higher tumor aggressiveness.

EXPERIMENTAL DESIGN

Global miRNA expression profiles were analyzed in highly purified malignant plasma cells from 18 pPCL untreated patients included in a prospective clinical trial. MiRNA expression patterns were evaluated in comparison with a representative series of multiple myeloma patients, in relation to the most recurrent chromosomal abnormalities (as assessed by fluorescence in situ hybridization and single-nucleotide polymorphism-array analysis), and in association with clinical outcome. MiRNA expression was also integrated with gene expression profiles in pPCL and multiple myeloma samples.

RESULTS

We identified a series of deregulated miRNAs in pPCL (42 upregulated and 41 downregulated) in comparison with multiple myeloma. Some of them, on the basis of their reported functions and putative target genes computed by integrative analysis, might have a role in the pathobiology of pPCL. As regards chromosomal aberrations, the expression of some miRNAs mapped to hotspot altered regions was associated with DNA copy number of the corresponding loci. Finally, 4 miRNA (miR-497, miR-106b, miR-181a*, and miR-181b) were identified as having expression levels that correlated with treatment response, and 4 (miR-92a, miR-330-3p, miR-22, and miR-146a) with clinical outcome.

CONCLUSIONS

Overall, our study provides insights into the possible contribution of miRNAs in the pathogenesis of pPCL and suggests targets for future therapeutic investigations.

Importance of epigenetic changes in cancer etiology, pathogenesis, clinical profiling, and treatment: what can be learned from hematologic malignancies?

Epigenetic alterations represent a key cancer hallmark, even in hematologic malignancies (HMs) or blood cancers, whose clinical features display a high inter-individual variability. Evidence accumulated in recent years indicates that inactivating DNA hypermethylation preferentially targets the subset of polycomb group (PcG) genes that are regulators of developmental processes. Conversely, activating DNA hypomethylation targets oncogenic signaling pathway genes, but outcomes of both events lead in the overexpression of oncogenic signaling pathways that contribute to the stem-like state of cancer cells. On the basis of recent evidence from population-based, clinical and experimental studies, we hypothesize that factors associated with risk for developing a HM, such as metabolic syndrome and chronic inflammation, trigger epigenetic mechanisms to increase the transcriptional expression of oncogenes and activate oncogenic signaling pathways. Among others, signaling pathways associated with such risk factors include pro-inflammatory nuclear factor κB (NF-κB), and mitogenic, growth, and survival Janus kinase (JAK) intracellular non-receptor tyrosine kinase-triggered pathways, which include signaling pathways such as transducer and activator of transcription (STAT), Ras GTPases/mitogen-activated protein kinases (MAPKs)/extracellular signal-related kinases (ERKs), phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR), and β-catenin pathways. Recent findings on epigenetic mechanisms at work in HMs and their importance in the etiology and pathogenesis of these diseases are herein summarized and discussed. Furthermore, the role of epigenetic processes in the determination of biological identity, the consequences for interindividual variability in disease clinical profile, and the potential of epigenetic drugs in HMs are also considered.

Management of newly diagnosed symptomatic multiple myeloma: updated Mayo Stratification of Myeloma and Risk-Adapted Therapy (mSMART) consensus guidelines 2013

Multiple myeloma remains an incurable neoplasm of plasma cells that affects more than 20,000 people annually in the United States. There has been a veritable revolution in this disease during the past decade, with dramatic improvements in our understanding of its pathogenesis, the development of several novel agents, and a concomitant doubling in overall survival. Because multiple myeloma is a complex and wide-ranging disorder, its management must be guided by disease- and patient-related factors; emerging as one of the most influential factors is risk stratification, primarily based on cytogenetic features. A risk-adapted approach provides optimal therapy to patients, ensuring intense therapy for aggressive disease and minimizing toxic effects, providing sufficient but less intense therapy for low-risk disease. This consensus statement reflects recommendations from more than 20 Mayo Clinic myeloma physicians, providing a practical approach for newly diagnosed patients with myeloma who are not enrolled in a clinical trial.

