bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anti-Platelet Factor 4/Heparin Antibodies in Patients with Gram Negative Bacteremia
Authors: Pongas Georgios , Dasgupta Swapan , Thiagarajan Perumal 
Published: October 2019

Abstract
Abstract 3391

Introduction
The anti-platelet factor 4(PF4)/heparin antibodies, arising as a result of previous heparin exposure, are causally related to the procoagulant state due to platelet and monocyte activation. Formation of these antibodies with subsequent thrombocytopenia or thrombosis has also been described in patients, who have not been previously exposed to heparin. The presence of anti-PF4/heparin antibodies in individuals correlates with the severity of periodontal disease, implying that their occurrence may be triggered by periodontal pathogens. In this study, we determined the presence of anti-PF4/heparin antibodies in gram-negative bacteremic patients in a hospital setting and propose a pathophysiologic mechanism of their presence.

Method
We developed an in house ELISA for quantifying anti-PF4/heparin antibodies using therapeutic heparin and PF4 isolated from platelets. We used serum from a patient with high optical density as a standard and assigned an unit of 100 arbitrarily to construct a standard curve. We tested the sera from gram negative bacteremic patients (n= 34) in the quantitative ELISA along with normal controls (n=10). We also developed an in house ELISA for studying cross reactivity between anti-PF4/heparin antibodies and lipopolysaccharide (LPS)/PF4. We tested the sera from patients (n=5) with heparin induced thrombocytopenia in this cross reactivity ELISA. To test the interaction of LPS with PF4, we labeled PF4 with Alexa488 and measured its binding to LPS by monitoring the changes in fluorescence emission spectrum following excitation at λ480.

Results
Patients with bacteremia had higher titers of antiPF4/heparin antibodies compared to normal controls (26.4 ± SD 33 units, N=34 versus 6.3 ± SD 2.38 units, N=10, P=0.032). Bacterial LPS interacted with alexa488-labeled PF4 in a concentration-dependent manner, as measured by the quenching of the excitation spectrum. Patients with ant-PF4/heparin antibodies also reacted with LPS/PF4 complex in ELISA. Prior absorption of serum with PF4/heparin complex coated on ELISA plates decreased the reactivity of the serum towards PF4/LPS complex (19–46%) in two out of the five patients tested suggesting some were cross-reaction between PF4/Heparin and PF4/LPS complex.

Conclusions
PF4 forms a complex with lipopolysaccharide and this complex is immunogenic. Antibodies to PF4/LPS complex can cross-react with PF4/heparin complex raising the possibility that these antibodies may be responsible for the detection of PF4/heparin in individuals never been exposed to heparin previously. These antibodies may also be at least partly responsible for increased thrombosis associated with infection.

Disclosures:
No relevant conflicts of interest to declare.
Mechanisms of Telomere Maintenance Dysfunction in B-Chronic Lymphocytic Leukemia Through CpG Island Methylation
Authors: Auchter Morgan , Medves Sandrine , Chambeau Laetitia , Gazzo Sophie , Moussay Etienne , Ammerlaan Wim , Morjani Hamid , Géli Vincent , Palissot Valérie , Berchem Guy J. , Salles Gilles , Wenner Thomas 
Published: October 2019

Abstract
Abstract 3489
Telomeres are a repetitive DNA sequences associated with a protein complex named shelterin that protect chromosome ends. Two types of mechanisms maintain telomere in cancer cells. The first involves telomerase an enzyme able to copy the telomeric motif that consists of three principal subunits, including the telomerase reverse transcriptase hTERT. The second, named ALT (Alternative Lengthening of Telomere), corresponds to the recombination between telomeres that involves notably a complex formed by the topoisomerase III alpha (hTopoIIIa), BLM, RMI1 and RMI2. Little is known about the involvement of the ALT mechanism in B-chronic lymphocytic leukemia (B-CLL). In fact this leukemic disease shows low telomerase activity, shelterin defect and telomeric dysfunction.
In an effort to characterize ALT cells from 31 B-CLL patients, we analyzed their telomere length and telomerase activity. B-CLL patients showed almost no hTERT transcript (detected in three cases), low telomerase activity (detected in 7 cases) and a telomere average size ranging from 3 to 10 kb. Moreover, a strong deregulation of genes encoding three shelterin proteins, TRF1, TRF2, Pot1, and an at least two fold downregulation of hTopoIIIa gene expression in 21 cases were observed, suggesting the presence of a telomere maintenance dysfunction affecting both mechanisms, telomerase dependent and ALT. CpG island methylation has been mapped for both promoters and if hTERT shows a disseminated methylation profile in 22 patients, for hTopoIIIα we identified nine CpG upstream the minimal promoter, being methylated in 19 of our 31 analyzed patients. We then performed luciferase experiments and we showed that methylation in this 9 CpG induced a strong inhibition of hTopoIIIa transcription. Finally we correlated telomere length and hTopoIIIa methylation status as we observed that 25.4% of the hTopoIIIa promoters were methylated in patients with shorter chromosomes and only 11.1 % were methylated in patients with longer telomeres (p<0.0025).
As nearly no telomerase activity have been detected in our patients and as downregulation of hTopoIIIa could increase recombination rate between sister chromatid, methylation of hTERT and hTopoIIIa promoter CpG islands may lead to telomere dysfunction and increased genetic instability in B-CLL.

