Plasma cell leukemia: update on biology and therapy

Plasma cell leukemia presenting as spontaneous tumor lysis syndrome with hypercalcemia

Tumor lysis syndrome (TLS) is an oncologic emergency in which tumor cells undergo lysis either spontaneously or due to the initiation of cancer therapy typically presenting with hypocalcemia. We described a 62‐year‐old male patient with spontaneous TLS and hypercalcemia without a known malignancy, who is later discovered to have plasma cell leukemia.

A high level of suspicion is needed for spontaneous tumor lysis syndrome to be diagnosed in early stages to provide a better chance of more immediate and effective treatments, especially in invasive malignancies such as plasma cell leukemia.

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.

Complete response following treatment of plasma cell leukemia with venetoclax and dexamethasone: A case report

INTRODUCTION

Plasma cell leukemia (PCL) is a rare but aggressive variant of multiple myeloma (MM) with a poor prognosis. Due to the limited number of prospective clinical trials studying PCL, treatment options are often extrapolated from data available for the treatment of MM. Venetoclax has recently demonstrated antimyeloma activity in patients with relapsed/refractory MM carrying the t(11;14) translocation. However, few cases have reported the analogous efficacy of venetoclax in PCL.

CASE REPORT

A 64-year-old Caucasian male developed relapsed PCL despite treatment with hyperCD (hyperfractionated cyclophosphamide and dexamethasone) and Dara-KRd (daratumumab, carfilzomib, lenalidomide, dexamethasone). Due to the refractory nature of his disease and the presence of a t(11:14) translocation, the patient was subsequently initiated on venetoclax 400 mg daily and dexamethasone 4 mg once weekly.

MANAGEMENT AND OUTCOME

The patient achieved a complete response by International Myeloma Working Group criteria three months after initiating venetoclax-dexamethasone, including a repeat bone marrow biopsy that showed no abnormal plasma cells. He successfully underwent consolidation with melphalan-based autologous stem cell transplantation. He remains disease-free 9 months after venetoclax initiation.

DISCUSSION

Combination all-oral therapy with venetoclax and dexamethasone can induce deep hematologic responses in patients with relapsed/refractory PCL carrying the t(11;14) translocation.

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.

Primary Plasma Cell Leukemia Revealed by a Mandibular Lesion: A Case Report

Primary plasma cell leukemia (PCL) is a rare and aggressive hematological malignancy exhibiting a circulating plasma cell count exceeding 20% of peripheral blood leukocytes or an absolute plasma cell count >2000/mm3. We report a case of a 37-year-old woman presented to the Department of Hematology with a two-month history of growth inside the oral cavity in the upper jaw and weakness. The physical examination revealed a voluminous mass involving the left side of the maxillary gingiva. The maxillofacial computerized tomography (CT) scan confirmed the presence of a solid tissue mass at the left upper maxilla. A biopsy sample obtained from the lesion showed a plasma cell infiltration. The laboratory findings revealed anemia, renal impairment with high levels of creatinine and calcium. Serum protein electrophoresis found a monoclonal peak at IgG lambda, a high level of lambda free light. The diagnosis was subsequently confirmed by a peripheral-blood smear revealed 25% of plasma cells and bone marrow aspiration with 50% of plasma cell infiltration. Primary plasma-cell leukemia (pPCL) was confirmed. The patient received VTD chemotherapy (bortezomib, thalidomide, and dexamethasone) followed by autologous stem cell transplant (ASCT), which resulted in complete remission. At the six-month follow-up, the patient relapsed with extramedullary multiple lesions under ineffective rescue therapy. Response to frontline treatments may be significant initially but short-lived with a dismal median overall survival below one year. This case report aims to highlight the need for awareness among clinicians of the relevance of examining other associated clinical features of pPCL, given its aggressive course and rapid progress without the therapy.

