An Inhibitor of TGF-β Promotes Proliferation of Normal but Not MPN Hematopoietic Cells and Is a Candidate Therapeutic Agent for the Treatment of MPN Patients Carrying JAK2 V617F or Calr pQ365fs Mutations

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 4089-4089
Author(s):  
Anna Rita Migliaccio ◽  
Camelia Iancu-Rubin ◽  
Rona Singer Weinberg ◽  
Ronald Hoffman ◽  
Amylou Constance Dueck ◽  
...  
Keyword(s):  
Stem Cells ◽  
Progenitor Cells ◽  
Board Of Directors ◽  
Research Funding ◽  
Jak2 V617f ◽  
Healthy Controls ◽  
Advisory Committees ◽  
Hematopoietic Stem ◽  
Erythroid Maturation ◽  
Β Receptor

Abstract The inhibitory effects exerted by transforming growth factor-β (TGF-β) on adult erythropoiesis has been well established. Canonical SMAD-depedent TGF-β signaling inhibits erythroid differentiation at multiple levels: it induces hematopoietic stem cells into quiescence (Chabanon et at Stem Cells. 2008;26:3150), it elicits a Smad5-dependent inhibition of progenitor cell proliferation (Bruno et al, Blood 1998; 91:1971) by increasing the length of G1 through reduction of G1 cyclin and cyclin-dependent protein kinases (Jacobsen et al, Blood 1995; 86:2957; Geng and Weinberg, PNAS 1993; 90:10315) and triggers Smad4-signaling accelerating terminal erythroid maturation (Zermati et al, Exp hematol 2000; 28:885; Choi et al MCB 2005;271:23). TGF-β is expressed by almost every cell type, but is produced in the greatest amount by megakaryocytes (Assonian et al, JBC 1983;258:7155; Massague, Cell 2008;134, 215). TGF-β has been implicated in the pathogenesis of primary myelofibrosis (PMF) by Schmitt et al (Blood. 2000;96:1342). Plasma, bone marrow and spleen washes of PMF patients, as well as those from murine PMF models, contain 2 fold-greater levels of total and bioactive TGF-β than those from normal controls (Zingariello et al, Blood 2013;121:3345). In addition, megakaryocytes from PMFpatients contain greater amounts of TGF-β than those from other MPNs such as polycythemia vera (PV) and essential thrombocythemia (Ciurea et al, Blood 2007;110:986). Published data, however, also suggest that malignant MPN cells are insensitive to TGF-β. Microarray analyses of PMF bone marrow and spleen cells revealed TGF-β signaling abnormalities which predict activation of non-canonical p38/ERK-dependent rather than canonical SMAD-dependent signaling (Ciaffoni et al, BCMD 2015;54:234). In addition, by phosphoproteomic profiling of PV erythroblasts (Erys) expanded in vitro express lower levels of pSmad2 as compared to Erys from healthy controls (Hricik et al. AJH 2013;88:723). The hypothesis that malignant MPN cells are insensitive to TGF-β was tested here by evaluating the effect of SB431542 [1,3,10 and 26µM], a small molecule inhibitor of TGF-β receptor 1, on ex vivo erythropoiesis in cultures generated by peripheral blood mononuclear cells from patients with JAK2 V617+-PV (n=2) and JAK2 V617F+ or CALR pQ365f+-PMF. Identical experiments were performed with Erys generated from adult peripheral blood (AB, n=3) and cord blood (CB, n=2) of healthy controls. All cultures were stimulated with SCF, IL-3 and EPO with and without dexamethasone (Dex). In cultures of JAK2 V617F+ -PV, SB431542 increased by 2-fold the numbers of progenitor cells observed by day 6, but had no effect on that of Erys observed by day 12-17 [fold increase (FI) ~4 fold in all cases]. Moreover, neither the number of progenitor cells nor that of Erys were affected by SB431542 treatment in cultures generated from JAK2 V617F+ (n=1) and CALR pQ365fs+ -PMF (n=1) patients (Fig. 1). This lack of effects was observed in cultures with and without Dex. By contrast, as expected, in cultures of AB, SB431542 significantly increased by 2.5-fold the number of progenitor cells observed by day 6 and that of Erys observed by day 14-17 (Fig. 1). This increase was associated with greater retention of an immature erythroid phenotype (CD36+ CD235a+ cells 16% vs 3%) and an increased proliferative index (>3 Erys in metaphases per field vs 0). This was observed up to day 17 in cultures both with and without Dex. The effects of SB431542 in cultures of CB were, however, affected by the presence of Dex. In cultures without Dex, SB431542 increased by 2-fold the number of progenitor cells by day 6 but had no effect on that of Erys by day 12-17 (FI=10-15 and CD36+CD235a+ cells >60%). In the presence of Dex, SB431542 did not affect the number of progenitor cells at day 6 but reduced that of Erys by 3-fold on day 12-17. These results suggest that in the case of CB, TGF-β promotes erythroid maturation in synergy with Dex. In conclusion, SB431542 promoted proliferation and maturation of normal adult progenitor cells but had no effect on PMF progenitor cells suggesting that treatments with TGF-β receptor 1 inhibitors may reactivate normal hematopoiesis in PMF patients by providing a proliferative advantage to the resident non-diseased hematopoietic stem cells over the malignant clone. This therapeutic approach will be explored in a MPD-RC, multi-center, phase II trial in patients with PMF. Disclosures Hoffman: Geron: Consultancy, Membership on an entity's Board of Directors or advisory committees; All Cells, LLC: Consultancy, Membership on an entity's Board of Directors or advisory committees; Promedior: Research Funding. Mascarenhas:Roche: Research Funding; Incyte Corporation: Research Funding; Kalobios: Research Funding; CTI Biopharma: Research Funding; Novartis Pharmaceuticals Corporation: Research Funding; Promedior: Research Funding.

Resistance to Danusertib (formerly PHA-739358) in BCR-ABL-Positive Cells Is Mediated by Upregulation of the Drug Transporter Abcg2 and Can Be Suppressed in Vitro by Combination Treatment with Imatinib.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1724-1724
Author(s):  
Tim H Brummendorf ◽  
Artur Gontarewicz ◽  
Gunhild Keller ◽  
Jürgen Moll ◽  
Melanie Braig ◽  
...  
Keyword(s):  
Stem Cells ◽  
Combination Therapy ◽  
Board Of Directors ◽  
Research Funding ◽  
Aurora Kinase ◽  
Epigenetic Mechanism ◽  
Advisory Committees ◽  
Hematopoietic Stem ◽  
Resistant Cells