Molecular pathogenesis of multiple myeloma: basic and clinical updates

Multiple myeloma is divided into two distinct genetic subtypes based on chromosome content. Hyperdiploid myeloma is characterized by multiple trisomies of chromosomes 3, 5, 7, 9 11, 15, 19 and 21, and lacks recurrent immunoglobulin gene translocations. Non-hyperdiploid myeloma in contrast is characterized by chromosome translocations t(4;14), t(14;16), t(14;20), t(6;14) and t(11;14). A unifying event in the pathogenesis of multiple myeloma is the dysregulated expression of a cyclin D gene, either directly by juxtaposition to an immunoglobulin enhancer, as a result of ectopic expression of a MAF family transcription factor, or indirectly by as yet unidentified mechanisms. Secondary genetic events include rearrangements of MYC, activating mutations of NRAS, KRAS or BRAF, a promiscuous array of mutations that activate NFkB and deletions of 17p. Among the poor-risk genetic features are t(4;14), t(14;16), t(14;20), del 17p and gains of 1q. Available evidence supports the use of a risk-stratified approach to the treatment of patients with multiple myeloma, with the early and prolonged use of bortezomib particularly in patients with t(4;14) and del 17p.

Stringent complete remission of primary plasma cell leukemia with reduced-dose bortezomib, lenalidomide and dexamethasone: a case report and review of the literature

Plasma cell leukemia (PCL) is an aggressive variant of multiple myeloma characterized by a high level of plasma cells circulating in the peripheral blood. The prognosis of PCL patients treated with conventional chemotherapy remains poor. Some reports have suggested that both bortezomib and lenalidomide are effective in treating PCL. We herein report a case of primary PCL in which the patient achieved stringent complete remission after receiving combination chemotherapy with reduced-dose bortezomib, lenalidomide and dexamethasone (VRd). This regimen was very effective, and no severe adverse events were observed. A reduced-dose VRd regimen can be considered in PCL patients.

Genome-wide analysis of primary plasma cell leukemia identifies recurrent imbalances associated with changes in transcriptional profiles

Primary plasma cell leukemia (pPCL) is a rare, yet aggressive form of de novo plasma cell tumor, distinct from secondary PCL (sPCL) which represents a leukemic transformation of pre-existing multiple myeloma (MM). Herein, we performed a comprehensive molecular analysis of a prospective series of pPCLs by means of FISH, single nucleotide polymorphism (SNP) array and gene expression profiling (GEP). IGH@ translocations were identified in 87% of pPCL cases, with prevalence of t(11;14) (40%) and t(14;16) (30.5%), whereas the most frequent numerical alterations involved 1p (38%), 1q (48%), 6q (29%), 8p (42%), 13q (74%), 14q (71%), 16q (53%), and 17p (35%). We identified a minimal biallelic deletion (1.5 Mb) in 8p21.2 encompassing the PPP2R2A gene, belonging to a family of putative tumor suppressors and found to be significantly down-regulated in deleted cases. Mutations of TP53 were identified in four cases, all but one associated with a monoallelic deletion of the gene, whereas activating mutations of the BRAF oncogene occurred in one case and were absent in N- and K-RAS. To evaluate the influence of allelic imbalances in transcriptional expression we performed an integrated genomic analysis with GEP data, showing a significant dosage effect of genes involved in transcription, translation, methyltransferase activity, apoptosis as well as Wnt and NF-kB signaling pathways. Overall, we provide a compendium of genomic alterations in a prospective series of pPCLs which may contribute to improve our understanding of the pathogenesis of this aggressive form of plasma cell dyscrasia and the mechanisms of tumor progression in MM.