Metastatic plasma cell leukemia to the skin: A case report with review of the literature

Plasma cell leukemia (PCL) is a rare variant of leukemia with an aggressive clinical course and a poor prognosis. The cutaneous involvement in PCL is very rare either at clinical presentation of leukemia, namely leukemia cutis, or in the metastatic PCL to the skin. We present a case of eruptive multiple cutaneous nodules in a 56-year-old man with metastatic PCL. Histologically, a diffuse dermal and subcutaneous infiltration of ovoid cells with amphophilic cytoplasm and eccentrically located nucleus consistent with plasmacytoid morphology was observed. Neoplastic cells showed strong immunoexpression for CD138 and CD38 consistent with plasma cells phenotype, and loss of expression of CD56. Kappa light chain restriction similar to the phenotype of his PCL was demonstrated. We suggest that the evaluation of new skin lesions in leukemic patients should include a histopathologic examination to establish the diagnosis as soon as possible and a correct management of the disease.

LncRNAs LY86-AS1 and VIM-AS1 Distinguish Plasma Cell Leukemia Patients from Multiple Myeloma Patients

Long non-coding RNAs (lncRNAs) are functional RNAs longer than 200 nucleotides. Due to modern genomic techniques, the involvement of lncRNAs in tumorigenesis has been revealed; however, information concerning lncRNA interplay in multiple myeloma (MM) and plasma cell leukemia (PCL) is virtually absent. Herein, we aimed to identify the lncRNAs involved in MM to PCL progression. We investigated representative datasets of MM and PCL patients using next-generation sequencing. In total, 13 deregulated lncRNAs (p < 0.00025) were identified; four of them were chosen for further validation in an independent set of MM and PCL patients by RT-qPCR. The obtained results proved the significant downregulation of lymphocyte antigen antisense RNA 1 (LY86-AS1) and VIM antisense RNA 1 (VIM-AS1) in PCL compared to MM. Importantly, these two lncRNAs could be involved in the progression of MM into PCL; thus, they could serve as promising novel biomarkers of MM progression.

High-output heart failure associated with primary plasma cell leukaemia due to arteriovenous shunting: a case report

Background

Primary plasma cell leukaemia is rarely associated with high-output heart failure, and the underlying mechanism is not well understood. We encountered a rare case of high-output heart failure caused by primary plasma cell leukaemia. Its underlying mechanism was clarified through imaging studies.

Case summary

A 49-year-old man with no specific medical history was admitted to our hospital because of heart failure that did not improve with diuretic therapy. His condition was diagnosed as high-output heart failure and primary plasma cell leukaemia after admission. Extensive bone involvement in primary plasma cell leukaemia and arteriovenous shunts in the same lesion were suspected after various imaging studies. The first cycle of chemotherapy with bortezomib, adriamycin, and dexamethasone led to remission of primary plasma cell leukaemia and improved heart failure symptoms. The patient received further chemotherapy in addition to autologous peripheral blood stem cell transplantation and maintenance therapy and had no recurrence of pPCL or heart failure for 1 year to date.

Discussion

Primary plasma cell leukaemia can be associated with high-output heart failure, which is caused by arteriovenous shunting at the lesion site with diffuse bone involvement. Imaging studies may lead to the early diagnosis of aetiology and treatment of patients with high-output heart failure associated with primary plasma cell leukaemia.

Necessity of flow cytometry assessment of circulating plasma cells and its connection with clinical characteristics of primary and secondary plasma cell leukaemia

Plasma cell leukaemia (PCL) is a rare and very aggressive plasma cell disorder. Preventing a dismal outcome of PCL requires early diagnosis with appropriate analytical tools. Therefore, the investigation of 33 patients with primary and secondary PCL was done when the quantity of circulating plasma cells (PCs) using flow cytometry (FC) and morphology assessment was evaluated. The phenotypic profile of the PCs was also analysed to determine if there is an association with clinical outcomes and to evaluate the prognostic value of analysed markers. Our results revealed that FC is an excellent method for identifying circulating PCs as a significantly higher number was identified by FC than by morphology (26·7% vs. 13·5%, P = 0·02). None of secondary PCL cases expressed CD19 or CD20. A low level of expression with similar positivity of CD27, CD28, CD81 and CD117 was found in both PCL groups. A decrease of CD44 expression was detected only in secondary PCL. Expression of CD56 was present in more than half of PCL cases as well as cytoplasmic nestin. A decreased level of platelets, Eastern Cooperative Oncology Group score of 2-3 and lack of CD20⁺ PC were associated with a higher risk of death. FC could be incorporated in PCL diagnostics not only to determine the number of circulating PCs, but also to assess their phenotype profile and this information should be useful in patients' diagnosis and possible prognosis.

