bluuebunny/crossref_metadata_2025_split huggingface dataset:
Arsenic Binding to RBCC Domain Modulates Oncogenic PML-RARa and Wild-Type PML as a Key Molecular Mechanism of Arsenic Trioxide Treatment for APL.
Authors: Zhang Xiaowei , Yan Xiaojing , Yang Feifei , Zhou Ziren , Wu Ziyu , Sun Hongbin , Liang Wenxue , Song Aixin , Huang Qiuhua , Zhou Guangbiao , Tong Jianhua , Zhang Yan , Wu Jihui , Hu Hongyu , Chen Saijuan , Chen Zhu 
Published: October 2019

Abstract
Abstract 592
Arsenicals represent one group of the oldest drugs used in both traditional Chinese medicine (TCM) and Western medicine since 2,000 years ago to treat a variety of ailments from periodic fever to cancer. Recently, this ancient remedy has been revived due to its remarkable therapeutic efficacy for acute promyelocytic leukemia (APL) through selective degradation of the leukemogenic PML-RARaƒn as well as the wild-type PML protein. However, the precise molecular mechanism leading to arsenic-initiated modulationƒn of the target proteins remained unclear. Here we show that arsenic directly binds to PML and PML-RARaƒn through their RBCC (RING-B box-coiled coil) domain which contains conserved cysteine/histidine residues with metal-binding ability. Among RBCC domain, the RING and B2 motif are responsible for arsenic binding in cells, with recombinant RING motif showing the highest affinity to arsenic binding in vitro. We also observed that arsenic tends to coordinate with three sulfur atoms from the three conserved cysteines in the RING zinc finger. Arsenic binding alters the native structure of RING coordinated with zinc and induces its oligomerization through arsenic-mediated conformational change by intramolecular coordination as well as cross-linking between two RING motifs. Following conformational change and oligomerization of PML RBCC with arsenic binding, PML and PML-RARa undergoes SUMOylation through enhanced interaction with Ubc9, the E2 ligase for SUMOylation. Our findings provide the evidence that the PML RBCC domain is the direct target of arsenic and that the structural change of PML RBCC induced by arsenic binding facilitates the enhanced interaction with the cellular enzymatic machinery for protein SUMOylation/ubiquitination, which ultimately leads to the degradation of PML-RARa and cell differentiation and/or apoptosis. This mechanism sheds new insights into the mechanism of action of As2O3 for APL treatment, a model of targeted cancer therapy.

Disclosures:
No relevant conflicts of interest to declare.
Platelet ADP Receptor P2Y12 Stabilizes Atherosclerosis Plaques by Regulating Alpha Granule Release and Inflammatory Cell Recruitment
Authors: Li Ding , Wang Yanhua , Wang Kemin , Zhang Lin , Chai Weiran , Sun Yueping , Ruan Changgeng , Chen Guo-Qiang , Gartner T. Kent , Liu Junling 
Published: October 2019

Abstract
Abstract 652

Atherosclerosis, a major cause of cardiovascular disease, is a complicated chronic inflammatory process. A variety of data demonstrate that platelets are crucial players in this pathological process. Platelet activation results in a-granule secretion and the secreted materials include adhesive proteins, chemokines and growth factors, which attract and mediate continuous inflammatory cell attachment to, and infiltration of dysfunctional endothelium and atherosclerotic plaques. Here, we show that the ablation of P2Y12, an ADP receptor highly expressed in platelets and smooth muscle cells, can significantly decrease monocyte infiltration of the aortic root, and thereby negatively affect enlargement of the atherosclerotic lesion in ApoE−/− mice fed on a high fat diet for 5 months. Ablation of P2Y12 in ApoE−/− mice also stabilizes the atherosclerotic plaques that do form in the double knockout mice. Plaque stability was demonstrated by Immunohistochemistry studies that revealed greater fibrous and diminished macrophage content in the atherosclerotic plaques. Bone marrow transplantation experiments confirmed that platelet P2Y12, but not smooth muscle P2Y12, is the key factor responsible for atherosclerosis formation. Further work demonstrated that P2Y12, through inhibition of the cAMP/PKA signaling pathway, critically regulates platelet expression of p-selectin and the release of PF4. This demonstration is crucial because PF4 is a chemokine documented to be important for atherosclerosis development. The results of in vitro assays demonstrated that under standard conditions, P2Y12+/+ platelets, but not P2Y12−/− platelets, released their a-granule contents during platelet activation and thereby enhanced monocyte migration. Compared to results obtained using P2Y12+/+ApoE−/− mice under the same conditions, the basal levels of PF4 and SDF-1a in platelet-poor plasma were significantly lower in P2Y12−/−ApoE−/− double knockout mice fed a high-fat diet, thereby providing in vivo support for our thesis that P2Y12 affects atherogenesis by regulating a-granule secretion. Our results point out that platelet P2Y12 modulates atherogenesis primarily through regulation of a-granule release, and secondarily by the resulting inflammatory cell recruitment, and therefore serves as a potential drug target for atherosclerosis prevention, in addition to being the target for prevention of thrombus formation in response to plaque rupture.

