MDS/AML-associated cytogenetic abnormalities in multiple myeloma and monoclonal gammopathy of undetermined significance: Evidence for frequent de novo occurrence and multipotent stem cell involvement of del(20q)

Evidence of two different molecular mechanisms as a consequence of an isolated 20q- abnormality in a case of multiple myeloma accompanied with myelodysplastic syndrome

The deletion of the long arm of chromosome 20 is a characteristic cytogenetic marker of myeloid disorders. Rarely, it is also found in lymphoproliferative diseases, including multiple myeloma (MM). The role of 20q- in MM is not fully understood. In the cases of MM which co-exist with primary or therapy-related dysplasia, this anomaly is mostly linked to the occurrence of myeloid neoplasms. On the other hand 20q- is found as an isolated anomaly in cases with MM that have no dysplastic features or is not accompanied with other hematological diseases which suggests that the 20q deletion is also important for the development of MM. This report describes an isolated 20q- anomaly in a case of a light chain myeloma co-existing with myelodysplastic syndrome (MDS). Fluorescent in situ hybridization (FISH) experiments have demonstrated the presence in the patient's bone marrow of a basic clone (stemline) with deletion of the PTPRT gene (located at 20q13.11) and two sidelines: one with deletion of the PTPRT and MAPRE1 genes (located at 20q11.12) found in the mature granulocytes and one with deletion of PTPRT and duplication of MAPRE1 found in the myeloma cells. These data have indicated that 20q- has appeared in the multipotent precursor cells and affects both myeloid and lymphoid lineage by two different molecular mechanisms - one possibly related to the pathogenesis of the MDS and another to the pathogenesis of the MM.

Increasing therapy-related myeloid neoplasms in multiple myeloma

BACKGROUND

Despite the longer survival achieved in multiple myeloma (MM) patients due to new therapy strategies, a concern is emerging regarding an increased risk of secondary primary malignancies (SPMs) and how to characterize those patients at risk. We performed a retrospective study covering a 28-year follow-up period (1991-2018) in a tertiary single institution.

MATERIAL AND METHODS

Data of 403 MM patients were recorded and compared with the epidemiologic register of the population area covered by our centre, calculating the standardize incidence ratio (SIR) for the different types of SPMs diagnosed in the MM cohort. Fine and Gray regression models were used to identify risk factors for SPMs.

RESULTS

Out of the 403 MM patients, 23 (5.7%) developed SPMs: 13 therapy-related myeloid (TRM) malignancies (10 of them (77%) myelodysplastic syndrome (MDS), 1 acute lymphoid leukaemia and 9 solid neoplasms. In the MM cohort, the relative risk of MDS was significantly higher than in the general population. Survival of patients with TRM malignancies was poor with a median of 4 months from the diagnosis, and most of them showed complex karyotype. Within the MM subset, multivariable analysis showed a higher risk of TRM malignancies in patients that previously received prolonged treatment with lenalidomide (>18 months).

CONCLUSIONS

Though the improvement in MM outcome during the last decades is an unprecedented achievement, it has been accompanied by the rise in TRM malignancies with complex cytogenetic profile and poor prognosis that are in the need of an improved biologic and therapeutic approach.

Mosaic chromosome 20q deletions are more frequent in the aging population

Deletions on the long-arm of chromosome 20, del(20q), are common karyotypic abnormalities in myeloid disorders. Bioinformatic analyses of the B-allele frequency and log R ratio values from genome-wide association data have identified individuals who are mosaic for large structural abnormalities (>2 Mb). We investigated the most common autosomal event, namely mosaic del(20q), in 46 254 nonhematologic cancer cases and 36 229 cancer-free controls. We detected 91 mosaic del(20q) in leukocytes (80%) and buccal material (20%). The mosaic del(20q) mapped to a well-characterized minimally deleted region (MDR) reported in myeloid disorders. Common breakpoint clusters map to the coordinates of 29.9 to 31.5 Mb on the centromeric side of mosaic del(20q), and 42.0 to 45.4 Mb and 48.1 to 50.7 Mb on the telomeric end (GRCh36). Multivariate analyses suggest del(20q) increases with age, and is more common in males but less common in individuals of African ancestry. No conclusive associations were noted between the presence of mosaic del(20q) and subsequent solid tumor risk. Our observations demonstrate that the MDR of del(20q) is the most common large scale mosaic autosomal abnormality in whole blood and has a frequency of ∼1 in every 1000 adults over the age of 50, which exceeds the expected incidence of myeloid leukemia in the population. Our results indicate that subclonal mosaic events of a region implicated in myeloid disorders on 20q are more frequent than the predicted population-estimated incidence of myeloid diseases, and thus suggest that these events can be tolerated until additional events accumulate that drive myeloid disorders.

