bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential Prognostic Effect of IDH1 Versus IDH2 Mutations in Myelodysplastic Syndromes: A Mayo Clinic Study of 277 Patients
Authors: Patnaik Mrinal M. , Hanson Curtis A. , Hodnefield Janice M , Lasho Terra L , Finke Christy , Knudson Ryan A , Ketterling Rhett P , Pardanani Animesh , Tefferi Ayalew 
Published: October 2019

Abstract
Abstract 971
Unlike the case in acute myeloid leukemia, there is limited information on the prognostic impact of IDH mutations in myelodysplastic syndromes (MDS). In the current study of 277 patients with MDS, IDH mutations were detected in 34 (12%) cases: 26 IDH2 (all R140Q) and 8 IDH1 (six R132S and two R132C). Mutational frequency was 4% (2 of 56) in refractory anemia with ring sideroblasts (RARS), 12% (16 of 130) in refractory cytopenia with multilineage dysplasia, 14% (2 of 14) in MDS-unclassifiable, 14% (6 of 42) in refractory anemia with excess blasts (RAEB)-1, and 23% (8 of 35) in RAEB-2. Normal karyotype was noted in all but one IDH1-mutated cases and 13 IDH2-mutated cases. Multivariable analysis identified presence of mutant IDH1 (p=0.0004; HR 4.0, 95% CI 1.9–8.8), revised International Prognostic Scoring System (IPSS-R) risk category (p<0.0001), and red cell transfusion need (p=0.002) as independent predictors of inferior survival (Figure 1). In a similar multivariable analysis, mutant IDH1 was the only variable associated with shortened leukemia-free survival (p=0.001; HR 7.0, 95% CI 2.3–20.8). The presence of IDH2 R140Q did not affect overall (p=0.54) or leukemia-free (p=0.81) survival (Figure 2). The current study suggests a powerful adverse prognostic effect for mutant IDH1 in MDS.

Disclosures:
No relevant conflicts of interest to declare.
Inhibition of RARα2 or Its Downstream Signaling Pathways Decreases Drug Resistance in Myeloma
Authors: Tricot Guido J. , Yang Ye , Xiao Fang , Zangari Maurizio , Xu Hongwei , Zhan Fenghuang 
Published: October 2019

Abstract
Abstract 989

Background:
We have previously reported that the 30% of newly diagnosed myeloma (MM) patients expressing RARα2, had a significantly inferior outcome. RARα2 expression was also significantly increased in rapidly relapsing myelomas compared to paired baseline samples, indicating the existence at diagnosis of a RARα2 subclone, which is drug-resistant. We further demonstrated that RARα2 expression was significantly higher in MM cell line-derived and primary MM stem cells (MMSC) than in CD138+ bulk MM cells. In this study, we further explore the role of RARα2 in myeloma drug resistance.

Materials and methods:
RARα2 related drug resistance was evaluated by clonogenic formation assays, using 20,000 MM cells from the RARα2 high-expressing ARK and KMS11 MM cell lines, treated with all-trans retinoic acid (ATRA) (1nM, 10nM), Wnt inhibitor CAY10404 (1 nM, 10nM), Hedgehog inhibitor cyclopamine (1nM, 10nM), bortezomib (1nM, 10nM), as well as doxorubicin (50nM, 100nM), etoposide (50nM, 100nM), and verapamil (50nM). To determine whether inhibition of RARa2 decreased drug resistance, 1.0 × 106 KMS11 cells, made resistant to bortezomib, were transfected with RARα2 shRNA and injected subcutaneously into 20 NOD/SCID mice. The 5TGM1 myeloma mice were used to determine whether targeting RARa2 or its signaling pathways could eliminate MMSC.

Results:
After serial replating for 6 weeks, MMSCs (CD138- fraction) exhibited greater clonogenic expansion than the control CD138+ fraction, while ATRA, an inhibitor of RARα2, induced potent clonogenic inhibition on MMSC. We also showed in vitro that over-expression of RARα2 in low-expressing MM cell lines, ARP1 and OCI-MY5 resulted in increased clonogenic potential and drug-resistance. In a xenograft myeloma mouse model, knockdown of RARα2 in the KSM11bortezomib-resistant cells decreased resistance to bortezomib. We further identified that RARα2 induced drug resistance by activating the drug efflux pump gene ABCC3 through Wnt and Hedgehog signaling. Inhibition of Wnt (CAY10404) signaling or the ABC transporter by verapamil overcame the drug-resistance in ARP1 and OCI-MY5 cells caused by RARα2 over-expression. Finally, targeting RARa2 or its pathways using ATRA, CAY10404 and cyclopamine significantly reduced the tumor burden as determined by idiotype IgG2 protein levels and increased survival compared to untreated controls (P < 0.05) in the 5TGM1 mice after injection of 5TGM1 MMSC.