Abstract Abstract 1724 Poster Board I-750 The success of imatinib (IM, formerly STI571, Gleevec®) in the treatment of chronic myeloid leukemia (CML) is compromised by the development of primary or acquired IM-resistance, particularly in advanced phase disease as well as by a limited IM-effect on immature hematopoietic stem cells, emphasizing the need for novel therapeutic strategies. The small molecule inhibitor Danusertib (formerly PHA-739358) potently inhibits Aurora and ABL kinases. Here, the individual contribution of each pathway to the effect of Danusertib was investigated. Starting at very low concentration, a dose-dependent reduction of BCR-ABL activity was observed, whereas inhibition of Aurora kinase activity, assessed by phosphorylation of histone H3-Ser10, required substantially higher concentrations. In primary CD34+ CML cells, including initially quiescent leukemic stem cells, combination therapy with IM and Danusertib revealed a synergistic anti-proliferative activity, which also affected immature CD34+38- cells. Neither mono- nor combination therapy led to substantial induction of apoptosis in quiescent stem cells. Interestingly, under treatment with Danusertib, the emergence of resistant clones in a well-established murine Ba/F3-p210 cell model was considerably less frequent than with IM. Surprisingly, Danusertib-resistant cells did not have mutations in BCR-ABL or Aurora kinase domains and remained IM-sensitive. Analysis of resistance mechanisms using DNA-microarray suggests an overexpression of Abcg2 efflux transporter to be causative for the resistance arising under Danusertib treatment. In support of this finding, stable retroviral overexpression of Abcg2 in parental Ba/F3-p210 cells induced a resistant phenotype against Danusertib. Furthermore, the Abcg2 inhibitor Fumitremorgin C (FTC) could restore the sensitivity of resistant cells to Danusertib. Finally, significant re-expression of Abcg2 in parental Ba/F3-p210 cells upon treatment with the demethylating agent 5-Azacytidine suggests that an epigenetic mechanism might play a role in the regulation of Abcg2 gene expression in resistant clones. Detailed analyses of the methylation patterns of the Abcg2 promoter region are currently being performed. In conclusion, simultaneous in vitro exposure of Ba/F3-p210 cells to Danusertib and IM significantly reduced the emergence of drug resistance, raising hope that both epigenetic modulation of drug transporters involved in development of resistance as well as hypothesis-driven combinations of kinase inhibitors may eventually achieve durable disease control even in 2nd and 3rd line treatment of CML. Disclosures Brummendorf: Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. Moll:Nerviano MS: Employment. Jost:MSD: Research Funding. Bokemeyer:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees. Holyoake:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol Myers Squib: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Balabanov:Novartis : Research Funding; Bristol Myers Squibb: Research Funding.

Antibody-Targeting of IL-3 Receptor-α Increases the Susceptibility of CD34+ CML Progenitors to Dasatinib-Induced Cell Death,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3745-3745
Author(s):  
Eva Nievergall ◽  
Deborah L. White ◽  
Hayley Ramshaw ◽  
Angel F. Lopez ◽  
Timothy P. Hughes ◽  
...  
Keyword(s):  
Stem Cells ◽  
Flow Cytometry ◽  
Progenitor Cells ◽  
Board Of Directors ◽  
Myeloid Leukemia ◽  
Research Funding ◽  
Blast Crisis ◽  
Chronic Phase ◽  
Advisory Committees ◽  
Cd34 Cells

Abstract Abstract 3745 Despite the remarkable efficacy of tyrosine kinase inhibitors (TKIs) in the treatment of chronic myeloid leukemia (CML), Ph+ CD34+ progenitor cells remain detectable even in patients with stable complete cytogenetic response. Over 40% of patients in stable complete molecular remission will develop molecular relapse within 6 months of stopping imatinib. While the exact causes are largely unknown, one of the proposed mechanisms is the protection of leukemic stem and early progenitor cells by the paracrine or autocrine production of cytokines, such as IL-3, GM-CSF and G-CSF, which activate survival pathways that bypass TKI-induced cytocidal effects. In acute myeloid leukemia (AML), the IL-3 receptor α chain (CD123) is recognized as a specific marker for CD34+/CD38− stem cells and therefore is attracting increasing interest as a therapeutic target. However, the function of CD123 in CML remains to date mostly unexplored. The aim of this study is to investigate potential synergy between TKIs and CSL362 (a humanized antibody version of 7G3 against CD123) in targeting CML progenitor and stem cells. CD34+ and CD34+/CD38− cells were isolated from mononuclear cells of newly diagnosed CML chronic phase and blast crisis patients. Flow cytometry studies indicated significantly increased CD123 expression on CD34+/CD38− cells of CML patients in both chronic phase and blast crisis when compared to normal hematopoietic stem cells (p<0.01 and p<0.001 for chronic phase and blast crisis, respectively; Figure A). A functional relevance of increased CD123 expression was demonstrated by IL-3-dependent increase in STAT5 phosphorylation (260.5% of baseline with 20 ng/ml IL-3; n=12; p<0.001) in CML CD34+ cells. Dasatinib inhibits STAT5 phosphorylation by blocking BCR-ABL signaling but only in the absence of IL-3 (62.5% of baseline for dasatinib alone vs. 130.8% for dasatinib + IL-3; n=3; p<0.01). In agreement, IL-3 effectively rescues dasatinib-induced cell death, as evaluated by AnnexinV/7-AAD staining (103.3% vs. 72.45%, n=5; p<0.01) and CFU-GM colony forming assays (69.39% vs. 46.13% relative to no treatment control; n=4; p<0.05). CSL362, in turn, revokes IL-3-mediated STAT5 phosphorylation (37.12% vs. 130.8%; n=3; p<0.001) and cytoprotection (45.05% vs. 69.39% CFC; n=4; p<0.01). In order to further elucidate the role of CSL362, CML CD34+ cells were cultured with increasing concentrations of dasatinib in the presence of IL-3 and CSL362 or BM4 isotype-matched control antibody. Even at very low dasatinib concentrations, CSL362 significantly reduces CML CD34+ colony forming cells (p<0.05; Figure B). Together these results substantiate a relevant role for IL-3-mediated resistance in CML progenitor cells and additionally confirming the ability of CSL362 to effectively bind to CD123 and impede IL-3 function. CSL362 furthermore has been optimized to mediate antibody dependent cell cytotoxicity (ADCC). CSL362 causes specific cell lysis of CML CD34+ progenitor cells in co-culture with allogeneic Natural killer cells as determined by increased lactate dehydrogenase release (ADCC activity of 42.4% ± 8.1%; n=3) and a decrease in the number of CFU-GM colonies by 74.1 % ± 12.2% (n=3). Collectively, our results indicate that a combination of dasatinib and CSL362 inhibits CML progenitor cell survival more effectively in vitro. Therefore, targeting IL-3 receptor α with CSL362 in chronic phase and blast crisis CML patients might provide a novel specific treatment approach aiding the elimination of refractory chronic myeloid leukemic stem and progenitor cells. A: Flow cytometry analysis reveals that CD123 expression is significantly higher in CD34+/CD38− cells of CML patients in chronic phase (CML-CP) and blast crisis (BC-CML) as compared to normal patients (NP), as previously documented for AML patients. ** p<0.01, *** p<0.001 by unpaired, two-tailed Student's t-test. B: In the presence of IL-3, CSL362 significantly reduces the number of colony forming cells. CD34+ cells of de novo CML-CP patients were cultured with dasatinib (0 to 10 nM) +IL-3 (1 ng/ml) ± CSL362 or BM4 (isotype control for CSL362). After 72 hours of culture live cells were plated for CFU-GM assay and colonies were counted after 2 weeks. Mean ± SE of three independent experiments is shown, n=4, p<0.05 by two-way ANOVA. Disclosures: Nievergall: CSL: Research Funding. White:CSL: Research Funding. Lopez:CSL: Research Funding. Hughes:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Ariad: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Hiwase:CSL: Research Funding.

