Spectrum of Hematological Malignancies in 130 Patients with Germline Predisposition Syndromes - Mayo Clinic Germline Predisposition Study

Introduction Germline predisposition syndromes (GPS) are inherited disorders associated with germinal aberrations that increase the risk of malignancies. While aberrations in certain genes increase the risk for all types of malignancies (Tp53, ATM, CDKN2A, CHEK2), there is a growing list of genes associated specifically with hematological malignancies (GATA2, RUNX1, DDX41, ETV6, ANKRD26). At our institution, we have established a hematology GPS clinic to diagnose and manage GPS and with this report, detail our experience with 130 patients. Methods GPS were investigated in pediatric and adult patients with one or more first degree relatives with hematological/visceral malignancies or in those with antecedent thrombocytopenia (ANKRD26, RUNX1, ETV6), or with specific syndromic features (short telomere syndromes/STS, GATA2 haploinsufficiency, Fanconi anemia/FA, Shwachman-Diamond syndrome/SDS). Depending on the phenotype, specific functional assays such as flow-FISH for telomere length assessment and chromosomal breakage assays were ordered. After informed consent and genetic counselling, germline testing was carried out on peripheral blood mononuclear cell, skin fibroblast, or hair follicle-derived DNA. A custom-designed marrow failure NGS panel (200 genes) was used in most cases and interrogation of variants, in silico studies, and functional assays were carried out as previously described (Mangaonkar et al MC Proc 2019). Copy number variations were identified by aCGH. At the time of progression/worsening cytopenias, bone marrow/lymph node biopsies and NGS (next generation sequencing) were carried out where indicated. Results 130 patients with germline predisposition have been identified to date. The spectrum of disorders seen include STS 29 (22%), FA 17 (13%), GATA2 16 (12%), Diamond Blackfan anemia/DBA 13 (10%), RUNX1-FPD 12 (9%), ATM deletions/mutations 11 (8%), ANKRD26 6 (5%), SDS 5 (4%), DDX41 4 (3%), MPL 3 (2%), CHEK2, MECOM, Tp53 mutations 2 (2%) each, and CBL, CEPBA, ELANE, NF1, CDKN2A, CSF3R, ETV6, and GATA1 mutations, 1 (1%) each. Evidence for clonal evolution (CCUS) and hematological malignancies were seen in 51 (39%) patients, involving all the aforementioned genes/syndromes with the exception of DBA, CBL, ETV6, MPL, CSF3R, and GATA1. Seven (64%) of 11 patients with germline ATM deletions/mutations developed lymphoid malignancies; homozygous ATM (Follicular NHL-1, Burkitt lymphoma-1, T-ALL-1, T-LPD-1) and heterozygous ATM (T-PLL-1, DLBCL-1, CLL-1). Clonal evolution occurred in 11 (69%) of 16 GATA2 haploinsufficient patients (CCUS-2, MDS-3, CMML-1, AML-5) and in 7 (58%) of 12 RUNX1-FPD patients (CCUS-1, MDS-1, MDS/MPN-3, AML-2). Five of 29 (17%) STS patients had clonal progression (CCUS-2, MDS-2, AML-1), and 5 (29%) of 17 FA patients progressed to MDS-2 or AML-3. JMML was seen in one patient with a germline NF1 mutation, while 1 (20%) of 5 SDS patients progressed to AML. NGS data at progression was available in 24 (55%) of 44 myeloid/CCUS progressions, with somatic truncating ASXL1 mutations being most frequent (29%), followed by RAS pathway mutations (15%). AML/MDS progressions in STS, FA, and SDS were universally associated with complex/monosomal karyotypes, translating to refractory disease. Seventeen (39%) of 44 patients with myeloid predisposition underwent allogenic HCT (GATA2-7, FA-3, RUNX1-FPD-3, STS-2, NF1-1, Tp53-1), with 10 (59%) being alive at last follow up (Table 1). Conclusion We demonstrate the spectrum of germline aberrations associated with predisposition to hematological malignancies and outline the phenotypic heterogeneity of clonal transformation. The advent of NGS allows identification of clonal progression earlier than morphological changes, with mutations in ASXL1 and RAS pathway genes being commonly implicated. This study supports the universal development of dedicated germline predisposition clinics. Disclosures Pruthi: CSL Behring: Honoraria; Genentech Inc.: Honoraria; Bayer Healthcare: Honoraria; HEMA Biologics: Honoraria; Instrumentation Laboratory: Honoraria; Merck: Honoraria.