Disclosures:
No relevant conflicts of interest to declare.
NF-κB Activation in Mesenchymal Stromal Cells Mediates Leukemia Cell Chemoresistance
Authors: Jacamo Rodrigo , Chen Ye , Wang Zhiqiang , Ma Wencai , Zhang Min , Battula Venkata L , Schober Wendy D. , Davis Richard E , Konopleva Marina , Andreeff Michael 
Published: October 2019

Abstract
Abstract 3518
Within the bone marrow (BM) microenvironment, BM mesenchymal stromal cells (BM-MSC) provide leukemia cells with a rich environment that serves as a sanctuary and protects them from chemotherapeutic agents. Interactions between leukemia cells and BM-MSC are thought to change the behavior of both stroma and leukemia cells resulting in an increased resistance to standard drugs. To discover interaction-induced changes in BM-MSCs that might promote microenvironment-mediated chemoresistance we used genome-wide gene expression profiling to study normal-donor BM-MSCs co-cultured with REH cells, a pre-B acute lymphoblastic leukemia (ALL) cell line. Upregulated genes in normal-donor BM-MSCs by co-culture included many cytokines and chemokines and implicated activation of NF-κB in BM-MSCs. Similar results were obtained by co-culturing normal-donor BM-MSCs with OCI-AML3 cells, an acute myeloid leukemia (AML) cell line. Increased expression of NF-κB target genes in BM-MSCs was also induced by co-culture with primary cells from ALL and AML patients, suggesting that NF-κB activation is a common consequence of leukemia-stroma interaction. Blocking canonical-pathway NF-κB activation by overexpressing a super-repressor form of IκBα in BM-MSC, significantly reduced stroma-mediated chemoresistance to vincristine (VCR) of leukemia cells in vitro and in vivo using an extramedullary bone marrow model. When small-molecule IKKβ inhibitors (MLN3316 and CDDO-Me) were used in co-cultures, blocking canonical-pathway NF-κB activation in ALL cell lines (REH or RS4;11) as well as BM-MSCs, the apoptotic effects of VCR on leukemia cells were further increased.

Conclusion:
results indicate that leukemia cells activate NF-κB in stromal cells and that such activation is in turn essential to promote survival of leukemia cells during chemotherapy. Targeting NF-κB in BM-MSC may ameliorate stroma-mediated chemoresistance and help in eliminating BM-resident leukemia cells.

Disclosures:
No relevant conflicts of interest to declare.
Role of DNA Methylation of the G0/G1 Switch Gene 2 (G0S2) in the Proliferation of Myeloid Leukemia Cells
Authors: Yamada Takeshi , Park Chun Shik , Shen Ye , Lacorazza H. Daniel 
Published: October 2019

Abstract
Abstract 3520
The G0/G1 switch gene 2 (G0S2) was originally identified in human blood mononuclear cells as an early response gene. We recently reported that G0S2 maintains quiescence in hematopoietic stem cells (Yamada et al., Plos One, 2012). In addition to hematopoietic stem cells, G0S2 also inhibits proliferation of lymphocytes and hematopoietic progenitor cells. Methylation of the G0S2 gene has been reported in lung, and head and neck cancer, suggesting that G0S2 has potential tumor suppressor function in solid tumors. However, the role of G0S2 in hematological malignancies has not been studied yet. To evaluate the impact of DNA demetylation of the G0S2 gene in human leukemia, we cultured a panel of myeloid (HEL, K562, HL-60, Kasumi) and lymphoid human leukemia cell lines (Jurkat, DND41, and H9) with 10 μM of 5-Azacytidine (5-Aza). Treatment with 5-Aza led to a significant increase of G0S2 expression in K562 cells (24.1-fold) and HL-60 cells (4.9-fold) and reduced proliferation. We show that retroviral overexpression of G0S2 in K562 cells caused inhibition of proliferation. Conversely, gene silencing of G0S2 in 5-Aza-treated K562 cells increased proliferation. Differentiation of K562 with hemin and HL-60 with all-trans retinoic acid was associated with an increase of G0S2 expression of 6.7-fold and 9.9-fold, respectively. Taken together, gain- and loss-of function studies revealed that G0S2 regulates cell proliferation and differentiation in human myeloid leukemia cells. Since G0S2 does not have a direct known function on the cell cycle, we hypothesized that G0S2 interacts with proteins involved in the control of cell proliferation. Mass spectrometric analysis of proteins pulled down with G0S2 in hematopoietic cells revealed that nucleolin, a molecule known to regulate ribosome biogenesis, physically interacts with G0S2 resulting in a perinuclear retention of nucleolin. This interaction was confirmed in K562 cells overexpressing G0S2 by reciprocal co-immunoprecipitation. This data suggest that silencing of G0S2 in leukemic cells prevents sequestration of nucleolin in the cytosol inhibiting its pro-proliferation functions. Collectively, our studies uncovered an important inhibitory role of G0S2 in the proliferation of leukemic cells, suggesting a possible tumor suppressor function in myeloid malignancies.