scholarly journals Hematopoietic Stem Cells Develop in the Absence of Endothelial Cadherin 5 Expression

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 1165-1165
Author(s):  
Heidi Anderson ◽  
Taylor Patch ◽  
Pavan Reddy ◽  
Elliott Hagedorn ◽  
Owen J. Tamplin ◽  
...  
Keyword(s):  
Stem Cells ◽  
Endothelial Cells ◽  
Hematopoietic Stem Cells ◽  
Board Of Directors ◽  
Research Funding ◽  
Hemogenic Endothelium ◽  
Employment Equity ◽  
Advisory Committees ◽  
Hematopoietic Stem ◽  
Equity Ownership

Abstract Rare endothelial cells in the aorta-gonad-mesonephros (AGM) transition into hematopoietic stem cells (HSCs) during embryonic development. Lineage tracing experiments indicate that HSCs emerge from Cadherin 5 (Cdh5, VE-cadherin)+ endothelial precursors, and isolated populations of Cdh5+ cells from mouse embryos and embryonic stem (ES) cells can be differentiated into hematopoietic cells. Cdh5 has also been widely implicated as a marker of AGM-derived hemogenic endothelial cells. Since Cdh5-/- mice embryos die before the first HSCs emerge, it is unknown if Cdh5 has a direct role in HSC emergence. Our previous genetic screen yielded malbec (mlbbw306), a zebrafish mutant for cdh5, with normal embryonic and definitive blood. Utilizing time-lapse imaging, parabiotic surgical pairing of zebrafish embryos, and blastula transplantation assays, we show that HSCs emerge, migrate, engraft, and differentiate in the absence of cdh5 expression. By tracing Cdh5-/- GFP+/+ cells inchimeric mice, we demonstrated that Cdh5-/- GFP+/+ HSCs emerging from E10.5 and E11.5 AGM or derived from E13.5 fetal liver not only differentiate into hematopoietic colonies but also engraft and reconstitute multi-lineage adult blood. These data establish that Cdh5, a marker of hemogenic endothelium in the AGM, is dispensable for the transition of hemogenic endothelium to HSCs. Disclosures Bauer: Biogen: Research Funding; Editas Medicine: 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. Orkin:Editas Medicine: Membership on an entity's Board of Directors or advisory committees; Biogen: Research Funding; Pfizer: Research Funding; Sangamo Biosciences: Consultancy.

scholarly journals GFI1 Is a Downstream Target of EVI1 in Normal Hematopoiesis

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 33-33
Author(s):  
Akira Chiba ◽  
Yosuke Masamoto ◽  
Hideaki Mizuno ◽  
Mineo Kurokawa
Keyword(s):  
Bone Marrow ◽  
Progenitor Cells ◽  
Board Of Directors ◽  
Research Funding ◽  
Hematopoietic Progenitor Cells ◽  
Rna Seq ◽  
Hematopoietic Progenitor ◽  
Advisory Committees ◽  
Hematopoietic Stem ◽  
Knock Out

Acute myeloid leukemia (AML) with high expression of a transcriptional factor, Ecotropic viral integration site 1 (EVI1), is associated with extremely poor prognosis. EVI1 is, however, also essential for maintaining normal hematopoietic stem cells (HSCs), rendering it potentially difficult to target this molecule. To overcome this therapeutic difficulty, it is important to comprehensively elucidate differentially regulated downstream targets between normal and leukemia cells. In this study, we searched downstream targets of EVI1 in normal hematopoiesis by combining a chromatin immunoprecipitation sequence (ChIP-seq) and RNA-sequence (RNA-seq) analysis using a mouse hematopoietic cell line 32D-cl3 with high EVI1 expression. We deleted Evi1 using CRISPR/Cas9 in 32D-cl3 cells. Evi1 knock-out (KO) 32D-cl3 cells showed comparable cell growth with parental cells in the presence of IL-3, which enables them to proliferate permanently without differentiation. When they are allowed to differentiate by adding G-CSF, the number of KO cells decreased sharply at day 5-6, compared with parental 32D-cl3 cells. Along with the decreased cell number, KO cells also demonstrated higher positive rate of Gr-1 at day 7, a typical marker of differentiation into granulocytes, indicating accelerated differentiation of KO cells. These results indicated that EVI1 is required to maintain undifferentiated status of 32D-cl3 cells in a differentiation-permissive conditions, which can model normal hematopoiesis. We knocked in 3×FLAG tag at the 3' end of the Evi1 gene to perform ChIP-seq using anti-FLAG antibody. By using these knock-in cells, ChIP-seq was performed on day 0 and day 3 of G-CSF treatment, when they had started to differentiate with still maintained EVI1 expression. The peaks observed in undifferentiated day 0 sample were considered to contain a group of genes involved in undifferentiated hematopoietic cells in cooperation with EVI1. Genes associated HDAC class I, RAC1 signaling were enriched in these genes. To investigate the functional implications of the result of ChIP-seq, RNA-seq data using two clones of KO cells and parental cells were combined. We found that 152 genes were significantly up-regulated, and 155 genes were down-regulated in the KO cells, with false discovery rate less than 0.05. Twenty-four genes were identified by extracting common genes between ChIP-seq and RNA-seq; namely, genes which had day 0-specific peaks in ChIP-seq, and whose expression were decreased in the KO cells. In order to further examine the physiological implications of 24 genes in vivo, we referred to the results of RNA-seq using murine bone marrow transplantation model, where murine hematopoietic progenitor cells retrovirally transduced with Evi1 were transplanted into irradiated syngeneic mice, finally leading to AML after a long latency. Samples obtained early after post transplantation and those after AML onset were compared to those of normal hematopoietic progenitor cells. Among the above 24 genes, the expression of 5 genes was increased early after transplantation and decreased after the onset of AML, that is, these genes were up-regulated by EVI1 but don't seem to be involved in AML maintenance. We functionally validated the role of these genes in 32D-cl3 cells. Of the above, CRISPR/Cas9-mediated knock-out of Gfi1(Growth Factor Independent 1 Transcriptional Repressor) and Mfsd2b (Major facilitator superfamily domain containing 2B) in 32D-cl3 cells led to high Gr-1 positivity at day 7 like Evi1-KO cells, suggesting that these genes are involved in the functions of EVI1 in the normal hematopoiesis. The mRNA expression of these genes was compared in LSK (Lineage- Sca1+ c-kit+) cells from the bone marrow of Evi1 conditional knockout (cKO) mice and control mice. The expression of Gfi1 and Mfsd2b was decreased in LSK cells from Evi1 cKO mice. Furthermore, retroviral expression of Gfi1 in LSK cells restored the reduced colony-forming ability of Evi1 cKO cells. These results collectively suggest that GFI1 is regulated by EVI1 and is involved in the function of EVI1 regulating the stemness of hematopoietic stem and progenitor cells in normal hematopoiesis. These findings provide us with the novel insights on EVI1-mediated HSC maintenance as well as on the therapeutic strategy that specifically targets leukemia-specific EVI1 effectors while preserving normal hematopoiesis. Disclosures Kurokawa: Shire Plc: Speakers Bureau; Jansen Pharmaceutical: Speakers Bureau; Ono: Research Funding, Speakers Bureau; Boehringer Ingelheim: Speakers Bureau; Bristol-Myers Squibb: Speakers Bureau; Eisai: Research Funding, Speakers Bureau; Sumitomo Dainippon Pharma: Research Funding, Speakers Bureau; Teijin: Research Funding; Takeda: Research Funding, Speakers Bureau; Kyowa Kirin: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astellas: Research Funding, Speakers Bureau; Otsuka: Research Funding, Speakers Bureau; Pfizer: Research Funding; Sanwa-Kagaku: Consultancy; MSD: Consultancy, Research Funding, Speakers Bureau; Chugai: Consultancy, Research Funding, Speakers Bureau; Bioverativ Japan: Consultancy; Celgene: Consultancy, Speakers Bureau; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Nippon Shinyaku: Research Funding, Speakers Bureau.