Conclusion:
Over-expression of RARa2 induces drug resistance by activating the drug efflux pump gene ABCC3 through activation of the Wnt and Hedgehog pathways, while inhibition of RARα2 decreases drug resistance. We also provide a possible strategy to eliminate MMSC by targeting RARa2 and/or its downstream targets, such as the Wnt and Hedgehog pathways.

Disclosures:
No relevant conflicts of interest to declare.
Notch Signaling in Graft-Versus-Host Disease
Authors: Maillard Ivan 
Published: October 2019

Abstract SCI-14
Notch is a highly conserved signaling pathway with multiple functions in health and disease. In the hematopoietic system, Notch was first described for its essential role at early stages of T cell development in the thymus and for its involvement in T cell acute lymphoblastic leukemia. In addition, Notch is being increasingly recognized as a potent regulator of antigen-driven mature T cell responses with context-dependent effects. These effects are influenced by the regulated expression of Jagged and Delta-like Notch ligands in antigen-presenting cells under the control of Toll-like receptors and other innate signals. We are investigating the importance of the Notch pathway in T cell alloimmunity in the setting of allogeneic bone marrow or peripheral blood stem cell transplantation (allo-BMT). After allo-BMT, alloimmune T cell responses mediate beneficial graft-versus-tumor (GVT) activity as well as detrimental graft-versus-host disease (GVHD). Using the pan-Notch inhibitor DNMAML and other genetic models of Notch inhibition, we have discovered an essential function for Notch signaling in donor-derived alloreactive T cells. In multiple mouse models of allo-BMT, infusion of Notch-deficient T cells as compared to wild-type T cells led to dramatically reduced GVHD severity and lethality. This effect was apparent for both CD4+ and CD8+ T cells and did not involve global immunosuppression, since Notch-deficient T cells proliferated normally and expanded in host lymphohematopoietic organs. However, Notch-deficient donor T cells failed to accumulate in the gut, a key GVHD target organ, and produced markedly decreased amounts of the pro-inflammatory cytokines IFN-γ, TNF-α, and IL-2. In parallel, Notch inhibition was associated with increased accumulation of FoxP3+CD4+ T cells. Decreased cytokine production could not be explained by a classical T helper differentiation defect. In contrast to their defective induction of GVHD, Notch-deficient T cells remained capable of mediating cytotoxic and anti-tumor responses both in vitro and in vivo, leading to preserved GVT activity even against large numbers of tumor cells. We are currently investigating the molecular and cellular mechanisms of Notch action in alloreactive T cells. We are also exploring the role of individual Notch receptors and ligands at the alloimmune synapse in vivo. Altogether, our findings identify Notch inhibition in donor T cells as a novel strategy to induce beneficial immunomodulation rather than global immunosuppression after allo-BMT.

Disclosures:
No relevant conflicts of interest to declare.
Modulation of HIF-2 Function with Small Molecules: Did Nature Beat Us to It?
Authors: Bruick Richard K. , Gardner Kevin H , MacMillan John , Tambar Uttam 
Published: October 2019

Abstract
Abstract SCI-39
Hypoxia inducible factors (HIFs) govern a mammalian cellular hypoxic response, regulating the transcription of hundreds of genes in response to low oxygen levels. Though this pathway performs critical functions under physiological conditions, increased levels of HIFs are also highly correlated with several disease states. As such, the development of artificial compounds that directly and selectively regulate HIF function is of interest. We have used a combination of biophysical, biochemical, and chemical approaches to study the structure and function of the Per-ARNT-Sim (PAS) domains of human HIFs, which serve as critical protein/protein interaction modules in assembling the functional HIF heterodimer. These studies have revealed the presence of a putative ligand-binding site within one of the HIF-2α PAS domains. A series of biased and unbiased approaches were undertaken to identify compounds that bind at this site and trigger conformational changes within the domain, leading to dissociation of the HIF-2 heterodimer in vitro and in living cells. Consequently, the expression of many hypoxia-inducible genes can be coordinately downregulated by a single agent. Despite its high amino acid identity, HIF-1α lacks a comparable ligand-binding site, indicating that these agents will be useful in deciphering differences in the biological roles of the HIF-1 and HIF-2 isoforms. The presence of a preformed cavity within HIF-2α is particularly as exciting as it suggests the potential for direct physiological regulation of HIF-2 by endogenous metabolite(s). Together, these studies offer further insight into HIF function and regulation while providing chemical tools that advance therapeutic applications.

