bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Functional Link Between CDK1 and Retinoic Acid Receptor γ (RARγ) in Response to Treatment with All-Trans Retinoic Acid
Authors: Hedblom Andreas , Laursen Kristian B , Miftakhova Regina R , Sarwar Martuza , Mongan Nigel P , Gudas Lorraine J , Persson Jenny L 
Published: October 2019

Abstract
Abstract 2485
Alterations in cell cycle pathways and retinoic acid signaling are implicated in the pathogenesis of leukemia and treatment response. The retinoic acid receptors (RARα, RARβ and RARγ) mediate the differentiation, cell cycle arrest and cellular response to all-trans retinoic acid (ATRA). However, it is largely unknown whether the cyclin dependent kinases (CDK1 and CDK2) mediate the ATRA effects, also whether and how CDK1 and CDK2 are functional linked to RARs. Therefore in the present study, we examined the function of CDKs and their regulation in relationship to the RAR α, β and γ.
The use of siRNA mediated knockdown of CDK1 in human leukemic U-937 cells affected cell cycle distribution, resulting in a decreased fraction of G0/G1 cells which coincided with the reduced expression of p27 protein. Treatment of U-937 si-CDK1 cells with ATRA demonstrated reduced terminal differentiation and decreased cell cycle arrest at G0/G1 phases in comparison to U-937 siRNA control cells. We observed a reduced responsiveness to ATRA treatment due to the loss of CDK1 function, and this was accompanied with the alterations in the expression of RARγ and the increased phosphorylation of Akt. However, loss of CDK2 function showed no effects on ATRA-mediated growth arrest and differentiation in U-937 cells.
We also found that nuclear CDK1 was actively phosphorylated and was rapidly degraded upon the induction of ATRA, in contrast to its cytoplasmic counterpart in human leukemic U-937 cells. When examining the functional link between RARs and the regulation of CDKs in response to ATRA, we found that RARβ and RARγ, but not RARα, participated in ATRA-mediated protein degradation of CDK1 and CDK2. Moreover, we compared the effects of ATRA on ubiquitin-mediated protein degradation in the F9 teratocarcinoma cells and in F9 cells harboring targeted deletions of the RARα, RARβ and RARγ genes. ATRA induced ubiquitin conjugates showed striking changes in patterns in cells lacking RARγ. This indicates that the blockage in protein degradation of CDK1 may be due to the loss of RARγ function. Among the RAR isoforms, RARγ co-localized with CDK1 predominantly in the nuclear bodies. There was no detectable complex formation between RARβ and CDK1. This suggests that the phosphorylation and degradation of the nuclear CDK1 and its interaction with RARγ may be important events in mediating ATRA-induced effects on cell cycle and differentiation.
Our study has revealed a novel mechanism by which CDK1 cooperates with RARγ to mediate the effects of all-trans retinoic acid.

Disclosures:
No relevant conflicts of interest to declare.
RNA-Sequencing of the Transcriptome of Ara-C Resistant Murine AML Cell Lines Identifies Potential Drug Targets
Authors: Rathe Susan K. , Stoltenberg Christopher B. , Largaespada David A. 
Published: October 2019

