scholarly journals Modeling Diamond Blackfan Anemia and p53 Activation in the Zebrafish

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. SCI-43-SCI-43
Author(s):  
Leonard I. Zon
Keyword(s):  
Stem Cells ◽  
Board Of Directors ◽  
Advisory Committees ◽  
Diamond Blackfan Anemia ◽  
Clonal Hematopoiesis ◽  
Calmodulin Inhibitors ◽  
Human Ipscs ◽  
Equity Ownership ◽  
Insight Into

Marrow dysplasias are pre-leukemic conditions that include ribosomopathies, a group of rare genetic diseases, or myelodysplasia preceded by clonal expansion in older adults with somatic mutations. To discover novel therapies for ribosomopathies, we performed two chemical suppressor screens using a ribosomal protein mutant zebrafish and human induced pluripotent stem cells (iPSCs) derived from ribosomopathy patients. In the zebrafish screen, we found calmodulin inhibitors rescued the anemia in zebrafish and also rescued the erythroid defect of the mouse (in vivo) and human (in vitro) models of marrow failure. The screen in RPS19 mutant human iPSCs identified a compound, SMER28, which enhanced erythropoiesis in anemia models through an autophagy-dependent mechanism. The compounds identified in our chemicals screens have provided new insight into the etiology of marrow failure, and calmodulin inhibitors will soon be studied in a clinical trial with adult Diamond-Blackfan anemia patients. To study the abnormal clonal hematopoiesis associated with myelodysplasia, we have generated a new system using the zebrafish in which single stem cells and their progeny express unique combinations of fluorescent proteins, allowing them to be tracked over time by their specific color. Mosaic mutagenesis induced by clustered regularly interspaced short palindromic repeats /cas9 and/or gene overexpression in this system led to expansion of specifically colored blood, modeling the clonal hematopoiesis of human myelodysplasia. Our studies should provide new insight into the ribosomopathies and myelodysplasia. Disclosures Zon: Marauder Therapeutics: Equity Ownership, Other: Founder; Scholar Rock: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Other: Founder; Fate, Inc.: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Other: Founder.

Gene-Correction Rescues Reprogramming of Fanconi Anemia Fibroblasts and Enables Hematopoietic Differentiation of FA Induced Pluripotent Stem Cells in Vitro and In Vivo

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 672-672
Author(s):  
Lars Mueller ◽  
Michael D. Milsom ◽  
Chad Harris ◽  
Rutesh Vyas ◽  
Kristina Brumme ◽  
...  
Keyword(s):  
Stem Cells ◽  
Board Of Directors ◽  
Hematopoietic Differentiation ◽  
Gene Correction ◽  
Advisory Committees ◽  
Median Percentage ◽  
Equity Ownership ◽  
Induced Pluripotent

Abstract Abstract 672 Fanconi anemia (FA) is a recessive syndrome characterized by progressive fatal bone marrow failure and chromosomal instability. FA cells have inactivating mutations in a signaling pathway that is critical for maintaining genomic integrity and repairing DNA damage caused by cross-linking agents. Transgenic expression of the implicated genes corrects the phenotype of hematopoietic cells but previous attempts at gene therapy failed largely due to inadequate numbers of hematopoietic stem cells available for gene correction and autologous engraftment. Induced pluripotent stem cells (iPSC) constitute an alternate source of autologous cells, which are amenable to ex vivo expansion and genetic correction. While fibroblasts from a limited number of FA patients have been reported to fail to undergo reprogramming (Raya et al., Nature, 2009), reproducible observations and mechanistic studies ascertained in an extended panel of patient cells and murine knock-out models are lacking to date. We undertook direct reprogramming of ten unique human FA primary fibroblast samples of the FA-A, FA-C, FA-G, and FA-D2 complementation groups. Using standard four-factor reprogramming, no human FA iPSC colonies were obtained in cells defective in the FA pathway. By contrast, reprogramming of gene-corrected patient samples, augmented by hypoxia (5%O2), yielded multiple pluripotent iPSC lines, confirming a critical cell-intrinsic role of the FA pathway in reprogramming. To determine if gene-corrected FA iPSC could be therapeutically useful, we performed karyotype analyses and evaluated in vitro hematopoietic differentiation in three FA-A iPSC lines. These FA patient iPSC lines were karyotypically normal and showed a robust multilineage hematopoietic differentiation potential, resulting in erythroid and myeloid hematopoietic colony forming units to a similar degree as compared to normal donor iPSC controls. We hypothesized that the reprogramming resistance of FA cells is due to defective DNA repair and genomic instability. To explore the mechanisms of the reprogramming defect, we transduced wild type (wt) tail-tip fibroblasts (TTF) with the reprogramming vectors. We observed significantly increased FANCD2 foci formation during reprogramming (median percentage of FANCD2 foci: mock-transduced TTF 2.5%, reprogrammed TTF 20.5%, n=8, p<0.01) indicating activation of the FA pathway. Next, we examined reprogramming in FA-deficient mouse cells. We observed a significantly higher incidence of reprogramming-induced double-strand DNA breaks and senescence in Fanca−/− TTF as compared to wt controls (γH2AX foci: wt 13%, Fanca−/− 19%; senescence: wt 47%, Fanca−/− 62%, median percentage, p<0.01). To evaluate whether these changes contribute to the reprogramming resistance of FA cells, we quantified the reprogramming efficiency of Fanca−/−, Fancc−/− and littermate wt TTF. The efficiency was 0.06% for Fanca−/− (n=8) and 0.38% for Fancc−/− (n=12) as compared to 0.55% for wt controls (n=13; p<0.01 and <0.05, respectively). To directly test the role of the FA pathway in reprogramming, TTF were transduced with retroviral vectors co-expressing FANCA and enhanced green fluorescent protein (eGFP) or encoding only eGFP as a control. Under hypoxic conditions, gene-correction of the Fanca−/− TTF with FANCA resulted in a significant reduction of senescence and rescued the reprogramming efficiency of Fanca−/− TTF to wt levels. While significant chromosomal aberrations were observed in uncorrected Fanca−/− iPCS, gene-corrected Fanca−/− iPSC did not show any significant chromosomal imbalances when analyzed by comparative genomic hybridization. To evaluate the capacity of FA iPSC to form blood cells in vivo, we injected wt, control transduced or gene-corrected Fanca−/− iPCS (CD45.1+) into wt blastocysts (CD45.2+) and analyzed the contribution of iPSC-derived hematopoietic cells in embryonic day 14.5 fetal livers. We observed 1.8–4% wt iPSC chimerism (n=15), 0.4–0.9% Fanca−/− iPSC chimerism (n=3) and 1.5 to 2.5% chimerism in gene-corrected Fanca−/− iPSC (n=11). Our data demonstrate that reprogramming activates the FA pathway. Gene-correction rescues the reprogramming block of FA cells and protects FA iPSC from genomic instability, thus yielding an expandable source of autologous stem cells with hematopoietic differentiation capacity that may be explored for future use in regenerative medicine. Disclosures: Daley: iPierian, Inc: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Epizyme, Inc: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Verastem, Inc: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Solasia, KK: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; MPM Capital, Inc: Consultancy, Membership on an entity's Board of Directors or advisory committees; Johnson & Johnson: Membership on an entity's Board of Directors or advisory committees.