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Clonal evolution in hematological malignancies and therapeutic implications

Leukemia ◽

10.1038/leu.2013.248 ◽

2013 ◽

Vol 28 (1) ◽

pp. 34-43 ◽

Cited By ~ 88

Author(s):

D A Landau ◽

S L Carter ◽

G Getz ◽

C J Wu

Keyword(s):

Hematological Malignancies ◽

Clonal Evolution ◽

Therapeutic Implications

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Heterogeneous disease-propagating stem cells in juvenile myelomonocytic leukemia

Journal of Experimental Medicine ◽

10.1084/jem.20180853 ◽

2021 ◽

Vol 218 (2) ◽

Cited By ~ 1

Author(s):

Eleni Louka ◽

Benjamin Povinelli ◽

Alba Rodriguez-Meira ◽

Gemma Buck ◽

Wei Xiong Wen ◽

...

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Single Cell ◽

Rna Sequencing ◽

Childhood Leukemia ◽

Clonal Evolution ◽

Juvenile Myelomonocytic Leukemia ◽

Hematopoietic Stem ◽

Ras Pathway ◽

Myelomonocytic Leukemia

Juvenile myelomonocytic leukemia (JMML) is a poor-prognosis childhood leukemia usually caused by RAS-pathway mutations. The cellular hierarchy in JMML is poorly characterized, including the identity of leukemia stem cells (LSCs). FACS and single-cell RNA sequencing reveal marked heterogeneity of JMML hematopoietic stem/progenitor cells (HSPCs), including an aberrant Lin−CD34+CD38−CD90+CD45RA+ population. Single-cell HSPC index-sorting and clonogenic assays show that (1) all somatic mutations can be backtracked to the phenotypic HSC compartment, with RAS-pathway mutations as a “first hit,” (2) mutations are acquired with both linear and branching patterns of clonal evolution, and (3) mutant HSPCs are present after allogeneic HSC transplant before molecular/clinical evidence of relapse. Stem cell assays reveal interpatient heterogeneity of JMML LSCs, which are present in, but not confined to, the phenotypic HSC compartment. RNA sequencing of JMML LSC reveals up-regulation of stem cell and fetal genes (HLF, MEIS1, CNN3, VNN2, and HMGA2) and candidate therapeutic targets/biomarkers (MTOR, SLC2A1, and CD96), paving the way for LSC-directed disease monitoring and therapy in this disease.

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Chromothripsis-Mediated Structural Variations and Clonal Evolution In Recurrent Childhood High Hyperdiploid Acute Lymphoblastic Leukemia

Blood ◽

10.1182/blood.v122.21.233.233 ◽

2013 ◽

Vol 122 (21) ◽

pp. 233-233

Author(s):

Cai Chen ◽

Christoph Bartenhagen ◽

Michael Gombert ◽

Vera Okpanyi ◽

Vera Binder ◽

...