scholarly journals A Novel Predictor of Response to Gemtuzumab Ozogamicin Therapy in AML Provides Strategies for Sensitization of Leukemia Stem Cells in Individual Patients

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 2765-2765
Author(s):  
Stanley W.K. Ng ◽  
Schoof E Erwin ◽  
Amanda Mitchell ◽  
Mark D. Minden ◽  
Lars Bullinger ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dna Damage ◽  
Board Of Directors ◽  
Research Funding ◽  
Gemtuzumab Ozogamicin ◽  
Therapeutic Window ◽  
Advisory Committees ◽  
Hematopoietic Stem ◽  
Resistance Factors ◽  
Predicted Probability

Abstract Acute myeloid leukemia (AML) patients with normal cytogenetics, NPM1 mutation, and no FLT3-ITD are considered to be at low molecular risk (LMR). We previously reported that most LMR patients have a low LSC17 score; these patients derive benefit from the addition of low fractionated doses of gemtuzumab ozogamicin (GO) to standard treatment and have favorable survival outcomes compared to patients with high LSC17 scores (Ng, Nature 2016). We recently developed a 13-gene sub-score (LMR13) that can be calculated from the LSC17 assay; a high LMR13 score identifies not only patients with molecularly-defined LMR disease, but also patients with LMR-like gene expression (GE), treatment response, and survival outcome. Similar to LMR cases, LMR-like patients gain a significant overall, event-free, and relapse-free survival (OS, EFS, RFS) benefit from the addition of GO treatment as observed in the ALFA-0701 trial cohort (OS: P=0.05; EFS: P=0.009; RFS: P=0.02). To gain mechanistic insight into the molecular determinants of GO response in LMR and LMR-like patients, we modelled the pathway through which GO traverses upon targeting a cell using a curated list of n=245 genes that includes the GO binding receptor CD33, lysosomal markers, ATP-binding cassette (ABC) transporters, DNA damage response/repair machinery, and pro/anti apoptotic factors. Sparse statistical regression was applied to a training dataset of n=495 AML patients (GSE6891) to identify the minimal subset of pathway components that were most associated with high LMR13 scores as a surrogate for GO responsiveness. This process selected n=16 genes which were then used to construct a random forest classifier to predict GO response. The final decision-tree based model, termed GO12, retained n=12 of the 16 pathway genes, and was able to accurately identify LMR and LMR-like patients across n=5 independent AML cohorts totaling n=1188 patients (AUC≈80.8%). As expected, ALFA-0701 patients who were predicted to be LMR-like with >50% certainty achieved significantly better survival when GO was added to their induction regimen (OS: P=0.03; EFS: P<0.001; RFS: P=0.001), while those with <50% certainty did not (Figure 1). The GO12 model also estimates the contribution of each GO pathway component to treatment sensitivity or resistance. For example, higher expression of ABCB1/ABCG1 transporter or the DNA damage repair gene APEX1 is associated with significantly lower GO response; these genes are key contributors to GO resistance. Conversely, higher lysosomal membrane marker LAMP1, pro-apoptotic BID, or GO-binding receptor CD33 GE was associated with significantly higher GO response. These results suggest that AML patients may be further sensitized to GO if treated in combination with inhibitors or agonists of specific pathway components that confer resistance or sensitivity to response, respectively. To determine if there is a therapeutic window of GO effects on normal versus leukemic hematopoietic stem cells, we applied the GO12 model to GE data derived from hematopoietic stem and progenitor cell (HSPC)-enriched human umbilical cord blood (hUCB) samples (GSE29105, GSE42414, GSE58299). The baseline predicted probability of GO sensitivity of these populations was at most 17%. Simulated GE knockdown (KD) of all possible combinations of the key resistance factors up to 3 standard deviations revealed a maximal model-predicted probability of GO response of 52%, consistent with robust inherent resistance of hUCB-HSPC to GO-mediated cytotoxicity. In contrast, applying the same analysis to GE data derived from AML patient samples predicted that LSC-containing populations can be sensitized to GO with up to 75% probability through double or triple KD of key GO resistance factors. Furthermore, analysis of chromatin accessibility (ATAC-Seq) data revealed that GO toxin (calicheamicin) DNA-binding motifs are situated within genomic loci where chromatin is significantly more open in LSC-enriched than in LSC-depleted or hUCB-derived HSPC/mature cell fractions (P<0.001, Figure 2), suggesting that LSC can be preferentially targeted by GO. Taken together, the GO12 response predictor represents a novel tool for rational selection of combination therapies to maximize GO response in individual patients with AML. Disclosures Bullinger: Amgen: Honoraria, Speakers Bureau; Bayer Oncology: Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Speakers Bureau; Sanofi: Research Funding, Speakers Bureau; Pfizer: Speakers Bureau; Bristol-Myers Squibb: Speakers Bureau; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Döhner:Astellas: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Pfizer: Research Funding; AbbVie: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Agios: Consultancy, Honoraria; Astex Pharmaceuticals: Consultancy, Honoraria; Celator: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Sunesis: Consultancy, Honoraria, Research Funding; AROG Pharmaceuticals: Research Funding; Amgen: Consultancy, Honoraria; Bristol Myers Squibb: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria; Agios: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Bristol Myers Squibb: Research Funding; Celator: Consultancy, Honoraria; AROG Pharmaceuticals: Research Funding; Astellas: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Pfizer: Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Jazz: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Sunesis: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria. Dombret:Seattle Genetics: Consultancy, Honoraria; Servier: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Menarini: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria; Ambit (Daiichi Sankyo): Consultancy, Honoraria; Sunesis: Consultancy, Honoraria; Agios: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Kite Pharma: Consultancy, Honoraria, Research Funding; Jazz Pharma: Consultancy, Honoraria, Research Funding; Ariad (Incyte): Consultancy, Honoraria, Other: Travel expenses, Research Funding, Speakers Bureau; Roche/Genentech: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria, Research Funding, Speakers Bureau; Amgen: Consultancy, Honoraria, Other: Travel expenses, Research Funding, Speakers Bureau; Cellectis: Consultancy, Honoraria, Other: Travel expenses; Celgene: Consultancy, Honoraria, Other: Travel expenses, Speakers Bureau; Immunogen: Consultancy, Honoraria; Shire-Baxalta: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Otsuka: Consultancy, Honoraria.

scholarly journals Rationale for and Results of a Phase I Study of the TGF-β 1/3 Inhibitor AVID200 in Subjects with Myelofibrosis: MPN-RC 118 Trial

