bluuebunny/crossref_metadata_2025_split huggingface dataset:
The B Cell Receptor Antagonist R406 Alters The Balance Between Anti-Apoptotic and Pro-Apoptotic Signals To Strongly Synergize With ABT-199 In Diffuse Large B Cell Lymphoma Cells
Authors: Zhang Yue , Francoise Powell , Devereaux Erik , Passino Melissa , Parmentier Julie , Byth Kate 
Published: October 2019

Abstract
SYK plays an essential role in B cell receptor (BCR) mediated survival in Diffuse Large B Cell Lymphoma (DLBCL). In a previous clinical investigation, fostamatinib, a potent Syk inhibitor, showed evidence of anti-tumour activity with an overall response rate of ∼20% in a cohort of DLBCL patients (JW Friedburg et al Blood. 2010, 115:2578-85). This finding prompted us to investigate the mechanism of action of fostamatinib in DLBCL. Our previous work demonstrated R406, the metabolic active form of fostamatinib, functions as a BCR antagonist in DLBCL cells. Treatment with R406 reduced MCL1 and down-regulated Bfl-1 expression, leading to apoptosis induction in sensitive cells. Due to R406’s impact on apoptosis machinery, here we explored the ability of R406 to combine with a selective Bcl2 inhibitor, ABT-199 in DLBCL cells.
Drug combinations were tested in DLBCL cells and synergy scores were determined using a 6x6 dose matrix followed by analysis via Chalice software (Zalicus). ABT-199 strongly synergized with R788, the prodrug of R406, in multiple R406 sensitive, but not resistant cell lines. In contrast, little effect was observed in combinations of R788 with other reagents, including ibrutinib (PCI-32765), bortezomib, CAL-101 and dasatinib. Flow-cytometry apoptosis analysis confirmed that R406 enhanced ABT-199-induced apoptosis in both ABC subtype and GCB subtype DLBCL cells. Further studies demonstrated R406 not only decreased anti-apoptotic proteins, but also activated pro-apoptotic proteins. Specifically, R406 suppressed ERK-dependent phosphorylation of BIM on S69, resulted in stabilization of BIM. In addition, R406 induced dephosphorylation of BAD at S136 in sensitive but not resistant cells, likely through inhibition of AKT kinase activity. Furthermore, treatment of R406 also upregulated other pro-apoptotic BH3-only proteins such as HRK1 and BMF1, which may partially contribute to the observed synergy.
In conclusion, we have demonstrated R406 strongly synergizes with ABT-199 in vitro, likely by altering the balance between anti-apoptotic and pro-apoptotic signals in DLBCL cells. This may provide a potential combination therapy to be tested in DLBCL.

Disclosures:
Zhang: AstraZeneca: Employment, Possible shareholder Other. Francoise:AstraZeneca: Employment, Possible shareholder Other. Devereaux:AstraZeneca: Employment, Possible shareholder Other. Passino:AstraZeneca: Possible shareholder Other. Parmentier:AstraZeneca: Possible shareholder Other. Byth:AstraZeneca: Employment, Possible shareholder Other.
Targeting BTK As a Treatment For Multiple Myeloma Stem Cells
Authors: Yang Ye , Gu Zhimin , Xu Hongwei , Huang Junwei , He Jie , Tao Yi , Tricot Guido J. , Zhan Fenghuang 
Published: October 2019

Abstract

Background
Multiple myeloma stem cells (MMSCs), characterized by drug-resistance and self-renewal, are very likely responsible for relapse. Though the phenotypic features of MMSCs are still controversial, it is believed that MMSCs are enriched in plasma cell progenitors. Bruton’s tyrosine kinase (BTK) plays a central role in B-cell development and plasma cell differentiation. BLAB/c. CBA/N mice carrying the defective BTK gene are resistant to pristine-induced plasmacytomagenesis suggesting activation of BTK is essential for plasma tumor initiation. In this study, we explore the role of BTK in maintaining MMSCs.

Materials and methods
Real-time-PCR was used to detect the BTK expression in MMSCs and compared to the bulk cells. BTK-related self-renewal and drug resistance were evaluated by clonogenic formation assays, using 10,000 MM cells from the BTK over-expressing ARP1 and OPM2 MM cell lines, treated with bortezomib (1nM, 10nM), as well as doxorubicin (50nM, 100nM), etoposide (50nM, 100nM), and verapamil (50nM). Flow cytometry was performed to detect the side population (SP) fraction and apoptosis in MM cells. Co-immunoprecipitation assay and western blot were utilized for the mechanistic BTK studies. Effect of BTK on MM progression in vivo was assessed in the 5TGM1 myeloma mice and NOD/SCID mice models.