Abstract
Abstract 2489
One frequently reported change to acute myeloid leukemia (AML) cells, as they become resistant to arabinoside cytarabine (Ara-C), is the downregulation of deoxycytidine kinase (Dck) (Veuger et al, Blood, 2000, Shi et al, Pharmacogenetics, 2004, Cai et al, Cancer Res, 2008, Song et al, Int J Oncol, 2009, Rathe et al, Leukemia, 2010). Dck is the rate limiting enzyme in the phosphorylation and activation of Ara-C. Transcriptome deep sequencing (RNA-seq) was performed on the transcriptome of two Ara-C resistant murine leukemia cell lines (B117H and B140H), as well their Ara-C sensitive parental cell lines (B117P and B140P). Previously published microarray analysis identified the downregulation of Dck as the primary common change in the B117H and B140H cell lines, when compared to their parental cell lines (Rathe et al, Leukemia, 2010). Analysis of the RNA-seq results identified an alternatively spliced form of Dck in the B117H cell line secondary to a genomic deletion/rearrangement, as well as a loss of heterozygosity. Indeed, knockdowns of Dck in the parental cell lines demonstrated that downregulation of Dck can result in a significant increase in the IC50 of Ara-C, consistent with the increase in Ara-C resistance displayed by the B117H and B140H cells. The RNA-seq analysis showed a number of significant expression changes that did not appear on the microarray analysis. These changes include the significant upregulation of specific isoforms of deoxyguanosine kinase (Dguok) and protein phosphatase 2 (formerly 2A), regulatory subunit A (PR65), beta isoform (Ppp2r1b). It has already been shown that downregulation of Dguok results in the upregulation of Dck (Franco et al, Exp Cell Res, 2007), thereby demonstrating an important balance between these two molecules. Ppp2r1b is a putative deactivator of Dck (Smal et al, Biochem Pharmacol, 2004), which may assist in the prevention of Ara-C metabolic activation and thereby contribute to resistance. This effort demonstrates the power of using RNA-seq transcriptome analysis to identify drug targets for the treatment of AML and suggests multiple genetic/epigenetic mechanisms contribute to alterations in Dck activity during the acquisition of Ara-C resistance.

Disclosures:
Largaespada: NeoClone Biotechnology, Inc.: Co-founder, Consultancy, Equity Ownership; Discovery Genomics Inc.: Co-founder, Consultancy, Equity Ownership.
Incidence, Characteristics, and Outcome of FLT3-ITD Mutations in AML Arising from an Antecedent Hematologic Disorder
Authors: Kadia Tapan , Ravandi Farhad , Borthakur Gautam , Jabbour Elias , Pierce Sherry , Garcia-Manero Guillermo , Faderl Stefan , Cortes Jorge E. , Kantarjian Hagop M. 
Published: October 2019

Abstract
Abstract 2522
Internal tandem duplication (ITD) mutations in FLT3 (fms-like tyrosine kinase III) are common in acute myeloid leukemia (AML) and are associated with increased relapse risk and adverse outcome. A subset of AML, arising from an antecedent hematologic disorder (AHD) such as myelodysplastic syndrome (MDS), is also associated with an adverse outcome. We sought to review our experience and define the incidence, characteristics, and outcome of FLT3-ITD in AML arising from AHD. We reviewed all cases of newly diagnosed AML, excluding acute promyelocytic leukemia from 2001–2010 at our institution. FLT3-ITD mutational analysis was performed using PCR-based DNA sequencing on 1254 cases. Overall, 187 (15%) patients (pts) had FLT3-ITD mutations. Of the 1254 pts, 545 (43%) were classified as having an AHD and 709 (57%) were not. The incidence of FLT3-ITD in pts with and without AHD was 11% (125/709) and 18% (62/545), respectively (p=0.002). As a separate analysis, among pts who had received any prior chemotherapy or radiation, the incidence of FLT3-ITD was 8% (17/201) vs. 16% (170/1053) in those who had not (p=0.005). Baseline characteristics of the patients with FLT3-ITD positive AML with or without AHD are shown in table 1. The 187 pts with FLT3-ITD were treated with several different therapies as their initial treatment for AML. These included: high dose cytarabine-based (HiDAC) in 131 (70%), conventional dose cytarabine-based in 28 (15%), hypomethylating agents (HMA) in 12 (6%), and other in 16 (9%). The response rates to HiDAC and HMA in each of the two cohorts is shown in table 1. The median overall survival of patients with FLT3-ITD and AHD was 40 weeks vs. 54 weeks in those without AHD (p=0.046, Figure 1). In conclusion, FLT3-ITD is relatively less common in AML arising from AHD and in therapy-related AML compared to de novo AML. AML pts with FLT3-ITD and AHD tend to be older, have a lower bone marrow and peripheral blasts, a lower serum LDH, and significantly shorter overall survival. Compared to those without AHD, the response rate to HiDAC-based therapy in patients with FLT3-ITD and AHD are similar, but the response rates to HMA-based therapy are higher. The role of HMA in the treatment of FLT3-ITD patients with and without AHD should be investigated further.Table 1.Figure 1.Figure 1.

