bluuebunny/crossref_metadata_2025_split huggingface dataset:
Overexpression of Ribosomal Proteins Is Insufficient for p53 Pathway Induction in Cell Lines and Primary CD34+ Cells
Authors: Raiser David M. , Ebert Benjamin L. 
Published: October 2019

Abstract
Abstract 3479
Diseases of ribosome dysfunction (ribosomopathies), such as Diamond-Blackfan anemia and 5q- syndrome, are caused by deficiencies in one or more ribosomal proteins (RPs) and are characterized by impaired erythropoiesis. The p53 pathway has been identified as a central player in the ribosomopathy disease phenotypes, but the precise mechanism by which p53 is aberrantly induced in the setting of RP deficiency has not been fully elucidated. The current hypothesis for this induction is that, in the context of RP deficiency, cellular levels of free (non-ribosome bound) RPs rise, and a subset of RPs with MDM2-binding ability interact with and inhibit the negative regulatory activity of MDM2 on p53, resulting in p53 stabilization. RPs that have been implicated in this capacity include rpL5, rpL11, rpL23a, and rpS7. This hypothesis also suggests that overabundance of these free ribosomal proteins might be sufficient to induce p53 activity, even in the absence of ribosome protein deficiency. To test this specific aspect of this hypothesis, we generated lentiviral expression vectors carrying the full-length cDNAs for rpL5, rpL11, rpL23a, and rpS7, as well as ARF (which served as a positive control, as ARF is known to induce p53 by binding and inhibiting MDM2), and we used each virus to individually infect A549 cells. Despite increased levels of transcript and protein observed for each of the cDNAs expressed, only ARF overexpression resulted in p53 stabilization and p21 induction. Similarly, when RPs were overexpressed in each pairwise combination, none of the RP pairs tested induced p53 above baseline levels. We also tested all of the overexpression constructs in primary human cord blood-derived CD34+ hematopoietic stem and progenitor cells (HSPCs), and p53 pathway induction was only observed with overexpression of ARF. These data suggest that overabundance of these specific ribosomal proteins alone is insufficient for p53 pathway induction via MDM2 inhibition.

Disclosures:
Ebert: Celgene: Consultancy; Genoptix: Consultancy.
Deregulated Expression of HDAC9 in B-Cells Leads to Lymphoproliferative Disorders As Well As Germinal Center and Post-Germinal Center Derived Lymphomas
Authors: Gil Veronica Sylvina , Stengel Sven , Bhagat Govind , Howell Louise , Catovsky Daniel , Pasqualucci Laura , Petrie Kevin , Zelent Arthur 
Published: October 2019

Abstract
Abstract 3505
Histone Deacetylase 9 (HDAC9) is a class IIa enzyme that, within the hematopoietic system, is preferentially expressed in the B-cell lineage. Previously we have observed that, compared with normal cellular counterparts, expression of HDAC9 appears deregulated in B-lymphoid tumors (Petrie et al., JBC 278: 16059, 2003 and unpublished results). To examine the role of HDAC9 in B-cell transformation we generated a mouse model that constitutively expresses human HDAC9 from early stages of B-cell development under the control of the immunoglobulin heavy chain (IgH) enhancer (Eμ). We demonstrate that from six months of age (6–12 months), Eμ-HDAC9 transgenic mice displayed splenomegaly in a statistically significant fraction of cases (3/17, 18%), which was associated with histopathologic and immunophenotypic evidence of lymphoproliferative disease (LPD) (p<0.0001). Later in life (12 to 23 months of age), 24% (19/78) of Eμ-HDAC9 mice developed a spectrum of mature clonal B-cell lymphoproliferations including monoclonal B-cell lymphocytosis (MBL, 12/78, 15%), splenic marginal zone lymphoma (SMZL, 4/78, 5%) and diffuse large B-cell lymphoma (DLBCL, 3/78, 4%). In contrast, a low background incidence of these malignancies (2%) was observed in control mice (p = 0.0008). Importantly, the HDAC9 gene is located within chromosomal region 7p21, which is a common target of frequent genomic gains in B-cell non-Hodgkin lymphoma (B-NHL) cases and B-NHL cell lines. Consistently, copy number gains in the 7p21.1 chromosomal region were found in 25/79 (32%) primary DLBCL cases analyzed (including one B-NHL patient with a copy number gain only within the 5' end of the HDAC9 gene). Mechanism underlying the role of HDAC9 in lymphomagenesis appears to involve deacetylation of both p53 (leading to deactivation of p53) and BCL6 (leading to activation of BCL6), consistent with a role of a general hypoacetylated state in B-NHL pathogenesis, which is underscored by recently identified inactivating mutations in a number of key histone acetyltransferases. In summary, aberrant expression of HDAC9 leads to the development of B-cell lymphoproliferations, including germinal center (GC) and post-GC lymphomas, showing similarities with those occurring in humans. These findings have relevant therapeutic implications in view of current attempts to use HDAC inhibitors as anti-lymphoma drugs.

