Genetic aberrations including chromosome 1 abnormalities and clinical features of plasma cell leukemia

Clinical and cytogenetic characteristics of primary and secondary plasma cell leukemia under the new IMWG definition criteria: a retrospective study

BACKGROUND

Plasma cell leukemia (PCL) is a rare and aggressive plasma cell disorder, exhibiting a more unfavorable prognosis than multiple myeloma. PCL is classified into pPCL and sPCL. Recently, the IMWG has recommended new PCL definition criteria, which require the presence of ≥5% circulating plasma cells in peripheral blood smears. Due to its low incidence, research on pPCL and sPCL is limited.

METHODS

We conducted a retrospective study and analyzed clinical and cytogenetic data of pPCL and sPCL patients. Overall survival (OS) and progression-free survival (PFS) were assessed by the Kaplan-Meier method, and survival distributions were compared using the log-rank test.

RESULTS

This is a small cohort comprising 23 pPCL and 9 sPCL patients. Notably, sPCL patients showed a higher incidence of extramedullary infiltration and a higher percentage of bone marrow plasma cells (p = 0.015 and 0.025, respectively). Although no significant difference was found between the two groups in OS and PFS, a trend emerged suggesting a superior survival outcome for pPCL patients, with a higher cumulative 1-year PFS rate (38.3% vs. 13.3%) and a lower early mortality rate (mortality rate at 3 months: 15% vs. 33%). We also suggested that pPCL patients carrying t(11;14) may have a longer median survival time than individuals with other cytogenetic abnormalities, but this was not confirmed due to the small sample size.

CONCLUSION

Our study revealed clinical and cytogenetic features of pPCL and sPCL patients according to the new diagnostic criteria. The findings suggested a generally better prognosis for pPCL than sPCL and the likelihood of t(11;14) translocation acting as a favorable prognostic factor in pPCL. It is important to note that our study had a limited sample size, which may lead to bias. We hope well-designed studies can be conducted to provide more results.

IgE Plasma Cell Leukemia Harboring t(11;14) and 1q Amplification

IgE plasma cell neoplasm is the rarest subtype of plasma cell neoplasms and is known for its poor prognosis and high incidence of t(11;14). However, t(11;14) has been classified as a standard-risk rather than high-risk cytogenetic abnormality in multiple myeloma. We have been unable to explain the discrepancy that the hallmark of IgE plasma cell neoplasm with a poor prognosis is a standard-risk cytogenetic abnormality. Here, we report a case of IgE primary plasma cell leukemia with extramedullary lesions of the liver, stomach, and lymph nodes. Plasma cell infiltration was pathologically confirmed in each organ. Cytogenetic analysis of plasma cells revealed t(11;14) and amplification of 1q21. Chemotherapy, with immunomodulatory imide drugs, proteasome inhibitors, and CD38 antibodies, was unsuccessful. In IgE plasma cell neoplasm, coexistence of other cytogenetic abnormalities with t(11;14) may be important. Investigating the presence of cytogenetic abnormalities coexisting with t(11;14) is not only useful for evaluating prognosis but also important for understanding the pathogenesis of the disease. Recently, venetoclax, an oral BCL2 inhibitor, has demonstrated promising efficacy in plasma cell neoplasm patients harboring t(11;14). Development of an effective venetoclax-based regimen for treating aggressive IgE plasma cell neoplasm with t(11;14) is expected.

Primary plasma cell leukemia in Latin America: demographic, clinical, and prognostic characteristics. A study of GELAMM group

Primary plasma cell leukemia (pPCL) is an infrequent and aggressive plasma cell disorder. The prognosis is still very poor, and the optimal treatment remains to be established. A retrospective, multicentric, international observational study was performed. Patients from 9 countries of Latin America (LATAM) with a diagnosis of pPCL between 2012 and 2020 were included. 72 patients were included. Treatment was based on thalidomide in 15%, proteasome inhibitors (PI)-based triplets in 38% and chemotherapy plus IMIDs and/or PI in 29%. The mortality rate at 3 months was 30%. The median overall survival (OS) was 18 months. In the multivariate analysis, frontline PI-based triplets, chemotherapy plus IMIDs and/or PI therapy, and maintenance were independent factors of better OS. In conclusion, the OS of pPCL is still poor in LATAM, with high early mortality. PI triplets, chemotherapy plus IMIDs, and/or PI and maintenance therapy were associated with improved survival.