Calmodulin Inhibition Rescues the Effects of Ribosomal Protein Deficiency in in Vitro and In Vivo Diamond Blackfan Anemia Models

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 672-672
Author(s):  
Elizabeth R Macari ◽  
Alison Taylor ◽  
David Raiser ◽  
Kavitha Siva ◽  
Katherine McGrath ◽  
...  
Keyword(s):  
Ribosomal Protein ◽  
Board Of Directors ◽  
Transcriptional Activity ◽  
Employment Equity ◽  
Advisory Committees ◽  
In Vivo Models ◽  
Diamond Blackfan Anemia ◽  
Equity Ownership

Abstract Ribosomal protein (RP) mutations are found in many diseases, including Diamond Blackfan anemia (DBA), where defective erythropoiesis, craniofacial abnormalities and increased cancer risk are major complications. RP mutations cause p53 activation through accumulation of free RPs that bind and sequester MDM2, the negative regulator of p53. We previously characterized a zebrafish mutant in rps29, a gene found mutated in DBA patients. Rps29-/- embryos have hematopoietic and endothelial defects, including decreased cmyb and flk1 expression and defects in hemoglobinization. Consistent with other animal models of RP dysfunction, p53 knockdown in rps29-/- embryos rescued these defects. To uncover novel compounds that correct the phenotypes of DBA, we performed a chemical screen in rps29-/- embryos. Several structurally distinct calmodulin (CaM) inhibitors successfully rescued hemoglobin (Hb) levels in the mutant embryo. To confirm that CaM inhibitors could rescue mammalian models of DBA, we applied them to human and murine models. Treating cord blood-derived CD34+ cells deficient in RPS19 with the CaM inhibitor, trifluoperazine (TFP), relieved the erythroid differentiation block. Injection of TFP in a DBA murine model significantly increased red blood cell number and Hb levels. Mechanistic studies in A549 cells infected with lentivirus expressing RPS19 shRNA demonstrated that TFP blocks p53 nuclear accumulation and induction of multiple p53 transcriptional target genes (p<0.05). Through p53 genetic manipulation, we determined that TFP inhibits p53 transcriptional activity through its c-terminal domain (CTD). Since this region has many residues that can be phosphorylated by CaM-dependent kinases, we hypothesized that TFP blocked phosphorylation of residues in the CTD. To test this hypothesis, phosphomimetic mutants were transfected into Saos2 cells and p53 transcriptional activity in response to TFP was evaluated using p21mRNA levels. TFP treatment of cells containing WT p53 or a transactivation domain mutant, S15D, resulted in a 4-fold reduction in p21 mRNA levels, while all four phosphomimetic mutants in the CTD had attenuated responses to TFP (<2-fold). The common CaM-dependent kinases that phosphorylate these CTD residues are Chk1 and Chk2. Investigation of the role of Chk1 and Chk2 found that a chk2 morpholino and multiple inhibitors of Chk2, but not Chk1, rescued Hb levels in the rps29-/- embryo (p<0.05). Chk2 inhibitors also mimic CaM inhibition in our in vitro assays. In conclusion, we have shown a novel mechanism by which CaM inhibitors mediate p53 activity through the CTD and can rescue the phenotypes of multiple in vitro and in vivo models of DBA. Our data strongly suggests that CaM or Chk2 inhibitors may be effective therapies for DBA patients, and a clinical trial is being planned with TFP. Disclosures Ebert: Genoptix: Consultancy, Patents & Royalties; H3 Biomedicine: Consultancy; Celgene: Consultancy. Zon:FATE Therapeutics: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Other: Founder; Scholar Rock: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Other: Founder.

scholarly journals Modeling Diamond Blackfan Anemia in Vivo Using Human Induced Pluripotent Stem Cells