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 6-8
Author(s):  
John Mascarenhas ◽  
Heidi E. Kosiorek ◽  
Lilian Varricchio ◽  
Rupali Bhave ◽  
Andrew T. Kuykendall ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Platelet Count ◽  
Progenitor Cells ◽  
Board Of Directors ◽  
Research Funding ◽  
Normal Donor ◽  
Advisory Committees ◽  
Hematopoietic Stem ◽  
Oncology Research ◽  
Grade 3

Preclinical Rationale: Myelofibrosis (MF) is a chronic myeloproliferative neoplasm for which there are limited therapies. TGFβ plays a pivotal role in the pathobiology of MF by not only promoting bone marrow fibrosis (BMF) and collagen deposition, but also by enhancing the dormancy of normal but not MF hematopoietic stem cells (HSCs). TGFβ has also previously been reported to inhibit normal megakaryocyte (MK) production (Bruno et al Blood 1998). TGFβ1 promotes the synthesis of collagen by normal human mesenchymal stromal cells (MSCs) and activates the TGFβ receptor I/SMAD pathway as well as non-canonical TGFβ pathways. We generated MKs from MF subject mononuclear cells (MNCs) and showed that they elaborated significantly greater levels of TGFβ1 than TGFβ2/3 TGFβ1 treatment reduced the numbers of hematopoietic colonies generated by normal but not MF MNCs. Treatment of MSCs with AVID200, a potent TGFβ1/3 protein trap, significantly decreased MSC proliferation, phosphorylation of SMAD2, and collagen expression. Robust expression of pSMAD2 was observed in the absence of exogenous TGFβ in normal donor or MF-MKs, Addition of AVID200 to -MKs decreased pSMAD2 without affecting total SMAD2/3, indicating that AVID200 blocks the effects of autocrine TGFβ produced by MKs and led to increased numbers of MKs. Moreover, treatment of primary MF MNCs with AVID200 led to increased numbers of progenitor cells with wild type JAK2 and a reduction of mutated colonies. AVID200 blocked TGFβ1-induced p57Kip2 expression and SMAD2 activation by MF MNCs allowing the normal progenitor cells to preferentially cycle, proliferate, and form hematopoietic colonies. Clinical Trial Design: Based on these findings, a phase 1 trial of AVID200 is ongoing in INT-2/high risk MF subjects resistant or intolerant to ruxolitinib; baseline platelet count of ≥ 25 x 109/L, and grade 2/3 BMF. Subjects received intravenous AVID200 (Lots A and B) in dose cohorts of 180 mg/m2 (A), 550 mg/m2 (A), 180 mg/m2 (B) on Day 1 of a 21 day cycle. Cohorts of 3 subjects with a target toxicity rate of 30% were enrolled to estimate the maximum tolerated dose (MTD). A modified toxicity probability interval design was used. Response was assessed by IWG/ELN criteria after 6 cycles of AVID200. Subjects attaining at least a CI or SD with a decrease in BMF by ≥1 grade, continued AVID200. Clinical Trial Results: 10 subjects were enrolled (1 withdrew before receiving treatment) and 9 were treated with AVID200 and were evaluable for DLT assessment [Table1]. Median time after ruxolitinib discontinuation was 3.5 months (0.5-12.2). No DLTs were observed. Grade 3/4 AEs (regardless of attribution) were observed in 6 (66.7%) subjects. Grade 3/4 non-hematologic AEs observed were epistaxis (1, 11.1%), extraocular muscle paresis (1, 11.1%), fatigue (1, 11.1%) and rash (1, 11.1%). Grade 3/4 hematologic AEs were anemia (3, 33.3%) and thrombocytopenia (2, 22.2%) [Table 2]. The median number of cycles received was 5.7 (range 0 - 12). 5 subjects received 6+ cycles and were evaluable. CI occurred in 2 subjects [anemia, spleen and TSS (n=1); TSS (n=1)] 1 of which is still being treated, 2 subjects had SD, 1 subject with 21% blasts prior to study treatment had progressive MPN-BP. 4 subjects failed to reach response evaluation after 6 cycles, 2 had PD due to increasing splenomegaly, 1 subject received an allogeneic transplant and 1 is still being treated [Cycle 2]. The median platelet count at baseline was 114 (range: 42-290) and 159 after cycle 6 [Figure 1]. Maximum changes in platelets from baseline was +64% [range -73%, 169%] in all subjects. 7 subjects had an increase in platelets from baseline during treatment. 2 subjects normalized their platelet count from thrombocytopenic levels. The effect of AVID200 on BMF is currently being examined. 2 subjects remain on treatment. Conclusions: AVID200 a TGFβ1/3 protein trap is well tolerated in advanced MF subjects. Clinical responses were observed at the 550 mg dose and the expansion efficacy cohorts at doses 2 and 3 are enrolling 12 additional subjects. Furthermore, AVID200 therapy improved thrombocytopenia in MF subjects which may be due to AVID200 inhibiting the effects of TGFβ1 on normal MKpoiesis. Updated subject safety and efficacy data along with correlative data will be presented. Disclosures Mascarenhas: Celgene, Prelude, Galecto, Promedior, Geron, Constellation, and Incyte: Consultancy; Incyte, Kartos, Roche, Promedior, Merck, Merus, Arog, CTI Biopharma, Janssen, and PharmaEssentia: Other: Research funding (institution). Kuykendall:Blueprint Medicines: Research Funding; BMS: Research Funding; Incyte: Research Funding; Novartis: Research Funding. Komrokji:Jazz: Honoraria, Speakers Bureau; Abbvie: Honoraria; Agios: Speakers Bureau; BMS: Honoraria, Speakers Bureau; Geron: Honoraria; Incyte: Honoraria; Acceleron: Honoraria; Novartis: Honoraria. Gerds:Gilead Sciences: Research Funding; Imago Biosciences: Research Funding; Sierra Oncology: Research Funding; Celgene: Consultancy, Research Funding; Roche/Genentech: Research Funding; CTI Biopharma: Consultancy, Research Funding; Apexx Oncology: Consultancy; AstraZeneca/MedImmune: Consultancy; Pfizer: Research Funding; Incyte Corporation: Consultancy, Research Funding. Migliaccio:Novartis: Research Funding. O'Connor-McCourt:Forbius: Current Employment. Tremblay:Forius: Current Employment. Nadler:Forbius: Consultancy; Nadler Pharma Associates: Current Employment; Symphogen: Consultancy; Iksuda Therapeutics: Consultancy; Tessa Therapeutics: Consultancy. Mesa:Celgene: Research Funding; Genetech: Research Funding; Samus: Research Funding; Promedior: Research Funding; CTI: Research Funding; LaJolla Pharma: Consultancy; Incyte: Research Funding; Sierra Onc: Consultancy; Abbvie: Research Funding; Novartis: Consultancy. Hoffman:Forbius: Consultancy; Abbvie: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Dompe: Research Funding; Protagonist: Consultancy.

scholarly journals Germline Runx1 Mutations Induce Inflammation in Hematopoietic Stem and Progenitor Cells and Predispose to Hematologic Malignancies