Disclosures:
No relevant conflicts of interest to declare.
Activity of a Heptad of Transcription Factors Is Associated with Stem Cell Programs and Clinical Outcome in Acute Myeloid Leukaemia
Authors: Diffner Eva , Beck Dominik , Gudgin Emma , Thoms Julie , Knezevic Kathy , Pridans Clare , Foster Sam , Goode Debbie , Lim Wheng Khong , Boelen Lies , Metzeler Klaus H. , Micklem Gos , Bohlander Stefan K , Buske Christian , Burnett Alan K , Ottersbach Katrin , Vassiliou George , Olivier Jake , Wong Jason WH , Gottgens Berthold , Huntly Brian , Pimanda John E 
Published: October 2019

Abstract
Abstract 3525
Leukaemic transformation is driven by aberrant transcriptional programs often in combination with abnormal proliferative signalling. These programs operate in normal hematopoiesis where they are involved in hematopoietic stem cell (HSC) proliferation and maintenance. ERG is a component of normal and leukemic stem cell signatures and high ERG expression has been proposed as a risk factor for poor prognosis in acute myeloid leukemia (AML). However, mechanisms that underlie ERG expression in AML and how its expression relates to leukemic stemness are unknown. We report that ERG expression in AML is associated with activity of the ERG+85 stem cell enhancer (SCE) and a heptad of transcription factors that combinatorially regulate genes in normal HSCs. Gene expression signatures derived from ERG+85 stem cell enhancer (Fig A) and heptad activity (Fig B) predict clinical outcome in a cytogenetically normal cohort of AML (CN-AML) patients when ERG expression alone fails. The heptad signature is an independent risk factor for poor overall and event-free survival (Fig C). There were no long-term survivors amongst patients with a heptad signature, FLT3 mutations and wild-type NPM1 (Fig D) pointing to a hitherto unappreciated link between aberrant signaling and transcriptional mediators of hematopoietic stem cell identity. In two independent cohorts, the heptad signature was as closely associated with wild-type NPM1 AML as the HOX signature was with mutant NPM1 AML (Fig E–F) suggestive of a collective role for these transcription factors in mediating the leukemic signature in the former. Taken together, these results show that key transcriptional regulators cooperate in establishing stem cell signatures in leukemic cells and that the underlying spectrum of somatic mutations contributes to the development of these signatures and modulate their influence on clinical outcome.

Disclosures:
No relevant conflicts of interest to declare.
The Etiology of Pleural Effusions Develping During Dasatinib Therapy in CML Could Be Variable: Need for Awareness and Investigations
Authors: Saikia Tapan , Gore Adwaita , Matwankar Sumaiya , Patil Priyadarshini , Jain Reetu , Dhabhar Boman 
Published: October 2019

Abstract
Abstract 4456
Dasatinib is a highly effective oral TKI for CML at various stages of the disease. The most common non-hematologic side-effect is pleural effusion. The exact mechanism of this pathology remains to be fully elicited, although studies report it to be an immunological phenomenon. Current literature shows dasatinib alone to be the cause of such effusions. More recently, pulmonary hypertensions have been reported on dasatinib therapy.
However, in our cohort of CML patients receiving dasatinib as a first or second line therapy, other pathologies were documented. Grade 2/3 unilateral pleural effusions were detected in 3 patients.