Update on primary plasma cell leukemia

Plasma cell leukemia (PCL) is a rare and highly aggressive plasma cell neoplasm developing in 0.5?4% of patients with multiple myeloma (MM). The diagnostic criteria were recently revised from 20% to ≥5% of circulating plasma cells in peripheral blood smears. PCL is classified as primary or secondary; primary PCL is when it presents in patients with no MM. Primary PCL shows clinical and laboratory features at presentation that differ from MM and exhibits a dismal prognosis even with the use of effective agents against MM. Therefore, intensive chemotherapy should be initiated immediately after diagnosis, and autologous stem cell transplantation is recommended for transplant-eligible patients. Maintenance therapy after transplantation may reduce the rate of early relapses. We reviewed the definitions of PCL, revised diagnostic criteria, clinical features, and appropriate initial treatments for primary PCL.

Identification of High-Risk Multiple Myeloma With a Plasma Cell Leukemia-Like Transcriptomic Profile

Primary plasma cell leukemia (pPCL) is an aggressive subtype of multiple myeloma, which is distinguished from newly diagnosed multiple myeloma (NDMM) on the basis of the presence of ≥ 20% circulating tumor cells (CTCs). A molecular marker for pPCL is currently lacking, which could help identify NDMM patients with high-risk PCL-like disease, despite not having been recognized as such clinically.

Genomics of Plasma Cell Leukemia

Simple Summary

Plasma cell leukemia (PCL) is a very aggressive plasma cell disorder with a dismal prognosis, despite the therapeutic progress made in the last few years. The implementation of genomic high-throughput technologies in the clinical setting has revealed new insights into the genomic landscape of PCL, some of which may have an impact on the development of novel therapeutic approaches. The purpose of this review is to provide a comprehensive overview and update of the genomic studies carried out in PCL.

Abstract

Plasma cell leukemia (PCL) is a rare and highly aggressive plasma cell dyscrasia characterized by the presence of clonal circulating plasma cells in peripheral blood. PCL accounts for approximately 2–4% of all multiple myeloma (MM) cases. PCL can be classified in primary PCL (pPCL) when it appears de novo and in secondary PCL (sPCL) when it arises from a pre-existing relapsed/refractory MM. Despite the improvement in treatment modalities, the prognosis remains very poor. There is growing evidence that pPCL is a different clinicopathological entity as compared to MM, although the mechanisms underlying its pathogenesis are not fully elucidated. The development of new high-throughput technologies, such as microarrays and new generation sequencing (NGS), has contributed to a better understanding of the peculiar biological and clinical features of this disease. Relevant information is now available on cytogenetic alterations, genetic variants, transcriptome, methylation patterns, and non-coding RNA profiles. Additionally, attempts have been made to integrate genomic alterations with gene expression data. However, given the low frequency of PCL, most of the genetic information comes from retrospective studies with a small number of patients, sometimes leading to inconsistent results.

Primary Plasma Cell Leukemia displaying t(11;14) have specific genomic, transcriptional and clinical feature

Primary plasma cell leukemia (pPCL) is an aggressive form of multiple myeloma (MM) that has not benefited from recent therapeutic advances in the field. Because very rare and heterogeneous, it remains poorly understood at the molecular level. To address this issue, we performed DNA and RNA sequencing of sorted plasma cells from a large cohort of 90 newly diagnosed pPCL, and compared to MM. We observed that pPCL presents a specific genomic landscape with a high prevalence of t(11;14) (about half) and high-risk genomic features such as del(17p), gain 1q, del(1p32). In addition, pPCL displays a specific transcriptome when compared to MM. We then aimed at specifically characterize pPCL with t(11;14). We observed that this sub-entity displayed significantly fewer adverse cytogenetic abnormalities. This translated into better overall survival when compared to pPCL without t(11;14) (39.2 months vs 17.9 months, p=0.002). Finally, pPCL with t(11;14) displayed a specific transcriptome, including differential expression of BCL2 family members. This study is the largest series of patients with pPCL reported so far.

