scholarly journals Minor GPI(-) Granulocyte Populations in Patients with Acquired Aplastic Anemia and Healthy Individuals Are Derived from a Few Piga-Mutated Hematopoietic Stem Progenitor Cells

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2181-2181
Author(s):  
Hiroki Mizumaki ◽  
Dung Cao Tran ◽  
Kohei Hosokawa ◽  
Kazuyoshi Hosomichi ◽  
Hiroyuki Takamatsu ◽  
...  
Keyword(s):  
Aplastic Anemia ◽  
Progenitor Cells ◽  
Research Funding ◽  
Bone Marrow Failure ◽  
Amplicon Sequencing ◽  
Digital Pcr ◽  
Healthy Individuals ◽  
Enrichment Method ◽  
Hematopoietic Stem ◽  
Magnetic Microbeads

Abstract [Background] Minor populations (0.003%-1.0%) of glycosylphosphatidylinositol-anchored protein-deficient granulocytes (GPI[-] Gs) are often detected in the peripheral blood (PB) of patients with acquired aplastic anemia (AA) and low-risk myelodysplastic syndromes and are thought to represent immune pathophysiology of bone marrow failure. We previously reported that minor GPI(-) G populations were detected in some healthy individuals (HIs) and persisted over several years at similar percentages (Katagiri T, et al. Stem Cells 2013). Several lines of evidence have suggested that small numbers of GPI(-) Gs detected in HIs are polyclonal populations mostly derived from short-lived PIGA-mutated committed progenitor cells. Minor GPI(-) G populations in AA patients may also be derived from multiple committed progenitor cells rather than from a few hematopoietic stem progenitor cells (HSPCs) with PIGA mutations. However, minor GPI(-) G populations usually persist for a long period of time at similar frequencies in AA patients, suggesting that they may instead be derived from a few HSPCs that have undergone PIGA mutations. This issue remains debated due to the inability to sequence the PIGA gene in the very few GPI(-) granulocytes available. We recently developed a sensitive method capable of detecting PIGA mutations in minor GPI(-) Gs using amplicon sequencing of GPI(-) Gs that were enriched with magnetic microbeads followed by FACS sorting. Using this method, we addressed whether minor GPI(-) G populations in AA patients and HIs are oligoclonal or polyclonal as well as which cell population they are derived from HSPCs or committed progenitor cells. [Methods] Five AA patients possessing 0.025%-0.898% GPI(-) Gs, 3 HIs who were found to have ≥0.003% (0.006%, 0.051%, and 0.059%) GPI(-) Gs during a screening of more than 200 HIs for GPI(-) Gs, 30 HIs (median: 37 years old, male/female:17/13) with 0% to 0.002% GPI(-) Gs, and 8 cord blood (CB) samples were subjected to enrichment of GPI(-) Gs for PIGA sequencing. Their leukocytes were treated with PE-labelled anti-CD55 monoclonal antibodies (mAbs) and anti-CD59 mAbs, and CD55 +CD59 + granulocytes were removed using magnetic microbeads labelled with anti-PE mAbs. CD11b +FLAER-negative granulocytes were sorted from the remaining granulocytes using FACSAria Fusion. DNA from sorted GPI(-) Gs was amplified using primers covering all exons of PIGA. Nucleotide sequences of the PIGA gene in GPI(-) Gs were determined using a next-generation sequencer. [Results] This novel enrichment method enabled the detection of only 1-4 different PIGA mutations in all 5 female AA patients (AA 1-5) with the total of different VAFs in each case reaching nearly 50% (Table 1). Limited kinds of PIGA mutations were also detected in three HIs (two males [HI 1 and 3] and one female [HI 2]). For HI 1 and HI 3, the VAFs of predominant PIGA-mutated sequences were longitudinally measurable using whole-blood DNA samples with droplet digital PCR, which showed no apparent changes in the VAF (0.020%-0.027% for HI 1 and 0.012%-0.025% for HI 3 over 4 and 6 years, respectively). The presence of mono or oligoclonal GPI(-) Gs in the 3 HIs prompted us to study 30 HIs who had been judged to be negative for minor GPI(-) G populations by a high-sensitivity flow cytometry method. The enrichment method unexpectedly identified clear CD11b highFLAER - GPI(-) G clusters in granulocytes from 24 of the 30 HIs (Figure 1a). The median number of GPI(-) Gs contained in 7 ml of PB was 31 (range, 1-136 cells). Sufficient amounts of DNA for NGS were obtained from sorted GPI(-) Gs of six subjects, and PIGA amplicon sequencing revealed 1-3 different PIGA mutations in four of the six subjects. The examination of fresh CB also revealed clear GPI(-) G clusters in four of eight samples (Figure 1b). PIGA amplicon sequencing of 79 GPI(-) Gs obtained from 1 male CB sample (CB 1) showed a sole PIGA mutation with VAFs of 95% (Figure 1c). [Conclusion] Minor GPI(-) G populations detectable in patients with AA and HIs are derived from a few PIGA-mutated HSPCs, not from committed myeloid progenitor cells, a finding that negates a hypothesis that a few PIGA-mutated HSPCs are selected from polyclonal PIGA-mutated HSPCs during transition from AA to florid PNH. Very small numbers of GPI(-) Gs are present much more frequently in HIs than previously thought and may also be derived from a few HSPCs with PIGA mutations that occur in HSPCs during the fetal stage. Figure 1 Figure 1. Disclosures Takamatsu: Bristol-Myers Squibb: Honoraria, Research Funding; Adaptive Biotechnologies, Eisai: Honoraria; SRL: Consultancy; Janssen: Consultancy, Honoraria, Research Funding. Yamazaki: Novartis Pharma: Honoraria; Kyowa Kirin: Research Funding; Kyowa Kirin: Honoraria. Nakao: Symbio: Consultancy; Kyowa Kirin: Honoraria; Novartis Pharma: Honoraria; Alexion Pharma: Research Funding.