Disclosures:
No relevant conflicts of interest to declare.
Mir-126 and Mir-195-Mediated Control of B Cell Fate in Leukemic and Normal Cells As a Potential Alternative for Transcriptional Factor
Authors: Kotani Ai , Okuyama Kazuki , Chanda Bidisha , Ikawa Tomokatsu , Kawamoto Hiroshi , Ando Kiyoshi , Tojo Arinobu , Lodish Harvey F. 
Published: October 2019

Abstract
Abstract 3533
microRNAs (miRNAs) control many developmental and physiological processes. However, it is assumed to work as a fine tuner in cell fate determination, which has been shown to be regulated by transcription factors.
Here, we challenge this canonical notion.
miR-126 is downregulated in MLL-AF4 ALL, biphenotypic leukemia expressing both B cell and myeloid markers, compared with other types of ALLs. CD19 and CD20, B cell differentiation markers, were upregulated when miR-126 is reexpressed in MLL-AF4 ALLs (Figure 1). Interestingly, we found that miR-126, in leukemic cells, induces B cell differentiation (Figure 2a) without changing the expression of E2A, EBF1, or PAX5, (Figure 2b) which are assumed to be critical regulators of B cell development indicating that miR-126 induced B cell differentiation independently of transcriptional factors, such as PAX5, E2A, and EBF1. To test the hypothesis, we tried to rescue block of B cell differentiation in EBF1 knock-out hematopoietic progenitor cells (EBF1 KO HPCs) by exogenous expression of miR-126. As a result, significant upregulation of B cell markers, such as B220, RAG1/2, and CD79a/b was induced by miR-126 in EBF1 KO HPCs which show complete block at pre-pro B cell stage.(Figure 3a) Moreover, miR-126 increased cell proliferation, indicating EBF1 KO HPCs differentiate into large preB cells. Moreover, miR-195, which is upregulated toward pro B cells then downregulated in B cell differentiation, also can partially rescue block of B cell differentiation in EBF1 KO HPCs. (Figure 3b) The block in B lymphopoiesis imposed by the absence of E2A or Pax5 can be overcome by exogenous expression of EBF1. Conversely E2A or Pax5 failed to compensate the effect of EBF1. Thereafter miR-126 and miR-195 potentiates to play more roles than E2A or Pax5 in this system and act as more than a fine tuner in B cell differentiation. Our results elucidate a novel mechanism for the regulation of cell fate independent of transcriptional factor, establish an important role for miRNAs in mammalian lineage specification, and suggest that miRNA could be a new possible therapeutic target for dedifferentiation induced by deregulation of transcriptional factors in ALL, which calls for further studies.

Disclosures:
No relevant conflicts of interest to declare.
Results of a Prospective Phase II Randomized Study of Deferasirox (Exjade®) to Prevent Iatrogenic Iron Overload in Patients Undertaking Induction/Consolidation Chemotherapy for Acute Myeloid Leukaemia (HREC/10/QRBW/135)
Authors: Kennedy Glen A , Morris Kirk , Pillai Elango , Curley Cameron , Butler Jason P. , Durrant Simon 
Published: October 2019

Abstract
Abstract 3577

Background:
Iron overload, as measured by raised serum ferritin, is recognised as a significant risk factor for excess transplant related mortality (TRM) in allogeneic stem cell transplantation (SCT). Due to blood transfusions received during initial induction/consolidation chemotherapy, almost all patients undertaking SCT with AML have significantly raised ferritin pre-SCT.