The Cytogenetic Profile of Primary and Secondary Plasma Cell Leukemia: Etiopathogenetic Perspectives, Prognostic Impact and Clinical Relevance to Newly Diagnosed Multiple Myeloma with Differential Circulating Clonal Plasma Cells

Plasma cell leukemia (PCL) is a rare and aggressive plasma cell dyscrasia that may appear as de-novo leukemia (pPCL) or on the basis of a pre-existing multiple myeloma (MM), called secondary plasma cell leukemia (sPCL). In this prospective study, we have applied a broad panel of FISH probes in 965 newly diagnosed MM (NDMM) and 44 PCL cases of both types to reveal the particular cytogenetic differences among the three plasma cell dyscrasias. In order to evaluate the frequency and patterns of clonal evolution, the same FISH panel was applied both at diagnosis and at the time of first relapse for 81 relapsed MM patients and both at MM diagnosis and during sPCL transformation for the 19 sPCL cases described here. pPCL was characterized by frequent MYC translocations and t(11;14) with a 11q13 breakpoint centered on the MYEOV gene, not commonly seen in MM. sPCL had a higher number of FISH abnormalities and was strongly associated with the presence of del(17p13), either acquired at the initial MM stage or as a newly acquired lesion upon leukemogenesis in the context of the apparent clonal evolution observed in sPCL. In clinical terms, sPCL showed a shorter overall survival than pPCL with either standard or high-risk (t(4;14) and/or t(14;16) and/or del(17p13) and/or ≥3 concomitant aberrations) abnormalities (median 5 months vs. 21 and 11 months respectively, p < 0.001), suggesting a prognostic stratification based on cytogenetic background. These observations proved relevant in the NDMM setting, where higher levels of circulating plasma cells (CPCs) were strongly associated with high-risk cytogenetics (median frequency of CPCs: 0.11% of peripheral blood nucleated cells for high-risk vs. 0.007% for standard-risk NDMM, p < 0.0001). Most importantly, the combined evaluation of CPCs (higher or lower than a cut-off of 0.03%), together with patients’ cytogenetic status, could be used for an improved prognostic stratification of NDMM patients.

Plasma cell leukemia: A review of the molecular classification, diagnosis, and evidenced-based treatment

Plasma cell leukemia is a rare and aggressive plasma cell dyscrasia associated with dismal outcomes. It may arise de novo, primary plasma cell leukemia, or evolve from an antecedent diagnosis of multiple myeloma, secondary plasma cell leukemia. Despite highly effective therapeutics, survival for plasma cell leukemia patients remains poor. Molecular knowledge of plasma cell leukemia has recently expanded with use of gene expression profiling and whole exome sequencing, lending new insights into prognosis and therapeutic development. In this review, we describe the molecular knowledge, clinical characteristics, evidenced-based therapeutic approaches and treatment outcomes of plasma cell leukemia.

Multiple Extramedullary-Bone Related and/or Extramedullary Extraosseous Are Independent Poor Prognostic Factors in Patients With Newly Diagnosed Multiple Myeloma

Background

Extramedullary (EM) lesions are common in multiple myeloma (MM) and are often related to the poor prognosis of MM but are scarcely understood.

Methods

In this retrospective study, the baseline characteristics of 357 newly diagnosed patients with extramedullary multiple myeloma (EMM) and their impact on the prognosis were analyzed. All patients received first-line treatment with bortezomib-based regimen.

Results

The overall incidence rate of EM was 22.4%, and the detection rate of PET/CT was significantly higher than other imaging methods (P = 0.015). The cohorts consisted of 10 cases of extramedullary extraosseous (EME) and 70 cases of extramedullary-bone related (EMB), including 53 cases with single site involvement (one case with EME) and 27 cases with multiple sites (>1 site) involvement (nine cases with EME). EMM patients had high levels of hemoglobin (Hgb, ≥10 g/dl) and serum lactate dehydrogenase (LDH, >245u/L) and are inclined to early-stage revised international staging system (R-ISS). Compared to patients without EM, those with EMM had worse progression-free survival (PFS) (P = 0.014) and overall survival (OS) (P = 0.032). In addition, patients without EM and those with a single site of EMB had similar PFS and OS, while patients with multiple sites of EMB or EME and multiple sites of EMB with EME had poor PFS and OS. Multivariate analysis confirmed that multiple sites of EMB and/or EME were independent prognostic predictors affecting PFS and OS in newly diagnosed MM patients.

Conclusions

This study suggested that among patients treated with bortezomib-based regimens, multiple sites of EMB and/or EME are independent poor prognostic factors for newly diagnosed MM patients, while a single site of EMB does not affect the survival of newly diagnosed MM patients. Thus, these findings could be used as a reference for the study of EMM patients in the new drug era, but prospective clinical studies are needed to provide evidence-based data for the diagnosis and treatment of EMM.

