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 ◽  
...  

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.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3308-3308
Author(s):  
Rose Ann Padua ◽  
Stephanie Beurlet ◽  
Patricia Krief ◽  
Nader Omidvar ◽  
Carole Le Pogam ◽  
...  

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.


Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 783-783
Author(s):  
Bradley Wayne Blaser ◽  
Jessica Moore ◽  
Brian LI ◽  
Owen J. Tamplin ◽  
Vera Binder ◽  
...  

Abstract The microenvironment is an important regulator of hematopoietic stem and progenitor cell (HSC/HSPC) engraftment during development and in recipients of hematopoietic stem cell transplantation (HSCT). Factors secreted by the hematopoietic microenvironment that promote HSC/HSPC engraftment in the developing zebrafish may therefore be therapeutic targets for enhancing HSC engraftment in patients undergoing HSCT. We previously described a novel behavior we called endothelial cuddling in which sinuosoidal endothelial cells of the niche make intimate interactions with stem cells. To find candidate extracellular factors regulating this behavior, gene expression profiling was performed on sorted zebrafish endothelial cells. Gene set enrichment analysis showed that expression of chemokines and TNF family members was significantly enriched in all endothelial cells. The leading edge gene sets included 16 chemokines and chemokine receptors. Thirteen of these genes were used as candidates in a gain-of-function screen to test whether overexpression was sufficient to stimulate the hematopoietic niche in favor of HSC engraftment. High level, global gene expression was induced at 36 and 48 hours post fertilization (hpf) using a heat shock-inducible system. One gene, CXCR1, enhanced HSC/HSPC engraftment when globally overexpressed (p=0.03, N=63). CXCR1 is a specific receptor for the chemokine IL-8/CXCL8 in higher vertebrates. Zebrafish IL-8 was used in similar gain of function experiments and was also sufficient to enhance HSC/HSPC engraftment (p=0.003, N=41). CXCR2 is a promiscuous chemokine receptor for IL-8, Gro-α and Gro-β and did not enhance HSC/HSPC engraftment in this system. To further characterize the effects of CXCR1 on HSC engraftment, it was overexpressed in transgenic zebrafish carrying a stem-cell specific reporter gene, Runx1:mCherry. HSC engraftment in the CHT was enhanced when CXCR1 expression was induced beginning at 36 hpf (3.0 +/- 2.0 vs 7.4 +/- 2.6 HSC per CHT) or 48 hpf (4.3 +/- 1.1 vs 9.4 +/- 3.6 HSC per CHT). Inhibition of CXCR1 signaling from 48 to 72 hpf using the selective CXCR1/2 antagonist, SB225002, decreased HSC engraftment in Runx1:mCherry animals (1.2 +/- 0.39 vs 0.4 +/- 0.2 HSC per CHT, p=0.03). We next hypothesized that overexpression of CXCR1 might also have effects on the endothelial cell niche itself. Using FLK1(VEGFR2):mCherry reporter zebrafish and 3-dimensional reconstruction of the CHT, we found that global overexpression of CXCR1 increased the volume of the endothelial cell niche (2.0 +/- 0.09 x 106 vs 2.4 +/- 0.1 x 106 μm3, p=0.005) while treatment with SB225002 reduced its volume (6.3 +/- 0.3 x 105 vs 4.9 +/- 0.5 x 105 µm3, p=0.04). Finally, we asked if CHT remodeling would still be enhanced if CXCR1 were constitutively expressed only within the endothelial cell niche. FLK1:CXCR1; FLK1:mCherry double transgenic animals had significantly increased CHT volume when compared with FLK1:mCherry single transgenic animals (1.1 +/- 0.05 x 106 vs 1.3 +/- 0.06 x 106 um3, p=0.02). These findings suggest a model whereby HSC/HSPCs actively participate in the remodeling of the endothelial niche via CXCR1/IL-8 in order to promote their own engraftment. Further, they suggest that CXCR1/IL-8 is a potential therapeutic target for enhancing HSC/HSPC engraftment in patients undergoing HSCT. Disclosures 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.


Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 770-770
Author(s):  
Owen J. Tamplin ◽  
Ellen M. Durand ◽  
Logan A. Carr ◽  
Sarah J. Childs ◽  
Elliott H. Hagedorn ◽  
...  

Abstract Hematopoietic stem cells (HSC) reside in a highly structured microenvironment called the niche. There is two-way communication between a stem cell and its niche that determines important cell fate decisions. HSC must remain quiescent to persist throughout life but also divide and contribute progenitors that will replenish the blood supply. Although there have been a number of elegant studies that have imaged the mammalian bone marrow, we still lack a high-resolution real-time view of endogenous HSC behaviors and interactions within the niche. To overcome these challenges, we developed a transgenic zebrafish line that expresses GFP or mCherry in HSC. We generated this line using the previously described mouse Runx1 +23 kb intronic enhancer. We confirmed the purity of these stem cells by adult-to-adult limiting dilution transplantation with as few as one cell. Based on long-term multi-lineage engraftment, we estimated a stem cell purity of approximately 1/35, which is similar to the KSL (Kit+Sca1+Lin-) population in mouse. Using a novel embryo-to-embryo transplantation assay that is unique to zebrafish, we estimated an even higher stem cell purity of 1/2. These experiments have defined the most pure HSC population in the zebrafish. Using this novel transgenic reporter we have tracked HSC as they migrate in the live zebrafish embryo. This allowed us to image HSC as they interact with other cell types in their microenvironment, including endothelial cells and mesenchymal stromal cells. We have shown that a small group of endothelial cells remodel around a single HSC soon after it lodges in the niche. Recently, we have also found that a single stromal cell can anchor an HSC as it divides. In most cases, we observed that an HSC divides perpendicular to the stromal cell, with one daughter cell remaining attached to the stromal cell and the other migrating away. To gain a much higher resolution view of these cellular events than is possible with confocal microscopy we looked for an alternative approach. A combined method is called “Correlative Light and Electron Microscopy” (CLEM), and involves identification of cells by confocal microscopy, followed by processing of the same sample for EM scanning. We have applied this method by: 1) tracking endogenous HSC in the live embryo; 2) fixing the same embryo for serial block-face scanning EM; 3) reconstructing 3D models from high resolution serial EM sections. We used easily visible blood vessels as anatomical markers that allowed us to pinpoint a single cell in a relatively large block of scanned tissue. As expected, the identified HSC was round, had a distinctive large nucleus, scant cytoplasm, and ruffled membrane. The HSC was surrounded by a small group of 5-6 endothelial cells, as predicted from our confocal live imaging. However at this very high resolution (10 nm/pixel), we could see that only part of the HSC surface was contacted and wrapped by an endothelial cell. Other regions of the HSC surface were contacted by small endothelial cell protrusions. Much of the HSC surface was surrounded by a narrow extracellular space with endothelial and stromal cells lying opposite. Strikingly, we were able to identify the firm anchored attachment between a single stromal cell and HSC that we showed previously oriented the plane of division. By combining confocal live imaging of a novel zebrafish HSC reporter, and serial block-face scanning EM, we have created the first high-resolution 3D model of an endogenous stem cell in its niche. Disclosures Tamplin: Boston Children's Hospital: Patents & Royalties. 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.


Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. SCI-8-SCI-8
Author(s):  
Amy E. Geddis

Abstract Abstract SCI-8 Compared to red cells, whose passage from embryonic to adult stages is marked by the expression of distinct forms of hemoglobin, the development of megakaryocytes during embryogenesis is less well understood. However, certain shared characteristics between megakaryocytes, endothelial cells, hematopoietic stem cells and erythrocytes infer developmental relationships between these lineages. Recent data support the model that hematopoietic stem cells derive from the hemangioblast, and that megakaryocytes and erythrocytes develop from a common precursor both in primitive and adult hematopoiesis. Evidence of these common origins can be found in the genetic programs that are activated during hematopoiesis, in that many of the cell surface markers and transcriptions factors that are characteristic of megakaryocytes can also be found in endothelial cells, stem cells and erythrocytes. In this session I will review current views on developmental thrombopoiesis, key megakaryocytic transcription factors and the experimental and clinical phenotypes associated with their disruption, and current controversies in lineage choice during megakaryocyte differentiation. Disclosures Geddis: Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding.


Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 222-222 ◽  
Author(s):  
Michael G Kharas ◽  
Christopher Lengner ◽  
Fatima Al-Shahrour ◽  
Benjamin L. Ebert ◽  
George Q. Daley

Abstract Abstract 222 Genes that regulate normal hematopoietic stem cells are commonly dysregulated in hematopoietic malignancies. Recently we published that the Msi2 RNA binding protein is an important modulator in both normal hematopoietic stem cells and leukemia (Kharas et al, Nat. Medicine 2010). The closely related Msi1 protein has been shown to regulate mRNA translation through binding to the 3'UTR. Based on the high homology in the RNA recognition motifs, Msi2 has been considered to have similar functions. Moreover, increased MSI2 expression in chronic myelogenous leukemia blast crisis and acute myeloid leukemia predicts a worse clinical prognosis. Previous studies have mainly utilized shRNAs to functionally assess the role of Msi2 in the hematopoietic compartment. However, it remains unclear how Msi2 affects hematopoietic stem cells (HSC) and what are its critical mRNA targets. To develop a model focusing on the HSC compartment and to avoid potential compensatory mechanisms during development, we created Msi2 conditional knockout mice and crossed them with Mx1-Cre mice. We induced excision with poly(I):poly(C), (pIpC), and tested the peripheral blood, bone marrow cells and splenocytes by Southern blotting and QPCR analysis to verify Msi2 deletion. Loss of Msi2 mRNA was confirmed in the Lineagelo, Sca1+ and c-Kit+ (LSK) population. Msi2 deleted bone marrow contained reduced myeloid colony forming capacity and replating efficiency. Mice conditionally deleted for Msi2 had normal white blood cell counts but smaller spleens. In addition, we observed normal percentages of the mature hematopoietic populations, including the myeloid and lymphoid compartments. Nevertheless, absolute numbers of long-term HSCs in the bone marrow were reduced by 3-fold. Bone marrow cells non-competitively transplanted into primary and secondary recipient mice showed a dramatic reduction in HSC chimerism. This defect was also observed when bone marrow was transplanted first to allow engraftment followed by Msi2 deletion. Furthermore, we were able to recapitulate this defect in vitro using the cobblestone-forming activity assay. These results indicate that Msi2 is both an important regulator of normal HSC maintenance and required for efficient engraftment. Most interestingly, Msi2 HSCs failed to maintain a normal quiescent HSC population. We performed microarrays to identify the pathways altered in the LSK population. The Msi2 deficient LSKs showed a reduced self-renewal and increased differentiation gene signature. Gene expression analysis indicates a defective self-renewal program in Msi2-deficient HSCs that is identical to the program gained in leukemic stem cells. These data suggest that MSI2 is a critical modulator of HSCs and may help explain its requirement in the most aggressive myeloid leukemias. 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.


Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1596-1596
Author(s):  
Hsuan-Ting Huang ◽  
Katie Kathrein ◽  
Yue-Hua Huang ◽  
Zachary Gitlin ◽  
Abby Barton ◽  
...  