Results
Our results revealed that BTK, iPS genes, Wnt and Hedgehog signaling pathways were significantly increased in MMSCs (CD138- and SP fraction) compared to bulk myeloma cells in both MM cell lines and primary MM cells. We also demonstrated that over-expression of BTK in the low-expressing MM cell lines, ARP1 and OPM2 increased the SP fraction, clonogenic potential and drug-resistance, while knockdown of BTK in high-expressing MM cell lines, OCI-MY5 and H929 abrogated these characteristics. Our in vivo study indicated that over-expression of BTK in ARP1 cells accelerates tumor formation in NOD/SCID mice compared to the EV control cells. Targeting BTK by shRNA or BTK inhibitor, CGI-1747 delayed MM tumor formation and MM progression in NOD/SCID mice and 5TGM1 model, respectively. Mechanistic studies identified that BTK activates the AKT pathway, inducing the drug-resistant genes, p-Bcl-2 and ABCB1, and inhibiting GSK3β leading to activation of the Wnt/ β-Catenin pathway. Inhibition of AKT by a specific inhibitor decreased Wnt and Hh proteins by western blot.

Conclusion
BTK plays an important role on maintaining MM stemness and drug-resistance through activating AKT, Wnt and Hh signaling pathways. Targeting BTK in MM may be a promising strategy to eliminate MMSCs.

Disclosures:
No relevant conflicts of interest to declare.
Molecular Responses At 3 Months Are Associated With a Better Subsequent Molecular response and Outcome In Children and Adolescents With CML In Chronic Phase: Results Of a Retrospective Analysis From The French Glivec Phase 4 Study
Authors: Millot Frédéric , Guilhot Joelle , Baruchel André , Petit Arnaud , Leblanc Thierry , Bertrand Yves , Mazingue Françoise , Lutz Patrick , Vérité Cécile , Berthou Christian , Galambrun Claire , Sirvent Nicolas , Yacouben Karima , Chastagner Pascal , Gandemer Virginie , Reguerre Yves , Couillaud Gérard , Cayuela Jean-Michel 
Published: October 2019

Abstract
Here we report a retrospective analysis based on BCR-ABL transcript level at 3 months after the start of imatinib assessing its impact on subsequent response and outcome in children and adolescents with chronic myeloid leukemia (CML) enrolled in the French prospective trial Glivec Phase 4 (Millot F et al, JCO 2011).

Methods
44 children were enrolled in the Glivec Phase 4 Study. The median age was 11.5 years (range: 10 months-17 years). The median follow-up was 49 months (range: 16 to 83). We retrospectively analyzed the rates of complete cytogenetic responses (CCR) and major molecular response (MMR) 1 year after the start of imatinib, the progression free survival (PFS) and the overall survival (OS).

Results
At 3 months after the start of imatinib, 40/44 (91%) patients were evaluable for molecular response. BCR-ABL transcripts levels were: BCR-ABL> 10% in 15 (37%) pts and BCR-ABL<10% in 25 (63%) pts. Children and adolescents with BCR-ABL >10% at 3 months had similar Sokal score distribution but a larger spleen size and a higher leukocyte count at diagnosis compared with patients with BCR-ABL <10%. The median dose of imatinib administered within the first 3 months of treatment was similar in patients with BCR-ABL >10% and those with <10% at 3 months. Two patients progressed to blastic phase 25 and 42 months after the start of imatinib and 1 died. Both of them had a BCR-ABL transcript level of more than 10% at 3 months after the start of imatinib. A transcript level <10% correlated with a better PFS (Table 1). Patients with a BCR-ABL transcript level <10% 3 months after the start of imatinib had a higher rate of CCR and MMR 12 months after the start of imatinib compared to those with a BCR-ABL transcript level >10% (Table 1). However the difference is statistically significant only for the molecular response.

Conclusion
The children and adolescents with >10% of BCR-ABL at 3 months after the start of imatinib are characterized by a higher propensity to fail the treatment and to progress. The value of a cut-off of 10% of BCR-ABL 3 months after the start of imatinib as a reliable surrogate marker of response at 1 year and outcome remains to be determined in a larger cohort of children and adolescents.