Aims:
To determine the efficacy of deferasirox (Exjade®) in preventing iatrogenic iron overload in patients receiving induction/consolidation chemotherapy for AML.

Methods:
Prospective randomised phase II study in AML patients planned to receive induction and/or consolidation chemotherapy. Iron studies and CRP were measured pre, mid and post each chemotherapy cycle. Patients were randomised to receive either therapy with deferasirox (starting at 5–10mg/kg/day PO and increasing to maximum 40mg/kg/day PO as tolerated) vs. no deferasirox therapy. Desferasirox was commenced once ferritin increased to >500μg/L and continued until transfusion independence after completion of all chemotherapy. The primary endpoint was ferritin concentration at completion of chemotherapy. Based on historical controls, to detect a difference of >1000μg/L in ferritin between groups a sample size of 14 per arm was required.

Results:
The study was terminated prematurely after 16 patients were enrolled (deferasirox arm n=10; control arm n=6) due to excess grade 2–4 GIT (frequency 1.26 vs. 0.75 events/chemotherapy cycle for deferasirox vs. control arm respectively; p=0.04) and infectious toxicity (frequency 2.22 vs. 1.38 events/chemotherapy cycle for deferasirox vs. control arm respectively; p=0.05) experienced in the deferasirox arm. Overall desferasirox was poorly tolerated, with mean maximum tolerated dose only 13.2mg/kg/day (range 5–20mg/kg/day) and 4/10 patients unable to continue the drug predominantly due to GIT toxicity. Post-treatment ferritin, % change in ferritin and number of transfusions received were no different between arms. Post-chemotherapy CR rate was lower in the desferasirox arm (60% vs. 100%; p=0.234), and all treatment-related deaths (n=3; all infectious-related) occurred in the desferasirox arm (p=0.25). Median OS was similar in both arms (median 450 vs. 476 days for deferasirox vs. control arm respectively; p=0.72).

Conclusions:
Use of desferasirox to prevent iatrogenic iron overload in AML patients undertaking induction/consolidation is ineffective, poorly tolerated, and associated with excess GIT and infectious toxicity.

Disclosures:
No relevant conflicts of interest to declare.
Influence of Ceacams Expression in Graft-Versus-Host Disease After Allogeneic Transplantation
Authors: Koldehoff Michael , Dreesen Janine D. , Elmaagacli Ahmet H. , Beelen Dietrich W. , Singer Bernhard B. 
Published: October 2019

Abstract
Abstract 4490

Background:
The carcinoembryonic antigen (CEA) family is involved in intercellular binding interactions that affect various normal and pathogenic processes associated with cellular growth and differentiation. In human, the CEA family are subdivided into the CEA-related cell-adhesion molecules (CEACAMs) and the pregnancy-specific glycoproteins (PSGs). Never before the influence of CEACAMs on patients who underwent allogeneic hematopoietic stem cell transplantation (HSCT) was evaluated.

Methods:
Here we analyzed in a retrospective study 33 patients (pts) for CEACAMs expression that underwent allogeneic HSCT for various diseases and analyzed their outcome. CEACAMs expressions were performed by flow cytometry and ELISA in whole blood, serum and urine samples.

Results:
We report the analysis of 19 pts with acute leukemia (58%), 5 pts with chronic leukemia (15%), 4 pts with MDS (12%) and 5 pts with advanced NHL (15%). The median age at transplant was 50.5 (range, 18–69) years. In this cohort 12 pts received grafts from HLA-identical siblings (36%), 16 pts from matched (49%) and 5 pts from mismatched (15%) unrelated donors. Transplantat consisted of unmanipulated peripheral blood stem cells (n=26, 79%) or bone marrow (n=7, 21%). Of all pts, 7 (21%) had relapsed after transplant. Among these pts, 31 (94%) developed acute GVHD (21 pts had an acute GvHD of grade ≥2). There was no significant correlation between CEACAMs expression after transplant between the variant leukemic disorders in the whole blood and the urine samples. Analysis of each CEACAMs for relapse showed no statistically differences. For CEACAM-6, we found a moderate up-regulation in pts with acute GvHD ≥2 versus acute GvHD <2 (p<0.1). In pts with severe acute GVHD (grade >3) comparing all other pts, we found significant induction of CEACAM-1 (118.5 ng/ml vs. 198.3 ng/ml, p<0.05) in urine samples and CEACAM-1 (109.2 vs. 157.5 ng/ml, p<0.04) in serum samples. However, no statistic differences were found in the CEACAM-1 in regards to chronic GVHD.