Disclosures:
No relevant conflicts of interest to declare.
MicroRNAs Mediate Resistance to Tyrosine Kinase Inhibitors in Philadelphia-Positive B-ALL by Down-Regulating Key Tumor Suppressors
Authors: Schatz Jonathan H. , Mavrakis Konstantinos , Wolfe Andrew L , Wendel Hans-Guido 
Published: October 2019

Abstract
Abstract 2553
The Philadelphia (Ph) chromosome (t(9;22)(q34;q11)) is the most common recurrent cytogenetic abnormality in adult B-cell acute lymphoblastic leukemia (B-ALL). Resulting expression of the BCR-ABL fusion gene product, a constitutively active tyrosine kinase, leads to an extremely poor prognosis when the disease is treated with chemotherapy alone. In recent years targeted therapy with tyrosine kinase inhibitors (TKIs) in combination with chemotherapy has improved outcomes. Therapeutic resistance remains a major clinical problem, however, with less than half of patients surviving three years from initial therapy in most series even with up-front TKI-chemotherapy regimens. TKI resistance in B-ALL may result from acquired mutations of the BRC-ABL protein or from BCR-ABL-independent causes, including feedback activation of BCL6 or activation of other oncogenic signaling pathways through poorly understood mechanisms. In this study, we screened a whole-genome library of microRNAs for ability to produce resistance to TKI therapy in murine pro-B cells transformed with BCR-ABL. Several initial candidates from the screen were individually confirmed to confer TKI resistance, including miR 148/152 and 19, known oncomirs in T-ALL. Computational analysis of the gene targets of validated miRs shows significant overlap at several tumor-suppressor pathways, including down-regulation of PTEN, a known mechanism of TKI resistance in Ph+ B-ALL cell lines. In sum, we have identified a novel mechanism of TKI resistance in Ph+ B-ALL mediated by miRs and leading to down-regulation of specific tumor suppressive intermediates. These findings will allow development of new therapeutic combinations to improve outcomes for B-ALL patients.

Disclosures:
No relevant conflicts of interest to declare.
Homoharringtonine in Combination with Cytarabine and Aclarubicin in the Treatment of Refractory/Relapsed Acute Myeloid Leukemia: a Single-Center Experience
Authors: Yu Wenjuan , Mao Liping , Qian Jiejing , Qian Wenbin , Meng Haitao , Mai Wenyuan , Tong Hongyan , Tong Yin , Jin Jie 
Published: October 2019

Abstract
Abstract 2595
Patients with refractory and relapsed acute myeloid leukemia (AML) have relatively unfavorable prognoses and require innovative therapeutic approaches. We evaluated the efficacy and toxicity profiles of homoharringtonine (HHT), cytarabine (Ara-c) and aclarubicin combination chemotherapy in 46 refractory and/or relapsed AML patients between February 2004 and December 2009.
Eleven cases were primary refractory disease and rest of them had relapsing disease. After one course of HAA treatment, complete remission (CR) was achieved in 35 of 46 patients (76.1%), while 3 cases showed partial remission (PR) (6.5%) and 8 cases (17.4%) had resistant to this regimen. One PR and one NR patient obtained CR after second course of HAA, yielding a total CR rate was 80.4%. Hematological toxicity was the most prominent toxicity of this regimen. Grade IV hematologic toxicity occurred in 91.3% cases. Neutrophil recovery time was 13 (5–60) days. Nonhematologic complications were mild to moderate nausea, vomiting, and mucositis and could be controlled by routine measures. Early death (ED) did not occur in these 46 patients.
There was no correlation between response rate and leukemia subtype (AML FAB subtype), leukocyte, blast count in bone marrow, platelet count and sex (P >0.05). However, poor karyotype and age (≥45 years old) were factors associated with increased risk of treatment failure. Of the 46 patients, one patient, who upon achieving CR after the first re-induction therapy refused further treatment, was ultimately lost to follow-up. The median overall survival rate (OS) was 29 (2–86) months in 45 cases. Relapse-free survival (RFS) was 36 (0.5–85) months in 36 CR cases. By the time of closeout, the estimated 3-year OS rate was 42% for all 45 cases, and 43% estimated RFS at 3 years for the 36 cases of CR. OS and RFS were influenced by leukemia-related factors and disease status: Hb <10g/dl and poor karyotype in both univariate and multivariate analyses.
Allogeneic stem cell transplantation was performed in 7 patients and all achieved CR, but 1 patient died of GVHD, 2 died of pneumonia, 1 relapsed followed by death and another 3 are still alive with CR. At present, 19 patients are still alive and 18 of these are in continuous remission with one alive with leukemia. The rest (26/45) of the patients are all deceased.
In conclusion, HAA is a good choice in cases with refractory/relapsing AML for salvage chemotherapy, preferably with a high efficacy and low-toxicity profile.