Keyword(s):

Acute Lymphoblastic Leukemia ◽

Copy Number ◽

Conflicts Of Interest ◽

Lymphoblastic Leukemia ◽

Clonal Evolution ◽

Copy Number Variations ◽

Chromosome 3 ◽

Structural Variations ◽

Childhood All ◽

A Genome

Abstract High hyperdiploid acute lymphoblastic leukemia (HeH-ALL) is characterized by 51-67 chromosomes and nonrandom gains of specific chromosomes (X, 4, 6, 10, 14, 17, 18, and 21). It presents the most frequent numerical cytogenetic alteration in childhood pre B-cell ALL occurring in 25-30% of cases. Recurrent disease will affect 15-20%. Pre-leukemic HeH clones are generated in utero, but cooperating oncogenic lesions are necessary for overt leukemia and remain to be determined. Recently, a phenomenon termed chromothripsis has been described in which massive structural variations occur in a single aberrant mitosis. Whole or partial chromosomes are shattered and some fragments are lost in the process of rejoining. Thus, characteristically, chromosomal copy numbers oscillate between two copy number states. Chromothripsis has been suggested to be a tumor-driving alteration that may be present in 2-3% of all human cancers. Its role as a potential cooperating or initiating lesion in HeH-ALL has not been determined. We applied state-of-the-art whole-genome next-generation-sequencing to analyze structural variations in six pediatric patients with recurrent HeH-ALL. Matched sample sets taken at diagnosis, remission and/or relapse were compared. Paired end sequencing was carried out on a Genome Analyzer IIx or a HiSeq 2000 (Illumina), respectively. Reads were aligned against the human reference genome (GRCh37) using BWA. Translocations were detected by GASV. Copy number variations were analyzed by FREEC. Structural variations were validated by PCR/Sanger sequencing and FISH. Of the six patients analyzed, five harbored on average one interchromosomal translocation or intrachromosomal inversion, but one patient presented with massive genomic rearrangements (Figure). These affected chromosome 3, 11, 12 and 20. Ten copy number shifts on chromosome 3 oscillating between two copy number states (2 and 3) indicated that these rearrangements were caused by chromothripsis. Breakpoint sequencing revealed that one of the identified translocations (t(12;20)(p13.1;p12.3)), was indeed a three-loci-rearrangement composed of small fragments derived from chromosomes 3, 12 and 20. Characteristically for chromothripsis, the breakpoints clustered closely. Three breakpoints separated by 224 bp and 64 kb were located in the transducin (beta)-like X-linked receptor 1 (TBL1XR1) gene. Other genes repeatedly targeted included the MACRO domain-containing protein 2 (MACROD2) gene (a deacetylase involved in deacetylation of lysine residues in histones and other proteins), the KIAA1467 gene (a transmembrane protein of the integrin alpha FG-GAP repeat containing 3 (ITFG3) family), and a novel regulatory lincRNA (ENSG00000243276). MACROD2 was previously observed as a target of chromothripsis in a colorectal carcinoma. Thus, the characterized breakpoints may identify fragile genomic sites prone to chromothriptic rearrangement. DNA repair was effectuated by non-homologous-end-joining as typical addition of non-template nucleotides with microhomologies of two to four nucleotides at the breakpoints demonstrated. Copy number profiles of this patient showed that at least two distinct leukemic clones could be identified at diagnosis. One had acquired chromothriptic alterations and presented the dominant clone at relapse indicating chemotherapy resistance and tumor-driving potential. Prior whole-exome sequencing did not reveal mutations in known oncogenes or tumor suppressor genes. Therefore, loss of function or expression of genes affected by chromosomal rearrangements, such as TBL1XR1 that is recurrently mutated in childhood ALL with ETV6-RUNX1 translocation, may account for the tumor-driving effect. All leukemic cells at diagnosis showed conformity concerning number and pattern of whole chromosome gains demonstrating that chromothripsis was not an initiating oncogenic event, but occurred secondary to high hyperdiploidy. Further aberrations (t(4;7), loss of 4q) were gained by the chromothriptic clone and could be detected by FISH in minor subclones pointing at ongoing clonal evolution. Taken together, our study reveals chromothripsis as a novel assisting and tumor-driving lesion in HeH ALL. Chromothripsis in HeH-ALL. Copy number variations and translocations at diagnosis (left) and relapse (right). (magenta: chromothriptic translocations; green: other translocations) Disclosures: No relevant conflicts of interest to declare.