Plasma cell leukemia: consensus statement on diagnostic requirements, response criteria and treatment recommendations by the International Myeloma Working Group

Plasma cell leukemia (PCL) is a rare and aggressive variant of myeloma characterized by the presence of circulating plasma cells. It is classified as either primary PCL occurring at diagnosis or as secondary PCL in patients with relapsed/refractory myeloma. Primary PCL is a distinct clinic-pathological entity with different cytogenetic and molecular findings. The clinical course is aggressive with short remissions and survival duration. The diagnosis is based upon the percentage (≥ 20%) and absolute number (≥ 2 × 10(9)/l) of plasma cells in the peripheral blood. It is proposed that the thresholds for diagnosis be re-examined and consensus recommendations are made for diagnosis, as well as, response and progression criteria. Induction therapy needs to begin promptly and have high clinical activity leading to rapid disease control in an effort to minimize the risk of early death. Intensive chemotherapy regimens and bortezomib-based regimens are recommended followed by high-dose therapy with autologous stem cell transplantation if feasible. Allogeneic transplantation can be considered in younger patients. Prospective multicenter studies are required to provide revised definitions and better understanding of the pathogenesis of PCL.

Improving overall survival and overcoming adverse prognosis in the treatment of cytogenetically high-risk multiple myeloma

Multiple myeloma (MM) is a heterogeneous disease with certain genetic features [e.g., t(4;14), del17p] associated with worse outcome. The introduction of thalidomide, lenalidomide, and bortezomib has dramatically improved the outlook for patients with MM, but their relative benefit (or harm) for different genetic patient subgroups remains unclear. Unfortunately, the small number of patients in each subgroup frequently limits the analysis of high-risk patients enrolled in clinical trials. Strategies that result in survival of high-risk genetic subgroups approximating that of patients lacking high-risk features are said to overcome the poor prognostic impact of these high-risk features. This outcome has been difficult to achieve, and studies in this regard have so far been limited by inadequate sample size. In contrast, strategies that compare the survival of high-risk genetic subgroups randomized to different treatment arms can identify approaches that improve survival. This type of analysis is clinically useful, even if the absolute gains do not improve outcomes to levels seen in patients without high-risk cytogenetics. Reviewing available data in high-risk MM from this perspective, it appears that bortezomib has frequently been associated with improved survival, whereas thalidomide maintenance has sometimes been associated with a shorter survival.

Synthetic miR-34a mimics as a novel therapeutic agent for multiple myeloma: in vitro and in vivo evidence

PURPOSE

Deregulated expression of miRNAs has been shown in multiple myeloma (MM). A promising strategy to achieve a therapeutic effect by targeting the miRNA regulatory network is to enforce the expression of miRNAs that act as tumor suppressor genes, such as miR-34a.

EXPERIMENTAL DESIGN

Here, we investigated the therapeutic potential of synthetic miR-34a against human MM cells in vitro and in vivo.

RESULTS

Either transient expression of miR-34a synthetic mimics or lentivirus-based miR-34a-stable enforced expression triggered growth inhibition and apoptosis in MM cells in vitro. Synthetic miR-34a downregulated canonic targets BCL2, CDK6, and NOTCH1 at both the mRNA and protein level. Lentiviral vector-transduced MM xenografts with constitutive miR-34a expression showed high growth inhibition in severe combined immunodeficient (SCID) mice. The anti-MM activity of lipidic-formulated miR-34a was further shown in vivo in two different experimental settings: (i) SCID mice bearing nontransduced MM xenografts; and (ii) SCID-synth-hu mice implanted with synthetic 3-dimensional scaffolds reconstituted with human bone marrow stromal cells and then engrafted with human MM cells. Relevant tumor growth inhibition and survival improvement were observed in mice bearing TP53-mutated MM xenografts treated with miR-34a mimics in the absence of systemic toxicity.

CONCLUSIONS

Our findings provide a proof-of-principle that formulated synthetic miR-34a has therapeutic activity in preclinical models and support a framework for development of miR-34a-based treatment strategies in MM patients.