Disclosures:
No relevant conflicts of interest to declare.
The Yin and Yang of Interleukin-21 in Allergy, Autoimmunity and Cancer
Authors: Leonard Warren J. 
Published: October 2019

Abstract
Abstract SCI-6
Interleukin-21 (IL-21) is a four-α-helical bundle type 1 cytokine. Its receptor consists of IL-21R and the common cytokine receptor γ chain, γc, which is shared by the receptors for IL-2, IL-4, IL-7, IL-9, and IL-15 and is encoded by the gene that is mutated in humans with X-linked severe combined immunodeficiency (XSCID). Each of these cytokines activates JAK1, which associates with the more distinctive receptor component, and JAK3, which associates with γc. IL-21 signals in part via the activation of STAT proteins, with STAT3 being induced more potently than STAT1 or STAT5 proteins. Interestingly, we have demonstrated that STAT3 globally cooperates with IRF4 in the induction of IL-21-regulated genes in T cells. IL-21 is produced by populations of CD4+ T cells, including Th17 cells, T follicular helper cells, and NKT cells. It is a pleiotropic cytokine that exerts a broad and complex array of biological actions on multiple lineages. IL-21 is pro-apoptotic for incompletely activated B cells, thereby serving a role for B cells similar to that of IL-2 related to activation-induced cell death in T cells. However, IL-21 also promotes the expansion and differentiation of activated B cells to plasma cells via its induction of Prdm1, which encodes BLIMP1, and the differentiation of cells into T follicular helper cells via its induction of Bcl6. IL-21 also promotes immunoglobulin class switch, and defective signaling by IL-21 and IL-4 explains the defective B cell function and panhypogammaglobulinemia that is observed in humans with XSCID. In addition, IL-21 has potent actions on CD8+ T cells, cooperating with IL-15 and IL-7 in the expansion of these cells. Conversely, IL-21 has inhibitory effects on antigen presentation by dendritic cells. IL-21 is implicated in multiple forms of autoimmunity, with IL21 and IL21R loci being associated with a range of human autoimmune diseases. Moreover, IL-21 is required for the development of systemic lupus erythematosus, type 1 diabetes mellitus, and experimental autoimmune uveitis in mouse model systems. In contrast to its promotion of autoimmune disease, IL-21 has potential anti-tumor actions, with elimination of established solid tumors in mouse models. In addition to these actions, IL-21 has also been demonstrated to be a potent inducer of IL-10 and thereby to exhibit immunosuppressive effects. In summary, IL-21 has a range of biological actions on multiple lineages, with varied effected related to apoptosis and differentiation, as well as both promoting autoimmunity yet limiting tumor growth. Regulation the actions of IL-21 in vivo therefore has potential clinical utility for a range of diseases.

Disclosures:
Leonard: NIH: I am an inventor on NIH patents and patent applications related to IL-21.
Acute Lymphocytic Leukemia and Down Syndrome
Authors: Izraeli Shai 
Published: October 2019