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Dysregulated Alternative Splicing Landscape Identifies Intron Retention as a Hallmark and Spliceosome as a Therapeutic Vulnerability in Aggressive Prostate Cancer

10.1101/634402 ◽

2019 ◽

Author(s):

Dingxiao Zhang ◽

Qiang Hu ◽

Yibing Ji ◽

Hsueh-Ping Chao ◽

Amanda Tracz ◽

...

Keyword(s):

Prostate Cancer ◽

Transcriptional Regulation ◽

Alternative Splicing ◽

Hematological Malignancies ◽

Intron Retention ◽

Therapy Resistance ◽

Copy Number Variations ◽

Castration Resistant ◽

Cancer Aggressiveness ◽

Transcriptional Alterations

ABSTRACTDysregulation of mRNA alternative splicing (AS) has been implicated in development and progression of hematological malignancies. Here we describe the first comprehensive AS landscape in the spectrum of human prostate cancer (PCa) development, progression and therapy resistance. We find that the severity of splicing dysregulation correlates with disease progression and establish intron retention (IR) as a hallmark of PCa stemness and aggressiveness. Systematic interrogation of 274 splicing-regulatory genes (SRGs) uncovers prevalent SRG mutations associated with, mainly, copy number variations leading to mis-expression of ~68% of SRGs during PCa evolution. Consequently, we identify many SRGs as prognostic markers associated with splicing disruption and patient outcome. Interestingly, androgen receptor (AR) controls a splicing program distinct from its transcriptional regulation. The spliceosome modulator, E7107, reverses cancer aggressiveness and abolishes the growth of castration-resistant PCa (CRPC) models. Altogether, we establish aberrant AS landscape caused by dysregulated SRGs as a novel therapeutic vulnerability for CRPC.Statement of significanceWe present the first comprehensive AS landscape during PCa evolution and link genomic and transcriptional alterations in SRGs to global splicing dysregulation. AR regulates splicing in pri-PCa and CRPC distinct from its transcriptional regulation. Intron retention is a hallmark for and spliceosome represents a therapeutic vulnerability in aggressive PCa.

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Harnessing the Power of Induced Pluripotent Stem Cells and Gene Editing Technology: Therapeutic Implications in Hematological Malignancies

Cells ◽

10.3390/cells10102698 ◽

2021 ◽

Vol 10 (10) ◽

pp. 2698

Author(s):

Ishnoor Sidhu ◽

Sonali P. Barwe ◽

Raju K. Pillai ◽

Anilkumar Gopalakrishnapillai

Keyword(s):

Stem Cells ◽

Induced Pluripotent Stem Cells ◽

Pluripotent Stem Cells ◽

Gene Editing ◽

Molecular Mechanisms ◽

Hematological Malignancies ◽

Disease Modeling ◽

Clonal Evolution ◽

Induced Pluripotent ◽

Ipsc Disease Modeling

In vitro modeling of hematological malignancies not only provides insights into the influence of genetic aberrations on cellular and molecular mechanisms involved in disease progression but also aids development and evaluation of therapeutic agents. Owing to their self-renewal and differentiation capacity, induced pluripotent stem cells (iPSCs) have emerged as a potential source of short in supply disease-specific human cells of the hematopoietic lineage. Patient-derived iPSCs can recapitulate the disease severity and spectrum of prognosis dictated by the genetic variation among patients and can be used for drug screening and studying clonal evolution. However, this approach lacks the ability to model the early phases of the disease leading to cancer. The advent of genetic editing technology has promoted the generation of precise isogenic iPSC disease models to address questions regarding the underlying genetic mechanism of disease initiation and progression. In this review, we discuss the use of iPSC disease modeling in hematological diseases, where there is lack of patient sample availability and/or difficulty of engraftment to generate animal models. Furthermore, we describe the power of combining iPSC and precise gene editing to elucidate the underlying mechanism of initiation and progression of various hematological malignancies. Finally, we discuss the power of iPSC disease modeling in developing and testing novel therapies in a high throughput setting.