Epigenetic Loss of the HLA-DR15 Expression on Hematopoietic Stem Progenitor Cells in Patients with Acquired Aplastic Anemia Characterized By Cyclosporine Dependency: A Novel Mechanism Underlying the Immune Escape of Hematopoietic Stem Progenitor Cells

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 23-24
Author(s):  
Noriaki Tsuji ◽  
Kohei Hosokawa ◽  
Ryota Urushihara ◽  
Mikoto Tanabe ◽  
Hiroyuki Takamatsu ◽  
...  
Keyword(s):  
Progenitor Cells ◽  
Research Funding ◽  
Hla Class I ◽  
Epigenetic Mechanism ◽  
Class I ◽  
Healthy Individuals ◽  
Hematopoietic Stem ◽  
Hla Dr ◽  
Immune Mediated ◽  
Ifn Γ

[Background] HLA-DR15 (DR15) has been implicated in the susceptibility to immune-mediated bone marrow (BM) failure, such as acquired aplastic anemia (AA), wherein the hematopoietic function depends on cyclosporine (CsA), paroxysmal nocturnal hemoglobinuria (PNH) with BM failure, and low-risk myelodysplastic syndrome responsive to immunosuppressive therapy. However, how DR15 contributes to the development of such immune-mediated BM failure remains unclear. Although the copy-number neutral loss of heterozygosity in chromosome 6p (6pLOH) of hematopoietic stem progenitor cells (HSPCs) in AA patients sometimes involves the HLA-DRB1 region, the frequency of the resultant DR15 loss is low, suggesting little involvement of this DR allele in the escape of HSPCs from cytotoxic T-cell attack. Several studies have recently reported that acute myeloid leukemia cells that relapse after allogeneic hematopoietic stem cell transplantation often lack HLA class II expression through an epigenetic mechanism and thereby escape the graft-versus-leukemia effect. The epigenetic loss of HLA class II expression may also occur in HSPCs that survive the immune attack in AA patients in remission. [Objectives/Methods] To test this hypothesis, we determined the HLA-DR expression on HSPCs defined by lineage-CD45dimCD34+CD38+ cells as well as their subpopulations, including common myeloid progenitors (CMPs), megakaryocyte-erythroid progenitors (MEPs), and granulocyte-monocyte progenitors (GMPs), in the peripheral blood of 52 AA patients (34 with DR15 and 18 without DR15) and 20 healthy individuals using flow cytometry (FCM) with anti-pan-HLA-DR antibodies. All patients were in remission after ATG-based therapy (ATG+CsA±thrombopoietin receptor agonists [TPO-RA] or anabolic steroids [AS], n=19), CsA-based therapy (CsA±TPO-RA or AS, n=27), and others (n=6), and 18 required low-dose CsA to maintain remission. Eighteen (35%) had HLA-class I allele-lacking (HLA-class I[-]) leukocytes due to 6pLOH and/or allelic mutations while 33 (63%) had 0.003-83.8% (median 0.194%) GPI-anchored protein-deficient (GPI[-]) granulocytes. HLA-DR(-) HSPCs detected in some patients were sorted together with their HLA-DR(+) counterparts and subjected to incubation in the presence of interferon gamma (IFN-γ) to see whether or not the DR expression was restored; in addition, they were subjected to RNA sequencing to compare the gene expression profiles between DR(-) and DR(+) HSPCs. [Results] Five (9.6%) of the 52 AA patients had 28.6% to 42.3% (median 34.0%) DR(-) cell populations in HSPCs, which were not detected in either monocytes or B lymphocytes of the same patients or in HSPCs of any healthy individuals (Figure 1a). All 5 patients possessed either HLA-DRB1*15:01 (n=3), DRB1*15:02 (n=1), or DRB1*15:01/15:02 (n=1), with the other DRB1 alleles differing among individuals, and their hematopoietic function depended on CsA, except for 1 patient (Case 5) whose HSPCs consisted of 69% GPI(+) and 31% GPI(-) cells. Of particular interest, Case 5's DR(-) cells were detected in GPI(+) HSPCs but not in GPI(-) HSPCs (Figure 1b). None of the 5 patients possessed HLA-class I(-) leukocytes, which were detected in 18 (38%) of 47 patients not possessing DR(-) HSPCs. In contrast to the patients possessing DR(-) HSPCs, CsA dependency was only observed in 13 (28%) of the 47 AA patients without DR(-) HSPCs. Incubation of sorted DR(-) HSPCs in the presence of IFN-γ for 72 h resulted in full restoration of the DR expression in all HSPC subpopulations (Figure 2). A comparison of the transcriptome profile between DR(-) and DR(+) HSPCs revealed that the signature of differentially expressed genes was enriched in immune response-related genes. [Conclusions] HSPCs that lacked DR due to an epigenetic mechanism were frequently detected in AA patients with DR15 characterized by CsA dependency. Although the loss of expression occurred in both DR alleles, the fact that only DRB1*15:01 or 15:02 was an allele shared by the five patients indicates that the DR loss phenomenon targeted DR15. The DR15(-) HSPCs may escape from antigen-specific CD4+ T-cell attack, which cannot be completely abolished by CsA. As demonstrated by findings of Case 5 showing the presence of a DR(-) cell population only in GPI(+) HSPCs, the lack of GPI may be a mechanism underlying substitution for the DR15 loss. Disclosures Takamatsu: Ono pharmaceutical: Honoraria, Research Funding; SRL: Consultancy, Research Funding; Janssen Pharmaceutical: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Adaptive Biotechnologies: Honoraria. Ishiyama:Alexion: Research Funding; Novartis: Honoraria. Yamazaki:Kyowa Kirin: Honoraria, Research Funding; Novartis: Honoraria. Nakao:Alexion: Research Funding; Novartis: Honoraria; Kyowa Kirin: Honoraria; Symbio: Consultancy.