Abstract Abstract 1596 Hematopoietic stem cells (HSC) are specified during embryogenesis, and the induction process involves not only transcription factors but also epigenetic factors that modulate chromatin to regulate the hematopoietic transcriptional programs. Here, we performed a reverse genetic screen to identify all the chromatin factors that are required for HSC induction in zebrafish. The zebrafish homologs of 350 human chromatin factors were identified by reciprocal BLAST and knocked down by injecting morpholinos designed against each homolog into the single cell embryo. Morphants were then analyzed for changes in blood formation by in situ hybridization for β-globin e3 expression in primitive erythrocytes at 16 somite stage and for c-myb and runx1 in definitive stem cells at 36 hours post fertilization. From the screen, we have identified known regulators of hematopoiesis such as bmi1, in which knock down results in loss of stem cell formation. We have also identified one novel HSC regulator chd7. Chd7 is a member of the chromodomain helicase DNA-binding domain family that functions at gene enhancer elements and in ribosomal RNA synthesis. Zebrafish embryos injected with chd7 morpholino had higher levels of β-globin e3 and c-myb/runx1 expression. Additional markers such as scl, gata1, fli1, and lmo2 were also upregulated, although vascular markers flk1 and ephrinB2 were downregulated. Early mesodermal markers eve1 and ntl expression appeared normal, suggesting that the effects of chd7 knock down occurs when the mesodermal precursor cell population becomes an HSC. Transplants of chd7 deficient Tg(c-myb:GFP) blastomeres into Tg(lmo2:DsRed) blastulas resulted in more chimeric embryos compared to controls, demonstrating that the phenotype is cell autonomous. In humans, haploinsufficiency for CHD7 is the main cause of CHARGE syndrome, and it has been recognized more recently that these patients are immunodeficient, though the etiology remains unknown. Our studies indicate a new role for chd7 in hematopoiesis in which it functions to repress HSC formation during embryogenesis. Disclosures: Zon: FATE, Inc.: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; Stemgent: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees.


Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2344-2344
Author(s):  
Natasha Arora ◽  
Shannon McKinney-Freeman ◽  
Garrett C Heffner ◽  
Il-Ho Jang ◽  
Pamela L. Wenzel ◽  
...  

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.


Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 4311-4311 ◽  
Author(s):  
Paul G. Richardson ◽  
Angela R. Smith ◽  
Brandon M. Triplett ◽  
Nancy A. Kernan ◽  
Stephan A. Grupp ◽  
...  