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 359-359
Author(s):  
Sergei Doulatov ◽  
Linda T Vo ◽  
Elizabeth R Macari ◽  
Stephanie S Chou ◽  
Manav Gupta ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Pluripotent Stem Cells ◽  
Disease Modeling ◽  
Erythroid Differentiation ◽  
Advisory Committees ◽  
Diamond Blackfan Anemia ◽  
Equity Ownership ◽  
Induced Pluripotent

Abstract Human induced pluripotent stem cells (iPSCs) represent a promising source of patient-specific cells for disease modeling, drug screens and cellular therapies. However, the inability to derive engraftable human hematopoietic stem and progenitor cells has limited their use for modeling of hematological diseases. We previously reported a strategy to respecify lineage-restricted CD34+hematopoietic precursors derived from iPSCs into multilineage progenitors that can be expanded in vitro and transplanted in vivo. Five transcription factors, HOXA9, ERG, RORA, SOX4 and MYB, enable expansion and maintenance of primitive CD34+CD38- cells, and allow their differentiation upon transgene silencing. Respecified iPSC-derived hematopoietic progenitors give rise to robust short-term engraftment with myeloid and erythroid lineages. Notably, the erythrocytes undergo definitive maturation and hemoglobin switching to express β-globin in vivo. This system presents a useful platform for modeling hematological disorders due to its capacity to generate large numbers of engraftable disease cells for in vitro and in vivo screens. Congenital anemias, such as Diamond Blackfan anemia (DBA) represent a defined system for understanding red blood cell development and more common idiopathic anemias. To model this disease in vitro, we combined factor-induced respecification with stepwise erythroid maturation. We show that respecified iPSCs from DBA patients recapitulate the defect in erythroid differentiation. Consistent with clinical observations, early erythroblasts show impaired proliferation marked by increased apoptosis and p21 expression, while terminal maturation is unaffected. Interestingly, while early passage iPSC lines display a profound erythroid defect, continuous passage restores a near-normal capacity for erythroid differentiation. Furthermore, transplanted DBA iPSC-derived progenitors give rise to normal myeloid, but fail to generate erythroid, engraftment. This validates this system as a powerful tool for disease modeling and drug discovery. Mice transplanted with DBA iPSC-derived progenitors treated with conventional anemia drugs, such as dexamethasone, show a modest improvement in human erythroid output suggesting the need for novel treatments. Using high-throughput chemical screens, we have identified several signaling pathways which may be attractive therapeutic targets in DBA and other anemias. Further characterization is currently underway to better target defective erythropoiesis and dissect underlying disease mechanisms. Disclosures Zon: FATE Therapeutics, Inc: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Other; Scholar Rock: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Other; Stemgent: Equity Ownership, Membership on an entity's Board of Directors or advisory committees.

Neonatal Recipients Offer Permissive Hematopoietic Microenvironment for Engraftment of Embryonic Murine Hematopoietic Stem Cells

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2344-2344
Author(s):  
Natasha Arora ◽  
Shannon McKinney-Freeman ◽  
Garrett C Heffner ◽  
Il-Ho Jang ◽  
Pamela L. Wenzel ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Board Of Directors ◽  
Early Embryo ◽  
Advisory Committees ◽  
Hematopoietic Stem ◽  
Hematopoietic Microenvironment ◽  
Equity Ownership

Abstract Abstract 2344 The first hematopoietic stem cells (HSC) that give rise to robust, long-term, multi-lineage reconstitution in irradiated adult recipients arise in the murine embryo at embryonic day 11.5 (E11.5). However, long-term multi-lineage engraftment in neonatal recipients has been observed from E9.0 yolk sac, suggesting that the neonatal hematopoietic microenvironment is more permissive for engraftment of embryonic HSCs. To resolve the apparent discrepancy between the numbers of candidate HSCs detected by direct visualization in the early embryo, relative to the numbers that can be measured by limiting dilution, we sought to characterize engraftment of neonatal recipients versus adult recipients with hematopoietic populations dissected from the aorta-gonad-mesonephros (AGM) region of the early embryo, the first putative site of intraembryonic origin of definitive HSCs. We dissected whole AGM from E11.5 embryos and injected cell dilutions from 2 embryo equivalents (ee) to 0.25 ee into the facial vein of day 1–2 neonatal recipients that had received sublethal conditioning with 350 rad irradiation. In neonatal recipients we detected robust, long-term, multi-lineage hematopoietic engraftment from as little as 0.25 ee. From less than 1 ee of whole AGM, the engraftment chimerism ranged from 5–20%. With 2 ee, chimerism was as high as 70%. Most animals showed balanced donor derived myeloid and lymphoid contribution by 10 weeks post-transplant. Interestingly, some animals had predominantly myeloid reconstitution for as long as 18 weeks, suggesting the presence of a novel long-term, myeloid-restricted, embryonic HSC. We also explored the neonatal engraftment potential of VE-cadherin+ CD45+ and VE-cadherin+ CD45− populations. As expected from the literature, only the VE-cadherin+ CD45+ population engrafted the neonatal recipients. Our data indicate that the neonate harbors a more permissive hematopoietic microenvironment that enables more robust engraftment of early embryonic hematopoietic populations, thereby allowing us to identify potentially novel classes of embryonic hematopoietic progenitors. We are currently exploring the neonatal engraftment potential of E9.5 and E10.5 embryonic populations, additional FACS-purified populations, and hematopoietic populations derived from pluripotent stem cells in vitro. Disclosures: Daley: iPierian, Inc: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Epizyme, Inc: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Verastem, Inc: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Solasia, KK: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; MPM Capital, Inc: Consultancy, Membership on an entity's Board of Directors or advisory committees; Johnson & Johnson: Membership on an entity's Board of Directors or advisory committees.