A clinical perspective on plasma cell leukemia; current status and future directions

Primary plasma cell leukemia (pPCL) is an aggressive plasma cell disorder with a guarded prognosis. The diagnosis is confirmed when peripheral blood plasma cells (PCs) exceed 20% of white blood cells or 2000/μL. Emerging data demonstrates that patients with lower levels of circulating (PCs) have the same adverse prognosis, challenging the clinical disease definition, but supporting the adverse impact of circulating PCs. The cornerstone of treatment consists of combination therapy incorporating a proteasome inhibitor, an immunomodulatory agent, steroids, and/or anthracyclines and alkylators as part of more-intensive chemotherapy, followed by consolidative autologous hematopoietic cell transplantation in eligible patients and then maintenance therapy. Monoclonal antibodies are also currently being evaluated in this setting with a strong rationale for their use based on their activity in multiple myeloma (MM). Due to limited therapeutic studies specifically evaluating pPCL, patients with pPCL should be considered for clinical trials. In contrast to MM, the outcomes of patients with pPCL have only modestly improved with novel therapies, and secondary PCL arising from MM in particular is associated with a dismal outlook. Newer drug combinations, immunotherapy, and cellular therapy are under investigation, and these approaches hopefully will demonstrate efficacy to improve the prognosis of pPCL.

Tumour Dissemination in Multiple Myeloma Disease Progression and Relapse: A Potential Therapeutic Target in High-Risk Myeloma

Simple Summary

Like in solid cancers, the process of dissemination is a critical feature of disease progression in the blood cancer multiple myeloma. At diagnosis, myeloma patients have cancer that has spread throughout the bone marrow, with patients with more disseminatory myeloma having worse outcomes for their disease. In this review, we discuss the current understanding of the mechanisms that underpin the dissemination process in multiple myeloma. Furthermore, we discuss the potential for the use of therapies that target the dissemination process as a novel means of improving outcomes for multiple myeloma patients.

Abstract

Multiple myeloma (MM) is a plasma cell (PC) malignancy characterised by the presence of MM PCs at multiple sites throughout the bone marrow. Increased numbers of peripheral blood MM PCs are associated with rapid disease progression, shorter time to relapse and are a feature of advanced disease. In this review, the current understanding of the process of MM PC dissemination and the extrinsic and intrinsic factors potentially driving it are addressed through analysis of patient-derived MM PCs and MM cell lines as well as mouse models of homing and dissemination. In addition, we discuss how patient cytogenetic subgroups that present with highly disseminated disease, such as t(4;14), t(14;16) and t(14;20), suggest that intrinsic properties of MM PC influence their ability to disseminate. Finally, we discuss the possibility of using therapeutic targeting of tumour dissemination to slow disease progression and prevent overt relapse.

Hematopoietic cell transplantation utilization and outcomes for primary plasma cell leukemia in the current era

The outcomes of patients with primary plasma cell leukemia (pPCL) after undergoing hematopoietic cell transplantation (HCT) in the novel agent era are unknown. We report outcomes of 348 patients with pPCL receiving autologous (auto-) HCT (n = 277) and allogeneic (allo-) HCT (n = 71) between 2008 and 2015. Median age was 60 years and 56 years for auto- and allo-HCT respectively. For auto-HCT, the 4-year outcomes were: non-relapse mortality (NRM) 7% (4-11%), relapse (REL) 76% (69-82%), progression-free survival (PFS) 17% (13-23%), and overall survival (OS) 28% (22-35%). Karnofsky performance status (KPS) > 90 and ≥very good partial response (VGPR) predicted superior OS in multi-variate analysis for auto-HCT. For allo-HCT, the 4-year outcomes were: NRM 12% (5-21%), REL 69% (56-81%), PFS 19% (10-31%), and OS 31% (19-44%). Compared with prior CIBMTR pPCL patients (1995-2006), inferior survival was noted in the current cohort (3-year OS, 39% vs. 38% in allo-HCT, and 62% vs. 35% in auto-HCT) respectively. However, we noted an increased HCT utilization, from 12% (7-21%) in 1995 to 46% (34-64%) in 2009 using SEER data (available till 2009). Despite modern induction translating to higher proportion receiving HCT, the outcomes remain poor in pPCL patients, mainly derived by high relapse rates post-HCT.