Case 1.
A 31 yr old male with CML-CP was on first line dasatinib 100 mg OD and CCyR was documented at 3 months. At 6 month, he was detected to have grade 1/2 bilateral pleural effusion and was managed with drug interruption and oral dexamethasone with no significant reduction of fluid. CBC was normal. Dasatinib was continued. At one year, he lost cytognetic response with emergence of complex karyotype and medullary lymphoid blast crisis was confirmed. Pleural fluid showed lymphoblasts proven by cytology and immunophenotype. He received vincristine and prednisone followed by a change to imatinib. His disease progressed further and died at 2 years from diagnosis.

Case 2.
A 39 yr old male with molecular relapse and M244V Abl Kd mutation at 8 years since diagnosis and 6.5 yrs on imatinib 400–800 mg daily was offered dasatinib 100 mg OD. After 24 months, he developed grade2 left pleural effusion which responded poorly to drug interruption, therapeutic tapping and prednisone. A few months later he developed constitutional symptoms and CT chest, bronchoscopy/BAL proved to have left lung tuberculosis. Currently, he is responding favorably to anti-tubercular therapy. He was switched back to imatinib and remains in cytogenetic remission.

Case 3.
A 21 yr old male with cytogenetic non-responder to imatinib 800 mg daily was put on dasatinib 100 mg OD. An MMR was achieved. He developed left pleural effusion after 4 years of dasatinib. Extensive investigation for any specific pathology was not productive. He was put on empiric anti-tubercular therapy with no response. It is being treated as a dasatinib induced effusion.

Conclusions.
During dasatinib therapy, the causes of pleural effusions could be varied – drug related, extramedullary blast crisis or tubercular. Radiological, cytological and microbiological investigations could be indicated after careful clinical evaluation.

Disclosures:
Saikia: Bristol -Myers Squibb: Research Funding, Speakers Bureau.
Multiple Myeloma On Top of Chronic Myelogenous Leukemia
Authors: Chalhoub Elie , Meouchy Joseph , Dakhil Shaker R. 
Published: October 2019

Abstract
Abstract 4457

Background:
The occurrence of multiple myeloma (MM) in patients with chronic myelogenous leukemia (CML) is an extremely rare event. There are only 10 cases reported in literature, with only 5 of them treated with imatinib. The longest was for 65 months.

Case presentation:
A 70-year-old Caucasian female presented for follow-up on her chronic myelogenous leukemia (CML). She was diagnosed 8 years prior and had a Philadelphia chromosome positive on FISH and PCR. She had been treated with Imatinib for 72 months and initially responded well, but later developed pancytopenia and hematologic and cytogenetic progression of her CML despite dose adjustments. She was switched to Nilotinib 15 months prior with partial cytogenetic response, and persistence of her pancytopenia. Her symptoms were fatigue and weight loss. She denied bleeding, fever, or back pain. Her physical exam was unremarkable. Her labs showed hemoglobin of 8.5 g/dL, WBC 2.2 K/μL with 48% segmented and platelets count of 30 K/μL.
Bone marrow biopsy and aspirate showed 15–20% clustered monoclonal plasma cells and persistence of CML. Serum IgG was 2248 mg/dL with an IgG Kappa monoclonal peak on serum protein electrophoresis. A skeletal bone survey revealed no lytic lesions. Otherwise her laboratory findings were unremarkable except for a creatinine of 1.39 mg/dL and a β-2-microglobulin of 4.6 mg/L. She was diagnosed with multiple myeloma, and started on chemotherapy with bortezomib, liposomal doxorubicin, and dexamethasone. Nilotinib was held. After 4 cycles of chemotherapy, her repeat bone marrow biopsy showed partial remission of MM, and persistence of CML. Her blood counts are improving.

Discussion:
A PubMed review of literature shows 10 reported cases of MM occurrence in patients with CML (1974–2012). Only 5 of these cases have been on Imatinib, for a duration ranging between 7 and 65 months. There were no reports about other tyrosine kinase inhibitors (TKI). This is the first reported case of MM on top of CML while on Nilotinib, and after the longest duration on Imatinib.

Conclusion:
Tyrosine kinase inhibitors (TKI) constitute a revolution in the treatment of CML. With marked improvement of survival, patients are now prone to other malignancies. Reporting more cases will help understand the long term effects of TKIs.

Disclosures:
No relevant conflicts of interest to declare.
Characterization of TPO Kinetics within 60 Days of Allogeneic Hematopoietic Stem Cell Transplantation and Its Correlation with Megakaryocyte Ploidy Distribution
Authors: Zhang Xiao-hui , Fu Hai-xia , Liu Dai-Hong , Xu Lan-Ping , Liu Kai-Yan , Huang Xiao-Jun 
Published: October 2019

Abstract
Abstract 4463

Background:
Thrombocytopenia is a critical complication following allogeneic hematopoietic stem cell transplantation (allo-HSCT), but its pathogenesis has remained obscure. Thrombopoietin (TPO) has been identified as a key cytokine for both megakaryogenesis and thrombopoiesis; however, the kinetics of TPO production after allo-HSCT has not been reported. This study characterized the kinetics of TPO and its correlation with the megakaryocyte ploidy distribution pattern within 60 days of allo-HSCT.