The Importance of an In-depth Study of Immunoglobulin Gene Rearrangements When Ascertaining the Clonal Relationship between Concomitant Chronic Lymphocytic Leukemia and Multiple Myeloma

Chronic lymphocytic leukemia (CLL) and multiple myeloma (MM) are hematological disorders that occur at different stages of B-cell development. It has been shown that CLL B-cells can differentiate into plasma cells in vitro and in vivo. CLL is the most frequent adult leukemia in the western world. It is a heterogeneous disease, characterized by clonal proliferation and the accumulation of mature CD5+ B lymphocytes (1). MM is a clonal plasma cell malignancy that accounts for more than 10% of all hematologic cancers (2). Although secondary cancers [particularly solid tumors (3-5)] can occur with CLL and MM, the concomitant occurrence of these two disorders in the same patient is rare [for a review of the few reported cases, see Ref. (6)]. The clonal relationship between these diseases has not always been clarified but is important in terms of understanding the pathogenesis and optimizing treatment. The clonal relationship between CLL and MM can be evaluated by (i) analyzing immunoglobulin (Ig) heavy chain and light chain (Ig kappa light chain and Ig lambda light chain) gene rearrangement, (ii) identifying and comparing somatic mutations, and (iii) studying chromosomic aberrations. Nevertheless, Ig rearrangements must always be interpreted in the light of specific phenomena such as allelic exclusion, B-cell receptor (BCR) revision (V_H and D_H gene replacement), BCR editing, and somatic mutations-events that were not considered in previous studies. These issues can be addressed by sequencing the rearranged Ig genes from sorted populations and interpreting the generated data. In the present study, we evaluated the putative clonal relationship between the two diseases by combining DNA copy number analysis with an assessment of Ig gene rearrangements [clonality assessment, V(D)J sequencing, and somatic hypermutation analysis] in highly enriched CD19+ CD5+ (CLL) and CD38+ CD138+ (MM) cell populations. Array comparative genomic hybridization data suggested a possible phylogenic progression from CLL to MM. Moreover, V(D)J sequencing indicated that both CLL and MM cells used the same V_H and J_H genes but different D_H genes. However, in-depth analysis and interpretation of Ig gene rearrangements ultimately suggested that the two diseases had distinct clonal origins.

Concomitant MDS with isolated 5q deletion and MGUS: case report and review of molecular aspects

Patients with monoclonal gammopathy of undetermined significance (MGUS) have a higher risk for the development of concomitant primary cancers such as multiple myeloma (MM) and myelodysplastic syndrome (MDS). We report the case of patient initially suffering from MGUS of the IgG lambda subtype for more than 10 yr, which evolved to MM and MDS with deletion (5q) with severe pancytopenia. Due to pancytopenia, he received dose-reduced treatment with lenalidomide and dexamethasone. He achieved an ongoing transfusion independency after about 1 month of treatment. Bone marrow taken 14 months after start of treatment showed a complete cytogenetic response of the del(5q) clone and a plasma cell infiltration below 5%. In contrast to the development of MM in MGUS patients, the subsequent occurrence of MDS after diagnosis of MGUS is infrequent. Moreover, the biological association of MDS with MGUS is not sufficiently understood, but the non-treatment-related occurrence supports the pathogenetic role of pre-existing alterations of stem cells. Here, we summarize data on concomitant MDS and MGUS/MM with particular emphasis on molecular aspects.

Therapy-related myelodysplastic syndrome/acute leukemia after multiple myeloma in the era of novel agents

Survival for patients with multiple myeloma has increased. Both melphalan and lenalidomide are associated with subsequent development of myelodysplasia. We reviewed the cases of all patients with multiple myeloma who had subsequent development of myelodysplastic syndrome (MDS) or acute non-lymphoblastic leukemia (ANLL) during a 12-year period in three centers. Of 55 patients identified, two received only lenalidomide before myelodysplasia developed. The median time between the diagnoses of multiple myeloma and MDS/ANLL was 52.7 months. Median survival after the diagnosis of MDS or ANLL was 6.7 months. Treatment of MDS comprised allogeneic stem cell transplant in eight patients (median survival, 219 days; one patient alive at 624 days) and a hypomethylating agent in 21 patients (response of stable or better in five patients). Myelodysplasia remains a devastating complication of therapy for multiple myeloma, with short survival and poor response rates to available modalities.