Disclosures:
No relevant conflicts of interest to declare.
Combination Chemotherapy With Tyrosine Kinase Inhibitors Can Overcome Bcr-Abl Mutations In Acute Lymphoblastic Leukemia Or Blast Crisis CML
Authors: Benjamini Ohad , Kantarjian Hagop M , O'Brien Susan , Thomas Deborah , Ravandi Farhad , Jain Preetesh , Pierce Sherry , Borthakur Gautam , Kadia Tapan M. , Jabbour Elias , Estrov Zeev , Luthra Rajyalakshmi , Cortes Jorge E. 
Published: October 2019

Background
Point mutations in the kinase domain of bcr-abl confer resistance to tyrosine kinase inhibitors (TKIs) in patients with blast phase chronic myeloid leukemia (CML-BC) and Philadelphia positive acute lymphoblastic leukemia (Ph+ ALL). In particular the presence of T315I mutation is highly resistant to most current available TKIs.
Inhibition Of Erythropoiesis By Iron Overload Is Mediated Through TGFβ Signaling
Authors: Gundabolu Krishna , Chen Huiyong , Li Huihui , Shakaladevanapura Lohith , Bhagat Tushar D. , Vallumsetla Nishant , Ginzburg Yelena , Verma Amit 
Published: October 2019

Abstract
Several diseases, such as β-thalassemia and myelodysplastic syndrome, are characterized by iron overload and dysfunction erythropoiesis. Multiple retrospective studies suggest that iron overload is associated with increased disease burden and shortened survival in patients. It is general consensus that iron overload has an inhibitory effect on erythroid differentiation, but direct evidence is lacking and the mechanisms underlying this phenomenon are incompletely understood. Excess iron is associated with the generation of reactive oxygen species (ROS) that result in cellular damage. We hypothesized that iron overload leads to the stimulation of myelosuppressive pathways that result in decreased erythropoiesis and resulting cytopenias. We first evaluated the effect of exogenous iron on the growth of primary human CD34+ stem cells and demonstrated that iron overload leads to decreased erythroid colony formation in vitro. Furthermore, in our in vivo experiments, we administered a total of 130 mg iron dextran IP over 20 days to C57BL/6 mice and compared these mice with PBS injected age and gender matched controls (n=5/group). We demonstrate that iron injection results in fewer circulating reticulocytes (200 vs. 310 x 109 cells/L; P=0.001) and hemoglobin (13.8 vs. 15 g/dL; P=0.0004). Using anti-CD44 and TER119 as flow cytometric markers, our data reveals a reduction in bone marrow erythroid burden (total erythroid precursors 9.6 vs. 15.3% in controls; P=0.04) with a disproportionately greater effect on orthochromatophilic erythroblasts (4.4 vs. 6.9%; P=0.02). As expected, bone marrow-derived erythroid precursors from iron loaded mice have more ROS (MFI 1497 vs. 958; P=0.05) as measured by flow cytometry, again with a disproportionately greater effect on orthochromatophilic erythroblasts (MFI 671 vs. 403; P=0.01). No effect on cell cycle was observed. To evaluate the mechanism behind iron induced suppression of erythropoiesis, we conducted a functional screen with variety of cytokine inhibitors. We observed that a specific inhibitor of the TGFβ receptor I kinase led to reversal of iron induced suppression of erythroid colonies from primary CD34+ cells in vitro. The ability of TGFβ kinase inhibitor, LY-215, in reversing iron mediated suppression was confirmed in variety of hematopoietic cell lines, resulting in the inhibition of iron induced apoptosis in these cells. Taken together, our data demonstrates for the first time that iron overload has direct suppressive effects on erythropoiesis. These effects are reversed by specific inhibitors of the TGFβ receptor I kinase and thus provide a preclinical rationale for these inhibitors in anemias associated with iron overload.

Disclosures:
No relevant conflicts of interest to declare.
Human Equilibrative Nucleoside Transporter 1 (hENT1) Expression Level Is a Potential Predictive Tool For Response To Decitabine In Patients With Myelodysplastic Syndrome
Authors: Wu Lingyun , Li Xiao , Chang Chunkang , Xu Feng , He Qi , Wu Dong , Su Jiying 
Published: October 2019

Abstract

Objective
The DNA methylation inhibitor decitabine is approved for the treatment of myelodysplastic syndromes (MDS). But there remains no effective factor to predict response to decitabine before therapy. Expression level of genes related to decitabine metabolism (including human equilibrative nucleoside transporter 1 (hENT1), hENT2, deoxycytidine kinase (dCK) and cytidine deaminase (CDA)) may influence the therapeutic effect of decitabine. In this study, we aimed to investigate whether the expression level of these genes could predict response to decitabine in MDS patients.

Patients and Methods
We performed Quantitative Real-Time PCR to examine expression of hENT1, hENT2, dCK and CDA prior to therapy in 60 MDS patients initially treated with decitabine. Response to decitabine and overall survival of patients treated with decitabine was analyzed grouped by the genes expression level.