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Clonal Evolution of Pre-Leukemic Hematopoietic Stem Cells Precedes Human Acute Myeloid Leukemia

Blood ◽

10.1182/blood.v118.21.4.4 ◽

2011 ◽

Vol 118 (21) ◽

pp. 4-4

Author(s):

Max Jan ◽

Thomas M. Snyder ◽

M. Ryan Corces-Zimmerman ◽

Irving L. Weissman ◽

Stephen R. Quake ◽

...

Keyword(s):

Stem Cells ◽

Myeloid Leukemia ◽

De Novo ◽

Clonal Evolution ◽

Leukemic Cells ◽

Founder Mutations ◽

Hematopoietic Stem ◽

De Novo Aml ◽

Clonal Progression ◽

Acute Myeloid

Abstract Abstract 4 Acute myeloid leukemia (AML) is an aggressive malignancy of hematopoietic progenitors with poor clinical outcomes. Despite the power of next-generation genome sequencing to describe AML genomes and to identify recurrent mutations, our fundamental understanding of the genomics of leukemogenesis is incomplete. Founding mutations in the majority of AML cases are largely unknown because pre-leukemic cells are clinically silent and are outcompeted by their malignant descendants. Our limited knowledge of founding mutations comes from infrequent cases of AML arising secondary to antecedent clonal bone marrow disorders or rare instances of inherited syndromes, but this does not include the large majority of de novo AML cases. Previously, we showed that non-leukemic hematopoietic stem cells (HSC) contain clonal antecedents of AML in patients in long-term remission post-therapy, and have proposed a model in which serial acquisition of mutations occurs in self-renewing HSC. More recently, we demonstrated the prospective separation of residual HSC from AML cells, based on differential expression of surface markers such as CD47 and TIM3.1,2 Here, we investigated this model and the nature of founder mutations through the genomic analysis of de novo AML and patient-matched residual non-leukemic HSC, speculating that these residual non-leukemic HSC might in fact constitute a reservoir of pre-leukemic HSC harboring founder mutations, but lacking the complete complement of abnormalities required to generate AML. Using exome sequencing, we identified mutations present in multiple individual AML genomes (mean 10 mutations per patient) and screened for them in the residual HSC. In most cases, we identified several mutations present in residual HSC that retained normal multilineage differentiation in vivo. These “early” mutations include NPM1c and novel AML mutations in genes involved in the cell cycle and mRNA biogenesis. Putative “late” mutations absent from residual HSC and only found in leukemic cells include FLT3 ITD and IDH1 R132H. Next, using custom-designed SNP Taqman genotyping assays, we analyzed single residual HSC for the presence of the identified “early” mutations. As hypothesized, we determined that a clonal progression of mutations occurs in non-leukemic HSC, based on the identification of individual cells containing subsets of these “early” mutations. Quantitative genetic analyses of the HSC compartment enabled us to reconstruct the subclonal architecture of normal and pre-leukemic stem cells. In all cases, normal HSC were 6–50 times more numerous than pre-leukemic HSC, and in one case where we identified two sequential populations of pre-leukemic HSC, the less mutated population was 25 times more numerous than its more mutated descendent. This result contrasts with the classical model of a linear succession of increasingly dominant pre-leukemic subclones, suggesting that the relationship between subclone size and clonal progression may be complex. In summary, our results show that pre-leukemic HSC reveal the clonal evolution of AML genomes from founder mutations. Ultimately, these clonal antecedents of leukemia may prove to be clinically important. Indeed, some cases of relapsed pediatric ALL have been shown to arise from a clone ancestral to the presenting leukemia. The same may be true in AML, in which relapsed disease develops from a pre-leukemic HSC clone that acquires additional novel mutations resulting in a genetically divergent leukemic relapse. This possibility suggests that pre-leukemic HSC constitute a cellular reservoir that may need to be targeted for more durable remissions. Disclosures: No relevant conflicts of interest to declare.