Simultaneous and sequential concurrent myeloproliferative and lymphoproliferative neoplasms

Concurrent manifestation of two chronic-stage myeloid and lymphoid/plasmacytoid neoplasms in one patient is rare and occurs in ≤1% of patients. There has been no systematic analysis of which combinations are frequent/infrequent and whether two concurrent diseases in one patient are clonally related or represent independent diseases. We therefore characterised a series of cases from our own archive (n = 65) and collected a large number of previously reported cases of patients in whom myeloid and lymphoid/plasmacytoid neoplasms co-occurred (n = 185). The most frequent combination was Philadelphia chromosome-negative myeloproliferative neoplasm with concurrent B cell chronic lymphocytic leukaemia, accounting for approximately 50% of double-disease patients. We compared the quantity of unsorted bone marrow cell-derived JAK2(V617F) and KIT(D816V) alleles with the quantity of the lymphoid/plasmacytoid compartment and analysed a subfraction of cases with fluorescence in situ hybridisation. Although a common aberrant progenitor has been reported in some cases in the literature, we found evidence of two independent chronic-stage myeloid and lymphoid/plasmacytoid neoplasms.

Longitudinal bone marrow evaluations for myelodysplasia in patients with myeloma before and after treatment with lenalidomide

Lenalidomide (LEN) treatment in multiple myeloma (MM) results in a superior outcome. However, there is concern for increased myelodysplastic syndrome/acute myeloid leukemia (MDS/AML) associated with LEN. Thus, bone marrow morphology and cytogenetics studies from 40 patients were evaluated for early signs of MDS prior to therapy, during therapy and at follow-up. Newly diagnosed patients with MM treated with LEN and dexamethasone (LD) alone or followed by autologous stem cell transplant (LD/ASCT), or patients with relapsed/refractory MM treated with LEN, bendamustine and dexamethasone (BLD) were included. One patient developed MDS. Baseline prevalence of mild morphologic myelodysplasia was highest in pretreated patients with MM (BLD, 71%), but was also seen in newly diagnosed patients (LD and LD/ASCT, 17%). The prevalence of myelodysplasia did not increase over time. Thus, this study did not reveal rapidly emerging MDS in 39 of 40 patients with MM treated with LEN. The development of MDS in one patient suggests that longer follow-up is needed for all.

Deletion(20q) as the sole abnormality in plasma cell myeloma is not associated with plasma cells as identified by cIg FISH

Deletion of 20q is a common finding in myeloid disorders but it is also observed in plasma cell myeloma (PCM). As a del(20q) in a patient receiving treatment for myeloma may indicate therapy-related myelodysplastic syndrome (t-MDS), it is important to differentiate chromosome abnormalities associated with myeloma from those reflecting t-MDS. We performed fluorescence in situ hybridization (FISH) using a 20q12 probe (D20S108) in conjunction with cytoplasmic immunoglobulin (cIg) staining in 20 PCM cases with a del(20q) in order to confirm the cell type involved. Of the nine cases studied with a clone showing a del(20q) as the sole abnormality, 8 of 9 demonstrated loss of the D20S108 signals in non-plasma cells only and 5 of 9 had either a confirmed myeloid malignancy in addition to PCM or showed evidence of dysplastic changes in the marrow; however, of the 11 patients with a del(20q) within a complex PCM karyotype, 4 of 11 showed loss of the D20S108 signals in plasma cells only and 7 of 11 showed no significant loss in either plasma cells or non-plasma cells. Therefore, our results indicate that a del(20q) as the sole abnormality in PCM is present in non-plasma cells and, therefore, suggests the presence of an associated myeloid malignancy.