Abstract SCI-8
Children with Down syndrome are at a markedly increased risk for acute lymphoblastic leukemia (DS-ALL). These leukemias are exclusively of the B lymphoid precursor phenotype and occur in a similar age to “common” sporadic ALLs with the striking absence of infant ALL. Recent studies reveal that DS-ALLs are heterogeneous and differ from sporadic ALLs. Only about a fifth of DS-ALLs carry the common cytogenetic aberrations typical to childhood ALL. Genomic rearrangements leading to the expression of a cytokine receptor, CRLF2, are detected in 60% of DS-ALL in comparison with up to 10% of sporadic ALLs. CRLF2 heterodimerizes with Interleukin 7 receptor-α (IL7R) to form the receptor to thymic stromal lymphopoietin (TSLP). This receptor is usually present in macrophages, dendritic cells, and some T lymphocytes and participates in allergic and inflammatory processes. The aberrant expression of the TSLP receptor is DS-ALL (and sporadic ALL) is often associated with additional mutations that cause constitutive activation of the downstream JAK-STAT and mTOR growth signaling pathways. These are either lymphoid specific activating mutations of JAK2 or JAK1 or mutations in CRLF2 or IL7R that cause ligand-independent receptor dimerization. The role of the trisomy in selecting these somatic abnormalities is presently unknown. Clinically, the prognosis of DS-ALL is inferior to sporadic ALL mainly because of increased treatment toxicity. However, recent data suggest that the inferior outcome may also be related to the genetic properties of the leukemic cells and that excessive chemotherapy dose reduction may not be appropriate for these patients. Therefore increased vigilance for infectious complications and optimal supportive care are required during periods of intensive chemotherapy. The common activation of the TSLP signaling pathway in DS-ALLs suggests a future for targeted therapy with JAK and/or mTOR inhibitors. Importantly, research of DS-ALL has proven relevant for the general patient population with ALL, as somatic mutations in the TSLP pathway have been discovered in children and adults with sporadic ALL. A major research challenge is the elucidation of the roles of constitutional and somatic trisomy 21 in leukemogenesis.

Disclosures:
No relevant conflicts of interest to declare.
EBV-Induced Lymphoproliferation
Authors: Rooney Cliona M. 
Published: October 2019

Abstract
Abstract SCI-9
The similar genome structures, methods of entry, replication, and egress of herpesviruses suggest a common evolutionary origin dating back about 200 million years. EBV, a gammaherpesvirus, has co-evolved with its human host alone for over 80 million years and has developed a relationship that is seldom detrimental to its host and may even be beneficial. For example, EBV-specific T cells with heterologous specificity may protect against other pathogens. Unlike RNA viruses, the sequence of EBV, including its strong immunogenic epitopes, is remarkably conserved even across geographically separated populations. This underscores the comfortable relationship that EBV has developed with the host immune response, which tightly controls but never eliminates the virus. Rarely, this relationship breaks down resulting in diverse diseases and malignancies with underlying causes that are poorly understood. Is mononucleosis restricted to adolescents because of a too active or an inadequate immune response? Why is post-transplant lymphoma (PTLD) not more common in T cell depleted stem cell recipients? How can EBV-positive malignancies develop in patients who have circulating T cells specific for the viral tumor antigens expressed in those malignancies and who control their general EBV infection? Patients with nasopharyngeal carcinoma (NPC) or EBV-positive lymphoma seldom display an elevated virus load in peripheral blood lymphocytes. To prevent EBV-associated diseases we must understand their root causes, which, in turn, require an understanding of the virus’ complex life cycle that comprises involve four types of latency in B cells and replication in both B cells and mucosal epithelium. Each phase of the life cycle is represented both in normal infected cells and in one or more diseases. For example, virus replication is observed in tonsillar epithelium and in the oral hairy leukoplakias of HIV patients. Virus replication is also indirectly associated with NPC; its development is preceded by elevated antibody titers to the viral lytic cycle antigens despite the fact that NPC cells express only latency proteins. There are four patterns of viral latency and three are observed in tumor cells. Type 1 latency (expression of only two of over 90 viral proteins) is observed in normal circulating B cells, Burkitt’s lymphoma and gastric carcinoma. Type 2 latency is shared by the T, B, and NK lymphomas that occur in immunocompetent individuals. Type 3 latency, the most immunogenic form of latency in which nine latency-associated proteins are expressed, is seen in tonsils, in lymphomas of the immunosuppressed and elderly, and in leiomyosarcoma. Therapies may specifically target the function or immunogenicity of the viral proteins, while prophylaxis, usually by vaccination, aims to prevent them. We will discuss the types of latency observed in EBV-associated lymphoproliferations in the context of immunotherapies that might be used to control them.