Myeloma Patient-Derived Mesenchymal Stem Cells Grown In 3-D Culture Induce Primary Myeloma Cell Proliferation and Resistance To Therapy

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1912-1912
Author(s):  
Jana Jakubikova ◽  
Richard W.J. Groen ◽  
Teru Hideshima ◽  
Danka Cholujova ◽  
Jan Sedlak ◽  
...  
Keyword(s):  
Stem Cells ◽  
Flow Cytometry ◽  
Mesenchymal Stem Cells ◽  
Board Of Directors ◽  
Flow Cytometry Analysis ◽  
Advisory Committees ◽  
Bm Niche ◽  
Equity Ownership ◽  
D Model

Abstract Introduction The neoplastic bone marrow (BM) milieu or so-called myeloma niche plays an essential role in initiation, development, and progression of multiple myeloma (MM). It is known that regulatory signaling molecules and cell-cell crosstalk interactions involved in the normal hematopoietic stem cell niche have also been implicated in MM. Defining phenotypic features and molecular signatures of the neoplastic BM niche in MM will provide the framework for future development of new treatment strategies targeting MM cells and their BM niche. Methods and Results To investigate the neoplastic BM microenvironment of MM patients, we compared a special gel-based 3-dimensional (3-D) model with a 2-dimensional (2-D) system for culturing MM patient-derived mesenchymal stem cells (MM-MSCs) ex-vivo. In the gel-based 3-D model, MM-MSCs formed compact clusters with active fibrous connections between clusters to create a MM niche-like structure. Phenotypic profiling of 3-D MM-MSCs clusters revealed high expression of MSC-specific markers including CD73, CD90, CD105, CD166, and HLA-ABC. On the other hand, 3-D MM-MSCs clusters lacked expression of CD45, CD34 and HLA-DR. In order to confirm differentiation potential of 3-D MM-MSC, we cultured them with differentiation media towards either osteogenic or adipogenic lineages. The lineage differentiation capacity of the 3-D system was comparable to the 2-D MM-MSCs, with stronger calcium mineralization of clusters associated with differentiation towards the osteoblastogenic lineage. Moreover, the production of osteopontin and angiopoietin-2 was evident in 3-D MM-MSCs. In these models of the neoplastic BM microenvironment in MM, significantly higher production of IL-6 (p=0.002), IL-8, MCP-1(MCAF), RANTES, VEGF and HGF (p<0.001) was observed in 3-D vs. 2-D MM-MSCs. To define the functional myeloma niche, key hematopoietic and/or neoplastic niche molecules were investigated by analyzing 30 MM-MSCs and 5 healthy volunteers MSCs. MM-MSCs cultured in 3-D vs. 2-D model have higher expression of N-cadherin and CXCL12 and decreased expression of nestin by flow cytometry analysis, reflecting the MM BM niche. Higher pattern of cytokine production of leptin, SCF and sTie-2 was evident in 3-D MM-MSCs compared to 2-D system, as well as cancer biomarkes like IGFBP-1, sEGFR and sHER2neu performed by multiplex luminex technology. Next, we observed statistically significant higher expression of extracellular matrix (ECM) molecules including fibronectin, laminin, collagen I, and collagen IV (p<0.001) at 7 days MM-MSC culture in 3-D compared to 2-D, as determined by confocal microscopy and flow cytometry analysis. Furthermore, the activation of integrins such as VLA-2, VLA-4 and VLA-5, on the MSCs surface was also increased in 3-D MM-MSCs, as confirmed by flow cytometry analysis. To investigate the pathogenesis of MM in neoplastic BM niche, we co-cultured BM aspirates of MM cells (N=30) with MM-MSCs in vitro. Co-culturing BM aspirates with (autologous) MM-MSCs increased MM cells (CD38+/CD138+/CD19-) as well as stimulated their proliferation (determined by CFSE proliferation dye) in 3-D vs. 2-D system. MM cells in 3-D MM-MSCs were 4-fold more resistant to bortezomib and pomalidomide as well as melphalan, compared to 2-D. Finally, MM cells expressing CXCR4, as well as MM side population with “stem-like” features, were significantly increased in 3-D MM-MSCs vs. 2-D MM-MSCs cultures. Conclusions Our 3-D MM-MSCs model mimics the neoplastic BM microenvironment and myeloma niche in vitro, and may be useful to identify novel targets, validate targeted therapies and determine mechanisms of drug resistance in MM. Disclosures: Hideshima: Acetylon Pharmaceuticals: Consultancy. Richardson:Millennium: Membership on an entity’s Board of Directors or advisory committees; Johnson & Johnson: Membership on an entity’s Board of Directors or advisory committees; Novartis: Membership on an entity’s Board of Directors or advisory committees. Anderson:celgene: Consultancy; onyx: Consultancy; gilead: Consultancy; sanofi aventis: Consultancy; oncopep: Equity Ownership; acetylon: Equity Ownership.