Molecular pathogenesis of multiple myeloma and its premalignant precursor

Multiple myeloma is a monoclonal tumor of plasma cells, and its development is preceded by a premalignant tumor with which it shares genetic abnormalities, including universal dysregulation of the cyclin D/retinoblastoma (cyclin D/RB) pathway. A complex interaction with the BM microenvironment, characterized by activation of osteoclasts and suppression of osteoblasts, leads to lytic bone disease. Intratumor genetic heterogeneity, which occurs in addition to intertumor heterogeneity, contributes to the rapid emergence of drug resistance in high-risk disease. Despite recent therapeutic advances, which have doubled the median survival time, myeloma continues to be a mostly incurable disease. Here we review the current understanding of myeloma pathogenesis and insight into new therapeutic strategies provided by animal models and genetic screens.

Clinical features and outcomes of plasma cell leukemia: a single-institution experience in the era of novel agents

Plasma cell leukemia (PCL) is a rare hematologic malignancy with aggressive clinical and biologic features. Data regarding its prognosis with the use of the novel agents, i.e., the immunomodulatory drugs thalidomide and lenalidomide, and the proteasome inhibitor bortezomib, are limited. We retrospectively reviewed clinical outcomes, response to therapy, and survival of 17 patients seen at the Penn State Hershey Cancer Institute since the availability of novel agents (2006–2011). Twelve patients had primary PCL (pPCL), and 5 secondary PCL (sPCL). PCL was associated with aggressive clinicobiological features, such as high-risk cytogenetics, elevated serum beta-2-microglobulin and lactate dehydrogenase, International Staging System stage III, and rapid relapse after therapy. With the use of thalidomide, lenalidomide, and bortezomib in 53%, 53%, and 88% patients, respectively, median overall survival (OS) was 18 months in the whole group (95% confidence interval, 11–21 months), and 21 and 4 months in pPCL and sPCL, respectively (P=0.015). OS was inferior to that of 313 consecutive patients with multiple myeloma (MM) treated in the same period, even when compared with a subset of 47 MM with high-risk cytogenetics. Although our data are limited by the small sample size, we conclude that novel agents may modestly improve survival in patients with PCL, when compared to historical controls. Novel therapies do not seem to overcome the negative prognosis of PCL as compared with MM.

How I treat plasma cell leukemia

Primary plasma cell leukemia (pPCL) is a rare and aggressive plasma cell proliferative disorder with a very poor prognosis and with distinct biologic, clinical, and laboratory features. Compared with multiple myeloma, pPCL presents more often with extramedullary involvement, anemia, thrombocytopenia, hypercalcemia, elevated serum β(2)-microglobulin and lactate dehydrogenase levels, as well as impaired renal function. Many of the genetic aberrations observed in newly diagnosed pPCL are typically found in advanced multiple myeloma. These cytogenetic abnormalities and mutations lead to increased proliferation, enhanced inhibition of apoptosis, escape from immune surveillance, and independence from the BM microenvironment, with changes in expression of adhesion molecules or chemokine receptors. The outcome of pPCL has improved with the introduction of autologous stem cell transplantation and combination approaches with novel agents, including bortezomib and immunomodulatory drugs, such as lenalidomide. In this review, we provide an overview of currently available therapeutic options with recommendations of how these treatment modalities can best be used to improve outcome for plasma cell leukemia patients.