Germline Risk Contribution to Genomic Instability in Multiple Myeloma

Genomic instability, a well-established hallmark of human cancer, is also a driving force in the natural history of multiple myeloma (MM) - a difficult to treat and in most cases fatal neoplasm of immunoglobulin producing plasma cells that reside in the hematopoietic bone marrow. Long recognized manifestations of genomic instability in myeloma at the cytogenetic level include abnormal chromosome numbers (aneuploidy) caused by trisomy of odd-numbered chromosomes; recurrent oncogene-activating chromosomal translocations that involve immunoglobulin loci; and large-scale amplifications, inversions, and insertions/deletions (indels) of genetic material. Catastrophic genetic rearrangements that either shatter and illegitimately reassemble a single chromosome (chromotripsis) or lead to disordered segmental rearrangements of multiple chromosomes (chromoplexy) also occur. Genomic instability at the nucleotide level results in base substitution mutations and small indels that affect both the coding and non-coding genome. Sometimes this generates a distinctive signature of somatic mutations that can be attributed to defects in DNA repair pathways, the DNA damage response (DDR) or aberrant activity of mutator genes including members of the APOBEC family. In addition to myeloma development and progression, genomic instability promotes acquisition of drug resistance in patients with myeloma. Here we review recent findings on the genetic predisposition to myeloma, including newly identified candidate genes suggesting linkage of germline risk and compromised genomic stability control. The role of ethnic and familial risk factors for myeloma is highlighted. We address current research gaps that concern the lack of studies on the mechanism by which germline risk alleles promote genomic instability in myeloma, including the open question whether genetic modifiers of myeloma development act in tumor cells, the tumor microenvironment (TME), or in both. We conclude with a brief proposition for future research directions, which concentrate on the biological function of myeloma risk and genetic instability alleles, the potential links between the germline genome and somatic changes in myeloma, and the need to elucidate genetic modifiers in the TME.

An update on biology, diagnosis and treatment of primary plasma cell leukemia

INTRODUCTION

Primary plasma cell leukemia (PPCL) is one of the most aggressive hematological malignancies. The prognosis of PPCL patients remains poor, although some improvements have been made in recent years. Areas covered: In this review recent clinical and biological advances in PPCL are reported. Some recommendations for the practical management of these patients are provided, with a particular focus on the role of novel agents and transplant procedures. A brief description of the currently ongoing clinical trials with new drugs is also enclosed. Expert opinion: PPCL still represents a difficult challenge for all hematologists. Here the authors provide a personal view on how the current, generally unsatisfactory results in this neoplastic disorder could be improved. In particular, dedicated studies exploring alternative therapies are necessary and eagerly awaited. Such studies should possibly be based on new biological information that could be of help in identifying novel genetic biomarkers for risk stratification and new actionable molecular targets.

Dysregulated Expression of the MicroRNA miR-137 and Its Target YBX1 Contribute to the Invasive Characteristics of Malignant Pleural Mesothelioma

INTRODUCTION

Malignant pleural mesothelioma (MPM) is an aggressive malignancy linked to asbestos exposure. On a genomic level, MPM is characterized by frequent chromosomal deletions of tumor suppressors, including microRNAs. MiR-137 plays a tumor suppressor role in other cancers, so the aim of this study was to characterize it and its target Y-box binding protein 1 (YBX1) in MPM.

METHODS

Expression, methylation, and copy number status of miR-137 and its host gene MIR137HG were assessed by polymerase chain reaction. Luciferase reporter assays confirmed a direct interaction between miR-137 and Y-box binding protein 1 gene (YBX1). Cells were transfected with a miR-137 inhibitor, miR-137 mimic, and/or YBX1 small interfering RNA, and growth, colony formation, migration and invasion assays were conducted.

RESULTS

MiR-137 expression varied among MPM cell lines and tissue specimens, which was associated with copy number variation and promoter hypermethylation. High miR-137 expression was linked to poor patient survival. The miR-137 inhibitor did not affect target levels or growth, but interestingly, it increased miR-137 levels by means of mimic transfection suppressed growth, migration, and invasion, which was linked to direct YBX1 downregulation. YBX1 was overexpressed in MPM cell lines and inversely correlated with miR-137. RNA interference-mediated YBX1 knockdown significantly reduced cell growth, migration, and invasion.

CONCLUSIONS

MiR-137 can exhibit a tumor-suppressive function in MPM by targeting YBX1. YBX1 knockdown significantly reduces tumor growth, migration, and invasion of MPM cells. Therefore, YBX1 represents a potential target for novel MPM treatment strategies.