Disclosures:
No relevant conflicts of interest to declare.
CD59 Deficiency Is Associated with Chronic Hemolysis and Childhood Chronic Immune Mediated Neuropathy
Authors: Mevorach Dror , Elpeleg Orly 
Published: October 2019

Abstract
Abstract 3187
CD59 deficiency is a common finding in red and white blood cells in patients with chronic hemolysis suffering from paroxysmal nocturnal hemoglobinuria (PNH) where acquired mutation in the PIGA gene leads to membrane loss of GPI-anchored membrane proteins, including CD59. The current study objective was the elucidation of the molecular basis of childhood familial chronic Coombs' negative hemolysis and relapsing polyneuropathy, mimicking chronic inflammatory demyelinating polyradiculoneuropathy in infants of North-African Jewish origin from four unrelated families. A founder mutation was searched using homozygosity mapping followed by exome sequencing. The expression of CD59, CD55 and CD14 was examined in blood cells by flow cytometry followed by western blot of the CD59 protein. A homozygous missense mutation in CD59, was identified in all the patients. The mutation segregated with the disease in the families and had a carrier rate of 1:66 among Jews of North-African origin. The mutated protein was present in the patients' cells in normal amount but was undetectable on the membrane surface.
Conclusion: This is the first clinical and molecular characterization of a novel clinical syndrome. CD59 mutation is associated with a failure of proper localization of CD59 protein in the cell surface. This is clinically manifested in infancy by chronic hemolysis and relapsing peripheral demyelinating disease.

Disclosures:
No relevant conflicts of interest to declare.
Monocyte Chemotactic Protein-1 Is Associated with Microvascular Abnormalities and Serum Ferritin Concentrations in Sickle Cell Disease Patients
Authors: Green Ralph , Miller Joshua W , Samarron Sandra L , Lin Xin , Cheung Anthony T , Wun Ted 
Published: October 2019

Abstract
Abstract 3255

Introduction:
Microvascular abnormalities underlie much of the morbidity observed in sickle cell disease (SCD). Adherence of sickle erythrocytes and leukocytes to the microvascular endothelium leads to vaso-occlusion and end organ ischemia/reperfusion injury. Monocyte chemotactic protein-1 (MCP-1) is a chemokine involved in the recruitment of monocytes to sites of endothelial activation or injury and thus contributes to the pathophysiology of vascular disease. In SCD patients, circulating MCP-1 concentrations are elevated during both steady state and vaso-occlusive crisis. However, the relationship between MCP-1 and microvascular abnormalities in SCD patients has not been assessed. In the present study, we measured a panel of circulating cytokines including serum MCP-1 and hematological biomarkers including serum ferritin in SCD patients who were being monitored by computer-assisted intravital microscopy (CAIM) to assess severity of microvasculopathy.

Methods:
The study included 31 steady state SCD patients (22 females, 9 males) ranging in age from 4–61 years. MCP-1 concentrations were measured by Luminex multiple analyte profiling. Ferritin concentrations were measured by chemiluminometric immunossay. The conjunctival microvasculature was assessed using CAIM. A severity index on a scale of 0–15 was calculated as described previously (Cheung et al, Am J Hematol 85:899, 2010) to quantify the degree of microvasculopathy observed among the patients.

Results:
The mean ± SD MCP-1 concentration was 445 ± 253 pg/ml (range: 122–1180 pg/ml), mean ± SD ferritin concentration was 1675 ± 1883 ng/ml (range 18–5825 ng/ml), and mean ± SD severity index was 5.0 ± 2.5 (range: 0–9). By multiple regression analysis, with controlling for age and gender, MCP-1 was directly correlated with severity index (p = 0.046), and serum ferritin was directly correlated with MCP-1 (p = 0.019).

Conclusions:
Monocyte recruitment to the site of endothelial injury involves chemotactic signaling mediated in part by MCP-1, levels of which rise in SCD. Our results indicate that MCP-1 is associated with and may directly contribute to the microvasculopathy observed in SCD patients. Furthermore, we find that MCP-1 levels are correlated with ferritin concentrations. Ferritin reflects body iron stores, and an increase of iron stores in SCD resulting from chronic blood transfusion as well as increased iron absorption associated with hemolysis may thus lead to monocyte/macrophage recruitment to the vascular endothelium and contribute to vasculopathy. Measurements of MCP-1 and ferritin may also serve as surrogate biomarkers of microvasculopathy severity and inflammation.

Disclosures:
Green: Emisphere - Consultancy : Consultancy; Teva Pharmaceuticals - expert testimony: Consultancy.