ABT-737 Targets Leukemic Stem Cells In Mouse Models of Mutant NRASD12/hBCL-2- Mediated Acute Myeloid Leukemia Progression with Increased Survival

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3308-3308
Author(s):  
Rose Ann Padua ◽  
Stephanie Beurlet ◽  
Patricia Krief ◽  
Nader Omidvar ◽  
Carole Le Pogam ◽  
...  
Keyword(s):  
Stem Cells ◽  
Disease Progression ◽  
Board Of Directors ◽  
Research Funding ◽  
Leukemic Stem Cells ◽  
Spleen Cells ◽  
Employment Equity ◽  
Advisory Committees ◽  
Equity Ownership ◽  
Bh3 Mimetic

Abstract Abstract 3308 Background: Animal models enable us to understand disease progression and provide us with reagents to test various therapeutic strategies. We have previously developed a mouse model of myelodysplasia/acute myelogenous leukemia (MDS/AML) progression using mutant NRASD12 and overexpression of human hBCL-2 (Omidvar et al Cancer Res 67:11657-67, 2007). Expanded leukemic stem cells (LSC) were identified as Lin-/Sca1+/KIT+ (LSK) populations, with increased myeloid colony growth and were transplantable. Increased hBCL-2 and RAS-GTP complex were observed in both MDS/AML diseases. The MDS-like disease had increased apoptosis, whilst the AML-like mice had liver apoptosis patterns similar to wild type. The single NRASD12 line also had increased apoptosis. In this present study using a BCL-2 homology domain 3 (BH3) mimetic ABT-737 (Abbott), we have evaluated the effects of targeting BCL-2 in our preclinical models. Methods & Results: Treatment with the inhibitor shows a reduction of LSK cells, reduced progenitor numbers in colony assays and clearance of the liver infiltrations in both MDS and AML models. Gene expression profiling of the MDS mice shows regulation of 399 genes upon treatment including 58 genes expressed by the single mutant RAS mice and not expressed in the untreated AML mice. 78 genes were shared between single NRASD12 and diseased mice and not the treated mice. These studies potentially identify the contribution of NRASD12 genes to disease progression. By confocal microscopy we observed that in the MDS mice the majority of the RAS and BCL-2 co-localized to the plasma membrane, where active pro-apoptotic RAS is normally located, whereas in the AML disease RAS and BCL-2 co-localized in the mitochondria, where BCL-2 is normally found (Omidvar et al 2007). After treatment with the inhibitor the AML co-localization of RAS and BCL-2 shifted to the plasma membrane where single NRASD12 is normally localized. Furthermore, increased RAS-GTP levels was detected in both Sca1+ and Mac1+ enriched spleen cells and interestingly an increase in BCL-2 expression was observed in peripheral blood and in spleen cells after treatment; this increase in BCL-2 was associated with a decrease in the phosphorylation of serine 70 and an increase in phosphorylation of threonine 56 of BCL-2. ABT-737 treatment led to increased phosphorylated ERK resembling RAS and reduced MEK and AKT phosphorylation, changes detected by western blots and the nanoimmunoassay (NIA, NanoPro, Cell Biosciences) that might account for the increased apoptosis, measured by TUNEL and In vivo imaging by single-photon emission computed tomography (SPECT) using Tc-99m-labelled AnnexinV (SPECT). In contrast, although treated MDS mice had increased apoptosis they did not have an increase in overall expression of BCL-2 or in RAS-GTP levels. Treatment of both MDS and AML models with this inhibitor significantly extended lifespan from diagnosis with mean survival of 28 days untreated vs 80 days treated (p=0.0003) and mean survival from birth of 39 untreated vs 85 days treated (p<0.0001) respectively Conclusions: Genomics, proteomics and imaging have been employed in the MDS/AML models to characterize disease progression and follow response to treatment to the BH3 mimetic ABT-737 in order to gain molecular insights in the evaluation of the efficacy. ABT-737 appears to target LSCs, induce apoptosis, regulating RAS and BCL-2 signalling pathways, which translated into significantly increased survival. Disclosures: Padua: Vivavacs SAS: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Auboeuf:GenoSplice technology: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. de la Grange:GenoSplice technology: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Fenaux:Celgene: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Janssen Cilag: Honoraria, Research Funding; ROCHE: Honoraria, Research Funding; AMGEN: Honoraria, Research Funding; GSK: Honoraria, Research Funding; Merck: Honoraria, Research Funding; Cephalon: Honoraria, Research Funding. Tu:Cell Biosciences Inc;: Employment. Yang:Cell Biosciences Inc;: Employment. Weissman:Amgen, Systemix, Stem cells Inc, Cellerant: Consultancy, Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Felsher:Cell Bioscience:. Chomienne:Vivavacs SAS: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees.

Novel Protein Agonist of Thrombopoiesis Acts Via a Physiocrine Pathway Distinct From That of Thrombopoietin

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2376-2376
Author(s):  
Minh-Ha T Do ◽  
Wei Zhang ◽  
Kyle Chiang ◽  
Chi-Fang Wu ◽  
Chulho Park ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Board Of Directors ◽  
Employment Equity ◽  
Advisory Committees ◽  
Platelet Production ◽  
Platelet Counts ◽  
Normal Platelet ◽  
Naturally Occurring ◽  
Equity Ownership