Prognostic impact of circulating plasma cells in patients with multiple myeloma: implications for plasma cell leukemia definition

The presence of circulating plasma cells in patients with multiple myeloma is considered a marker for highly proliferative disease. In the study herein, the impact of circulating plasma cells assessed by cytology on survival of patients with multiple myeloma was analyzed. Wright-Giemsa stained peripheral blood smears of 482 patients with newly diagnosed myeloma or plasma cell leukemia were reviewed and patients were classified into 4 categories according to the percentage of circulating plasma cells: 0%, 1–4%, 5–20%, and plasma cell leukemia with the following frequencies: 382 (79.2%), 83 (17.2%), 12 (2.5%) and 5 (1.0%), respectively. Median overall survival according to the circulating plasma cells group was 47, 50, 6 and 14 months, respectively. At multivariate analysis, the presence of 5 to 20% circulating plasma cells was associated with a worse overall survival (relative risk 4.9, 95% CI 2.6–9.3) independently of age, creatinine, the Durie-Salmon system stage and the International Staging System (ISS) stage. Patients with ≥5% circulating plasma cells had lower platelet counts (median 86×10⁹/L vs. 214×10⁹/L, P<0.0001) and higher bone marrow plasma cells (median 53% vs. 36%, P=0.004). The presence of ≥5% circulating plasma cells in patients with multiple myeloma has a similar adverse prognostic impact as plasma cell leukemia.

Whole-exome sequencing of primary plasma cell leukemia discloses heterogeneous mutational patterns

Primary plasma cell leukemia (pPCL) is a rare and aggressive form of plasma cell dyscrasia and may represent a valid model for high-risk multiple myeloma (MM). To provide novel information concerning the mutational profile of this disease, we performed the whole-exome sequencing of a prospective series of 12 pPCL cases included in a Phase II multicenter clinical trial and previously characterized at clinical and molecular levels. We identified 1, 928 coding somatic non-silent variants on 1, 643 genes, with a mean of 166 variants per sample, and only few variants and genes recurrent in two or more samples. An excess of C > T transitions and the presence of two main mutational signatures (related to APOBEC over-activity and aging) occurring in different translocation groups were observed. We identified 14 candidate cancer driver genes, mainly involved in cell-matrix adhesion, cell cycle, genome stability, RNA metabolism and protein folding. Furthermore, integration of mutation data with copy number alteration profiles evidenced biallelically disrupted genes with potential tumor suppressor functions. Globally, cadherin/Wnt signaling, extracellular matrix and cell cycle checkpoint resulted the most affected functional pathways. Sequencing results were finally combined with gene expression data to better elucidate the biological relevance of mutated genes. This study represents the first whole-exome sequencing screen of pPCL and evidenced a remarkable genetic heterogeneity of mutational patterns. This may provide a contribution to the comprehension of the pathogenetic mechanisms associated with this aggressive form of PC dyscrasia and potentially with high-risk MM.

Bortezomib, Doxorubicin, Cyclophosphamide, Dexamethasone Induction Followed by Stem Cell Transplantation for Primary Plasma Cell Leukemia: A Prospective Phase II Study of the Intergroupe Francophone du Myélome

PURPOSE

Primary plasma cell leukemia (pPCL) is a rare and aggressive malignancy with a poor prognosis. With conventional chemotherapy, patients typically die within 1 year. In all but one of the retrospective studies reported to date, bortezomib and lenalidomide seem to improve survival. We conducted a prospective phase II trial in patients with pPCL to assess the efficacy of an alternate regimen that combines standard chemotherapy, a proteasome inhibitor, and high-dose melphalan and autologous stem cell transplantation (HDM/ASCT) followed by either allogeneic transplantation or bortezomib/lenalidomide maintenance.

PATIENTS AND METHODS

Patients 70 years old and younger with newly diagnosed pPCL received four alternating cycles of bortezomib, dexamethasone plus doxorubicin or cyclophosphamide. Peripheral blood stem cells were collected from responding patients with < 1% of circulating plasma cells before HDM/ASCT. As consolidation, young patients received a reduced-intensity conditioning allograft, whereas the remaining patients underwent a second HDM/ASCT followed by 1 year of bortezomib, lenalidomide, dexamethasone. The primary end point was progression-free survival (PFS).

RESULTS

Forty patients (median age, 57 years; range, 27 to 71 years) were enrolled. The median follow-up was 28.7 months. In the intention-to-treat analysis, the median PFS and overall survival were 15.1 (95% CI, 8.4; -) and 36.3 (95% CI, 25.6; -) months, respectively. The overall response rate to induction was 69%. One patient underwent a syngeneic allograft and 25 HDM/ASCT (16 of whom subsequently received a reduced-intensity conditioning allograft and seven a second ASCT followed by maintenance).