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To portray clonal evolution in blood cancer, count your stem cells

Blood ◽

10.1182/blood.2020008407 ◽

2020 ◽

Author(s):

Anne-Marie Lyne ◽

Lucie Laplane ◽

Leila Perié

Keyword(s):

Stem Cells ◽

Natural Selection ◽

Hematological Malignancies ◽

Clonal Evolution ◽

Significant Proportion ◽

Indirect Evidence ◽

Neutral Evolution ◽

Hematopoietic Stem ◽

Linear Pattern ◽

Linear Evolution

Clonal evolution, the process of expansion and diversification of mutated cells, plays an important role in cancer development, resistance and relapse. While clonal evolution is most often conceived of as driven by natural selection, recent studies uncovered that neutral evolution shapes clonal evolution in a significant proportion of solid cancers. In hematological malignancies, the interplay between neutral evolution and natural selection is also disputed. Because natural selection selects cells with a higher fitness-providing a growth advantage to some cells relative to others-the architecture of clonal evolution serves as indirect evidence to distinguish natural selection from neutral evolution and has been associated with different prognoses for the patient. Linear architecture, when the new mutant clone grows within the previous one, is distinctive of hematological malignancies and typically interpreted as driven by natural selection. Here we wish to discuss the role of natural selection and neutral evolution in the production of linear clonal architectures in hematological malignancies. While it is tempting to attribute linear evolution to natural selection, we argue that a lower number of contributing stem cells accompanied by genetic drift can also result in a linear pattern of evolution as illustrated by simulations of clonal evolution in hematopoietic stem cells. The number of stem cells contributing to long-term clonal evolution is not known in the pathological context and we advocate that estimating these numbers in the context of cancer and ageing is crucial to parsing out neutral evolution from natural selection, two processes that require different therapeutic strategies.

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Analysis of Clonal Evolution of AML Using Simultaneous Single-Cell DNA/RNA Analysis

Blood ◽

10.1182/blood-2020-143320 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 1-1

Author(s):

Ryosaku Inagaki ◽

Masahiro Marshall Nakagawa ◽

Yasuhito Nannya ◽

Qi Xingxing ◽

Lanying Zhao ◽

...

Keyword(s):