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2201-2201
Author(s):  
Mohd Hafiz Ahmad ◽  
Mahesh Hegde ◽  
Waihay J. Wong ◽  
Andrew Dunbar ◽  
Anneliese Carrascoso ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Dna Damage ◽  
Progenitor Cells ◽  
Board Of Directors ◽  
Research Funding ◽  
Bone Marrow Cells ◽  
Hematologic Malignancies ◽  
Advisory Committees ◽  
Hematopoietic Stem

Abstract Patients with Familial Platelet disorder (FPD) have a germline RUNX1 mutation and are at high risk to developing hematologic malignancies (HM), primarily myelodysplastic syndrome and acute myeloid leukemia (lifetime risk~40%). To understand how germline RUNX1 mutations predispose to HM in vivo, we developed a Runx1 R188Q/+ mouse strain , mimicking the FPD-associated R201Q missense mutation. Analysis of the bone marrow cells in Runx1 R188Q/+ mice revealed a significant increase in the total number of bone marrow cells. Immunophenotypic analysis using Sca-1 and Cd86 markers revealed a significant increase in Sca-1 expression in hematopoietic stem and multi-potential progenitor cells, indicating a systemic inflammation in the bone marrow. In addition, the frequency of common-myeloid, granulocytic-monocytic and granulocytic progenitor cells were found significantly increased in the Runx1 R188Q/+ bone marrow. Accordingly, their colony-forming unit capacity was increased when compared to wildtype controls (wt/Runx1 R188Q/+ CFU average = 45/85), indicating a myeloid bias. The number and size of platelets were not altered in Runx1 R188Q/+ mice. However, platelet function was significantly reduced. The activation of the Cd41/Cd61 fibrinogen receptor complex in membrane after thrombin treatment was reduced in Runx1 R188Q/+ platelets. Similarly, the translocation of P-selectin by alpha granules and the secretion of serotonin by the dense granules were also reduced. Hematopoietic progenitor cells isolated from Runx1 R188Q/+ mice revealed a significant reduction in DNA-damage repair response in vitro. Quantitative analysis of nuclei with 53bp1-positive foci in response to ionizing radiation showed a marked increase in 53bp1-positive foci in Runx1 R188Q/+ nuclei, suggesting that Runx1 R188Q/+ cells have a defective repair of double strand DNA breaks. Furthermore, expression of DNA-damage repair pathway-associated Pmaip1 (Noxa) was significantly reduced in irradiated Runx1 R188Q/+ hematopoietic progenitor cells. To understand underlying mechanism responsible for the observed myeloid bias in Runx1 R188Q/+ cells, transcription profiling analysis was performed in myeloid progenitors from wildtype and Runx1 R188Q/+ mice, utilizing RNA-sequencing. A total of 39 genes were significantly deregulated (&gt; 1.5 FC; FDR&lt;0.05), including 8 up- and 31 down-regulated genes. The expression of three repressed genes with important function in hematopoietic differentiation and malignancy (Cdh1, Gja1, and Fcer1a) were validated by qRT-PCR. To study the FPD-associated pre-leukemic process in vivo, wildtype and Runx1 R188Q/+ mice were monitored for 20 months. Although Runx1 R188Q/+ mice remained healthy for 18 months, somatic mutations in their leukocytes were evident at 12 months. Targeted sequencing of 578 cancer genes (mIMPACT panel) in leukocyte DNA of two Runx1 R188Q/+ mice identified somatic mutations in Kdm6a, Setd1b, Amer1, and Esco1 (variant allele frequencies between 0.5% and 2.8%). These mutations were confirmed at stable frequency for eight following months. Since loss of the second Runx1 allele is a frequent somatic event in progression to FPD/HM, we evaluated the predisposition to HM in Mx1Cre-Runx1 R188Q/fl mice over time. Unlike Runx1 R188Q/+ mice, Runx1 R188Q/Δ mice succumbed to myeloid leukemia with a median latency of 37.5 weeks and full penetrance. In addition, the expression of oncogenic Nras-G12D, in Runx1 R188Q/Δ mice reduced the median latency to 14.7 weeks. These studies demonstrate that FPD-associated Runx1 germline mutations induce inflammation in hematopoietic stem cells, induce myeloid expansion with defective DNA-damage response and predispose to HM over time. These studies suggest that anti-inflammatory therapies in pre-symptomatic FPD patients may reduce clonal expansion and predisposition to HM. Disclosures Ebert: Exo Therapeutics: Membership on an entity's Board of Directors or advisory committees; Skyhawk Therapeutics: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Deerfield: Research Funding; GRAIL: Consultancy. Levine: Isoplexis: Membership on an entity's Board of Directors or advisory committees; Auron: Membership on an entity's Board of Directors or advisory committees; C4 Therapeutics: Membership on an entity's Board of Directors or advisory committees; Zentalis: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; QIAGEN: Membership on an entity's Board of Directors or advisory committees; Ajax: Membership on an entity's Board of Directors or advisory committees; Imago: Membership on an entity's Board of Directors or advisory committees; Mission Bio: Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria; Prelude: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy; Lilly: Honoraria; Morphosys: Consultancy; Roche: Honoraria, Research Funding; Incyte: Consultancy; Astellas: Consultancy; Amgen: Honoraria.

scholarly journals High Burden of Clonal Hematopoiesis in First Responders Exposed to the World Trade Center Disaster

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3720-3720
Author(s):  
Sakshi Jasra ◽  
Orsi Giricz ◽  
Rachel Zeig-Owens ◽  
David Goldfarb ◽  
Angelica Barreto-Galvez ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dna Replication ◽  
Board Of Directors ◽  
Research Funding ◽  
Somatic Mutations ◽  
First Responders ◽  
Fragile Sites ◽  
Advisory Committees ◽  
Hematopoietic Stem ◽  
Clonal Hematopoiesis