scholarly journals The Depletion of TGF-β Co-Receptor CD109 Induces Erythroid Differentiation of TF-1 Cells: A Model of Preferential Commitment of PIGA-Mutated Hematopoietic Stem Cells in Immune-Mediated Bone Marrow Failure

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3874-3874
Author(s):  
Tanabe Mikoto ◽  
Noriharu Nakagawa ◽  
Kohei Hosokawa ◽  
Luis Espinoza ◽  
Kana Maruyama ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Line ◽  
Progenitor Cells ◽  
Blood Cells ◽  
Bone Marrow Failure ◽  
Erythroid Differentiation ◽  
Healthy Individuals ◽  
Hematopoietic Stem ◽  
Immune Mediated

Abstract [Background] Glycosylphosphatidylinositol-anchored proteins (GPI-APs) on hematopoietic stem progenitor cells (HSPCs) may play an important role in the regulation of the HSPC commitment, given the fact that a lack of GPI-APs due to PIGA mutations allows HSPCs to preferentially undergo commitment into mature blood cells under immune pressure against HSPCs in patients with acquired aplastic anemia. CD109, one of the GPI-APs expressed by keratinocytes and HSPCs in humans, serves as a TGF-β co-receptor and is reported to inhibit TGF-β signaling in keratinocytes; however, the role of CD109 on HSPCs has not been clarified. TF-1 is one of a few myeloid leukemia cell lines that express CD109, the proliferation of which is dependent on GM-CSF. Since TF-1 undergoes erythroid differentiation in response to δ-5-aminolevulinic acid (δ-ALA), and its differentiation is reportedly inhibited by TGF-β, a lack of GPI-APs due to PIGA mutation and/or the knockout (KO) of CD109 may affect the differentiation of TF-1 cells. [Objectives/Methods] To gain insights into the role of GPI-APs on HSPCs, we established a PIGA-mutated TF-1 cell line by culturing TF-1 in the presence of α-toxin for several months, and a CD109 KO TF-1 cell line using a CRISPR-Cas 9 system. The erythroid differentiation of the cells was assessed by testing the expression of glycophorin A (GPA) on TF-1 cells using flow cytometry (FCM) and iron staining. We also determined the CD109 expression by HSPCs from healthy individuals and C57BL/6 mice using FCM and a quantitative PCR. [Results] Both GPI-AP-deficient TF-1 cells that had a PIGA mutation (7 nucleotide deletion at position 291-297 [TTGTCAC] in exon 2) and CD109 KO TF-1 cells showed slower proliferation than wild-type (WT) TF-1 cells. Similarly to TF-1 cells treated with δ-ALA, both mutant cells expressed GPA, exhibited erythroid morphology, and were positive for iron granules, suggesting that GPI-APs inhibited the erythroid differentiation of WT TF-1 cells that were cultured in RPMI1640 containing 10% fetal bovine serum (FBS), and that the GPI-AP that plays a key role in the inhibition of erythroid differentiation is CD109. Since low levels (1-2 ng/ml) of TGF-β in the serum-containing culture medium were suspected to inhibit the erythroid differentiation of WT TF-1 through its binding to CD109, WT TF-1 cells were cultured in a serum-free medium Expi293 Expression Medium for 10 days. While control TF-1 cells cultured in the serum-containing RPMI1640 were negative for the expression of GPA, 77.0-84.5% of the cultured TF-1 cells expressed GPA and exhibited erythroid morphology. CD109 was expressed by 12.1-18.3% of CD34+CD38- cells, 4.5-7.4% of common myeloid progenitor cells (CMPs), 20.8-42.4% of megakaryocyte-erythrocyte progenitor cells (MEPs), and 14.2-22.0% of granulocyte macrophage progenitor cells (GMPs) in the bone marrow of healthy individuals, while murine CD48-CD150+CD34- LSK cells were negative for either CD109 protein or mRNA. [Conclusions] CD109 protects TF-1 cells from differentiating into erythroid cells in serum-containing culture. In contrast to keratinocytes, the CD109 on TF-1 cells, and possibly on HSPCs, may enhance TGF-β signaling, and the lack of the GPI-AP might make PIGA-mutated HSPCs insensitive to TGF-β, leading to the preferential commitment of mutant HSPCs to mature blood cells in immune-mediated bone marrow failure. Disclosures Nakao: Kyowa Hakko Kirin Co., Ltd.: Honoraria; Novartis: Honoraria; Alexion Pharmaceuticals, Inc.: Consultancy, Honoraria.