Abstract Introduction Hepatic veno-occlusive disease, also called sinusoidal obstruction syndrome (VOD/SOS), is an unpredictable, potentially life-threatening complication of conditioning for hematopoietic stem cell transplant (HSCT). Severe VOD/SOS (ie, with multi-organ dysfunction [MOD]) may be associated with >80% mortality. Defibrotide is approved for treatment of severe VOD/SOS in the EU. In the US, defibrotide is available through an ongoing, expanded-access study. The optimal time to initiate VOD/SOS treatment with defibrotide is of interest. Methods In the expanded-access study, patients were eligible in the original protocol if they had VOD/SOS and renal/pulmonary MOD by Baltimore criteria post-HSCT or by biopsy. The protocol was amended to include (1) post-chemotherapy patients, (2) patients without MOD, and (3) VOD/SOS per modified Seattle criteria. Defibrotide 25 mg/kg/day was given in 4 divided doses for a recommended ≥21 days. Here, Day +100 survival in patients with HSCT was examined post hoc based on time from VOD/SOS diagnosis (with or without MOD as relevant to study entry criterion) to initiation of defibrotide. Two analyses were conducted: (1) survival rate analyzed by treatment initiation for the entire population before or after each of the following days: 1, 2, 3, 4, 7, and 14, using Fisher's exact test; (2) survival rate for only those patients with treatment initiated on a particular day: 0, 1, 2, 3, 4, 5, 6, 7, 8-14, and ≥15, with a Cochran-Armitage test for trend across days. Results Among HSCT patients enrolled through 2013 who received ≥1 dose of defibrotide, treatment date was available for 573 patients. Of these, 351 also had MOD. Defibrotide was started on the day of diagnosis in >30% of patients; >90% of patients started defibrotide before day 7 post-diagnosis. In the population-wide analysis of treatment initiation before or after days 1, 2, 3, 4, 7, and 14, earlier initiation of defibrotide was associated with higher survival rates (Table), and was statistically significant for all cut-points considered except 14 days, with only 2.8% of patients beginning treatment post-day 14. Survival differences between earlier vs. later initiation ranged from 8.8% to 22.1% overall (MOD: 12.8% to 25.6%; Table) for the cut-points considered. In the analysis of relationship between Day +100 survival and treatment initiation day, survival rates were generally higher if treatment was initiated earlier. This was demonstrated by a statistically significant trend over time for better outcomes with earlier initiation (Figure). Similar results for both analyses were obtained for all patients with VOD/SOS and for the subgroup of patients with MOD. Conclusions Data indicate decreased Day +100 survival associated with longer treatment delays, confirmed by the Cochran Armitage trend test (P<0.001). Thus, defibrotide treatment should be initiated as soon as possible after VOD/SOS diagnosis. Table. Day +100 Survival by Defibrotide Initiation Day n (%) HSCT VOD/SOS (N=573) HSCT VOD/SOS with MOD (n=351) Initiation Period Alive Dead Unknown Alive Dead Unknown ≤1 Day 183 (53.5) 142 (41.5) 17 (5.0) 103 (50.2) 93 (45.4) 9 (4.4) >1 Day 105 (45.5) 116 (50.2) 10 (4.3) 56 (38.4) 85 (58.2) 5 (3.4) Difference (95% CI)a 8.8% (0.2%, 17.3%) 12.8% (2.0%, 23.4%) P valueb 0.045 0.021 ≤2 Days 235 (55.7) 166 (39.3) 21 (5.0) 132 (52.2) 111 (43.9) 10 (4.0) >2 Days 53 (35.1) 92 (60.9) 6 (4.0) 27 (27.6) 67 (68.4) 4 (4.1) Difference (95% CI)a 22.1% (12.6%, 31.2%) 25.6% (13.8%, 36.9%) P valueb <.001 <.001 ≤3 Days 251 (53.5) 193 (41.2) 25 (5.3) 138 (49.5) 129 (46.2) 12 (4.3) >3 Days 37 (35.6) 65 (62.5) 2 (1.9) 21 (29.2) 49 (68.1) 2 (2.8) Difference (95% CI)a 20.3% (9.6%, 30.8%) 21.7% (8.6%, 34.5%) P valueb <.001 0.001 ≤4 Day 263 (52.6) 212 (42.4) 25 (5.0) 146 (48.7) 142 (47.3) 12 (4.0) >4 Day 25 (34.2) 46 (63.0) 2 (2.7) 13 (25.5) 36 (70.6) 2 (3.9) Difference (95% CI)a 20.2% (7.7%, 32.4%) 24.2% (9.1%, 38.9%) P valueb 0.002 0.002 ≤7 Days 275 (51.6) 232 (43.5) 26 (4.9) 152 (47.4) 156 (48.6) 13 (4.0) >7 Days 13 (32.5) 26 (65.0) 1 (2.5) 7 (23.3) 22 (73.3) 1 (3.3) Difference (95% CI)a 20.9% (4.5%, 37.1%) 25.2% (6.1%, 43.8%) P valueb 0.013 0.011 ≤14 Days 282 (50.6) 249 (44.7) 26 (4.7) 156 (45.9) 171 (50.3) 13 (3.8) >14 Days 6 (37.5) 9 (56.3) 1 (6.3) 3 (27.3) 7 (63.6) 1 (9.1) Difference (95% CI)a 13.1% (-12.9%, 39.5%) 17.7% (-14.6%, 51.5%) P valueb 0.433 0.344 aAlive and Dead. 95% CI calculated using exact method. bFisher's exact test, Alive and Dead. Support: Jazz Pharmaceuticals. Disclosures Richardson: Gentium S.p.A.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Off Label Use: Defibrotide is an investigational treatment for hepatic veno-occlusive disease/sinusoidal obstruction syndrome in the United States.. Kernan:Gentium S.p.A.: Research Funding. Grupp:Novartis: Consultancy, Research Funding. Antin:Gentium S.p.A.: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Miloslavsky:Jazz Pharmaceuticals: Employment, Equity Ownership. Hume:Jazz Pharmaceuticals: Employment, Equity Ownership. Hannah:Jazz Pharmaceuticals: Consultancy. Nejadnik:Jazz Pharmaceuticals: Employment, Equity Ownership. Soiffer:Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Gentium S.p.A.: Membership on an entity's Board of Directors or advisory committees.


Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1961-1961
Author(s):  
John F. DiPersio ◽  
Jonathan Hoggatt ◽  
Steven Devine ◽  
Lukasz Biernat ◽  
Haley Howell ◽  
...  