CONCLUSION

In this prospective trial in patients with pPCL, we show that bortezomib, dexamethasone plus doxorubicin or cyclophosphamide induction followed by transplantation induces high response rates and appears to significantly improve PFS.

Primary plasma cell leukaemia in a 22-year-old woman: A case report

Introduction

Primary plasma cell leukaemia is a rare and highly aggressive disease that is commonly diagnosed a decade earlier than multiple myeloma, at a median age of 55 years. However, it has also been described in younger patients, as documented in this case report. It often presents with hepatosplenomegaly and lymphadenopathy, whilst the presence of bony lesions are less-commonly seen when compared to multiple myeloma.

Case presentation

This report describes the case of a young woman who presented with symptoms of anaemia and a history of menorrhagia. On further careful examination, she was found to have additional signs and symptoms and was later diagnosed with primary plasma cell leukaemia.

Management and outcome

On admission, the patient received supportive care measures, including blood products. At diagnosis, a specific chemotherapy regimen was commenced; however, this failed to induce remission. The decision to continue with supportive care only was made and the patient died seven months later.

Discussion

This case study is presented because of its rarity, the young age of the patient at presentation and the unusual clinical and laboratory findings. Persistent anaemia unresponsive to standard treatment should raise the index of suspicion and further investigations directed to exclude malignancies should be considered.

Molecular Classification and Pharmacogenetics of Primary Plasma Cell Leukemia: An Initial Approach toward Precision Medicine

Primary plasma cell leukemia (pPCL) is a rare and aggressive variant of multiple myeloma (MM) which may represent a valid model for high-risk MM. This disease is associated with a very poor prognosis, and unfortunately, it has not significantly improved during the last three decades. New high-throughput technologies have allowed a better understanding of the molecular basis of this disease and moved toward risk stratification, providing insights for targeted therapy studies. This knowledge, added to the pharmacogenetic profile of new and old agents in the analysis of efficacy and safety, could contribute to help clinical decisions move toward a precision medicine and a better clinical outcome for these patients. In this review, we describe the available literature concerning the genomic characterization and pharmacogenetics of plasma cell leukemia (PCL).

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.

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.

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.

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.

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.

Flow cytometric immunophenotypic characteristics of 36 cases of plasma cell leukemia

Prospective flow cytometric analysis of antigens expression on bone marrow and peripheral blood plasma cells of 36 plasma cell leukemia (PCL) patients enabled to establish the following immunophenotype of leukemic plasma cell: CD38(++), CD138(+), CD54(+), CD49d(+), CD29(+), CD44(+), CD126(+), CD19(-), CD45(-). In one-third of patients PCL cells express CD56, CD71 and CD117. Expression of CD54 on plasma cells was higher as compared to expression of adhesion molecules CD11a, CD18 and CD11b (p<0.01). Expression of CD18, CD11a, CD11b was lower on bone marrow and higher on peripheral blood cells. In conclusion, impaired expression of adhesion molecules such as CD11a/CD18 or CD56 may explain hematogenic dissemination characterizing PCL.

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.

Plasma cell leukaemia and other aggressive plasma cell malignancies

Extramedullary plasma cell cancers, such as plasma cell leukaemia (PCL) and multiple extramedullary plasmacytomas (MEP) are very aggressive malignancies. These can be primary (de-novo) or secondary due to progressive prior multiple myeloma (MM). Recent reports suggest an increase in incidence of these disorders. Compared to MM, organ invasion is common in PCL, while soft tissue tumors involving the head, neck or paraspinal area are common sites for MEP. Markers of poor prognosis are frequently observed in these extramedullary forms of plasma cell cancers, and survival is significantly inferior compared to patients with MM. Conventional chemotherapeutic and radiotherapy approaches have been employed with variable results. Even high dose chemotherapy with autologous stem cell rescue has not been able to demonstrate consistent improvement in survival outcome. Although not specifically evaluated, novel anti-plasma cell agents, such as the proteasome inhibitor bortezomib, and immunomodulatory drugs, such as lenalidomide, appear to be active against these aggressive cancers. Clinical and translational research directed at improved understanding of disease biology and development of novel therapeutics is urgently needed.