Methods and Results:
A total of 46 consecutive patients who underwent allo-HSCT from October 2008 to December 2008 were included in the study. The TPO levels and the ploidy distribution pattern of MKs were measured using ELISA and flow cytometric analysis, respectively. The results indicate that the TPO levels and the platelet counts followed opposite trends after allo-HSCT. Multivariate analysis indicate that endogenous TPO levels before allo-HSCT, and the number of transplanted CD34+ cells were significant predisposing factors for rapid platelet engraftment (P=0.010 and 0.007, respectively). Furthermore, we found a reduction of ploidy and an increase in immature MKs in patients with higher endogenous TPO levels (> 250 pg/ml) on day 60 after allo-HSCT. Moreover, lower TPO levels (≤250 pg/ml) on day 60 after allo-HSCT were associated with significantly improved 2-year OS (P=0.032) and reduced TRM (P=0.026).

Conclusion:
Our results suggest that increased endogenous TPO levels may not be sufficient after allo-HSCT, and that the decreased ability of TPO may account for the appearance of antibodies. The use of exogenous rhTPO may promote platelet recovery after allo-HSCT. However, these possibilities need to be examined further.

Disclosures:
No relevant conflicts of interest to declare.
Comparative Efficacy of Tandem Autologous Versus Autologous Followed by Allogeneic Hematopoietic Cell Transplantation in Patients with Multiple Myeloma: A Systematic Review and Meta-Analysis
Authors: Kharfan-Dabaja Mohamed A. , Hamadani Mehdi , Reljic Tea , Bensinger William I. , Djulbegovic Benjamin , Kumar Ambuj 
Published: October 2019

Abstract
Abstract 4519

Background:
Despite advances in our understanding of clinical, genetic, and molecular aspects of multiple myeloma (MM) coupled with availability of more effective therapies, it remains an incurable disease. Combining cytoreduction from high-dose (chemo- or chemoradio-) therapy with adoptive immunotherapy forms the basis of an autologous-allogeneic (auto-allo) hematopoietic cell transplantation (HCT) strategy. However, when an auto-allo HCT approach is compared to tandem autologous (auto-auto) HCT, conflicting results have been reported. Accordingly, we performed a systematic review of published studies comparing auto-auto HCT with auto-allo HCT in patients with newly diagnosed MM.

Methods:
A systematic search of MEDLINE thru Nov 5, 2011, and pertinent conference proceedings, was conducted. Included studies allocated newly diagnosed MM patients to auto-allo HCT if an HLA-matched sibling donor was available versus auto-auto if sibling donor was not available (biologic randomization). Independent, dual data extraction was performed. Pooling of data from similar outcomes was done using the random-effects model.

Results:
Our search identified 152 publications, of which five (manuscript=four, abstract=one) met inclusion criteria. The five included trials enrolled 1538 patients (auto-allo=565, auto-auto=973). At least a very good partial response was assessed in one study (522 patients) and did not differ among the treatment arms [risk ratio (RR) (95% CI) = 0.97 (0.87–1.09), p=0.66]; but complete remission, assessed in five studies (1130 patients), was higher in the auto-allo HCT arm [RR(95% CI) =1.65 (1.25–2.19), p=0.0005]. Event-free survival did not differ among auto-allo HCT group versus auto-auto HCT group on per-protocol analysis [hazard ratio (HR) (95% CI) = 0.78 (0.58–1.05)), p=0.11] of three trials (409 patients), or ITT analysis [HR(95% CI) = 0.83 (0.60–1.15), p=0.26] in three trials (1229 patients). Overall survival (OS) did not differ among these treatment arms whether analyzed on per-protocol [HR(95% CI) = 0.88 (0.33–2.35), p=0.79] in two trials (214 patients), or by ITT [HR(95% CI) = 0.80 (0.48–1.32), p=0.39] analysis in three trials (1229 patients). Non-relapse mortality (NRM) was worse with auto-allo HCT [RR(95%CI) = 3.55 (2.17–5.80), p<0.00001] in four trials (1047 patients).

Conclusion:
Despite higher CR rates, there is no apparent improvement in OS with auto-allo HCT; but this approach results in higher NRM in patients with newly diagnosed MM.

Disclosures:
No relevant conflicts of interest to declare.