Disclosures:
No relevant conflicts of interest to declare.
Transcriptional Deregulation of Homeobox Gene ZHX2 in Hodgkin Lymphoma
Authors: Nagel Stefan , Schneider Björn , Meyer Corinna , Kaufmann Maren , MacLeod Roderick AF , Drexler Hans G. 
Published: October 2019

Abstract
Abstract 2629
Hodgkin/Reed-Sternberg (HRS) cells represent the malignant fraction of infiltrated lymph nodes in Hodgkin lymphoma (HL). Although HRS cells display multiple chromosomal aberrations, few are recurrent and the targeted genes unknown. However, understanding the pathology of HL and developing rational therapies may well require identification and characterization of these genes and their deregulating mechanisms. Recently, we have identified a novel chromosomal rearrangement in HL cell line L-1236, t(4;8)(q27;q24), which targets ZHX2 at the recurrent breakpoint 8q24. ZHX2 encodes a transcription factor of the homeobox gene family and possesses tumour suppressor activity connected with a worse prognosis in HL-related multiple myeloma. Comparative expression analysis in HL cell lines and primary hematopoietic cells indicated aberrant downregulation in HL as well. In L-1236 the translocation breakpoint at 8q24 deletes the regulative far upstream region of ZHX2, indicating loss of activating elements. Therefore, we have looked for potential binding sites within this deleted region to analyze deregulation of this B-cell tumour suppressor gene. Accordingly, we identified two transcription factors, homeodomain protein MSX1 and bZIP protein XBP1, regulating ZHX2 expression. SiRNA-mediated knockdown and reporter gene analyses indicated that both factors activated transcription of ZHX2 directly via their corresponding binding sites. Furthermore, MSX1-cofactor histone H1C mediated repression of ZHX2 and showed enhanced expression levels in L-1236. As analyzed by fluorescence in situ hybridization (FISH) and genomic arrays, the gene loci of MSX1 at 4p16 and H1C at 6p21 were rearranged in several HL cell lines, correlating with their altered expression activity. As compared to primary hematopoietic cells, XBP1 expression was reduced in 6/7 HL cell lines while one cell line showed elevated levels, corresponding to a chromosomal rearrangement therein. Interestingly, the neighbouring pro-apoptotic genes EDEM1 and BHLHE40 were removed by del(3p26) in this cell line and activated by XBP1 in other HL cells. Taken together, our results demonstrate multiple mechanisms decreasing expression of tumour suppressor gene ZHX2 in HL cells: loss of enhancing binding sites, reduced expression of activators MSX1 and XBP1, and overexpression of MSX1-corepressor H1C. Moreover, chromosomal deregulations of genes involved in this regulative network highlight their role in development and malignancy of B-cells.