Abstract Abstract 2376 Thrombopoietin (TPO) is recognized as the main regulator of platelet production, yet its genetic ablation in mice does not completely obliterate thrombopoiesis, suggesting that alternate pathways could lead to platelet formation. We recently identified a naturally-occurring protein that acts as a potent agonist of platelet production by a mechanism distinct from that of TPO. This protein belongs to a novel class of human extracellular signaling proteins called physiocrines that are generated from tRNA synthetases by alternative splicing or proteolysis. Physiocrines interact with several classes of receptors through unique mechanisms to modulate cellular differentiation and tissue homeostasis in normal and pathological processes. The newly identified thrombopoietic physiocrine, termed ATYR0030, is an engineered version of a naturally-occurring physiocrine derived from the tyrosyl tRNA synthetase (YRS). In vivo, systemic administration of ATYR0030 or YRS physiocrine to rats led to an increase in platelets counts comparable to that seen with TPO treatment, but with a greater effect in animals with low baseline platelet levels. When injected into normal animals preselected for low platelet counts, ATYR0030 treatment resulted in an increase in platelets up to, but not beyond, normal levels (Figure 1), suggesting a role in platelet homeostasis and differentiating its effects from the known activity of TPO. Intravenous administration of ATYR0030 also accelerated recovery of platelet counts in carboplatin-treated rats, indicating a possible role in bone marrow reconstitution after chemical insult. Consistent with homeostatic properties, no toxicity was seen in a repeat-dose 28-day non-GLP safety study in rats dosed up to 100-fold above the efficacious range. Histopathology assessment revealed no tissue abnormalities, no increase in bone marrow reticulin and no hyperplasia of myeloid precursors. Clinical chemistry and hematology parameters were in the normal range with a modest increase in platelet counts, as anticipated in animals with normal platelet levels. Our in vitro data suggest that ATYR0030 may play a role in megakaryopoiesis by facilitating cell migration and adhesion to the vasculature. In contrast to TPO, ATYR0030 does not directly signal through the TPO receptor and does not activate the JAK/STAT pathway but rather appears to engage specific G-protein coupled receptors. In vitro, ATYR0030 does not stimulate proliferation of cultured M07e human megakaryoblasts or primary bone marrow cells isolated from AML patients (Figure 2). The parent synthetase is present in human platelets and is secreted in response to platelet activation, perhaps providing a feedback mechanism to stimulate the release of new platelets. In an effort to link the biological activity of ATYR0030 and the role that the parent synthetase plays in human physiology, we have begun to analyze samples from patients with abnormal platelets counts to determine circulating levels of the parent synthetase. The unique thrombopoietic activity of ATYR0030 may lead to an orthogonal approach to restoring normal platelet levels in thrombocytopenic patients who currently have limited treatment options. For example, in the myelodysplastic syndrome population, TPO-receptor agonists carry a risk of stimulating blast proliferation and accelerating disease progression to acute myeloid leukemia (AML). The distinct proliferation profile of ATYR0030 may translate into important safety benefits by reducing the risk of progression to AML. In addition, the potential role of ATYR0030 in regulating platelet homeostasis may provide a greater safety margin in the normalization of platelet levels, thereby also limiting the risk of thrombosis. Leveraging the therapeutic potential of this thrombopoietic physiocrine may lead to the development of a novel treatment option with a favorable safety profile. Disclosures: Do: aTyr Pharma: Employment, Equity Ownership, Patents & Royalties. Zhang:aTyr Pharma: Employment, Equity Ownership. Chiang:aTyr Pharma: Employment, Equity Ownership. Wu:aTyr Pharma: Employment, Equity Ownership, Patents & Royalties. Park:aTyr Pharma: Equity Ownership. Yang:aTyr Pharma: Consultancy, Equity Ownership, Patents & Royalties, Research Funding. Kunkel:aTyr Pharma: Consultancy, Stock Ownership. Ashlock:aTyr Pharma: Employment, Equity Ownership. Mendlein:aTyr Pharma: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Belani:Atyr Pahrma: Consultancy, Equity Ownership, Patents & Royalties. Vasserot:aTyr Pharma: Employment, Equity Ownership, Patents & Royalties. Watkins:aTyr Pharma: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees.

Expression Of Aldehyde Dehydrogenase Reflected Diverse Stem Cell Properties In Acute Myeloid Leukemia

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1344-1344
Author(s):  
Van T. Hoang ◽  
Eike C. Buss ◽  
Isabel Hoffmann ◽  
Abraham Zepeda-Moreno ◽  
Natalia Baran ◽  
...  
Keyword(s):  
Stem Cells ◽  
Acute Myeloid Leukemia ◽  
Clinical Study ◽  
Board Of Directors ◽  
Myeloid Leukemia ◽  
Aldh Activity ◽  
Advisory Committees ◽  
Low Frequencies ◽  
Acute Myeloid

Abstract Separation of leukemic stem cells (LSC) and residual hematopoietic stem cells (HSC) from the same individual patient with acute myeloid leukemia (AML) is essential for a proper understanding of the leukemic driving mechanisms. We have studied the role of aldehyde dehydrogenase (ALDH) for this purpose and have defined the functional properties of ALDHbright cells in specific subgroups of AML. We have examined the ALDH activity by flow cytometry in bone marrow samples (BM) from 14 healthy donors and 73 patients with de novo AML. The median frequency of cells with high ALDH activity (ALDHbright cells) in the healthy subjects was 1.92% with a range from 0.58 to 3.16%. For patients with AML, the median number of ALDHbright cells was 0.25% with a broad range from 0.004 to 33.57%. Whereas the majority of patients with AML (n = 56) had low frequencies of ALDHbright cells (median 0.11%; range 0.004 – 1.77%; defined as ALDH-low AML), 17 patients had relatively numerous ALDHbright cells (median 9.01; range 3.54 – 33.57%; defined as ALDH-numerous AML). In both groups, ALDHbright cell populations were highly enriched for CD34+CD38- cells. The ALDHbright cells derived from ALDH-low AML did not contain chromosomal and molecular aberrations characteristic of the original leukemia, and were able to induce multi-lineage hematopoiesis in NSG mouse models. Thus, genetically and functionally normal HSC could be successfully isolated in the ALDHbright subset, whereas LSC were enriched in ALDHdimCD34+CD38- subset for patients with ALDH-low AML. For 17 patients with ALDH-numerous AML, the ALDHbright subset was consistently contaminated with LSC. In clinical follow-ups, patients with ALDH-numerous AML showed resistance to induction chemotherapy and were characterized by a very poor long-term outcome that was comparable to patients with high-risk cytogenetic or molecular genetic markers. In four patients with ALDH-numerous AML we demonstrated that the ALDHbrightCD34+CD38- subset contained chemotherapy-resistant clones with repopulating ability. Furthermore, such ALDHbright cells were characterized by a lower cell-cycle activity and an increased resistance to cytarabine in comparison with ALDHdim blasts in in vitro assays. Our data have provided evidence that LSC and residual HSC can be separated using ALDH in patients with low frequencies of ALDHbright cells. In patients with ALDH-numerous AML, the ALDHbright subset is associated with leukemic features both in vitro and in animal models. Thus our data demonstrated the feasibility of appropriate comparisons of LSC versus HSC from the same patient with specific subtypes of AML and the impact of LSC properties on clinical outcome. Disclosures: Buss: Novartis: Travel support Other; Micromet/Amgen: Reimbursements for participation in a clinical study , Reimbursements for participation in a clinical study Other. Ho:Sanofi-Aventis: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees; Genzyme: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees.