Disclosures:
No relevant conflicts of interest to declare.
Cytogenetics Abnormalities Predict the Outcome of Allogeneic Transplantation In AML: A CIBMTR Study
Authors: Armand Philippe , Perez Waleska , Zhang Mei-Jie , Kim Haesook , Klumpp Thomas R. , Cin Paola Dal , Waller Edmund K , Litzow Mark R. , Liesveld Jane L. , Lazarus Hillard M. , Artz Andrew , Gupta Vikas , Savani Bipin N. , McCarthy Philip L. , Cahn Jean-Yves , Schouten Harry , Finke Jurgen , Ball Edward D. , Aljurf Mahmoud , Cutler Corey , Rowe Jacob M. , Antin Joseph H. , Isola Luis M , Bartolomeo Paolo Di , Camitta Bruce , Miller Alan M , Cairo Mitchell S. , Stockerl-Goldstein Keith E. , Sierra Jorge , Savoie Mary Lynn , Halter Joerg , Stiff Patrick J , Nabhan Chadi , Jakubowski Ann A. , Bunjes Donald , Petersdorf Effie W. , Devine Steven M , Maziarz Richard , Bornhauser Martin , Lewis Victor A , Marks David I. , Bredeson Christopher N , Soiffer Robert , Weisdorf Daniel J. 
Published: October 2019

Abstract
Abstract 680

Cytogenetics play an essential role in determining the prognosis of patients with AML. However, there is still no validated cytogenetics grouping scheme that specifically applies to patients undergoing allogeneic stem cell transplantation, which hampers accurate prognostication and risk stratification. We studied 821 adult patients (median age 41, range 18–74) who underwent SCT between 1999 and 2004 for AML (excluding APL) in CR1 or CR2 and who were reported to the CIBMTR from centers with >20 patients meeting study criteria. 75% of patients received a myeloablative conditioning. 496 patients had a normal karyotype. The primary cytogenetics reports were manually reviewed for 92% of the patients with an abnormal karyotype. We compared the ability of the 6 existing grouping schemes (MRC, CALGB, EORTC/GIMEMA, SWOG/ECOG, DFCI, and Monosomal Karyotype (MK) classifications) to stratify patients, using both the Akaike Information Criterion in multivariable models and the C-statistic. Among all existing schemes, the DFCI system provided a marginally superior stratification for overall and leukemia-free survival. We also built a new classification using individual cytogenetic abnormalities in a Cox model that included other significant covariates (performance status, therapy-related disease, conditioning intensity, graft source, donor match, duration of CR1, and gender match). This CIBMTR scheme (see Table), which is similar to the DFCI scheme except for the inclusion of patients with t(8;21) in the intermediate group, could stratify patients into 3 groups with similar treatment-related mortality but significantly different overall survival, leukemia-free survival, and incidence of relapse. This scheme appeared to apply to both patients in CR1 and in CR2 (see FiguresF2). This transplant-specific scheme could be adopted for prognostication purposes and to stratify patients with karyotypic abnormalities entering transplantation clinical trials. Future studies may clarify the relative outcome of patients with t(8;21) and refine this scheme with the inclusion of molecular abnormalities.