Disclosures:
No relevant conflicts of interest to declare.
R-ACVBP Benefits to Younger Patients with Non-Germinal Centre Diffuse Large B-Cell Lymphoma As Compared to R-CHOP in the GELA Trial LNH03-2B
Authors: Molina Thierry Jo , Canioni Danielle , Copie-Bergman Christiane , Recher Christian , Fournier Marion , Haioun Corinne , Briere Josette , Berger Francoise , Fermé Christophe , Copin Marie-Christine , Casasnovas Rene-Olivier , Thieblemont Catherine , Leroy Karen , Salles Gilles Andre , Jardin Fabrice , Jais Jean-Philippe , Gaulard Philippe , Coiffier Bertrand , Tilly Herve 
Published: October 2019

Abstract
Abstract 2632
Hans algorithm using immunohistochemistry correlates well with gene expression data in Diffuse large B-cell lymphomas (DLBCL) (Meyer PN, 2011) and has demonstrated in some studies clear survival differences in favor of germinal-centre (GC) vs non-germinal centre (n-GC) B-cell among DLBCL treated with R-CHOP. We undertook an immunohistochemical study among patients aged 18 to 59 years with aaIPI 1 included in the GELA trial LNH 03-2B that compared R-ACVBP intensified immunochemotherapy to standard R-CHOP. This trial demonstrated an improvement of EFS, PFS and overall survival (OS) of patients treated with R-ACVBP (C Recher et al, in press). Our goal was to evaluate survival of patients with GC and n-GC DLBCL according to treatment regimens. We analyzed by immunohistochemistry the expression of CD10, BCL6 and MUM1 and classified patients as GC or n-GC according to the Hans algorithm. Among the 380 patients enrolled in this study, 229 patients were available for Hans algorithm classification. There was no differences considering clinical characteristics of these 229 patients (age, sex, B symptoms, PS, Stage, LDH, number of extranodal sites, bulky mass, bone marrow involvement) compared to the whole LNH03-2B population. 175 DLBCL cases were present on a tissue microarray (TMA) and 54 other cases were analyzed using unstained slides. 101 patients were classified as GC and 128 as n-GC. 107 patients were treated by R-ACVBP and 122 by R-CHOP. EFS, PFS and OS were not different between the GC and n-GC profile among the whole population (P=.82, P=.90, P=.68, respectively). There was no statistical difference in EFS, PFS and OS between R-ACVBP and R-CHOP in GC patients (P=.78; P=.84, P=.33, respectively). Interestingly, EFS, PFS and OS were significantly much longer among n-GC patients treated by R-ACVBP compared to R-CHOP (P=.02; P=.007, P=.007, respectively). Results were similar considering only TMA population (P=.02, P=.001, P=.001, respectively). This subgroup analysis suggests that the survival benefit related to R-ACVBP over R-CHOP in the LNH 03-2B is in large part linked to a survival improvement in the n-GC population. This algorithm, easy to apply on routine paraffin-embedded tissue, might be useful in the future to select patients that can primarily benefit from this intensive regimen.

Disclosures:
No relevant conflicts of interest to declare.
Gene Expression Profiling Identifies the JAK/STAT and NFκB Pathways to Be Important in Peripheral T-Cell Lymphomas and Natural-Killer T-Cell Lymphomas
Authors: Tang Tiffany , Allen George , Koo Ghee Chong , Tay Kevin , Tan Daryl , Quek Richard , Tao Miriam , Tan Soo Yong , Teh Bin Tean , Lim Soon Thye 
Published: October 2019

Abstract
Abstract 2658

Background:
Peripheral T-cell lymphomas (PTCL) carry a poorer prognosis compared to their B-cell counterparts and the molecular pathogenesis of PTCL is still largely unknown. The aims of this study are to characterize the molecular signatures and identify signaling pathways involved in the different subsets of PTCL and NKTCL.
Materials and Methods: RNA was extracted from tumors of 60 patients with newly diagnosed PTCL and NKTCL: 21 with angioimmunoblastic T-cell lymphoma (AITL), 12 anaplastic large-cell lymphoma (ALCL), 15 peripheral T-cell lymphoma not-otherwise-specified (PTCL-NOS) and 12 with natural-killer T-cell lymphoma (NKTCL). Comparisons were made using published gene expression data files of normal T and NK T-cells. Gene expression profiling was performed using the Affymetrix HG-U133 Plus 2.0 GeneChip platform.