Relatively Low Sensitivity of CD109(-) Hematopoietic Stem/Progenitor Cells (HSPCs) to TGF-β: A Possible Mechanism Responsible for the Preferential Commitment of Piga Mutant HSPCs in Immune-Mediated Bone Marrow Failure

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3911-3911
Author(s):  
Noriharu Nakagawa ◽  
Kohei Hosokawa ◽  
Luis Espinoza ◽  
Kana Maruyama ◽  
Takamasa Katagiri ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Aplastic Anemia ◽  
Progenitor Cells ◽  
Research Funding ◽  
Lower Sensitivity ◽  
Wild Type ◽  
Hematopoietic Stem ◽  
Immune Mediated ◽  
Cd34 Cells

Abstract [Background] An increase in the numbers of glycosylphosphatidylinositol-anchored protein-deficient [GPI(-)] blood cells is often detected in patients with acquired aplastic anemia (AA) and low-risk myelodysplastic syndrome (MDS), and is associated with good response of their bone marrow (BM) failure to immunosuppressive therapy. Although some immune mechanisms are thought to play a role in the preferential commitment of hematopoietic stem/progenitor cells (HSPCs) with PIGA mutations in such BM failure patients, the exact mechanisms are unknown. Our previous studies suggested that GPI(-)T cells in patients with paroxysmal nocturnal hemoglobinuria (PNH) were less susceptible to TGF-ƒÀ-mediated inhibition of proliferation triggered by anti-CD3 and anti-CD28 antibodies than GPI(+)T cells of the same patient. The lower sensitivity of PIGA mutant HSPCs to TGF-ƒÀ, a cytokine capable of inhibiting the cell cycling of dormant HSPCs, than GPI(+) HSPCs may also explain the preferential commitment of GPI(-) HSPCs in immune-mediated BM failure. However, little is known about the GPI-APs that affect the sensitivity of HSPCs to TGF-ƒÀ. [Objectives/Methods] We assessed the roles of GPI-APs in the signal transduction of CD34(+) cells of a PNH patient and the myeloid leukemia cell line TF-1 in response to TGF-ƒÀ. We also assessed the TGF-ƒÀ-mediated inhibition of cell proliferation in TF-1 cells with or without a PIGA mutation. CD109, a GPI-AP that serves as a TGF-ƒÀ co-receptor in human keratinocytes, of TF-1 cells, was knocked out from TF-1 cells using a CRISPR-Cas 9 system, and the sensitivity to TGF-ƒÀ was compared between CD109(+) and CD109(-) TF-1 cells. [Results] The treatment of BM mononuclear cells from a florid PNH patient with TGF-ƒÀ induced SMAD2 phosphorylation in GPI(-) CD34(+) cells to a lesser degree than in GPI(+) CD34(+) cells (fold increase in pSMAD2 MFI, 1.0 vs. 2.6, Figure 1). TGF inhibited PIGA-mutant TF-1 (PNH-TF-1) proliferation to a lesser degree (percentage of inhibition, 19%}13%) than wild-type TF-1 cells (67%}3%) in an MTT-based proliferation assay. Transfection of PIGA into PNH-TF-1 cells restored GPI-AP expression as well as sensitivity to TGF-ƒÀ (53%}10% vs. 19%}13% in PNH-TF-1 cells). CD109 coimmunoprecipitated with TGF-ƒÀ in TF-1 cells, and its expression was confirmed on BM CD34+ cells of healthy individuals, particularly CD34+CD38+CD123-CD45RA- megakaryocyte-erythroid progenitor cells, as well as on TF-1 cells. The pSMAD2 induction in CD109(-) TF-1 cells by TGF-ƒÀ was less pronounced (relative increase in pSMAD2 MFI, 7.65}2.15 vs. 10.74}2.28) than that in CD109(+) TF-1 cells (Figure 2). [Conclusions] CD109 deficiency is involved in the lower sensitivity of GPI(-) HSPCs to TGF-ƒÀ than GPI(+) HSPCs. This deficiency may account for the preferential activation of PIGA mutant HSPCs in immune-mediated BM failure, in which TGF-ƒÀ suppresses activation of wild-type HSPCs. Disclosures Hosokawa: Aplastic Anemia and MDS International Foundation: Research Funding. Nakao:Alexion Pharmaceuticals: Honoraria, Research Funding.