Introduction The World Trade Center (WTC) disaster exposed first responders to high levels of aerosolized carcinogens (Lioy et. al. Env. Health Perspect 2002). Clonal hematopoiesis is associated with exposure to smoking and genotoxic stimuli (Jaiswal et. al. NEJM 2014; Genovese et. al. NEJM 2015). We sought to determine its incidence in WTC-exposed first responders. We also assessed the effect of WTC particulate matter (WTC-PM) on genome integrity in vitro, and in murine studies. Methods Deep targeted sequencing was performed on blood collected from 481 first responders (429 WTC-exposed firefighters, 52 WTC-exposed emergency medical service workers) and 52 non-exposed first responders. Samples were analyzed for 237 genes mutated in hematologic malignancies and interpreted using reference databases. Non synonymous somatic mutations were annotated and analyzed. Results In the WTC-exposed cohort, 57 individuals with 66 somatic mutations of expected pathogenic potential were identified (overall prevalence 11.9%). In the non-exposed cohort, only one pathogenic mutation was found in the IDH2 gene (overall prevalence 1.9%). There was a strong association between increasing age and prevalence of mutations in the WTC-exposed cohort (Fig 1A). DNMT3A (16/66), TET2 (7/66), SF3B1 and SRSF2 (3/66 each) were the most common genes identified in the WTC-exposed cohort (Fig 1B). Median VAF was 12% and missense mutations were most frequent alteration. Aging, smoking, DNA repair and alkylating agent exposure related mutational signatures were observed with a cytosine to thymine (C→T) transition being most common. Next, we assessed the effect of WTC-PM on genome integrity and replication in vitro. WTC-PM that was collected in the first three days after 9/11 was used in concentrations mimicking exposure levels. Lymphocytes exposed to WTC-PM demonstrated a significant increase in phosphorylated H2AX foci accumulation, suggesting a DNA damage response (Fig 2). Since common fragile sites (CFSs) detect basal levels of stress in the cell, and activate DNA damage response (DDR), we profiled DNA replication dynamics at CFS-FRA16D at very high resolution using the single molecule analysis of replicated DNA (SMARD) assay. Treatment with WTC-PM significantly altered replication at two common fragile sites (regions 1 and 2 of FRA16D, Fig 3A) with replication pausing being observed at multiple sites (Fig 3B-I, white rectangles). Striking increase in replication initiation was seen, characterized as dormant origins activated to rescue replication pausing (Fig 3E, J). These alterations were accompanied by a corresponding increase in replication speed, conditions that lead to DNA replication errors and mutagenesis (Fig 3F, K). Next, we treated mice with WTC-PM via the oropharyngeal route to mimic first responder exposures, and then harvested and analyzed their bone marrow compartments. Significant expansion of hematopoietic stem cells (Kit+, Sca1+, Lineage-ve, KSL) was seen in WTC-PM treated mice (Fig 4A,B). Whole genome sequencing of sorted stem cells showed a significant increase in non-synonymous SNPs, deletions and indels in the WTC-PM treated samples when compared to control (Fig 4C-E). These genomic alterations were found to occur at low VAF throughout the whole genome, demonstrating widespread genotoxic effects of WTC-PM on hematopoietic stem cells in vivo (Fig 4F). Discussion We report a high burden of mutations in 11.9% (57/481) WTC-exposed first responders compared to the non-exposed cohort (1.9%, 1/52). The frequency of the somatic mutations was many fold higher than in previous studies (Jaiswal et. al. NEJM 2014; Genovese et. al. NEJM, 2015). In the 50-59 year age group, 10% of WTC-exposed individuals carried somatic mutations, compared to the frequency of 2.5% reported by Jaiswal et. al. for the same age group. Despite deeper sequencing performed in our study, the median VAF in our study was 12%, indicating that the difference in technique did not bias our study towards increased detection of small, subclinical clones when compared to previous studies. Furthermore, we demonstrate that WTC-PM can perturb DNA replication and increased genomic instability in vivo, potentially leading to higher burden of clonal hematopoiesis in WTC-exposed first responders. These results demonstrate adverse environmental exposures can be associated with a high rate of clonal hematopoiesis. Disclosures Landgren: Sanofi: Membership on an entity's Board of Directors or advisory committees; Adaptive: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Other: IDMC; Theradex: Other: IDMC; Abbvie: Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Membership on an entity's Board of Directors or advisory committees. Fletcher:Genoptix/Neogenomics: Employment. Ebert:Broad Institute: Other: Contributor to a patent filing on this technology that is held by the Broad Institute.; Celgene: Research Funding; Deerfield: Research Funding. Steidl:GlaxoSmithKline: Research Funding; Celgene: Consultancy; Aileron Therapeutics: Consultancy, Research Funding; Stelexis Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Other: Scientific Co-Founder; Pieries Pharmaceuticals: Consultancy; BayerHealthcare: Consultancy, Research Funding; Novartis: Consultancy, Research Funding. Will:Novartis Pharmaceuticals: Research Funding. Verma:Stelexis: Equity Ownership, Honoraria; Acceleron: Honoraria; Celgene: Honoraria; BMS: Research Funding; Janssen: Research Funding.

Imetelstat Rapidly Induces and Maintains Substantial Hematologic and Molecular Responses in Patients with Essential Thrombocythemia (ET) Who Are Refractory or Intolerant to Prior Therapy: Preliminary Phase II Results

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 179-179 ◽  
Author(s):  
Gabriela M. Baerlocher ◽  
Elisabeth Oppliger Leibundgut ◽  
Christina Ayran ◽  
Martha Blaney ◽  
Bart Burington ◽  
...  
Keyword(s):  
Platelet Count ◽  
Maintenance Therapy ◽  
Progenitor Cells ◽  
Board Of Directors ◽  
Essential Thrombocythemia ◽  
Research Funding ◽  
Jak2 V617f ◽  
Advisory Committees ◽  
Allele Burden ◽  
Prior Therapy

Abstract Abstract 179 Background: Myeloproliferative neoplasms (MPNs), such as essential thrombocythemia (ET), are driven by neoplastic progenitor cells. The JAK2 V617F mutation can be detected in approximately 50% of patients (pts) with ET, and the JAK2 V617F allele burden can be used to measure the treatment-induced molecular response (MR) over time. Telomerase is upregulated in neoplastic progenitor cells and sustains indefinite replication. Imetelstat is a first in class, potent, specific inhibitor of telomerase which selectively distributes to bone marrow and inhibits thrombopoiesis. In vitro studies demonstrate that imetelstat selectively inhibits spontaneous megakaryocytic colony-forming unit (CFU-Meg) growth from the blood of pts with ET but not from healthy individuals. Phase I studies have demonstrated that imetelstat inhibits telomerase activity in pts at doses of 7.5 mg/kg and above. Therefore, unlike conventional cytoreductive therapy and JAK2 kinase inhibitors, imetelstat may be uniquely able to selectively inhibit proliferation of neoplastic clonogenic cells in pts with ET and modify the biology and progression of the disease. Methods: A phase II study enrolled pts with ET who had failed or were intolerant to at least one prior therapy, or who refused standard therapy. Pts were treated with imetelstat 7.5 mg/kg or 9.4 mg/kg IV weekly. After attainment of best platelet response in the induction phase, maintenance dosing with imetelstat was commenced with dosing based upon platelet count. Primary endpoint was best overall hematologic response (HR) with complete response (CR) defined as platelet count <400 × 103/μl maintained for at least 4 consecutive weeks in the absence of new thromboembolic events. A key secondary endpoint was rate of MR in patients with JAK2 V617F molecular mutations. JAK2 V617F allele burden was measured by allele-specific quantitative real-time PCR with a limit of detection of 0.1%. CFU-Meg growth pre- and post-treatment and tolerability were also assessed. Results: As of July 9, 2012, 13 pts were treated. Median age was 60 yrs (range 21–83) with a median of 2 prior treatments (range 1–3). Median years since initial diagnosis were 5.8 (range 0.3 to 24.9) and initial platelet count was 809 × 103/μl (range 601 to 1359 × 103/μl). Best overall HR was 100%, with 11 of 13 pts achieving a confirmed CR after a median of 6.1 weeks (range 5.1 to 14.1 wks). Twelve of 13 pts remain on maintenance therapy (median time on study 26.1 weeks) and despite transient elevations of platelets above best response, pts continue to be responsive to imetelstat. Four pts have reached 1 year of therapy and continue to be treated with ongoing HR. Dosing frequency on maintenance therapy was generally reduced with time. A substantial decrease in JAK2 V617F allele burden was demonstrated in all 5 JAK2 V617F-positive pts (mean allele burden reduction of 82%; range of 59–94%, see table below). Four pts who were eligible for MR assessment by LeukemiaNetcriteria (initial JAKV617F allele burden >10%) reached molecular partial responses (PR): one pt after 12 weeks, which has been maintained through 1 year, and 3 other pts at 24, 36 and 48 weeks of therapy. One additional pt with JAK2 V617F levels of 4.8% prior to therapy has also had a 75% reduction after 12 weeks of treatment. A reduction in the spontaneous growth of CFU-Meg was also observed in the 2 pts tested, with 93% and 96% reduction from baseline, respectively. Long-term administration of imetelstat was generally well tolerated. Common adverse events reported on therapy were mild to moderate gastrointestinal toxicities, reductions in neutrophil counts, and fatigue. Conclusions: Imetelstat rapidly induces and maintains hematologic responses in pts with ET who have failed or are intolerant to conventional therapies. Importantly, substantial MR is observed in all JAK2 V617F-positive pts and inhibition of the neoplastic clonogenic growth ex-vivo is demonstrated. The reduction in JAK2 V617F allele burden and cytokine-independent growth of CFU-Meg suggests that imetelstat has a relatively selective inhibitory effect on the growth of the neoplastic clone(s) which drive ET and has the potential to modify the underlying biology of MPNs. Additional data will be presented from this ongoing study. Disclosures: Baerlocher: Geron Corporation: Research Funding. Oppliger Leibundgut:Geron Corporation: Research Funding. Ayran:Geron Corporation: Employment. Blaney:Geron Corporation: Employment. Burington:Geron Corporation: Employment. Morfeld:Geron Corporation: Employment. Odenike:Sanofi Aventis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees. Reddy:Geron Corporation: Employment. Roeth:Geron Corporation: Research Funding. Stuart:OncoMed Pharmaceuticals: Consultancy; Geron Corporation: Consultancy, Employment.