Selinexor Demonstrates Marked Synergy with Dexamethasone (Sel-Dex) in Preclinical Models and in Patients with Heavily Pretreated Refractory Multiple Myeloma (MM)

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4773-4773 ◽  
Author(s):  
Christine I. Chen ◽  
Martin Gutierrez ◽  
David S. Siegel ◽  
Joshua R. Richter ◽  
Nina Wagner-Johnston ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Transcriptional Activation ◽  
Nuclear Export ◽  
Research Funding ◽  
Phase 1 ◽  
Advisory Committees ◽  
Nuclear Retention ◽  
Heavily Pretreated ◽  
Equity Ownership

Abstract Introduction: The nuclear export protein exportin 1, (XPO1) is overexpressed in a wide variety of cancers including MM and often correlate with poor prognosis. Selinexor (KPT-330) is an oral Selective Inhibitor of Nuclear Export (SINE) XPO1 antagonist in Phase 1 and 2 clinical studies. Selinexor forces nuclear retention and reactivation of tumor suppressor proteins (TSPs) and reduction of many proto-oncogenes, including MDM2, MYC and Cyclin D. In addition, selinexor potently deactivates NF-κB, through forced nuclear retention of IκBα. Together these effects induce selective apoptosis in MM cells and inhibition of NF-κB dependent osteoclast activation. XPO1 is also responsible for nuclear export of the glucocorticoid receptor (GR). We hypothesized that selinexor will enhance the activity of dexamethasone (DEX)-bound GR, resulting in synergistic tumor cell killing. Methods: In vitro tumor cell viability measurements were based on MTT (CellTiter 96¨/Promega) and combination indices were calculated using CalcuSyn software. For xenograft studies, utilized NOD-SCID mice with subcutaneous inoculation of MM.1s cells. GR nuclear localization was measured with immunofluorescent anti-GR (phosphor-S211) antibody and quantitative imaging. To assess GR transcriptional activation, GR binding to a GCR consensus sequence was measured in nuclear extracts using an ELISA method (GR ELISA kit/Affymetrix). Patients (pts) with heavily pretreated refractory MM were dosed with oral selinexor at doses of up to 60 mg/m2 (8-10 doses/4 wk cycle) as part of a Phase 1 program in advanced hematological malignancies. Response we defined based on the IMWG criteria. The effect of combining DEX with selinexor was analyzed in all pts who received selinexor at moderate to high doses (30-60 mg/m2). Safety and efficacy were analyzed separately in three groups: no DEX, <20 mg DEX and 20 mgs DEX. Results: In MM.1s cells Sel-Dex showed synergy for nuclear retention of the DEX activated GR (Ser211-phosphorylated) and concomitant GR transcriptional activation. Sel-Dex showed highly synergistic cytotoxicity in MM.1s cells in vitro and in vivo, with a corresponding increase in apoptosis. Selinexor alone was potently cytotoxic in the DEX resistant MM cell lines MM.1R and ANBL6, but addition of DEX provided no additional effect. Twenty-eight pts with heavily pretreated refractory MM (16 M, 12 F; median age 62; ECOG PS 0/1: 7/21; median prior regimens: 6) received selinexor at 30 – 60 mg/m2 with either 0, <20, or 20 mgs DEX. All pts have received a proteasome inhibitor and an Imid and the majority of the pts have received pomalidomide (68%) and/or carfilzomib (36%). The most common Grade 1/2 AEs for these three groups were: nausea (82%/86%/70%), fatigue (55%/86%/40%), anorexia (36%/71%/60%), and vomiting (36%/57%/10%). Of the 28 pts treated; 10 heavily pretreated refractory MM pts treated with a combination of selinexor (45 mg/m2 twice weekly) and DEX (20 mg with each selinexor dose) were found to have dramatically improved disease response (n=10, ORR 60%), with one stringent complete response (sCR, 10%), 5 partial responses (PR, 50%) and clinical benefit rate (CBR) rate of 80% (Figure 1). Treatment with ³30mg/m2 selinexor and <20 mg DEX (n=7), resulted in ORR of 14% and CBR of 86%, while treatment with selinexor (30-60 mg/m2) without DEX (n=12) showed best response of stable disease (50%). Sel-Dex was also associated with an increase in time on study relative to selinexor alone, with 7 of out 10 pts in the 20 mg DEX combo group still on study (11-25 weeks). Five additional pts were treated with selinexor at a dose of 60 mg/m2 in combination with 20 mg DEX. Response evaluation is pending. Conclusions: Sel-Dex combination is markedly synergistic in preclinical models, which is supported by the preliminary clinical data presented. One potential mechanism underlying this synergy is the amplification of GR activity due the combined effects of selinexor-induced nuclear retention of activated GR coupled with DEX-mediated GR agonism. These results provide a promising basis for the continuing study of Sel-Dex for treatment of pts with refractory MM. Phase 2 studies of Sel-Dex in pts with MM refractory to both pomalidomide and carfilzomib are planned for early 2015. Disclosures Chen: Celgene: Honoraria; Janssen: Honoraria. Off Label Use: Lenalidomide maintenance therapy after ASCT. Gutierrez:Senesco: PI Other. Siegel:Celgene, Millennium, Onyx: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Baz:Celgene: Research Funding; Millennium: Research Funding; Bristol Myers Squibb: Research Funding; Karyopharm: Research Funding; Sanofi: Research Funding. Kukreti:Celgene: Honoraria. Azmi:Karyopharm Therpeutics: Research Funding. Kashyap:Karyopharm Therapeutics: Employment. Landesman:Karyopharm Therapeutics: Employment. Marshall:Karyopharm Therpeutics: Employment. McCartney:Karyopharm Therpeutics: Employment. Saint-Martin:Karyopharm Therpeutics: Employment. Norori:Karyopharm Therpeutics: Consultancy. Savona:Karyopharm Therpeutics: Membership on an entity's Board of Directors or advisory committees. Rashal:Karyopharm Therapeutics: Employment. Carlson:Karyopharm Therapeutics: Employment. Mirza:Karyopharm Therpeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees. Shacham:Karyopharm Therapeutics Inc.: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Kauffman:Karyopharm Therapeutics: Employment, Equity Ownership. Reece:Millennium: Honoraria, Research Funding; Millennium: Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Otsuka: Honoraria, Research Funding; Otsuka: Honoraria, Research Funding; Merck: Research Funding; Merck: Research Funding; BMS: Research Funding; BMS: Research Funding; Novartis: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Amgen : Honoraria; Amgen : Honoraria.