Accelerated telomere shortening in glycosylphosphatidylinositol (GPI)–negative compared with GPI-positive granulocytes from patients with paroxysmal nocturnal hemoglobinuria (PNH) detected by proaerolysin flow-FISH

Blood ◽  
2005 ◽  
Vol 106 (2) ◽  
pp. 531-533 ◽  
Author(s):  
Fabian Beier ◽  
Stefan Balabanov ◽  
Tom Buckley ◽  
Klaus Dietz ◽  
Ulrike Hartmann ◽  
...  
Keyword(s):  
Telomere Length ◽  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Bone Marrow Failure ◽  
Disease Stage ◽  
Healthy Individuals ◽  
Hematopoietic Stem ◽  
Replicative Stress ◽  
Selective Growth Advantage ◽  
Bone Marrow Failure Syndromes ◽  
The Impact

Abstract Telomere length has been linked to disease stage and degree of (pan-)cytopenia in patients with bone marrow failure syndromes. The aim of the current study was to analyze the impact of replicative stress on telomere length in residual glycosylphosphatidylinositol-positive (GPI+) versus GPI– hematopoiesis in patients with paroxysmal nocturnal hemoglobinuria (PNH). Peripheral blood granulocytes from 16 patients and 22 healthy individuals were analyzed. For this purpose, we developed proaerolysin flow-FISH, a novel methodology that combines proaerolysin staining (for GPI expression) with flow-FISH (for telomere length measurement). We found significantly shortened telomeres in GPI– granulocytes (mean ± SE: 6.26 ± 0.27 telomere fluorescence units [TFU]), both compared with their GPI+ counterparts (6.88 ± 0.38 TFU; P = .03) as well as with age-matched healthy individuals (7.73 ± 0.23 TFU; P < .001). Our findings are in support of a selective growth advantage model of PNH assuming that damage to the GPI+ hematopoietic stem-cell (HSC) compartment leads to compensatory hyperproliferation of residual GPI–HSCs.

scholarly journals Mutations in the Telomerase Complex and Expression Levels of the TERT Gene Determine Severity and Outcome of Disease in Aplastic Anemia Patients

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1502-1502 ◽  
Author(s):  
Arati Khanna-Gupta ◽  
Durga Sarvepalli ◽  
Snigdha Majumder ◽  
Coral Karunakaran ◽  
Malini Manoharan ◽  
...  
Keyword(s):  
Aplastic Anemia ◽  
Disease Severity ◽  
Poor Prognosis ◽  
Conflicts Of Interest ◽  
Bone Marrow Failure ◽  
Response To Therapy ◽  
Hematopoietic Stem ◽  
Expression Levels ◽  
Shelterin Complex ◽  
Tert Expression