Cell death via DR5, but not DR4, is regulated by p53 in myeloma cells

Myeloma cells are sensitive to TRAIL through the two death receptors DR4 and DR5. Because p53 directly modulates expression of death receptors, we investigated here whether p53 can modulate myeloma sensitivity to TRAIL. We found that p53 affects the sensitivity of myeloma cells to the DR5 agonistic human antibody lexatumumab but not the DR4 antibody mapatumumab. TP53 wild-type myeloma cells overexpressed DR5 in correlation with sensitivity to lexatumumab. Both nongenotoxic (nutlin-3a) and genotoxic (melphalan) p53-inducing stresses increased DR5 expression only in TP53 wild-type cells and synergistically increased lexatumumab efficiency yet did not increase DR4 expression, nor sensitivity to mapatumumab. Silencing of p53 strongly decreased DR5 expression and induced resistance to nutlin-3a and lexatumumab but did not modulate DR4 expression or sensitivity to mapatumumab. Increase of lexatumumab efficiency induced by nutlin-3a was related to a p53-dependent increase of DR5 expression. In primary myeloma cells, nutlin-3a increased DR5 expression and lexatumumab efficiency but did not increase mapatumumab efficiency. Taken together, our findings indicate that p53 controls the sensitivity of myeloma through DR5 but not DR4 and suggest that a subset of patients with multiple myeloma may benefit from DR5 therapy.

Whole-genome sequencing of multiple myeloma from diagnosis to plasma cell leukemia reveals genomic initiating events, evolution, and clonal tides

The longitudinal evolution of a myeloma genome from diagnosis to plasma cell leukemia has not previously been reported. We used whole-genome sequencing (WGS) on 4 purified tumor samples and patient germline DNA drawn over a 5-year period in a t(4;14) multiple myeloma patient. Tumor samples were acquired at diagnosis, first relapse, second relapse, and end-stage secondary plasma cell leukemia (sPCL). In addition to the t(4;14), all tumor time points also shared 10 common single-nucleotide variants (SNVs) on WGS comprising shared initiating events. Interestingly, we observed genomic sequence variants that waxed and waned with time in progressive tumors, suggesting the presence of multiple independent, yet related, clones at diagnosis that rose and fell in dominance. Five newly acquired SNVs, including truncating mutations of RB1 and ZKSCAN3, were observed only in the final sPCL sample suggesting leukemic transformation events. This longitudinal WGS characterization of the natural history of a high-risk myeloma patient demonstrated tumor heterogeneity at diagnosis with shifting dominance of tumor clones over time and has also identified potential mutations contributing to myelomagenesis as well as transformation from myeloma to overt extramedullary disease such as sPCL.

Hematopoietic cell transplantation for primary plasma cell leukemia: results from the Center for International Blood and Marrow Transplant Research

There is limited data on hematopoietic cell transplantation (HCT) in primary plasma cell leukemia (pPCL), an aggressive plasma cell disorder. We report outcomes of 147 patients with pPCL receiving autologous (n=97) or allogeneic (n=50) HCT within 18 months after diagnosis between 1995 and 2006. Median age was 56 years and 48 years for autologous HCT and allogeneic HCT respectively. Progression-free survival (PFS) at 3 years was 34% (95% CI, 23%-46%) in the autologous group and 20% (95% CI, 10%-34%) in the allogeneic group. Cumulative incidence of relapse at 3 years was 61% (95% CI, 48%-72%) in the autologous group and 38% (95% CI, 25%-53%) in the allogeneic group. Overall survival (OS) at 3 years was 64% (95% CI, 52%-75%) in the autologous group and 39% (95% CI, 26%-54%) in the allogeneic group. Non-relapse mortality (NRM) at 3 years was 5% (95% CI, 1-11%) in the autologous group and 41% (95% CI, 28%-56%) in the allogeneic group. The encouraging OS after autologous HCT, establishes the safety and feasibility of this consolidative treatment option after initial induction therapy for pPCL. Allogeneic HCT, although associated with a significantly lower relapse rate, carries a much higher risk of NRM and no overall survival benefit.

Frontline chemotherapy with bortezomib-containing combinations improves response rate and survival in primary plasma cell leukemia: a retrospective study from GIMEMA Multiple Myeloma Working Party

BACKGROUND

The best therapeutic approach for primary plasma cell leukemia (PPCL) remains unknown so far. In very limited studies, the poor clinical outcome of this aggressive variant of multiple myeloma seemed to be ameliorated by the use of the proteasome inhibitor bortezomib. Aiming to provide more consolidated data, this multicenter retrospective survey focused on unselected and previously untreated PPCL patients who had received bortezomib as frontline therapy.