Anti-Tumor Activities of XBP1 Antigen-Specific Cytotoxic T Lymphocytes Are Enhanced By HDAC6 Inhibitor ACY241

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2143-2143
Author(s):  
Jooeun Bae ◽  
Matthew Ho ◽  
Brandon Nguyen ◽  
Arghya Ray ◽  
Dharminder Chauhan ◽  
...  
Keyword(s):  
Breast Cancer ◽  
T Lymphocytes ◽  
Board Of Directors ◽  
Cytotoxic T Lymphocytes ◽  
Cytokine Production ◽  
Suppressor Cells ◽  
Advisory Committees ◽  
Hdac6 Inhibitor ◽  
Equity Ownership

Abstract The effects of histone deacetylase (HDAC) inhibition on immune effector cells may have significant clinical implications; however, this has not yet been elucidated. The goal of this study was to investigate the immunomodulatory potential of the selective HDAC6 inhibitor ACY241 in combination with a cancer vaccine to enhance the efficacy of antigen-specific cytotoxic T lymphocytes (CTL) and the specific activities against tumor cells. Here, we report the effects of ACY241 treatment on antigen expression, immune activation, proliferation, and functional activities of XBP1 antigen-specific cytotoxic T lymphocytes (XBP1-CTL). The antigen-specific CTL were generated in vitro by repeated stimulation with novel immunogenic heteroclitic HLA-A2 XBP1 peptides (YISPWILAV, YLFPQLISV), as described previously by our group (Bae et al. Leukemia 2011; Bae et al. Oncoimmunology 2014l; Bae et al. Leukemia 2016). We found that treatment with ACY241 up-regulated key co-stimulatory (CD28, CD40L) and activation (CD38, CD69, CD137) molecules on XBP1-CTL, without inducing expression of co-inhibitory checkpoints (PD1, LAG3, CTLA4, VISTA). In addition, ACY241 increased the frequency of memory CTL subsets and enhanced their anti-tumor activities (cytotoxic activity, Th1-type cytokine production, CTL proliferation) against HLA-A2+ and XBP1+ multiple myeloma, breast cancer, and colon cancer cells. The XBP1-CTL responses were dramatically increased in combination with ACY241, including higher levels of tumor-specific CD107a up-regulation, perforin release, IFN-g/IL-2/TNF-a cytokine production and proliferation of the CD3+CD8+ T cells expressing CD28/CD38 in response to the specific XBP1 peptides. ACY241 also enhanced the expression of various tumor-associated antigens (XBP1, CD138, CS1, BCMA, CD44), MHC class I/II molecules, along with co-stimulatory B7 molecules (CD80, CD86) on HLA-A2+ myeloma (U266), breast cancer (MDA-MB231) and colon cancer (SW480) cell lines. Furthermore, in vitro ACY241 treatment consistently decreased the frequency of immune suppressor cells including myeloid-derived suppressor cells (CD14- CD15+/CD11b+ CD33+/HLA-DRlow) and regulatory T cells (CD25+ FOXP3+/CD3+ CD4+) in peripheral blood or bone marrow mononuclear cells from multiple myeloma patients in a dose-dependent manner. In conclusion, our data demonstrates the immunomodulatory effects of selective HDAC6 inhibition by ACY241 and supports its potential role for improving tumor-specific CTL function and tumor cell recognition when used in combination with antigen-specific cancer vaccine. Disclosures Bae: OncoPep Inc.: Consultancy, Equity Ownership. Chauhan:Stemline Therapeutics: Consultancy. Hideshima:Acetylon: Consultancy; C4 Therapeutics: Equity Ownership. Munshi:OncoPep Inc.: Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Anderson:OncoPep Inc.: Equity Ownership, Membership on an entity's Board of Directors or advisory committees.

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