Abstract Acquired Aplastic anemia (AA) is a bone marrow failure syndrome characterized by pancytopenia and marrow hypoplasia, and is mediated by immune destruction of hematopoietic stem cells. Mutations in several genes including telomerase, a ribonucleoprotein enzyme complex, consisting of a reverse transcriptase enzyme (TERT), an RNA template (TERC), and several stabilizing proteins, and the associated shelterin complexes have been found in both congenital and idiopathic AA. In particular, several TERT and TERC mutations reduce telomerase activity in vitro and accelerate telomere attrition in vivo. Shortened telomeres have been observed in a third of idiopathic AA patients, but only 10% of these patients have mutations in genes of the telomerase complex. We have recently demonstrated that in addition to keeping telomeres from shortening, telomerase directly regulates transcriptional programs of developmentally relevant genes (Ghosh et al, Nat Cell Biol, 2012, 14, 1270). We postulate that changes in expression of telomerase associated genes, specifically TERT, contribute to the etiology of aplastic anemia. In an effort to better understand the molecular and clinical correlates of this disease, 24 idiopathic AA patient samples were collected at a tertiary medical center in Bangalore, India. Following informed consent, we performed RT-PCR analysis on harvested RNA from each patient and measured levels of TERT expression compared to that of normal controls (n=6). An 8 fold reduction in TERT expression was observed in 17/24 patients, while 7/24 patients maintained normal TERT expression. In general, TERT-low patients were younger in age (mean age 29y) compared with the TERT-normal patients (mean age 40y). TERT-low patients were more likely to have severe aplastic anemia (SAA) leading to higher mortality and poorer response to therapy, with 6/17 patients dying and 4/17 not responding to ATG therapy. Targeted panel sequencing of the 24 samples on an Illumina platform revealed that while TERT-normal patients had no mutations in genes associated with the telomerase/shelterin complex, TERT-low patients carried predicted pathogenic variants in TERT, TEP1, TINF2, NBN, TPP1, HSP90A and POT1 genes, all associated with the telomerase complex. Somatic gene variants were also identified in other AA associated genes, PRF1 and CDAN1, in the TERT-low cohort. In addition, novel predicted pathogenic mutations associated with the shelterin complex were found in two TERT-low patients in the TNKS gene. We also detected mutations in TET2, BCORL1, FLT-3, MLP and BRAF genes in TERT-low patients. Mutations in these genes are associated with clonal evolution, disease progression and poor prognosis. Our observations were further illustrated in a single patient where normal TERT expression was noted at initial clinical presentation. ATG therapy led to CR, but the patient returned within a year and succumbed to E.coli related sepsis. At that stage he had low TERT expression, suggesting that TERT expression can change as the disease progresses. Taken together, our data support the hypothesis that loss of TERT expression correlates with disease severity and poor prognosis. Our observations further suggest that preliminary and periodic evaluation of TERT expression levels in AA patients is likely to serve as a predictor of disease severity and influence the choice of therapy. Disclosures No relevant conflicts of interest to declare.

scholarly journals Paroxysmal Nocturnal Hemoglobinuria Clones Are Infrequent in Hepatitis-Associated Aplastic Anemia at the Time of Diagnosis

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 5016-5016
Author(s):  
Wenrui Yang ◽  
Xin Zhao ◽  
Guangxin Peng ◽  
Li Zhang ◽  
Liping Jing ◽  
...  
Keyword(s):  
Aplastic Anemia ◽  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Conflicts Of Interest ◽  
Bone Marrow Failure ◽  
Clonal Evolution ◽  
Extrinsic Factors ◽  
Clone Size ◽  
Hematopoietic Stem ◽  
Over Time ◽  
Pnh Clone

Aplastic anemia (AA) is an immune-mediated bone marrow failure, resulting in reduced number of hematopoietic stem and progenitor cells and pancytopenia. The presence of paroxysmal nocturnal hemoglobinuria (PNH) clone in AA usually suggests an immunopathogenesis in patients. However, when and how PNH clone emerge in AA is still unclear. Hepatitis associated aplastic anemia (HAAA) is a special variant of AA with a clear disease course and relatively explicit immune pathogenesis, thus serves as a good model to explore the emergence and expansion of PNH clone. To evaluate the frequency and clonal evolution of PNH clones in AA, we retrospectively analyzed the clinical data of 90 HAAA patients that were consecutively diagnosed between August 2006 and March 2018 in Blood Diseases Hospital, and we included 403 idiopathic AA (IAA) patients as control. PNH clones were detected in 8 HAAA patients (8.9%,8/90) at the time of diagnosis, compared to 18.1% (73/403) in IAA. Eight HAAA patients had PNH clone in granulocytes with a median clone size of 3.90% (1.09-12.33%), and 3 patients had PNH clone in erythrocytes (median 4.29%, range 2.99-10.8%). Only one HAAA patients (1/8, 12.5%) had a PNH clone larger than 10%, while 24 out of 73 IAA patients (32.9%) had larger PNH clones. Taken together, we observed a less frequent PNH clone with smaller clone size in HAAA patients, compared to that in IAAs. We next attempted to find out factors that associated with PNH clones. We first split patients with HAAA into two groups based on the length of disease history (≥3 mo and < 3mo). There were more patients carried PNH clone in HAAA with longer history (21.4%, 3/14) than patients with shorter history (6.6%, 5/76), in line with higher incidence of PNH clone in IAA patients who had longer disease history. Then we compared the PNH clone incidence between HAAA patients with higher absolute neutrophil counts (ANC, ≥0.2*109/L) and lower ANC (< 0.2*109/L). Interestingly, very few VSAA patients developed PNH clone (5%, 3/60), while 16.7% (5/30) of non-VSAA patients had PNH clone at diagnosis. We monitored the evolution of PNH clones after immunosuppressive therapy, and found increased incidence of PNH clone over time. The overall frequency of PNH clone in HAAA was 20.8% (15/72), which was comparable to that in IAA (27.8%, 112/403). Two thirds of those new PNH clones occurred in non-responders in HAAA. In conclusion, PNH clones are infrequent in HAAA compared to IAA at the time of diagnosis, but the overall frequency over time are comparable between the two groups of patients. In SAA/VSAA patients who are under the activated abnormal immunity, longer clinical course and relatively adequate residual hematopoietic cells serve as two important extrinsic factors for HSCs with PIGA-mutation to escape from immune attack and to expand. Disclosures No relevant conflicts of interest to declare.