PATIENTS AND METHODS

Twenty-nine patients with PPCL were collected. Bortezomib was given at standard doses and schedules, in various combinations with dexamethasone, thalidomide, doxorubicin, melphalan, prednisone, vincristine, and cyclophosphamide.

RESULTS

An overall response rate of 79% was observed, with 38% of at least very good partial remission. Grade 3-4 hematological, neurological, infectious, and renal toxic effects occurred in 20%, 21%, 16%, and 4% of patients, respectively. After a median follow-up of 24 months, 16 patients were alive (55%), 12 of whom were in remission phase and 4 relapsed. The best long-term results were achieved in patients who received stem-cell transplantation after bortezomib induction.

CONCLUSION

Bortezomib, used as initial therapy, is able to increase the percentage and the quality of responses in PPCL patients, producing a significant improvement of survival.

Chromosome abnormalities defined by conventional cytogenetics in plasma cell leukemia: what have we learned about its biology?

Cancer cells are characterized by having chromosomal abnormalities. The number of aberrations and the specific chromosomes affected are likely correlated with tumor progression. In this study, we analyzed the karyotype of 126 plasma cell leukemia (PCL) patients to identify the most frequently occurring imbalances and to design a model of karyotypic evolution. The Mitelman database of chromosome was searched and abnormal karyotypes were assessed. The main clones were analyzed and chromosomal gains and losses were used to design a model of genetic acquisition based on the calculation of a variable called time to occurrence. Our comprehensive study of genetic abnormalities of a large number of PCL karyotypes suggests that PCL is mainly characterized by the presence of whole chromosome losses as well as IgH rearrangements which is similar to that observed in non-hyperdiploid multiple myeloma (MM). Temporal analysis suggests that most PCL have around 10 abnormalities at diagnosis. It is possible that accumulation of abnormalities such as 17p13 (TP53) and 1p losses may trigger the extramedullary features of PCL. Our study demonstrates that cytogenetics is a valuable tool to evaluate the role of genetic imbalances on karyotypic evolution by using a mathematical model.

Clinical outcomes of patients with plasma cell leukemia in the era of novel therapies and hematopoietic stem cell transplantation strategies: a single-institution experience

BACKGROUND

PCL carries a poor prognosis and the optimal management remains unknown.

PATIENTS AND METHODS

To evaluate the outcome of patients with PCL in the era of novel agents and innovative transplantation strategies, we conducted a review of patients with PCL who were treated at our institution from August 2003 to October 2009. Our primary endpoint was to determine overall survival, which was calculated from time of PCL diagnosis to death or last follow-up. Secondary endpoints included response rates and analyses regarding how the novel agents and presence of adverse cytogenetic analyses affected outcomes.

RESULTS

We identified 25 patients with PCL (13 with primary PCL [pPCL], 12 with secondary PCL [sPCL]) from our institution. Eighteen patients received bortezomib-based regimens, 19 received high-dose melphalan followed by autologous hematopoietic stem cell transplantation (HCT), and 6 underwent allogeneic HCT. The median overall survival for all patients was 23.6 months. Bortezomib-treated patients had a median survival of 28.4 months vs. 4.0 months for the non-bortezomib-treated group (P < .001).

CONCLUSIONS

Our analysis suggests that patients with PCL who were treated with bortezomib and/or allogeneic HCT had improved outcomes.