Single Cell ◽

Signaling Pathway ◽

Research Funding ◽

Clonal Evolution ◽

Blast Cell ◽

Driver Mutations ◽

Advisory Committees ◽

Ras Pathway ◽

Blast Cells ◽

Blast Count

Background Acute myeloid leukemia (AML) was defined by an increase of immature myeloid cells, or blasts that exceed ≥20% in bone marrow or peripheral blood. Many lines of evidence suggest that the development of AML is shaped by clonal evolution through multiple rounds of positive selection driven by newly acquired mutations, ultimately leading to an increased blast count. This process has been analyzed in detail in the case of progression from myelodysplastic syndromes (MDS) to secondary AML (sAML), which is invariably accompanied by expansion of cells that acquired new driver alterations, generating clonal substructures in many cases (Walter et al. NEJM. 2012, Makishima et al. Nat. Genet. 2015). However, it has not been fully elucidated how these newly acquired mutations contribute to increased blast cells that define AML. Results In order to understand how driver mutations contribute to the phenotype of blasts, we first focused on the driver mutations that have known to be enriched in sAML, including those in IDH1/2, NPM1, FLT3,NRAS, KRAS, PTPN11, CBL and WT1, and compared BM blast count (BC) and mutant cell fraction (MCF) of each driver mutation in 27 cases with sAML. Compared with BC, IDH1- or IDH2-mutated cells exhibited a larger MCF in most cases, suggesting that newly acquired IDH1/2 mutations contribute clonal expansion but only a part of the expanded cells undergo differentiation block and the remaining cells can differentiate into mature cells. Of interest, we observed lower MCFs than BC in approximately half of the cases with signaling pathway mutations, including FLT3 and RAS pathway (NRAS, KRAS, PTPN11 and CBL) mutations, in which MCFs for signaling pathway mutation accounted for less than 2/3 of BC, which was also observed in de novo AML cases. In fact, signaling pathway mutations in two representative cases were confirmed to account only for 30.4% and 3.4% of blast cells, using ddPCR of the blast cells collected as the CD45dim SSClow fraction, which were confirmed to show a blast morphology. These results suggest a possibility that the presence of mutant cells might affect the phenotype of the surrounding unmutated cells. Thus, to investigate the mechanism of such non-cell autonomous effects of mutations on blast cell morphology, we developed an advanced single-cell sequencing platform that enables simultaneous measurements of both mutations and gene expression profiles at a single-cell level and applied this to the analysis of immature (CD34+ Lin-) BM cells from 2 sAML cases with multiple RAS pathway mutations showing disproportionately small MCF compared to BC, in which gene expression of mutated and unmutated cells were evaluated separately. The same BM faction in 13 healthy donors was also analyzed as normal control. In single-cell mutation analysis, multiple RAS pathway mutations in both cases represented independent clones. As expected, cells carrying each RAS pathway mutation at sAML showed an immature myeloid phenotype. However, most of the cells, even carrying MDS mutations alone, also exhibited an immature myeloid phenotype similar to the RAS pathway mutated cells, although the latter cells showed upregulated RAS signaling compared with the former cells. Cells solely carrying MDS mutations in MDS phase showed multi-lineage differentiation, which was no longer observed in those cells in sAML phase. This was in contrast to another case who acquired MYC amplification on sAML progression, where nearly all cells having MYC-amplification showed an immature myeloid phenotype, whereas the remaining MDS clones lacking MYC-amplification retained multilineage differentiation even at the sAML phase. These results suggest that RAS mutants might have a non-cell autonomous effect on the surrounding cells including those hematopoietic cells lacking those mutations and other stromal cells, preventing their differentiation to mature cells, although we cannot exclude another possibility that altered BM microenvironment could influence the phenotype of both mutated and unmutated cells. Conclusions Although an acquisition of new mutations is essential for the progression of MDS to sAML, our results suggest that the blast cell phenotype may not solely be determined by cell-intrinsic effects of such mutations, but non-cell autonomous effects of mutated cells (and possibly also of an altered BM microenvironment) may have a role in increased blast count and therefore AML progression. Disclosures Inagaki: Sumitomo Dainippon Pharma Co., Ltd.: Current Employment. Nakagawa:Sumitomo Dainippon Pharma Co., Ltd.: Research Funding. Ogawa:KAN Research Institute, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Eisai Co., Ltd.: Research Funding; Sumitomo Dainippon Pharma Co., Ltd.: Research Funding; Asahi Genomics Co., Ltd.: Current equity holder in private company; Otsuka Pharmaceutical Co., Ltd.: Research Funding; Chordia Therapeutics, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding.

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Clinical Spectrum of Germline Mutations with Predisposition to Myeloid Neoplasms- 2016 World Health Organization Classification Update

Blood ◽

10.1182/blood.v128.22.300.300 ◽

2016 ◽

Vol 128 (22) ◽

pp. 300-300

Author(s):

Thanh Ho ◽

Juliana Perez Botero ◽

William J Hogan ◽

Saad S Kenderian ◽

Naseema Gangat ◽

...