Disclosures:
No relevant conflicts of interest to declare.
A Minor Genetic Variation In the Granzyme B Gene Predicts Relapse After HLA-Fully-Matched Unrelated Bone Marrow Transplantation for Hematologic Malignancies
Authors: Espinoza Luis J. , Takami Akiyoshi , Yamada Kayoko , Yamada Mayu , Motohashi Yuki , Nakata Katsuya , Morishita Eriko , Ohtake Shigeki , Nakao Shinji 
Published: October 2019

Abstract
Abstract 681

Granzyme B (GZMB) is a serine protease with important roles mediating target-cell apoptosis induced by natural killer cells and cytotoxic CD8+ T cells. The polymorphism rs8192917 (A55G) in the GZMB gene has been reportedly associated with the ability of effector cells to secrete GZMB. In this study we analyzed the impact of GZMB polymorphism on transplant outcomes in patients undergoing unrelated HLA-fully-matched myeloablative bone marrow transplantation (BMT) through the Japan Marrow Donation Program. The GZMB genotypes were retrospectively analyzed in a cohort of 360 pairs of patients with hematologic malignancies and their unrelated donors. The presence of the G/G genotype in the donor side was associated with a significantly higher incidence of relapse (62% vs. 32%, P=0.04; Fig 1). Multivariate analysis revealed that the donor G/G genotype, which is expected to produce lower levels of GZMB after stimulation, (Girnita et al, Transplantation 2009) was an independent risk factor for relapse (hazard ratio, 4.17; 95% confidence interval, 1.63 to 10.70; P=0.003). The host GZMB genotypes did not significantly influence the transplant outcomes. These results suggest an association of low GZMB secretors with disease relapse. These could therefore be useful in selecting the donor and creating therapeutic strategies for improving the final outcome of allogeneic BMT.

Disclosures:
No relevant conflicts of interest to declare.
Platelet Factor 4 Levels Inversely Correlate with Platelet Transfusion Needs In Pediatric Patients Treated for Standard Risk Acute Lymphoblastic Leukemia
Authors: Lambert Michele , Reznikov Alisa , Nguyen Yvonne , Rauova Lubica , Poncz Mortimer 
Published: October 2019

Abstract
Abstract 725
Platelet factor 4 (PF4) is a chemokine found almost exclusively in megakaryocytes and platelets. PF4 has been previously shown to be a negative paracrine inhibiting megakaryopoiesis in vitro in humans and mice. We confirmed this finding and also found an inverse correlation between PF4 and steady-state platelet counts in mice. In both chemotherapy- and radiation-induced thrombocytopenia, platelet PF4 levels inversely correlated with platelet count recovery after bone marrow injury, and blocking this effect ameliorated the thrombocytopenia. We now asked whether platelet PF4 levels are of clinical relevance on human platelet biology in patients undergoing chemotherapy. We selected pediatric patients who had completed treatment for standard risk acute lymphoblastic leukemia at the Children's Hospital of Philadelphia, as this was a fairly large population that have reached remission after relatively uniform therapy. Enrolled patients had completed therapy since January 1999. Blood samples were obtained and medical records were retrospectively reviewed for platelet counts, platelet transfusion requirements and duration of therapy during delayed intensification (DI). DI was chosen for investigation as a preliminary study showed that 35% of our patients require platelet transfusion during DI and need for transfusion at that point in therapy is unlikely to be related to primary underlying bone marrow disease. To date, 68 subjects have been enrolled. Sixty-two subjects had evaluable PF4 levels. PF4 levels were independent of age and sex. Leukemia survivors did not have significantly different PF4 levels when compared to a pediatric control population. There was a direct relationship between measured total PF4 level and platelet count (Pearson r 0.36, p<0.006) although contrary to animal studies, there was no correlation between PF4 per platelet and platelet count. Transfusion data from the first 22 patients have been evaluated. Patients who did not require platelet transfusion during DI had markedly lower PF4 per platelet (6.35 ± 1.85 SE) when compared to patients who required transfusion (13.26 ± 1.89 SE, p<0.02). In addition, duration of therapy (for girls) was inversely correlated with PF4 per platelet (r 0.689, p=0.04), consistent with animal data in which platelet count recovery was inversely correlated with PF4 per platelet. These data suggest that PF4 may be an important in vivo regulator of human platelet counts in the setting of bone marrow injury. Further clinical studies will confirm these findings and begin to explore potential interventions to allow for intensified chemotherapy regimens in subjects at risk for more severe chemotherapy-induced thrombocytopenia based on their level of this negative paracrine of megakaryopoiesis.