Plasma cell myeloma and related neoplasms

Session 1 of the 2009 Workshop of the Society for Hematopathology/European Association of Haematopathology, Cleveland, OH, focused on plasma cell neoplasms. This report summarizes the salient diagnostic, clinical, and genetic features of plasma cell myeloma (PCM) and related neoplasms. Based on the cases submitted to the workshop, we highlight common diagnostic issues and unusual manifestations of plasma cell neoplasms, such as t(11;14)+ PCM, plasma cell leukemia, and nonsecretory plasmacytoma, as well as plasmablastic transformation of PCM. Additional issues repeatedly raised at the workshop included the differential diagnosis of extramedullary dissemination of PCM vs primary extramedullary plasmacytoma and plasmablastic lymphoma; systemic plasma cell neoplasms in immunocompromised people; and Epstein-Barr virus-associated plasma cell neoplasms. Difficult cases with borderline features presented by submitters emphasized the necessity of integrating clinical, immunophenotypic, and genetic features for appropriate classification of these disorders.

Primary plasma cell leukemia in the era of new drugs: has something changed?

Primary plasma cell leukemia (PPCL) is a rare and aggressive variant of multiple myeloma. This disease is associated with a very poor prognosis, and unfortunately it has not significantly improved during the last three decades. Autologous stem cell transplantation is generally recommended in eligible patients, but survival in transplanted PPCL patients is significantly lower than that of multiple myeloma. Recent preliminary data indicate that new drugs, in particular lenalidomide and bortezomib, could significantly improve the clinical outcome of PPCL, increasing response rate and duration, as well as survival. In this review we report an updated literature analysis about the current therapeutic scenario of PPCL, with a particular focus on the use of novel agents.

Treatment of multiple myeloma

The treatment of multiple myeloma has changed dramatically in the past decade. The increase in the number of active agents has generated numerous possible drug combinations that can be used in the first-line and relapsed settings. As a result, there is considerable confusion about the choice of regimens for initial therapy, role of transplantation in the era of new drugs, end points for therapy, and the role of maintenance therapy. A hotly debated area is whether treatment approaches should achieve cure or disease control, which impacts greatly on the treatment strategy employed. This article provides an update on the treatment of multiple myeloma, with a focus on recent advances, newly diagnosed disease, role of transplantation and maintenance therapy. A synthesized approach to the treatment of myeloma is presented, along with a discussion of key paradigms that need to be challenged.

Plasma cell leukemia

Plasma cell leukemia (PCL) is a rare, yet aggressive plasma cell (PC) neoplasm, variant of multiple myeloma (MM), characterized by high levels of PCs circulating in the peripheral blood. PCL can either originate de novo (primary PCL) or as a secondary leukemic transformation of MM (secondary PCL). Presenting signs and symptoms are similar to those seen in MM such as renal insufficiency, hypercalcemia, lytic bone lesions, anemia, and thrombocytopenia, but can also include hepatomegaly and splenomegaly. The diagnostic evaluation of a patient with suspected PCL should include a review of the peripheral blood smear, bone marrow aspiration and biopsy, serum protein electrophoresis (SPEP) with immunofixation, and protein electrophoresis of an aliquot from a 24h urine collection (UPEP). The diagnosis is made when a monoclonal population of PCs is present in the peripheral blood with an absolute PC count exceeding 2000/μL and PC comprising 20% or more of the peripheral blood white cells. The prognosis of PCL is poor with a median survival of 7 to 11 months. Survival is even shorter (2 to 7 months) when PCL occurs in the context of refractory or relapsing MM. There have been no prospective randomized trials investigating the treatment of PCL. Recommendations are primarily based upon data from small retrospective series, case reports, and extrapolation of data from patients with MM. In general, patients are treated with induction therapy followed by hematopoietic cell transplantation (HCT) in those who are appropriate candidates for this approach. The best induction regimen for PCL is not known and there is great variability in clinical practice. Newer agents that are being incorporated into frontline and salvage therapy for MM have also demonstrated activity in PCL such as Immunomodulatory agents and the use of bortezomib with different combinations.