In multiple myeloma, bone-marrow lymphocytes harboring the same chromosomal abnormalities as autologous plasma cells predict poor survival

Chromosomal abnormalities in plasma cells (PCs) from multiple myeloma (MM) provide a clonal signature to identify malignant cells. BM-lymphocytes from MM aspirates, defined by stringent criteria, were screened for the same chromosomal abnormalities as autologous PCs, including translocations, deletions, and amplifications. For 200 MM patients, we evaluated BM mononuclear cells to identify lymphocytes and autologous PCs on the same slide, followed by interphase fluorescence in situ hybridization to characterize their chromosomal abnormalities. Of all patients having a given chromosomal abnormality(s) in PCs, 45% showed that same abnormality(s) in 2–37% (median = 5%) of BM-lymphocytes. Most translocations, amplifications, and deletions found in MM PCs were also detected in lymphocytes, above the healthy-donor “cut-off.” In patients having chromosomally abnormal CD20⁻ PCs, chromosomally abnormal lymphocytes were found among CD20+ cells confirming them as B cells. Exceptions were amplification of 1q21 or p53 deletion, which characterize PCs but were undetectable in BM-lymphocytes, suggesting that processes leading to these abnormalities may be exclusive to PCs. For a set of 75 patients whose BM-lymphocytes and PCs were analyzed by all six probe sets, 58% of those with abnormal PC also had abnormal BM-lymphocytes harboring from one to five different abnormalities. Confirming the clinical significance of chromosomally abnormal BM-lymphocytes, MM patients having abnormalities in both lymphocytes and PC had significantly worse survival than those with abnormalities only in PC (HR = 2.68). The presence of at least one chromosomal abnormality in BM-lymphocytes appears to have greater clinical significance than particular abnormalities. Chromosomally abnormal BM-lymphocytes correlate with poor outcome and by extrapolation with more aggressive disease.

Multiple myeloma: current perspectives

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

The prognostic significance of cytogenetics and molecular profiling in multiple myeloma

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

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.

Myelodysplastic syndromes

Session 4 of the 2007 Workshop of the Society for Hematopathology/European Association for Haematopathology was devoted to myelodysplastic syndromes (MDSs). Submitted cases highlighted important issues and difficulties in relation to the diagnosis and classification of MDS. Much of the discussion focused on the correlation, or lack of it, between morphologic examination and other diagnostic techniques, cytogenetics in particular. The cases included examples of isolated del(5q) chromosomal abnormality, including the "classical" 5q- syndrome and other myeloid neoplasms. Other cytogenetic abnormalities in MDSs and the role of cytogenetics in diagnosing MDSs were addressed. Particularly challenging is the correct identification of fibrotic subtypes of MDSs and their separation from subsets of acute myeloid leukemia with myelofibrosis such as acute panmyelosis with myelofibrosis. The association and eventual relation of MDSs (hypoplastic in particular) with aplastic anemia, paroxysmal nocturnal hemoglobinuria, and other nonneoplastic disorders were illustrated. Novel cytogenetic and molecular genetic approaches are likely to revolutionize the classification of MDSs. However, it is unlikely that these new techniques will be capable, on their own, of adequately stratifying patients for treatment purposes. At least for the foreseeable future, the diagnosis of MDS requires integration of morphologic, immunophenotypic, and genetic features in the light of patient history and clinical manifestations.

Multiple myeloma--an update on diagnosis and treatment

Multiple myeloma is a plasma cell (PC) malignancy characterized by the accumulation of monoclonal PCs in the bone marrow and the production of large amounts of a monoclonal immunoglobulin or paraprotein. In the past years, new approaches in the diagnosis and treatment were introduced aiming to identify high-risk patients who need proper anti-myeloma treatment. Intensive therapy including autologous hematopoietic stem cell transplantation and the new agents bortezomib, thalidomide, and lenalidomide have improved patients' responses. Further optimalization of the different treatment schedules in well-defined patient groups may prolong their survival. Patient stratification is currently based on patient characteristics, extent of myeloma disease, and associated cytogenetic and laboratory anomalies. More and more gene expression studies are introduced to stratify patients and to individualize therapy.