scholarly journals Efficacy and Safety of a FLAG-Sequential Regimen Followed By Hematopoietic Stem Cell Transplantation for Myelodysplasia or Acute Leukemia in Fanconi Anemia: A Franco-Brazilian Report

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 2498-2498
Author(s):  
Pierre-Edouard Debureaux ◽  
Flore Sicre de Fontbrune ◽  
Carmem M. S. Bonfim ◽  
Jean-Hugues Dalle ◽  
Nimrod Buchbinder ◽  
...  
Keyword(s):  
Cumulative Incidence ◽  
Research Funding ◽  
Bone Marrow Failure ◽  
Clonal Evolution ◽  
Infectious Complications ◽  
Hematopoietic Stem ◽  
Free Survival ◽  
History Of ◽  
Syncytial Virus

Background: Fanconi anemia (FA) is the most frequent genetic cause of bone marrow failure (BMF) due to a DNA repair mechanism defect. The natural history of FA is marked by progressive BMF during early childhood. Throughout life, the hematopoietic situation may change by clonal evolution toward myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML). Hematopoietic stem cell transplantation (HSCT) is the only curative treatment for bone marrow failure in FA patients. The role of HSCT for FA patients with AML or advanced MDS is less defined. Currently, HSCT first line result offers 50% Overall Survival (OS) for patients with cytogenetic abnormalities only and 30% OS for patients with advanced MDS or AML in FA (Ayas et al., JCO 2013; Mitchell et al., BJH 2014). We previously reported a FLAG-sequential approach in 6 patients with FA (5 AML and 1 advanced MDS), all alive at a median follow-up of 28 months (Talbot et al., Hematologica 2014). We update here those patients and report 12 more patients treated by FLAG-sequential since then. Materials & Methods: This retrospective study (2006-2019) was conducted in 7 centers in France and Brazil on behalf of the French Reference Center for Aplastic Anemia to evaluate FLAG-sequential in FA patients with morphological clonal evolution (no patients with cytogenetic abnormalities only). The study was conducted in accordance with the Declaration of Helsinki. Anonymous data collection was declared to the appropriate authorities. The FLAG-sequential treatment consisted of FLAG, Fludarabine 30 mg/m²/d for five days and Cytarabine 1 g/m²x2/d with G-CSF for five days, which was followed three weeks later by Cyclophosphamide 10 mg/kg/d for four days, Fludarabine 30 mg/m²/d for four days and TBI 2 Gy (Fig 1A). In a haploidentical setting, Cyclophosphamide at 30 mg/kg/d was performed only in post-transplantation, at Days +4 and +5 (Fig 1B). Results: Eighteen patients were included with 14 AML, 1 acute lymphoblastic leukemia (ALL), and 3 RAEB-2 (Table 1). The median age at the time of HSCT was 22 years (4-37 years). Fifteen patients (83%) were older than 10 years at the time of HSCT. The median follow-up was 31 months (3- 153 months). Eight patients (44%) had complex karyotype. None of the included patients had a history of solid malignancies before HSCT. All patients engrafted. The cumulative incidence of neutrophil engraftment at Day 60 was 94% (95% CI 63-100%) with a median of 18 days (12-343 days). The cumulative incidence of platelet engraftment at Day 60 was 83% (95% CI 50%-96%) with a median of 25 days (17-245 days). The donor chimerism was complete at Day +100 for 15 patients. The three patients without full donor chimerism at Day +100 either had a relapse (n=1) and 2 early deaths before Day+100 from steroid-refractory aGVHD (n=1) or septic shock (n=1). None of the patients received a second HSCT. Non-relapse mortality (NRM) at 3 years was 32% (95% CI 6-58%) (Fig 2). Cumulative incidence of grades II to IV aGVHD was 56% (35% grades III to IV). Cumulative incidence of extensive cGVHD was 16%. Infectious complications during HSCT include the following: CMV (n=8), EBV (n=2), adenovirus (n=4), BK virus (n=7), respiratory syncytial virus (n=1), candidaemias (n=2) and invasive aspergillosis (n=3). Progression free survival (PFS) and OS at 3 years were 53% (95%CI 32-89%) and 53% (95%CI 32-89%), respectively (Fig 2). Cumulative incidence of relapse at 3 years was 13% (95%CI 0-31%) (Fig 2). Seven patients died during the study. Causes of death were relapse (n=2), aGVHD (n=2), cGVHD (n=1), septic shock (n=1), and respiratory syncytial virus associated with invasive aspergillosis (n=1). GVHD-relapse free survival (GRFS) at 3 years was 48% (95%CI 29-78%). One patient had anal epidermoid carcinoma at 4 years after HSCT, which required multiple surgical ablations. Conclusion: With almost 3 years follow-up, which is long enough for our results to be considered robust, we report an OS and PFS of 53%, which compares favorably to historical controls since all of our 18 patients were treated with florid disease at time of HSCT (and not with cytogenetic abnormality only, known to be associated with a better prognosis). Toxicity is still a concern in this particular population of FA patients with notably a high rate of infectious complications. Future well designed prospective clinical trials will refine this sequential strategy, which appears promising in this particular difficult clinical situation. Disclosures Socie: Alexion: Consultancy. Peffault de Latour:Alexion: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Amgen: Research Funding.