Primary plasma cell leukemia: a retrospective multicenter study of 73 patients

BACKGROUND

Epidemiological and clinical information on primary plasma cell leukemia (pPCL) are rarely reported. The aims are to evaluate the clinical features, prognostic factors, and efficacy of treatments in pPCL.

PATIENTS AND METHODS

A multicenter retrospective cohort study was carried out from January 2000 to December 2008 in 26 Italian hematology divisions. A total of 128 cases of plasma cell leukemia were collected, and 73 of them (57%) were classified as primary (male/female 43/30).

RESULTS

Sixty-four patients had at least 1 sign of end-organ damage and 10 had extramedullary localization. One patient died early; of the remaining patients, 36 (50%) received anthracycline-based regimens as first-line therapy, 17 (24%) single alkylating agents, and 30 (42%) bortezomib or thalidomide as additional (n = 11) or unique treatments (n = 19). Twenty-three patients (31%) underwent autologous and/or allogeneic hematopoietic stem cell transplantation (HSCT). The median overall survival (OS) was 12.6 months; complete or partial response was achieved in 22 (30%) and 18 patients (25%), respectively; the median duration of response (DOR) was 16.4 months. HSCT patients had a longer OS and DOR (median 38.1 and 25.8 months, respectively) compared with nontransplanted patients (9.1 and 7.3 months, respectively, P < 0.001). OS was influenced by nonresponse to treatment, hypoalbuminemia, and HSCT. DOR was favorably influenced only by HSCT.

CONCLUSIONS

pPCL is an aggressive disease with a poor prognosis and a low response rate to conventional therapy. HSCT is effective, increasing OS and DOR by 69% and 88%, respectively. The use of bortezomib and thalidomide may improve outcomes.

Many multiple myelomas: making more of the molecular mayhem

Multiple myeloma (MM) is malignancy of isotype-switched, BM-localized plasma cells that frequently results in bone destruction, BM failure, and death. Important molecular subgroups are identified by three classes of recurrent immunoglobulin gene translocations and hyperdiploidy, both of which affect disease course. From a clinical standpoint, it is critical to identify MM patients carrying the t(4;14) translocation, which is present in 15% of myelomas and is associated with dysregulation of WHSC1/MMSET and often FGFR3. These patients should all receive bortezomib as part of their initial induction treatment because this has been shown to significantly prolong survival. In contrast, patients with translocations affecting the MAF family of transcription factors, del17p, or gene-expression profiling (GEP)-defined high-risk disease appear to have a worse prognosis that is not dramatically improved by any intervention. These patients should be enrolled in innovative clinical trials. The remaining patients with cyclin D translocations or hyperdiploidy do well with most therapies, and the goal should be to control disease while minimizing toxicity.

Mutated RAS and constitutively activated Akt delineate distinct oncogenic pathways, which independently contribute to multiple myeloma cell survival

We have recently shown that approximately half of primary multiple myeloma (MM) samples display constitutive Akt activity, which disposes them for sensitivity to Akt inhibition. The Akt pathway counts among the signaling conduits for oncogenic RAS and activating mutations of K- and N-RAS frequently occur in MM. We therefore analyzed the relation between RAS mutation and Akt dependency in biopsies and CD138-purified cells from MM patients (n = 65) and the function of oncogenic RAS for MM cell survival in a range of MM cell lines with differing RAS status. Whereas RAS mutations do not predict Akt dependency, oncogenic RAS retains an important role for MM cell survival. Knockdown of either K- or N-RAS strongly decreased the viability of MM cells that harbored the respective oncogenic isoform, whereas ablation of wild-type RAS isoforms had little or no effect. Silencing of oncogenic RAS did not affect the Akt pathway, again indicating lack of a direct link. Combined inhibition of RAS and Akt strongly enhanced MM cell death. These data suggest that oncogenic RAS and Akt may independently contribute to MM cell survival. Targeting of both pathways could provide an attractive therapeutic strategy for patients with oncogenic RAS and dysregulated Akt signaling.