scholarly journals Outcome of Hematopoietic Stem Cell Gene Therapy for Wiskott-Aldrich Syndrome

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 4629-4629 ◽  
Author(s):  
Roxane Labrosse ◽  
Julia Chu ◽  
Myriam Armant ◽  
Jet van der Spek ◽  
Alexandra Miggelbrink ◽  
...  
Keyword(s):  
Stem Cells ◽  
Gene Therapy ◽  
T Cells ◽  
Board Of Directors ◽  
Research Funding ◽  
Advisory Committees ◽  
Hematopoietic Stem ◽  
Cd34 Cells ◽  
Autoimmune Cytopenias ◽  
Mobilized Peripheral Blood

Background Wiskott-Aldrich syndrome (WAS) is a rare X-linked disorder characterized by combined immunodeficiency, eczema, microthrombocytopenia, infections, autoimmunity and lymphoma. Gene therapy (GT) using autologous CD34+ cells is an emerging alternative treatment with advantages over standard allogeneic hematopoietic stem cell transplant for patients who lack well matched donors, avoiding graft-versus-host-disease. An initial experience with gene therapy using a γ-retroviral vector showed correction of hematological defects in 9/10 patients, but was aggravated by development of leukemia in 7 of them. We report the outcomes of a phase I/II clinical trial in which 5 WAS patients underwent GT using a self-inactivating lentiviral (SIN-LV) vector expressing the human WAS cDNA under the control of a 1.6kB fragment of the human WAS promoter. Subjects and Methods Five patients with severe WAS (clinical score 3-5) were enrolled at a median age of 1.8 years (1.4 - 8 years) at a single pediatric tertiary care center. WAS protein (WASP) was absent or markedly decreased in 2 and 3 subjects, respectively. Purified CD34+ cells from mobilized peripheral blood (n = 4) or both mobilized peripheral blood and bone marrow (n = 1) were transduced ex-vivo with the SIN-LV vector and re-infused after conditioning with busulfan (target AUC of 70-80 mg*h/L) and fludarabine (120mg/m2). The median dose of CD34+ cells infused was 9.8 x 106 cells/kg (6.3 - 24.9 x 106 cells/kg) with a mean vector copy number (VCN) of 1.7 copies/cell in CD34+ cells (0.54 - 3.37). In addition to eczema, thrombocytopenia and WAS-related infections in all patients, two subjects also had autoimmunity pre-GT, manifested as skin vasculitis and autoimmune cytopenias. Results All 5 subjects were alive and well at median follow-up of 4.8 years (2.5 - 5.9 years). Multi-lineage vector gene marking was sustained over time. All subjects had improvement or resolution of eczema and none have had any intercurrent severe infectious events. WASP expression measured by flow cytometry in T cells was increased over baseline in all patients, but remained below normal levels and correlated with VCN and cell dose received. Proliferation of T cells in response to anti-CD3, which was initially defective in 4/5 patients, improved post-GT. Humoral immune deficiency was also ameliorated, as evidenced by independence from Ig replacement and vaccine responses in those tested. All subjects remained platelet transfusion-free and none have had severe bleeding events. Platelet levels increased to >50 x 103 cells/uL in two patients with a VCN ≥2 in transduced stem cells and myeloid VCN ~1 copy/cell in neutrophils; the other 3 subjects sustained platelet counts <50 x 103 cells/uL. Cytoskeleton function was highly abnormal in myeloid cells pre-GT, as shown by the near absence of podosome formation in monocyte-derived dendritic cells. At 12 months post-GT, the % of podosome-forming cells was improved in all subjects, and reached the level of healthy controls in the 2 patients with highest VCN in myeloid cells. Both subjects with pre-existing autoimmunity had post-GT autoimmunity: patient 4 had a flare of autoimmune cytopenias at 18 months post-GT, and patient 5 developed refractory autoimmune hepatitis and hemolytic anemia at 8 months post-GT. While all subjects had WASP expression in lymphocytes, those with autoimmunity had poor recovery of T cells, Tregs, and transitional B cells at the time of clinical symptoms. IL-10 producing regulatory B cells were deficient pre-GT and recovered to varying degrees in all subjects. No severe GT-related adverse events have occurred to date. Replication-competent lentivirus was not detected. Analysis of integration site distributions in five subjects showed reconstitution to be highly polyclonal, with no clones expanded to >20% of the transgene-marked cell population. To date, there have been no malignancies reported, either related to GT or WAS itself. Conclusion In summary, our data confirm and extend the safety and efficacy of GT in correcting disease manifestations associated with WAS, as seen in other studies using SIN-LV. Higher VCN in the drug product and in transduced stem cells correlated with better reconstitution of platelets and myeloid function. In contrast to other groups, we found in our study that patients with poor lymphocyte reconstitution post-GT may be at risk of ongoing autoimmunity despite high-level gene marking. Disclosures London: ArQule, Inc: Consultancy; United Therapeutics: Consultancy. Despotovic:Novartis: Research Funding; Amgen: Research Funding; Dova: Honoraria. Forbes:Takeda: Consultancy. Galy:Genethon: Employment. Williams:Novartis: Membership on an entity's Board of Directors or advisory committees; bluebird bio: Other: License of certain IP relevant to hemoglobinopathies. Potential for future royalty/milestone income. Received payment in past through BCH institutional licensing agreement., Research Funding; Orchard Therapeutics: Membership on an entity's Board of Directors or advisory committees, Other: Co-founder, potential for future royalty/milestone income, Research Funding; Alerion Biosciences: Membership on an entity's Board of Directors or advisory committees, Other: Co-founder. OffLabel Disclosure: CliniMACS technology for CD34+ cell selection

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