Deletion (20q) as the sole abnormality in Waldenström macroglobulinemia suggests distinct pathogenesis of 20q11 anomaly

The deletion of the long arm of chromosome 20, or del(20q), is a common cytogenetic abnormality in various myeloid disorders but is less commonly seen in lymphoid neoplasms. Here we report a case of Waldenström macroglobulinemia with del(20q) as the sole cytogenetic anomaly. No translocation including immunoglobulin genes was identified by spectral karyotyping (SKY) analysis. Reviewing all 11 reported cases of plasma cell dyscrasia possessing sole del(20q), including our case, none of 4 cases with del(20q) as an initial anomaly developed myelodysplastic syndrome-acute myeloid leukemia (MDS/AML), but at least 3 cases with del(20q) appearing after chemotherapy developed MDS/AML at or after the time of del(20q). We propose that the del(20q) may have different clinical significance in plasma cell dyscrasia: one is when del(20q) appears at diagnosis and may involve the initial event of oncogenesis, and the other is when del(20q) appears after treatment and is associated with therapy-related and potential MDS/AML risk.

Derivative (1;7)(q10;p10) in multiple myeloma. A sign of therapy-related hidden myelodysplastic syndrome

Therapy-related myelodysplastic syndrome (MDS) is a major problem in long-term cancer survivors, therefore early detection and prevention of therapy-related secondary neoplasia is an important issue. We searched for therapy-related MDS and analyzed cytogenetic changes in 155 patients with multiple myeloma (MM) from a single institution. Of the total 155 MM patients with cytogenetic results, 7 patients showed de novo appearance of myeloid-related cytogenetic changes, and 5/7 had -7/7q-, including 3 with der(1;7)(q10;p10): 3 patients developed MDS (i.e. 2 patients with der(1;7)(q10;p10) and 1 with a complex abnormality including -5 and 7q-). Among five patients receiving more than 2 g of melphalan, three developed MDS, and two of them showed der(1;7)(q10;p10) before or at the time of MDS diagnosis. Although morphologic identification of MDS was difficult in some cases, we concluded that the presence of 7q-, specifically der(1;7)(q10;p10), during chemotherapy involving melphalan for MM patients might indicate hidden MDS status and appropriate therapeutic options should be considered for such patients.

Random aneuploidy in neoplastic and pre-neoplastic diseases, multiple myeloma, and monoclonal gammopathy

In this study we evaluated the aneuploidy rate of cells from patients considered to have a premalignant condition (monoclonal gammopathy or MGUS) and patients with multiple myeloma, as well as healthy controls. By applying a fluorescence situ hybridization technique, we estimated the random aneuploidy rate of alpha-satellite (centromeres) probes from chromosomes 9 and 18. The monosomy and total aneuploidy rates were higher in the two study groups compared to the control group. The monosomy rate was significantly higher in the MGUS group compared to the group with chromosome 18 alpha-satellite probes, a finding that was reported before in preneoplastic conditions. Our results support the cancer aneuploidy theory that carcinogenesis is initiated by a random aneuploidy, which is induced either spontaneously or by a carcinogen. The resulting karyotype instability sets a chain reaction of aneuploidization, which generates even more abnormal and eventually cancer-specific combinations and rearrangements of chromosomes.

Targeting plasma cells improves detection of cytogenetic aberrations in multiple myeloma: phenotype/genotype fluorescence in situ hybridization

Standard fluorescence in situ hybridization (FISH) easily detects nonrandom karyotypic abnormalities in multiple myeloma (MM) at disease presentation, when tumor burden is high. In contrast, the detection of residual MM using the standard 200 unselected nonmitotic nuclei FISH approach correlates poorly with residual disease detected by morphology, flow cytometry, immunohistochemistry, or reverse-transcription polymerase chain reaction (RT-PCR). We have used sequential May-Grunwald Giemsa stain to identify plasma cell populations, followed by FISH analyses (target FISH or T-FISH) to detect immunoglobulin heavy-chain gene (IGH) rearrangements, 13q or 17p deletions, or hyperdiploidy. In this study, 115 samples were collected from 100 patients with MM regardless of treatment status. In this proof-of-principle prospective study, T-FISH detected MM in 52 samples (45%), a percentage similar to that obtained by pathology. Disease detection increased from 5.6% with standard FISH to 48% with T-FISH, and cell culture experiments showed that T-FISH consistently detected a clonal abnormality at dilutions of 10(-3). In five patients, T-FISH further identified myelodysplastic-associated karyotypic changes restricted to myeloid cells. Our observations suggest that T-FISH identifies cell lineage involvement of cytogenetic abnormalities, improves detection of low-level or residual MM, and may define the coexistence of hematologic karyotypic changes in individual patients.