Background Granulocyte colony-stimulating factor (G-CSF) is the standard of care for mobilization of hematopoietic stem cells (HSCs). G-CSF requires 4-7 days of injections and often multiple aphereses to acquire sufficient CD34+ cells for transplant. The number of CD34+ HSCs mobilized can be variable and patients who fail to mobilize enough CD34+ cells are treated with the combination of G-CSF plus plerixafor. G-CSF use is associated with bone pain, nausea, headaches, fatigue, rare episodes of splenic rupture, and is contraindicated for patients with autoimmune and sickle cell disease. MGTA-145 (GroβT) is a CXCR2 agonist. MGTA-145, in combination with plerixafor, a CXCR4 inhibitor, has the potential to rapidly and reliably mobilize robust numbers of HSCs with a single dose and same-day apheresis for transplant that is free from G-CSF. MGTA-145 plus plerixafor work synergistically to rapidly mobilize HSCs in both mice and non-human primates (Hoggatt, Cell 2018; Goncalves, Blood 2018). Based on these data, Magenta initiated a Phase 1 dose-escalating study to evaluate the safety, PK and PD of MGTA-145 as a single agent and in combination with plerixafor. Methods This study consists of four parts. In Part A, healthy volunteers were dosed with MGTA-145 (0.0075 - 0.3 mg/kg) or placebo. In Part B, MGTA-145 dose levels from Part A were selected for use in combination with a clinically approved dose of plerixafor. In Part C, a single dose MGTA-145 plus plerixafor will be administered on day 1 and day 2. In Part D, MGTA-145 plus plerixafor will be administered followed by apheresis. Results MGTA-145 monotherapy was well tolerated in all subjects dosed (Table 1) with no significant adverse events. Some subjects experienced mild (Grade 1) transient lower back pain that dissipated within minutes. In the ongoing study, the combination of MGTA-145 with plerixafor was well tolerated, with some donors experiencing Grade 1 and 2 gastrointestinal adverse events commonly observed with plerixafor alone. Pharmacokinetic (PK) exposure and maximum plasma concentrations increased dose proportionally and were not affected by plerixafor (Fig 1A). Monotherapy of MGTA-145 resulted in an immediate increase in neutrophils (Fig 1B) and release of plasma MMP-9 (Fig 1C). Neutrophil mobilization plateaued within 1-hour post MGTA-145 at doses greater than 0.03 mg/kg. This plateau was followed by a rebound of neutrophil mobilization which correlated with re-expression of CXCR2 and presence of MGTA-145 at pharmacologically active levels. Markers of neutrophil activation were relatively unchanged (<2-fold vs baseline). A rapid and statistically significant increase in CD34+ cells occurred @ 0.03 and 0.075 mg/kg of MGTA-145 (p < 0.01) relative to placebo with peak mobilization (Fig 1D) 30 minutes post MGTA-145 (7-fold above baseline @ 0.03 mg/kg). To date, the combination of MGTA-145 plus plerixafor mobilized >20/µl CD34s in 92% (11/12) subjects compared to 50% (2/4) subjects receiving plerixafor alone. Preliminary data show that there was a significant increase in fold change relative to baseline in CD34+ cells (27x vs 13x) and phenotypic CD34+CD90+CD45RA- HSCs (38x vs 22x) mobilized by MGTA-145 with plerixafor. Mobilized CD34+ cells were detectable at 15 minutes with peak mobilization shifted 2 - 4 hours earlier for the combination vs plerixafor alone (4 - 6h vs 8 - 12h). Detailed results of single dose administration of MGTA-145 and plerixafor given on one day as well as also on two sequential days will be presented along with fully characterized graft analysis post apheresis from subjects given MGTA-145 and plerixafor. Conclusions MGTA-145 is safe and well tolerated, as a monotherapy and in combination with plerixafor and induced rapid and robust mobilization of significant numbers of HSCs with a single dose in all subjects to date. Kinetics of CD34+ cell mobilization for the combination was immediate (4x increase vs no change for plerixafor alone @ 15 min) suggesting the mechanism of action of MGTA-145 plus plerixafor is different from plerixafor alone. Preliminary data demonstrate that MGTA-145 when combined with plerixafor results in a significant increase in CD34+ fold change relative to plerixafor alone. Magenta Therapeutics intends to develop MGTA-145 as a first line mobilization product for blood cancers, autoimmune and genetic diseases and plans a Phase 2 study in multiple myeloma and non-Hodgkin lymphoma in 2020. Disclosures DiPersio: Magenta Therapeutics: Equity Ownership; NeoImmune Tech: Research Funding; Cellworks Group, Inc.: Membership on an entity's Board of Directors or advisory committees; Karyopharm Therapeutics: Consultancy; Incyte: Consultancy, Research Funding; RiverVest Venture Partners Arch Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees; WUGEN: Equity Ownership, Patents & Royalties, Research Funding; Macrogenics: Research Funding, Speakers Bureau; Bioline Rx: Research Funding, Speakers Bureau; Celgene: Consultancy; Amphivena Therapeutics: Consultancy, Research Funding. Hoggatt:Magenta Therapeutics: Consultancy, Equity Ownership, Research Funding. Devine:Kiadis Pharma: Other: Protocol development (via institution); Bristol Myers: Other: Grant for monitoring support & travel support; Magenta Therapeutics: Other: Travel support for advisory board; My employer (National Marrow Donor Program) has equity interest in Magenta. Biernat:Medpace, Inc.: Employment. Howell:Magenta Therapeutics: Employment, Equity Ownership. Schmelmer:Magenta Therapeutics: Employment, Equity Ownership. Neale:Magenta Therapeutics: Employment, Equity Ownership. Boitano:Magenta Therapeutics: Employment, Equity Ownership, Patents & Royalties. Cooke:Magenta Therapeutics: Employment, Equity Ownership, Patents & Royalties. Goncalves:Magenta Therapeutics: Employment, Equity Ownership, Patents & Royalties. Raffel:Magenta Therapeutics: Employment, Equity Ownership. Falahee:Magenta Therapeutics: Employment, Equity Ownership, Patents & Royalties. Morrow:Magenta Therapeutics: Employment, Equity Ownership, Patents & Royalties. Davis:Magenta Therapeutics: Employment, Equity Ownership.


Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3129-3129
Author(s):  
Hans C. Lee ◽  
Sikander Ailawadhi ◽  
Cristina Gasparetto ◽  
Sundar Jagannath ◽  
Robert M. Rifkin ◽  
...  

Background: Multiple myeloma (MM) is common among the elderly, with 35% of patients (pts) diagnosed being aged ≥75 years (y). With increasing overall life expectancy, the incidence and prevalence of newly diagnosed and previously treated MM patients ≥80 y is expected to increase over time. Because elderly pts are often excluded from clinical trials, data focused on their treatment patterns and clinical outcomes are lacking. The Connect® MM Registry (NCT01081028) is a large, US, multicenter, prospective observational cohort study of pts with newly diagnosed MM (NDMM) designed to examine real-world diagnostic patterns, treatment patterns, clinical outcomes, and health-related quality of life patient-reported outcomes. This analysis reviews treatment patterns and outcomes in elderly pts from the Connect MM Registry. Methods: Pts enrolled in the Connect MM registry at 250 community, academic, and government sites were included in this analysis. Eligible pts were adults aged ≥18 y with symptomatic MM diagnosed ≤2 months before enrollment, as defined by International Myeloma Working Group criteria; no exclusion criteria were applied. For this analysis, pts were categorized into 4 age groups: <65, 65 to 74, 75 to 84, and ≥85 y. Pts were followed from time of enrollment to the earliest of disease progression (or death), loss to follow-up, or data cutoff date of February 7, 2019. Descriptive statistics were used for baseline characteristics and treatment regimens. Survival outcomes were analyzed using Cox regression. Time to progression (TTP) analysis excluded causes of death not related to MM. Results: Of 3011 pts enrolled (median age 67 y), 132 (4%) were aged ≥85 y, and 615 (20%) were aged 75-84 y at baseline. More pts aged ≥85 y had poor prognostic factors such as ISS stage III disease and reduced hemoglobin (<10 g/dL or >2 g/dL <LLN) compared with other age groups, although no notable differences between creatinine and calcium levels were observed across age groups (Table). A lower proportion of elderly pts (75-84 and ≥85 y) received triplet regimens as frontline therapy. More elderly pts received a single novel agent, whereas use of 2 novel agents was more common in younger pts (Table). The most common frontline regimens among elderly pts were bortezomib (V) + dexamethasone (D), followed by lenalidomide (R) + D, whereas those among younger pts included RVD, followed by VD and CyBorD (Table). No pt aged ≥85 y, and 4% of pts aged 75-84 y received high-dose chemotherapy and autologous stem cell transplant (vs 61% in the <65 y and 37% in the 65-74 y age group). The most common maintenance therapy was RD in pts ≥85 y (although the use was low) and R alone in other age groups (Table). In the ≥85 y group, 27%, 10%, and 4% of pts entered 2L, 3L, and 4L treatments respectively, vs 43%, 23%, and 13% in the <65 y group. Progression-free survival was significantly shorter in the ≥85 y age group vs the 75-84 y age group (P=0.003), 65-74 y age group (P<0.001), and <65 y age group (P<0.001; Fig.1). TTP was significantly shorter in the ≥85 y group vs the <65 y group (P=0.020); however, TTP was similar among the 65-74 y, 75-84 y, and ≥85 y cohorts (Fig. 2). Overall survival was significantly shorter in the ≥85 y group vs the 75-84 y, 65-74 y, and <65 y groups (all P<0.001; Fig. 3). The mortality rate was lowest (46%) during first-line treatment (1L) in pts aged ≥85 y (mainly attributed to MM progression) and increased in 2L and 3L (47% and 54%, respectively); a similar trend was observed in the younger age groups. The main cause of death was MM progression (29% in the ≥85 y vs 16% in the <65 y group). Other notable causes of death in the ≥85 y group included cardiac failure (5% vs 2% in <65 y group) and pneumonia (5% vs 1% in <65 y group). Conclusions: In this analysis, elderly pts received similar types of frontline and maintenance regimens as younger pts, although proportions varied with decreased use of triplet regimens with age. Considering similarities in TTP across the 65-74 y, 75-84 y, and ≥85 y cohorts, these real-world data support active treatment and aggressive supportive care of elderly symptomatic pts, including with novel agents. Additionally, further clinical studies specific to elderly patients with MM should be explored. Disclosures Lee: Amgen: Consultancy, Research Funding; GlaxoSmithKline plc: Research Funding; Sanofi: Consultancy; Daiichi Sankyo: Research Funding; Celgene: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Janssen: Consultancy, Research Funding. Ailawadhi:Janssen: Consultancy, Research Funding; Takeda: Consultancy; Pharmacyclics: Research Funding; Amgen: Consultancy, Research Funding; Celgene: Consultancy; Cellectar: Research Funding. Gasparetto:Celgene: Consultancy, Honoraria, Other: Travel, accommodations, or other expenses paid or reimbursed ; Janssen: Consultancy, Honoraria, Other: Travel, accommodations, or other expenses paid or reimbursed ; BMS: Consultancy, Honoraria, Other: Travel, accommodations, or other expenses paid or reimbursed . Jagannath:AbbVie: Consultancy; Merck & Co.: Consultancy; Bristol-Myers Squibb: Consultancy; Karyopharm Therapeutics: Consultancy; Celgene Corporation: Consultancy; Janssen Pharmaceuticals: Consultancy. Rifkin:Celgene: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Durie:Amgen, Celgene, Johnson & Johnson, and Takeda: Consultancy. Narang:Celgene: Speakers Bureau. Terebelo:Celgene: Honoraria; Jannsen: Speakers Bureau; Newland Medical Asociates: Employment. Toomey:Celgene: Consultancy. Hardin:Celgene: Membership on an entity's Board of Directors or advisory committees. Wagner:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; American Cancer Society: Other: Section editor, Cancer journal. Omel:Celgene, Takeda, Janssen: Other: Patient Advisory Committees. Srinivasan:Celgene: Employment, Equity Ownership. Liu:TechData: Consultancy. Dhalla:Celgene: Employment. Agarwal:Celgene Corporation: Employment, Equity Ownership. Abonour:BMS: Consultancy; Celgene: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Janssen: Consultancy, Research Funding.


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