Phenotypic correction of Fanconi anemia group C knockout mice

Blood ◽  
2000 ◽  
Vol 95 (2) ◽  
pp. 700-704 ◽  
Author(s):  
Kimberly A. Gush ◽  
Kai-Ling Fu ◽  
Markus Grompe ◽  
Christopher E. Walsh
Keyword(s):  
Bone Marrow ◽  
Progenitor Cells ◽  
Mitomycin C ◽  
Fanconi Anemia ◽  
Bone Marrow Cells ◽  
Bone Marrow Failure ◽  
Genetic Disorder ◽  
Hematopoietic Stem ◽  
Marrow Cells

Fanconi anemia (FA) is a genetic disorder characterized by bone marrow failure, congenital anomalies, and a predisposition to malignancy. FA cells demonstrate hypersensitivity to DNA cross-linking agents, such as mitomycin C (MMC). Mice with a targeted disruption of the FANCC gene (fancc −/− nullizygous mice) exhibit many of the characteristic features of FA and provide a valuable tool for testing novel therapeutic strategies. We have exploited the inherent hypersensitivity offancc −/− hematopoietic cells to assay for phenotypic correction following transfer of the FANCC complementary DNA (cDNA) into bone marrow cells. Murine fancc −/− bone marrow cells were transduced with the use of retrovirus carrying the humanfancc cDNA and injected into lethally irradiated recipients. Mitomycin C (MMC) dosing, known to induce pancytopenia, was used to challenge the transplanted animals. Phenotypic correction was determined by assessment of peripheral blood counts. Mice that received cells transduced with virus carrying the wild-type gene maintained normal blood counts following MMC administration. All nullizygous control animals receiving MMC exhibited pancytopenia shortly before death. Clonogenic assay and polymerase chain reaction analysis confirmed gene transfer of progenitor cells. These results indicate that selective pressure promotes in vivo enrichment offancc-transduced hematopoietic stem/progenitor cells. In addition, MMC resistance coupled with detection of the transgene in secondary recipients suggests transduction and phenotypic correction of long-term repopulating stem cells.

scholarly journals Secondary CNL after SAA reveals insights in leukemic transformation of bone marrow failure syndromes

2020 ◽  
Vol 4 (21) ◽  
pp. 5540-5546
Author(s):  
Laurent Schmied ◽  
Patricia A. Olofsen ◽  
Pontus Lundberg ◽  
Alexandar Tzankov ◽  
Martina Kleber ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Aplastic Anemia ◽  
Myeloid Leukemia ◽  
Bone Marrow Failure ◽  
Driver Mutations ◽  
Leukemic Transformation ◽  
Hematopoietic Stem ◽  
Bone Marrow Failure Syndromes ◽  
Proinflammatory Responses ◽  
Stem And Progenitor Cells

Abstract Acquired aplastic anemia and severe congenital neutropenia (SCN) are bone marrow (BM) failure syndromes of different origin, however, they share a common risk for secondary leukemic transformation. Here, we present a patient with severe aplastic anemia (SAA) evolving to secondary chronic neutrophilic leukemia (CNL; SAA-CNL). We show that SAA-CNL shares multiple somatic driver mutations in CSF3R, RUNX1, and EZH2/SUZ12 with cases of SCN that transformed to myelodysplastic syndrome or acute myeloid leukemia (AML). This molecular connection between SAA-CNL and SCN progressing to AML (SCN-AML) prompted us to perform a comparative transcriptome analysis on nonleukemic CD34high hematopoietic stem and progenitor cells, which showed transcriptional profiles that resemble indicative of interferon-driven proinflammatory responses. These findings provide further insights in the mechanisms underlying leukemic transformation in BM failure syndromes.

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