Results
The patients responded to decitabine presented increased mean hENT1 expression levels compared to non-responders (0.8± 0.2 fold vs. 1.6±0.2 fold, p = 0.008). Among the 31 hENT1 high expression patients, 27(87.1%) achieved response, compared to 15/29 (51.7%) in low hENT1 patients (χ2=8.927, p=0.003). 41.9% (13/31) in hENT1 high expression patients and 10.3% (3/29) in low hENT1 patients achieved CR (χ2=7.646, p=0.006). Patients with hENT1 high expression showed longer survival time compared to low hENT1 patients (22 vs. 16 months; p = 0.027). However, the expression level of hENT2, dCK and CDA did not affect response rate and survival in MDS patients treated with decitabine.

Conclusion
hENT1 expression level is a potential predictive tool for response to decitabine in patients with MDS. High expression of hENT1 predicts prolonged survival in MDS patients treated with decitabine.

Disclosures:
No relevant conflicts of interest to declare.
The Role Of PRDM1 and Its Interacting Proteins In The Pathogenesis Of Chronic Lymphocytic Leukemia
Authors: Shukla Ashima , Chaturvedi Nagendra K , Joshi Shantaram S , Bierman Philip , Cornish Adam , Pandey Sanjit , Guda Chittibabu 
Published: October 2019

Abstract
Chronic Lymphocytic Leukemia (CLL) represents the most common adult leukemia in western countries, affecting approximately 10,000 individuals every year in United States of America. In order to develop effective therapeutic strategies there is a need to understand the precise molecular events associated with CLL development and progression. In an attempt to understand the process we performed transcriptome analysis of CLL cells from peripheral blood (PB) of 7 good prognosis and 8 poor prognosis patients. Additionally to validate the results further, we have utilized gene expression profiling data of CLL cells from 77 good or poor prognosis patients. Using transcriptome and gene expression profiling, we identified PR Domain Zinc Finger Protein1 (PRDM1) as one of the candidate tumor suppressor genes in CLL. PRDM1/BLIMP1 is a transcriptional repressor which is crucial for terminal differentiation of mature B cells into plasma cells. PRDM1 has been shown to promote differentiation by repressing genes essential for B cell receptor signaling and cellular proliferation. Our results demonstrated that PRDM1 expression was significantly (p < 0.05) decreased in CLL cells from poor prognosis compared to good prognosis CLL cases (Figure 1). In addition, to determine the clinical significance, the expression levels of PRDM1 were found to correlate with time to treatment in CLL patients (Figure 2). Lower expression of PRDM1 was associated (p=0.001) with shorter time to treatment in CLL (n = 40). Furthermore, using IPA analyses we identified PRDM1 interacting partners. Among those, there was increased expression of BCL2, PAX5, EHMT2, SPIB and decreased expression of BCL6, IRF4, BCR, CASP3, pFOS, TP53 and HDAC2 in CLL cells from poor prognosis patients in comparison with good prognosis. Also we have observed the differential expression of TLE1, a co-repressor molecule associated with PRDM1 and member of the Groucho family of proteins.Figure1Transcript levels of PRDM1 in Good Prognosis and Poor Prognosis.Figure1. Transcript levels of PRDM1 in Good Prognosis and Poor Prognosis.Figure2Clinical correlation of PRDM1 expression with time to treatment.Figure2. Clinical correlation of PRDM1 expression with time to treatment.
Together these results are suggestive of a role for PRDM1 as a negative regulator of CLL aggressiveness and progression. These studies warranted additional investigation to elucidate the mechanism of PRDM1 mediated CLL progression and to identify a therapeutic target.

Disclosures:
No relevant conflicts of interest to declare.
ALDH Genes and Reactive Aldehydes Play Important Roles in HSCs and Leukemia and May Be Exploited to Treat AML
Authors: Gasparetto Maura , Jordan Craig T. , Minhajuddin Mohammad , Pollyea Daniel A , Vasilou Vasilis , Reigan Philip , Humphries R. Keith , Smith Clayton A. 
Published: October 2019