Trend of depression and its association with sociodemographic and clinical factors among multiple myeloma hospitalizations: A Portuguese nationwide study from 2000 to 2015

OBJECTIVE

Patients hospitalized with multiple myeloma (MM) are particularly vulnerable to depression. The present study aims to determine the frequency of depression among MM hospitalized patients, in order to assess the possible differences between those with and without depression in relation to sociodemographic and clinical variables and to measure the impact of depression on hospitalization outcomes.

METHODS

An observational retrospective study was performed using an administrative data set of all hospitalizations with a primary diagnosis of MM between 2000 and 2015 in Portuguese mainland public hospitals. Codes related to depressive disorders were grouped to generate the dichotomous variable of depression (yes/no). A multivariate analysis was conducted and adjusted odd ratios (aOR) calculated between different variables and depression.

RESULTS

Of a total of 14.575 MM hospitalizations studied, a concurrent code of depression was registered in 666 patients (4.6%). A greater odds of depression was observed in female patients (aOR = 2.26; 95%CI = 1.91-2.66), transplanted patients (aOR = 1.78; 95%CI = 1.44-2.20), patients with plasma cell leukemia (aOR = 1.79; 95%CI = 1.22-2.64) and patients with a higher Charlson Comorbidity Index (CCI) (aOR = 1.10; 95%CI = 1.05-1.15). Length of stay was longer in patients with a registered diagnosis of depression (aOR = 1.01; 95%CI = 1.01-1.02) while the odds of in-hospital mortality were lower in these patients (aOR = 0.53; 95%CI = 0.41-0.68).

CONCLUSIONS

These results may help identify MM inpatients at higher risk of presenting depression (female gender, younger age, high CCI, plasma cell leukemia, transplant procedure). This will enable timely psychological assessment and treatment to prevent worse outcomes and higher healthcare costs associated with depression.

Secondary Plasma Cell Leukemia: A Case Report

Plasma cell leukemia (PCL) is a rare and aggressive variant of myeloma and has a poor prognosis. It needs prompt recognition in order to institute timely treatment. Given its relatively low incidence, it is an evolving area of research as well. This case report describes a patient with PCL in the setting of a previously treated myeloma. The report also reviews the clinicopathologic, cytogenetic, and immunophenotypic characteristics of PCL and its management.

Utilizing multiparametric flow cytometry in the diagnosis of patients with primary plasma cell leukemia

The diagnosis of primary plasma cell leukemia (pPCL) has been made by quantifying circulating plasma cells (cPCs) morphologically on a peripheral blood (PB) smear. However, this technique is not sufficiently sensitive. Multiparametric flow cytometry (MFC) provides a readily available and highly sensitive method to identify and quantify cPCs that could complement PB smear assessment. However, an optimal quantitative cutoff for cPCs by MFC to identify pPCL has not been established. Thus, a total of 591 patients newly diagnosed multiple myeloma (NDMM) patients who had their PB samples evaluated morphologically by PB smear, and immunophenotypically by MFC prior to beginning therapy were evaluated. The presence of ≥200 cPCs/μL by MFC (N = 25 or 5% of the total population) was chosen to identify patients with ≥5% cPCs by PB smear with a specificity of 99% and a sensitivity of 77%. For patients with ≥200 cPCs/μL by MFC compared to the remainder of the cohort, the median Time to next therapy (TTNT) was 18 vs 30 months and the median OS was 38 vs 70 months respectively. Thus, MFC assessment of PB can be utilized in conjunction with the morphological assessment of a PB smear to aid in improving the identification of pPCL among NDMM patients.

Enhanced expression of FCER1G predicts positive prognosis in multiple myeloma

Background: Multiple myeloma (MM) is the second most common hematologic malignancy worldwide and does not have sufficient prognostic indicators. FCER1G (Fc fragment Of IgE receptor Ig) is located on chromosome 1q23.3 and is involved in the innate immunity. Early studies have shown that FCER1G participates in many immune-related pathways encompassing multiple cell types. Meanwhile, it is associated with many malignancies. However, the relationship between MM and FCER1G has not been studied.