Keyword(s):

Bone Marrow ◽

Who Classification ◽

Bone Marrow Failure ◽

Clonal Evolution ◽

Germline Mutations ◽

World Health ◽

Chromosomal Breakage ◽

Myeloid Neoplasms ◽

Telomere Biology ◽

Health Organization

Abstract Background: The 2016 revision to the World Health Organization (WHO) classification of myeloid neoplasms has specifically categorized germline mutations that are associated with myeloid clonal evolution (Arber et al. Blood 2016). This group consists of myeloid neoplasms with an isolated germline predisposition (CEBPA, DDX41), myeloid neoplasms associated with congenital thrombocytopenia (ETV6, RUNX1, ANKRD26) and germline myeloid neoplasms with multi-organ dysfunction (GATA2, chromosomal breakage disorders, telomere biology disorders etc). We carried out this study to describe the clinical spectrum of germline disorders with predisposition to myeloid neoplasms as categorized by the 2016 WHO classification revision. Methods: After Institutional Review Board (IRB) approval, the adult and pediatric bone marrow failure syndrome database (1990-2016) and the electronic medical record were queried for germline disorders involving GATA2, CEBPA, DDX41, ETV6, RUNX1, ANKRD26, Down syndrome and Noonan syndrome. Chromosomal breakage assays (Diepoxybutane/Mitomycin-C), flow-fluorescent in-situ hybridization (FISH) for telomere length assessment, Fanconi anemia complementation assays and Sanger/Next Generation sequencing (NGS) for the aforementioned germline disorders with myeloid predisposition were carried out in Clinical Laboratory Improvement Amendments (CLIA)-certified laboratories. These disorders were then classified based on the 2016 WHO classification revision. Results : 54 individuals (37 families) were included in the study. Eleven (20%) patients belonging to 5 families were identified as having germline mutations with a preexisting platelet disorder: ETV6 (n=1), ANKRD26 (n=5), RUNX1 (n=5). Forty-three (79%) patients (32 families) had inherited syndromes with multi-organ dysfunction: GATA2 (n=11, 26%), bone marrow failure syndromes (n=14, 33%) and telomere biology disorder (n=14, 33%). There was one patient with neurofibromatosis with a germline PTPN11 mutation who developed juvenile myelomonocytic leukemia, while there were three patients with Down syndrome; 2 with transient abnormal myelopoiesis and one who developed acute megakaryocytic leukemia. The clinical phenotype, prevalence and characteristics of myeloid clonal evolution and outcomes are presented in Table 1. No patients with germline CEBPA or DDX41 mutations were identified. Patients with germline platelet disorders did not have any prominent non-hematological manifestations. Erythrocytosis (20%) with long-standing thrombocytopenia (100%) was a unique feature associated with ANKRD26 mutations. Non-hematologic clues such as human papillomavirus (HPV)-driven warts, primary lymphedema (Emberger syndrome) and frequent atypical infections with monocytopenia were seen in patients with germline GATA2 mutations, and preceded myeloid clonal evolution (morphologic, cytogenetic and molecular). Notably, the age at presentation and penetrance of myeloid transformation was variable, with individuals from the same family developing symptoms during the first decade of life and others remaining asymptomatic to date (fifth decade). Somatic ASXL1 mutations were detected in all 3 (100%) patients with GATA2 mutations and in one patient with ANKRD26 mutation that developed myeloid clonal evolution. In our study myeloid clonal evolution was seen in 40% with RUNX1 mutations, 27% with GATA2 mutations, and 20% with ANKRD26 mutations. We could not calculate the same for bone marrow failure syndromes as the total number of cases seen are still being assessed. Outcomes with allogeneic stem cell transplantation were favorable in appropriately selected patients (Table 1). Conclusion : The 2016 WHO revision to the classification of myeloid neoplasms highlights the importance of recognition and molecular characterization of germline mutations (syndromic and non-syndromic) with risk for myeloid clonal evolution. While some of these disorders (GATA2, Fanconi anemia, telomere biology disorders) may have important non-hematological clues, many present with isolated thrombocytopenia (RUNX1, ETV6). The age and frequency of myeloid evolution is highly variable. Acquisition of somatic ASXL1 mutations at the time of clonal myeloid transformation highlights the role of epigenetic dysregulation in disease evolution. Disclosures Kenderian: Novartis: Patents & Royalties, Research Funding.

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