Conclusions:
These results suggest that pts with high levels of CEACAM-1 confirms a relevant association of the development of acute GVHD and CEACAM profiling could be an early indicator of severe acute GvHD.

Disclosures:
No relevant conflicts of interest to declare.
Incidence and Risk Factors for Hypogammaglobulinemia in Pediatric Allogeneic Stem Cell Transplant (SCT) Patients
Authors: Frangoul Haydar , Min Elliot , Lu Zengqi , Mario Mario , Ho Richard , Brown Valerie , Domm Jennifer 
Published: October 2019

Abstract
Abstract 4492

Objectives:
Impairment of antibody immunity correlates with an increased risk of infections after SCT primarily due to encapsulated bacteria. Patients with hypogammaglobulinemia are more prone to recurrent infections that can potentially be fatal. The incidence of this complication is not well known in children following allogeneic SCT. We sought to evaluate the incidence and risk factors of this complication in pediatric recipients of allogeneic SCT.

Methods:
All patients receiving allogeneic SCT at Vanderbilt Children's Hospital between 1999 and 2011 were included in this analysis. Excluded were patients with primary immune deficiency. IgG levels were measured every 2 weeks following SCT for the first 100 days and then monthly thereafter. Hypogammaglobulinemia was defined as IgG<500 mg/dL. All patients with hypogammaglobulinemia received IVIG replacement therapy. Detailed patient and outcome characteristics were recorded.

Results:
A total of 177 patients with a median age of 9 years were included in this analysis. 137 (77%) had malignant diseases and 108 (61%) received cells from an unrelated source. Bone marrow was the stem cell source in 120 (68%) while 30 (17%) received PBSC and 27 (15%) received cord blood. 137 of 177 (77.4%) patients developed hypogammaglobulinemia at a median of 69 days (range 5–339) after transplant. In multivariable analysis patients who developed hypogammaglobulinemia were significantly younger HR=1.05 (95% CI, 1.02–1.1, p=0.002), have malignant disease: HR=2.73: (95% CI:1.6–4.7,p<0.001), received unrelated donor transplant: HR=2.78 (95% CI: 1.75–5.0, p<0.001) and developed acute GVHD: HR=2.24 (95% CI: 1.50–3.32, p<0.001). Patients who developed chronic GVHD and survived for more than 1 year post-transplant were more likely to still be receiving IVIG replacement for hypogammaglobulinemia, (HR=115.5, 95% CI: 14.58–914.1, p<0.001). All patients who are alive >1 year post transplant and are off immune suppression have normal IgG levels and are not requiring replacement therapy.

Conclusions:
Hypogammaglobulinemia is a common complication in pediatric patients following allogeneic SCT. Younger patients, those with malignant diseases and recipients of unrelated donor SCT are at higher risk. Acute and chronic GVHD increased the risk of developing hypogammaglobulinemia. Close monitoring of IgG level should be considered in those at highest risk.

Disclosures:
No relevant conflicts of interest to declare.
Comparative Single-Center Analysis of Hematopoietic Cell Transplantation From Unrelated Umbilical Cord Blood or Haploidentical Related Donor or Mismatched Unrelated Donor in Patients with Hematologic Malignancies
Authors: Fu Chengcheng , Wang Jing , Depei Wu 
Published: October 2019