Methods: In this study, we integrated nine independent gene expression omnibus (GEO) datasets and analyzed the associations of FCER1G expression and myeloma progression, ISS stage, 1q21 amplification and survival in 2296 myeloma patients and 48 healthy donors.

Results: The expression of FCER1G showed a decreasing trend with the advance of myeloma. As ISS stage and 1q21 amplification level increased, the expression of FCER1G decreased (P = 0.0012 and 0.0036, respectively). MM patients with high FCER1G expression consistently had longer EFS and OS across three large sample datasets (EFS: P = 0.0057, 0.0049, OS: P = 0.0014, 0.00065, 0.0019 and 0.0029, respectively). Meanwhile, univariate and multivariate analysis indicated that high FCER1G expression was an independent favorable prognostic factor for EFS and OS in MM patients (EFS: P = 0.006, 0.027, OS: P =0.002,0.025, respectively).

Conclusions: The expression level of FCER1G negatively correlated with myeloma progression, and high FCER1G expression may be applied as a favorable biomarker in MM patients.

A successful case of venetoclax-based therapy in relapsed/refractory secondary plasma cell leukemia

Background

Secondary plasma cell leukemia (sPCL) patients typically are either refractory to conventional therapies or have short remissions to drug regimens used in multiple myeloma (MM), which highlights sPCL’s aggressive nature and association with advanced stage disease. t(11,14) is correlated with increased BCL-2 expression, which makes it a cytogenic marker of interest for use of the BCL-2 inhibitor venetoclax. Little data of venetoclax’s use has been published in plasma cell leukemia. We present a case of a refractory/relapsed sPCL patient displaying t(11,14) who achieved a very good partial response (VGPR) from venetoclax therapy in combination with dexamethasone and bortezomib.

Case report

Our case describes a 67-year-old male initially diagnosed with IgG kappa MM in 2013, which transformed into non-secretory secondary plasma cell leukemia. Over a two-year period, despite responses to various therapies, the patient continued to experience relapses and exhausted options of novel agents seen in MM treatment. The patient was started on venetoclax in combination with bortezomib and oral dexamethasone.

Management and outcome

Due to the patient’s disease transformation into a non-secretory form of sPCL, PET/CT scans were relied upon to monitor disease progression. The PET/CT scan after three months of venetoclax combination treatment showed a very good partial response to therapy, with near resolution of metabolically active osseous disease.

Discussion

The success of venetoclax-based therapy in achieving a very good partial response suggests its utility in relapsed/refractory sPCL patients, who have exhausted various combinations of drug regimens used in treatment of MM and have historically poor survival outcomes.

A case of IgE myeloma transformed into IgE-producing plasma cell leukaemia

This is a case report of a challenging diagnosis of IgE monoclonal gammopathy of undetermined significance, which transformed into myeloma, then transformed into IgE-producing plasma cell leukaemia in a 71-year-old male who was followed in Brest, France, from 2015 to 2019. The IgE-producing variant is the rarest sub-type of multiple myeloma, and plasma cell leukaemia is considered to be the rarest and the most aggressive of human monoclonal gammopathies. In November 2015, hypogammaglobulinemia was detected during a systematic check-up. A kappa light chain monoclonal gammopathy was first diagnosed due to an increase of the free kappa/lambda light chains ratio. No monoclonal immunoglobulin was detected by either serum protein electrophoresis (Capillarys 2, Sebia, Issy-les-Moulineaux, France) or immunofixation (Hydrasys 2, Sebia, Issy-les-Moulineaux, France). In June 2018, a blood smear led to the diagnosis of plasma cell leukaemia. A monoclonal peak was detected and identified as IgE-kappa. Analysis of an archival sample taken three years earlier, revealed the presence of a monoclonal IgE, which had been missed at diagnosis. Chemotherapy with bortezomib and dexamethasone was introduced. The patient survived 10 months after the diagnosis of leukaemia. This case shows that an abnormal free light chain ratio should be considered as a possible marker of IgE monoclonal gammopathy even in the absence of a solitary light chain revealed by immunofixation. In addition, the use of an undiluted serum may increase the sensitivity of the immunofixation for the detection of IgE monoclonal gammopathies compared to the 1:3 dilution recommended by the manufacturer.