Abstract
ALDH1A1 is expressed at high levels in normal HSCs and we previously reported that its function might involve metabolism of compounds termed reactive aldehydes. We also reported that loss of ALDH1A1 led to a compensatory increase in a related isoform, ALDH3A1, which also metabolizes reactive aldehydes. Double knockouts for both ALDH1A1/3A1 accumulate reactive aldehydes, which appear to impact a number of cellular processes including signal transduction and gene expression. As reactive aldehydes also cause DNA damage, we hypothesized that excess accumulation of reactive aldehydes may predispose to leukemic transformation of HSCs. In support of this, we found that ALDH1A1/3A1 double knockout HSCs readily form acute leukemia following transduction with a NUP98-HOXA10 fusion gene, which rarely causes leukemic transformation in wild type HSCs. Furthermore, in human AML, frequent absence of ALDH1A1 and the universal absence of ALDH3A1 was observed. A human AML cell line, Kasumi-1, was found to be ALDH1A1/3A1 deficient and to have high levels of intracellular reactive aldehydes. In addition, Kasumi-1 was highly sensitive to DNA damage and cell death following exposure to exogenous 4-HNE, a prototypic reactive aldehyde. In contrast, normal CD34+ HSCs were relatively resistant to 4-HNE. Based on these observations, we further hypothesized that treatment of ALDH1A1/3A1 deficient AMLs with clinically relevant compounds that further increase intracellular 4-HNE levels would selectively eliminate AML while sparing normal CD34+ HSCs. To test this, Kasumi-1 were exposed to a series of compounds including the pro-oxidant Arsenic tri-oxide (ATO), the sesquiterpene lactone parthenolide (PTL) and 4-HC, the active metabolite of cyclophosphamide (Cy) and a substrate of ALDH1A1. All increased intracellular 4-HNE levels and DNA damage. Exposure to combinations of 4-HC, ATO and PTL induced high levels of cell death in Kasumi-1. In contrast, Kasumi-1 cells engineered to express ALDH1A1 through lentiviral gene transfer and normal CD34+ HSCs were relatively resistant to several of these treatments. Primary ALDH1A1/3A1- AMLs were also relatively sensitive to treatment with these same compounds.
In conclusion, ALDHs and reactive aldehydes may play important roles in HSCs and leukemia and exploitation of their biology may lead to novel therapies for AML and possibly other cancers. As an initial application of this treatment strategy, we are developing a clinical trial to treat patients with relapsed/refractory ALDH1A1/3A1 deficient AML with Cy/ATO.

Disclosures:
No relevant conflicts of interest to declare.
Maintaining High Level Of Care At Outreach Sickle Cell Clinics
Authors: Hamm Jennifer , Hilliard Lee , Howard Thomas H. , Lebensburger Jeffrey D. 
Published: October 2019

Introduction
Parents of children with sickle cell disease often seek care at large, university based sickle cell clinics. A major health care barrier for children in Alabama involves the cost and time of travelling to and from university based clinics. To reduce this health care barrier, the University of Alabama at Birmingham (UAB) developed The Children and Youth Sickle Cell Network(®) (CYSN(®)). This network consists of the central sickle cell clinic located at UAB and four outreach sickle cell clinics located in Montgomery (100 miles south of UAB), Opelika (110 miles southeast of UAB), Huntsville (100 miles north of UAB), and Tuscaloosa (60 miles west of UAB). The goal for these clinics is to maintain a similar level of medical care while reducing the health care barrier of transportation.

Objective
To determine if the outreach clinics provide similar care to university based clinics, we evaluated three surrogate preventive care markers to compare access to care in central vs. outreach clinics: 1) attendance rates, 2) number of patients on hydroxyurea, and 3) percent of MRIs obtained for screening of silent infarct among eligible patients.

Methods
A retrospective review of all CYSN(r) clinic visits from June 2012 to June 2013 was performed to determine clinic attendance rates. All patients on hydroxyurea were categorized by clinic location. Every patient attending CYSN(r) clinic between ages of 6 and 15 years had their medical record reviewed for completion of a screening MRI/MRA.

Results
At the central Birmingham clinic, the appointment show rate was 59.8% as compared to the Montgomery, Opelika, Huntsville, and Tuscaloosa show rates which were 57.7%, 73.1%, 59.4%, and 70% respectively. At UAB, institutional guidelines were developed for offering hydroxyurea to patients based on clinical indications and applied to all clinics. The percentage of patients on hydroxyurea therapy in Birmingham is 22.2%, while the percentages in Montgomery, Opelika, Huntsville, and Tuscaloosa are 21.5%, 32%, 21.4% and 24.4%, respectively. Finally, screening MRI/MRA to evaluate for evidence of silent cerebral infarctions is performed in Birmingham but offered to children ages 6-15 years at all sickle cell clinics. In Birmingham, 63.6% of eligible patients completed MRI/MRA screening. This percentage is similar for patients in Montgomery, Opelika, and Tuscaloosa who were screened at 66.7%, 83.3%, and 67.7% respectively.

Conclusions
Our data suggests that outreach clinics can provide similar levels of medical care for children with sickle cell disease. Sickle cell centers treating patients that must travel long distances should consider developing outreach clinics to help reduce this major health care barrier.

Disclosures:
No relevant conflicts of interest to declare.