Disclosures:
No relevant conflicts of interest to declare.
Next-Generation Sequencing Analysis of 23 Therapy-Related Acute Myeloid Leukemia Transcriptomes
Authors: McNerney Megan E. , Brown Christopher D. , White Kevin P. 
Published: October 2019

Abstract
Abstract 850
Therapy-related acute myeloid leukemia/myelodysplastic syndrome (t-AML) is a fatal complication that occurs in up to 5% of patients treated with chemotherapy or radiation. As more cancer patients achieve longer remissions, t-AML has increased in incidence, yet remains refractory to current therapy, with a median survival of 8–10 months. T-AML is thought to be a direct product of genetic mutations induced by alkylating agents, topoisomerase-II inhibitors, and radiation. Two main subtypes of t-AML have been described that differ in their morphology, cytogenetic karyotype, and prognosis: alkylator-agent-induced and topoisomerase-II inhibitor-induced. To identify expressed genetic variants that distinguish the two subtypes of t-AML, we have sequenced the leukemic mRNA of 23 t-AML samples using Illumina paired-end technology, yielding over 1 billion base pairs of aligned sequence per sample. The alkylator agent-related group is comprised of 13 samples with deletions of part or all of chromosomes 5 and/or 7, or with complex karyotypes. 10 samples with other karyotypes, including normal karyotype and balanced translocations, constitute the topoisomerase-II-related group. In addition, 13 de novo AML patient samples with a spectrum of cytogenetic abnormalities similar to the t-AML samples have been similarly sequenced. We have found over 13,000 single nucleotide variants (SNVs) per sample. SNP array analysis on 2 samples demonstrates 92% sensitivity and 98% specificity for SNP identification. Phenotypically relevant SNVs are prioritized by population-level allele frequency estimates, evolutionary constraint estimates, and the predicted coding region change. This analysis has yielded approximately 200 rare, predicted deleterious SNVs per sample. Some of these variants include those previously reported to be aberrant in AML (for example, FLT3, P53, RUNX1, PTPN11, CBL, and TET2), validating our analysis pipeline. Putative disease-relevant SNVs are being compared between the two main subtypes of t-AML, as well as between therapy-related and de novo AML by analyzing the frequency of the aberrant gene or biological pathway within the groups. We have found that SNVs frequently occur in the same gene or pathway in multiple samples. These findings are being validated within tumor and paired normal DNA, as well as in a larger cohort of 100 t-AML leukemia samples and 50 de novo AML leukemia samples using single-base primer extension assays. Furthermore, comparisons of transcript expression level and isoform usage are being made between groups and cytogenetic types. This information will allow the identification of pathways altered in t-AML, correlation of mutations with clinical outcome, identification of potential biomarkers, and generation of candidate targets for leukemia therapeutics.

Disclosures:
No relevant conflicts of interest to declare.
The COPII Pathway and Hematologic Disease
Authors: Ginsburg David 
Published: October 2019

Abstract
Abstract SCI-18
Combined deficiency of factor V and factor VIII is a rare autosomal recessive bleeding disorder associated with coordinately decreased levels of two key blood coagulation factors. Genetic studies of affected families identified a novel pathway for the selective transport of a subset of secreted proteins, including factors V and VIII, from the ER to the Golgi. Patients with this disorder carry mutations in one of two components of this pathway, LMAN1 or MCFD2, which together form a receptor for the recruitment of specific cargo to the COPII vesicle for export from the ER. Mutations in other COPII components have recently been identified in other human genetic disorders, including deficiency of SEC23B in patients with congenital dyserythropoietic anemia type II. The molecular pathogenesis of these disorders will be discussed, along with the insights these findings have provided into the function of the mammalian COPII pathway.

Disclosures:
No relevant conflicts of interest to declare.
Translating Epigenetic Alterations Into Improvements In Patient Care
Authors: Reddy Pavan 
Published: October 2019

Abstract
Abstract SCI-24
Histone deacetylases (HDACs) catalyze the removal of acetyl groups from the lysine residues of histone tails and non-histone proteins and play a key role in epigenetic modifications. HDAC inhibitors (HDACi) have emerged as epigenetic regulators with significant ant-tumor effects. Many of these are in cancer clinical trials. Their immuno-modulatory effects have largely been unrecognized. Several recent lines of investigation have demonstrated that targeting HDACs can potently modulate immune responses. We have shown that certain of HDAC inhibitors have important anti-inflammatory or immunosuppressive effects in experimental models of allogeneic bone marrow transplantation (BMT). Data generated by us demonstrate that HDACi regulate experimental acute graft-versus-host (GVHD), in part, through modulation of the functions of host antigen presenting cells (APCs) such as dendritic cells (DCs). HDACi regulated experimental GVHD in a STAT-3 acetylation dependent induction of indoleamine 2, 3 dioxygenase (IDO) by the host antigen APCs. The preclinical murine data were complemented by analyses of DCs from healthy humans and post-BMT samples. In an effort to translate these observations we have initiated a Phase II clinical trial that will determine whether addition of HDACi, suberoylinalide hydroxamic acid (SAHA, vorinostat) will reduce the rates of acute GVHD following matched related donor allogeneic BMT after reduced intensity conditioning (RIC). The study is ongoing and fifteen patients are so far evaluable for the primary end-point. The preclinical data, the rationale for the trial development and the clinical progress along with the ongoing correlative studies from the trial that are based on the preclinical data will be presented.