Bortezomib-based Regimens Improve the Outcome of Patients with Primary or Secondary Plasma Cell Leukemia: A Retrospective Cohort Study

Objective:

The management experience for plasma cell leukemia (PCL) is still limited by PCL’s rare incidence and aggressive course. The goal of this study was to further identify the efficacy of bortezomib-containing regimens for PCL in Chinese patients.

Materials and Methods:

In this study, 56 consecutive PCL patients [14 primary PCL (pPCL) and 42 secondary PCL (sPCL) cases] were retrospectively enrolled and 42/56 patients received bortezomib-based regimens (BBRs), including 10/14 pPCL and 32/42 sPCL patients. The patients’ survival data, clinical information, and safety data were collected and analyzed.

Results:

In pPCL and sPCL patients, the overall response rate in the bortezomib group was 90.0% and 25.0%, respectively. The median progression-free survival from PCL diagnosis for pPCL and sPCL was 8.3 months vs. 2.9 months (p=0.043) and median overall survival (OS) from PCL diagnosis was 23.3 months vs. 4.0 months. The OS for patients receiving BBRs was significantly longer for both pPCL (8.3 vs. 1.2 months, p=0.002) and sPCL (4.3 vs. 1.1 months, p<0.001). In multivariate COX analysis, BBR treatment [p=0.008, hazard ratio (HR)=0.38, 95% confidence interval (CI)=0.19-0.77] and very good partial response or better (≥VGPR) (p=0.035, HR=0.19, 95% CI=0.04-0.74) were independent predictors of OS for sPCL patients. For pPCL patients, BBR predicted OS (p=0.029, HR=0.056, 95% CI=0.004-0.745) instead of ≥VGPR (p=0.272, HR=3.365, 95% CI=0.38-29.303).

Conclusion:

It was found that BBRs could significantly improve OS for both pPCL and sPCL patients.

Transcriptome analysis reveals significant differences between primary plasma cell leukemia and multiple myeloma even when sharing a similar genetic background

Primary plasma cell leukemia (pPCL) is a highly aggressive plasma cell dyscrasia characterised by short remissions and very poor survival. Although the 17p deletion is associated with poor outcome and extramedullary disease in MM, its presence does not confer the degree of aggressiveness observed in pPCL. The comprehensive exploration of isoform expression and RNA splicing events may provide novel information about biological differences between the two diseases. Transcriptomic studies were carried out in nine newly diagnosed pPCL and ten MM samples, all of which harbored the 17p deletion. Unsupervised cluster analysis clearly distinguished pPCL from MM samples. In total 3584 genes and 20033 isoforms were found to be deregulated between pPCL and MM. There were 2727 significantly deregulated isoforms of non-differentially expressed genes. Strangely enough, significant differences were observed in the expression of spliceosomal machinery components between pPCL and MM, in respect of the gene, isoform and the alternative splicing events expression. In summary, transcriptome analysis revealed significant differences in the relative abundance of isoforms between pPCL and MM, even when they both had the 17p deletion. The mRNA processing pathway including RNA splicing machinery emerged as one of the most remarkable mechanisms underlying the biological differences between the two entities.

Primary plasma cell leukemia: A case report and review of the literature

Due to the rarity and fulminant nature of the condition, there are limited data driving dialogue for optimal treatment strategies for plasma cell leukemia (PCL). Additionally, the current diagnostic definition of PCL has not been prospectively studied which may result in delays to initiating early aggressive treatment due to underdiagnosis.

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.

Contemporary patient-tailored treatment strategies against high risk and relapsed or refractory multiple myeloma

Recurrence of disease due to chemotherapy drug resistance remains a major obstacle to a more successful survival outcome of multiple myeloma (MM). Overcoming drug resistance and salvaging patients with relapsed and/or refractory (R/R) MM is an urgent and unmet medical need. Several new personalized treatment strategies have been developed against molecular targets to overcome this drug resistance. There are several targeted therapeutics with anti-MM activity in clinical pipeline, including inhibitors of anti-apoptotic proteins, monoclonal antibodies, antibody-drug conjugates, bispecific antibodies, fusion proteins, and various cell therapy platforms. For example, B-cell maturation antigen (BCMA)-specific CAR-T cell platforms showed promising activity in heavily pretreated R/R MM patients. Therefore, there is renewed hope for high-risk as well as R/R MM patients in the era of personalized medicine.