Abstract
Abstract 4535
One of the truly revolutionary advances in hematopoietic cell transplantation (HCT) is the increasingly successful use of alternative donors, as only 1/4 of patients who require an allogeneic hematopoietic cell transplant will have a HLA-matched sibling donor. A substantial proportion of the need has been met by HLA-matched volunteer unrelated donors, but an unmet need still exists, particularly for people who need a more immediate source of hematopoietic cells in China. Thereby, three alternative graft sources, umbilical cord blood (UCB), haploidentical (haplo) related donor, and mismatched unrelated donor (MMUD) are available.
We report a retrospective analysis of 95 patients with hematologic malignancies who received umbilical cord blood transplantation (UCBT) as a primary unrelated stem-cell source (n=20), or haploidentical (haplo) related donor (n=46), or mismatched unrelated donor (MMUD) (n=29), compare the days of hematopoietic reconstitution & engraftment, and rate of acute graft-versus-host disease (GVHD), and overall survival (OS). The average days of hematopoietic reconstitution (WBC >1.0*10E9) among UCBT recipients were significantly longer than those among haplo/MMUD recipients,(19.77 in UCBT,13.86 in haplo and 11.97 in MMUD, p<0.001). Whereas the average days of full engraftment (STR >95%) among haplo recipients were longer than those among UCBT/MMUD recipients,(24.85 in haplo, 19.29 in UCBT and 20.54 in MMUD, p=0.028). Multivarite analysis demonstrated no apparent differences in the rate of II-IV aGVHD (45% in UCBT, 41.3% in haplo and 55.2% in MMUD, p=0.498), so as to the rate of III-IV aGVHD (30% in UCBT, 41.3% in haplo and 17.2% in MMUD, p=0.543). Overall survival at 2 years was 75% in UCBT, 63% in haplo and 84% in MUUD (p=0.049), and the TRM was 29.4% in UCBT, 39.4% in haplo and 19.2% in MMUD (p=0.245).
It shows that UCB is associated with decreased II-IV aGVHD, but hematologic recovery is slow. Haplo HCT is characterized by donor availability for transplantation and post transplant adoptive cellular immunotherapy, but may be complicated by a high transplantation related mortality (TRM). A MMUD transplant may also be an option, but GVHD may be of greater concern. These data gives us some suggestion for using donor availability to decide on the best option for each individual patient.

Disclosures:
No relevant conflicts of interest to declare.
Continuous High-Dose Idarubicin and Busulfan As Conditioning Regimen for Chinese Patients with Acute Myeloid Leukemia Undergoing Autologous Stem Cell Transplantation
Authors: Ming Hong , Qian Sixuan , Peng Liu , Hanxin Wu , Hongxia Qiu , Hua Lu , Sujiang Zhang , Wei Xu 
Published: October 2019

Abstract
Abstract 4539

Objective:
To investigate the efficacy and toxicity of continuous high-dose idarubicin and busulfan as conditioning regimen for Chinese patients with acute myeloid leukemia (AML) undergoing autologous stem cell transplantation (ASCT).

Methods:
A total of 27 patients with AML were enrolled in our prospective study, including 25 of first complete remission and 2 of second complete remission. Twelve patients were male, and 15 were female, with ages ranging from 14 to 56 (median, 31) years. All the patients were given induction and consolidation treatments and underwent ASCT receiving a continuous infusion of high-dose idarubicin (20 mg/m2 qd, days -13 to -11) and busulfan (oral busulfan 1 mg/kg q6h or intravenous busulfan 0.8 mg/kg q6h, d-5∼-2) as conditioning regimen.

Results:
All the patients acquired hematopoietic reconstitution. The median number of days to neutrophil (©ƒ0.5×109/l) and platelet (©ƒ20×109/l) recovery was 10 and 12, respectively. After a median follow-up of 23 months from diagnosis, the median overall survival (OS) and the median disease-free survival (DFS) were 19(7∼87) and 15(6∼85) months, respectively. A total of 18 patients (73.4%) are alive (17 in continuous complete remission) and 10 (37.4%) relapsed after transplant. Those who underwent standard dose of idarubicin (12 mg/m2 qd, days1–3) and cytarabine (100∼200 mg/m2 qd, days1–7) as induction treatment showed lower relapse rate and better OS and DFS as compared to other induction regimens without significant difference. Patients with favorable karyotypes and molecular biological types acquired better OS and DFS as compared to those with intermediate karyotypes and molecular biological types, but there was no significant difference. Myelosuppression and infections due to neutropenia was the most frequent adverse effects, severe nonhematologic toxicity was not observed in all patients. The patients in our study acquired similar OS and DFS compared to those with intermediate karyotypes and molecular biological types who underwent allogeneic transplantation (HLA identical sibling donor) in first complete remission, and the side effects were minor.

Conclusion:
Continuous high-dose idarubicin and busulfan as conditioning regimen for Chinese patients with AML undergoing ASCT was effect and well tolerable.

Disclosures:
No relevant conflicts of interest to declare.