Disclosures:
No relevant conflicts of interest to declare.
Hemogenic Endothelium
Authors: Speck Nancy A. , Tober Joanna , Chen Michael , de Bruijn Marella , Chan Mun Chiang 
Published: October 2019

Abstract
Abstract SCI-44
Hematopoietic stem cells (HSCs) develop from endothelium in the midgestation mouse conceptus, starting at 10.5 days post coitus, through the formation of intra-aortic clusters. Studies in mouse, zebrafish, chick, and frog embryos established that Runx1 (AML1) is the earliest specific marker of the endothelium from which HSCs and definitive hematopoietic progenitors form. Conditional deletion of Runx1 in vascular endothelial cadherin (VEC) positive cells blocks the emergence of intra-aortic hematopoietic clusters, definitive hematopoietic progenitors (HPs), and HSCs, demonstrating that Runx1 is required in endothelial cells for HP and HSC formation. On the other hand, Runx1 deletion in fetal liver HPs and HSCs with Vav-Cre, or deletion in adult HSCs with Mx1-Cre, does not eliminate HP and HSC function, although it does affect homeostasis. These data (and others) demonstrated that the absolute requirement for Runx1 in HP and HSC formation is transient, and over by the time HPs and HSCs colonize the fetal liver. We are further defining the developmental windows during which Runx1, and the gene encoding its non-DNA binding partner CBFβ, are required for HP and HSC specification and commitment. We have taken two complementary approaches. One approach is to delete Runx1 at specific times and assess the effect on HPs. The second approach is to restore CBFβ function at specific times, or in specific cells in otherwise CBFβ deficient embryos and determine whether that rescues HP or HSC formation. From these experiments we can draw several conclusions: 1) Runx1 is absolutely required before the 40 somite pair stage in the AGM region, as deletion before then severely impairs HP formation or activity; 2) CBFβ activity is required before 9.5 dpc for HP and HSC formation; 3) CBFβ activity in endothelium alone is sufficient for HP formation, but insufficient for HSC formation. Together the data indicate that Runx1-CBFβ activity is required over a period of several days during embryogenesis to specific and commit HSCs.

Disclosures:
No relevant conflicts of interest to declare.
Improving Adoptive Immunotherapy Using Less-Differentiated T Cells
Authors: Restifo Nicholas P. , Sukumar Madhu , Gattinoni Luca 
Published: October 2019

Abstract
Abstract SCI-49
Recent findings in mice and humans indicate that current treatments based on the adoptive immunotherapy of cancer might be vastly improved with the use of “younger” cells. Analysis of human clinical trials conducted at the NCI reveals that poor clinical responses after ACT are associated with short telomeres and low expression of CD27, a costimulatory molecule, whose loss may indicate poor proliferative capacity. In a mouse model of adoptive immunotherapy developed in our laboratory (pmel-1), we found that transfer of less differentiated tumor-specific T cells results in substantially greater tumor regression compared with the transfer of terminally differentiated cells. Using progressively less-differentiated, Wnt-stimulated T cells, we have been able to reduce the number of tumor-specific T cells needed to induce tumor regression by almost 1,000-fold. Thus, reprogramming terminally-differentiated cells to less-differentiated T cells might substantially increase the success of adoptive immunotherapy. The possibility of cellular de-differentiation was vividly illustrated by groundbreaking work from Yamanaka showing that expressing transcription factors such as Oct-3/4, Sox2, Klf-4 and c-Myc could re-program the mouse somatic cells and induce pluripotent stem cells. Subsequently, human iPS cells were generated using a similar genetic approach. We seek to generate iPS-derived, tumor-specific lymphocytes that are robustly proliferative, have long telomeres and are unencumbered by the epigenetic changes associated with terminal differentiation, exhaustion and senescence. If significant safety concerns can be addressed preclinically, we plan to infuse iPS-dervied, tumor-specific T cells to treat patients with metastatic cancer that is refractory to all available treatments.

Disclosures:
No relevant conflicts of interest to declare.