Real-world data on prognosis and outcome of primary plasma cell leukemia in the era of novel agents: a multicenter national study by the Greek Myeloma Study Group

We have studied the efficacy and the prognostic impact of novel agents in 50 primary plasma cell leukemia (pPCL) patients registered in our database. Eighty percent of patients were treated upfront with novel agent-based combinations; 40% underwent autologous stem cell transplantation (ASCT). Objective response rate was 76; 38% achieved at least very good partial response (≥vgPR) and this correlated significantly with bortezomib-based therapy plus ASCT. At the time of evaluation, 40 patients had died. Early mortality rate (≤1 month) was 6%. Median progression-free survival (PFS) and overall survival (OS) were 12 months and 18 months respectively, both significantly longer in patients treated with bortezomib-based therapy + ASCT vs. others (PFS: 18 vs. 9 months; p = 0.004, OS: 48 vs. 14 months; p = 0.007). Bortezomib-based therapy + ASCT predicted for OS in univariate analysis. In multivariate analysis, achievement of ≥vgPR and LDH ≥ 300 U/L were significant predictors for OS. These real-world data, based on one of the largest reported national multicenter series of pPCL patients treated mostly with novel agents support that, among the currently approved induction therapies, bortezomib-based regimens are highly effective and reduce the rate of early mortality whereas in combination with ASCT consolidation they prolong OS.

Incidence, characteristics, and outcome of solitary plasmacytoma and plasma cell leukemia. Population-based data from the Swedish Myeloma Register

Solitary plasmacytoma (SP) and plasma cell leukemia (PCL) are uncommon (3-6%) types of plasma cell disease. The risk of progression to symptomatic multiple myeloma (MM) is probably important for the outcome of SP. PCL is rare and has a dismal outcome. In this study, we report on incidence and survival in PCL/SP, and progression to MM in SP, using the prospective observational Swedish Multiple Myeloma Register designed to document all newly diagnosed plasma cell diseases in Sweden since 2008. Both solitary bone plasmacytoma (SBP) (n=124) and extramedullary plasmacytoma (EMP) (n=67) have better overall survival (OS) than MM (n=3549). Progression to MM was higher in SBP than in EMP (35% and 7% at 2 years, respectively), but this did not translate into better survival in EMP. In spite of treatment developments, the OS of primary PCL is still dismal (median of 11 months, 0% at 5 years). Hence, there is a great need for diagnostic and treatment guidelines as well as prospective studies addressing the role for alternative treatment options, such as allogeneic stem cell transplantation and monoclonal antibodies in the treatment of PCL.

Leukemia Cutis Associated with Secondary Plasma Cell Leukemia

Plasma cell leukemia is an uncommon, aggressive variant of leukemia that may occur de novo or in association with multiple myeloma. Leukemia cutis is the cutaneous manifestation of leukemia, and indicates an infiltration of the skin by malignant leukocytes or their precursors. Plasma cell leukemia cutis is a rare clinical presentation of leukemia. We present a man who developed plasma cell leukemia cutis in association with multiple myeloma. Cutaneous nodules developed on his arms and legs 50 days following an autologous stem cell transplant. Histopathologic examination showed CD138-positive nodular aggregates of atypical plasma cells with kappa light chain restriction, similar to the phenotype of his myeloma. In spite of systemic treatment of his underlying disease, he died 25 days after the presentation of leukemia cutis. Pub-Med was searched for the following terms: cutaneous plasmacytomas, leukemia cutis, plasma cell leukemia nodules, plasma cell leukemia cutis, and secondary cutaneous plasmacytoma. Papers were reviewed and appropriate references evaluated. Leukemia cutis in plasma cell leukemia patients is an infrequent occurrence. New skin lesions in patients with plasma cell leukemia should be biopsied for pathology and for tissue cultures to evaluate for cancer or infection, respectively. The diagnosis plasma cell leukemia cutis is associated with a very poor prognosis.