Amplification of IGH/CCND1 fusion gene in a primary plasma cell leukemia case

The IGH/CCND1 fusion gene has been reported in many hematologic tumors such as mantle cell lymphoma, chronic lymphocytic leukemia, prolymphocytic leukemia, multiple myeloma, and plasma cell leukemia. We report a case of plasma cell leukemia showing five IGH/CCND1 fusion signals by interphase fluorescence in situ hybridization (FISH). Conventional cytogenetic analysis and multicolor spectral karyotyping showed a complex karyotype that did not include t(11;14). Metaphase FISH studies revealed three IGH/CCND1 fusion signals, two of which were amplified signals. These findings indicate that IGH/CCND1 fusion gene was amplified and interspersed in several chromosomes. The patient was treated with intensive chemotherapy. However, the clinical course was very aggressive. The amplification of the IGH/CCND1 fusion gene may contribute to the aggressive course of the disease. To our knowledge, this is the first case showing amplification of the IGH/CCND1 gene in plasma cell neoplasms.

Frequent upregulation of MYC in plasma cell leukemia

Plasma cell leukemia (PCL) is a rare form of monoclonal gammopathy, which can originate de novo or evolve from multiple myeloma (MM) as a terminal leukemic phase. Previous cytogenetic studies of PCL have reported the presence of complex karyotypes with involvement of multiple unidentified chromosomal regions. We report here the analysis of 12 PCL (10 primary and two secondary) by metaphase and FISH analysis combined with oligonucleotide array data (244 k, Agilent). Interphase-FISH results were compared with those from a series of 861 newly diagnosed patients with MM. Cytogenetic analysis was successful on 11 patients, all of whom showed clonal chromosomal abnormalities. Compared with MM, t(11;14)(q13;q32) (42% versus 15%; P = 0.027) and t(14;16)(q32;q23) (25% versus 4%; P = 0.010) were more frequent in PCL, although neither the specific partner chromosome involved in the IgH translocation nor the ploidy status predicted for survival. Chromosomes 1, 8, 13, and 16 showed the highest number of copy number alterations with 8q24 being the chromosomal region most frequently involved. In eight of 12 patients we found abnormalities (translocations, one amplification, small deletions, and duplications) that directly targeted or were very close to MYC. Only four of these changes were detected by routine FISH analysis using commercial probes with the others exclusively detected by arrays. Quantitative reverse transcription polymerase chain reaction demonstrated that these different abnormalities were associated with increased levels of MYC mRNA. We conclude that MYC dysregulation by complex mechanisms is one of the major molecular events in the oncogenesis of PCL.

Plasma cell leukemia: a highly aggressive monoclonal gammopathy with a very poor prognosis

Plasma cell leukemia (PCL) is an aggressive variant of multiple myeloma and is characterized by the presence of >20% and/or an absolute number of greater 2 x 10(9)/L plasma cells circulating in the peripheral blood. PCL represents approximately 2-4% of all MM diagnosis and exists in two forms: primary PCL (PPCL, 60% of cases) presents de novo, whereas secondary PCL (SPCL, accounts for the remaining 40%) consists of a leukemic transformation in patients with a previously diagnosed MM. Because the mechanisms contributing to the pathogenesis of PCL are not fully understood, immunophenotyping, genetic evaluation (conventional karyotype, FISH, GEP and array-CGH), and immunohistochemistry are really important tools to investigate why plasma cells escape from bone marrow and become highly aggressive. Since treatment with standard agents and steroids is poorly effective, a combination of new drugs as part of the induction regimens and bone marrow transplant (autologous and allogeneic approaches) could nearly overcome the poor prognosis exhibited by PCL patients.

Systemic joint laxity and mandibular range of movement

Primary plasma cell leukemia (pPCL) is a rare and aggressive form of multiple myeloma (MM) that is characterized by the presence of ≥20% circulating plasma cells. Overall survival remains poor despite advances of anti-MM therapy. The disease biology as well as molecular mechanisms that distinguish pPCL from non-pPCL MM remain poorly understood and, given the rarity of the disease, are challenging to study. In an attempt to identify key biological mechanisms that result in the aggressive pPCL phenotype, we performed whole-exome sequencing and gene expression analysis in 23 and 41 patients with newly diagnosed pPCL, respectively. The results reveal an enrichment of complex structural changes and high-risk mutational patterns in pPCL that explain, at least in part, the aggressive nature of the disease. In particular, pPCL patients with traditional low-risk features such as translocation t(11;14) or hyperdiploidy accumulated adverse risk genetic events that could account for the poor outcome in this group. Furthermore, gene expression profiling showed upregulation of adverse risk modifiers in pPCL compared to non-pPCL MM, while adhesion molecules and extracellular matrix proteins became increasingly downregulated. In conclusion, this is one of the largest studies to dissect pPCL on a genomic and molecular level.