Results:
The Affymetrix expression profiling distinguishes the 48 PTCL samples from normal T-cell controls (p<0.005). Similarly, the molecular signature of 12 NKTCL significantly differs from normal NK cells. The JAK/STAT pathway is significantly upregulated in AITL and a subset of PTCL-NOS compared to normal T cells and ALCL (p<0.005). [Figure 1] Pathways related to NFκB significantly distinguish PTCL from normal T-cells and it also distinguishes NKTCL from normal NK T-cells. Unsupervised hierarchical clustering by gene expression profiles is able to separate the subsets of PTCL (AILT, ALCL, NKTCL) in concordance with their immmunohistochemical diagnosis. PTCL-NOS however, are dispersed across the clusters reflecting its molecular heterogeneity. [Figure 2]

Discussion:
Gene expression profiling identifies distinct molecular pathways in PTCL. In particular, the JAK-STAT pathway is upregulated in AITL and the NFκB pathway is dysregulated in PTCL and NKCL. Our results suggest that targeting the key kinases in these pathways may be effective in the treatment for this subset of lymphomas with poor prognosis.

Disclosures:
Tan: Janssen: Honoraria, Research Funding; Celgene: Honoraria; Novartis: Research Funding.
Excellent Long-Term Survival of Patients with Waldenström‘s Macroglobulinemia (WM) treated in Private Oncology Practices and a University hospital with different Treatment Strategies
Authors: Hensel Manfred , Brust Jürgen , Plöger Christoph , Schuster Dieter , Memmer Marie-Luise , Rieger Michael , Hensel Lara , Mosthaf Solveigh , Franz-Werner Judith , Feustel Hans-Peter , Mosthaf Franz , Karcher Andreas , Fuxius Stefan , Ho Anthony D. , Witzens-Harig Mathias 
Published: October 2019

Abstract
Abstract 2671

Background:
WM is a rare type of malignant B-cell lymphoma, defined as a lymphoplasmocytic lymphoma in bone marrow and a monoclonal gammopathy of immunoglobulin-M (IgM) type. Due to the paucity of large clinical trials, a standard treatment regimen is still controversial. The purpose of this study was to compare the standard treatment and outcome of patients (pts) treated in private oncology practices (PP) and a university hospital (UH) in a region of southern Germany (Nordbaden).

Methods:
We retrospectively reviewed the charts of all pts with WM of the last 2 decades of 4 PP in Mannheim, Heidelberg, Karlsruhe and Speyer and the department of hematology of the University of Heidelberg.

Results:
170 patients with WM could be identified, 74 from PP, 96 from the UH. The median age of the 170 pts was 63.3 years (range 29.1–88.5). The clinical symptoms were splenomegaly in 21.2%, hyperviscosity in 15.9%, lymphadenopathy in 15.9%, and polyneuropathy in 11.2%. 12.9% had a previous phase of IgM-MGUS. Pts from PP were older (median 65.3 vs. 62.5, p=0.01). Mean hemoglobine level at diagnosis was lower in pts from UH (11.4 vs. 12.2, p=0.04). There was no significant difference in mean platelet count, IgM and ß2-microglobuline level at diagnosis. 54% of pts from PP have received treatment during the observation time, as compared to 78.1% of the UH (p<0.001). The most common first line treatment protocols of PP were Chlorambucil (17/40, 42.5%), Bendamustin (17.5%) and Rituximab(R)-Bendamustin (17.5%). The UH most commonly administered R-Pentostatin-Cyclophosphamide (28%), Chlorambucil (17.3%) and COP (16%). 35% of the treated pts of PP have received R, as compared to 62.6% of the pts of the UH (p<0.001). 60% of the treated pts of PP have received Bendamustin, as compared to 8% of the pts of the UH (p<0.001). The time to first treatment was significantly shorter in pts from the UH (median 13.7 mo.) as compared to PP (52.9 mo.) (p=0.05). Median overall survival of all pts was 25.0 yrs and did not differ between PP and UH.

Conclusion:
Pts with WM treated in PP were older and had higher initial hemoglobin levels as compared to pts from the UH. Treatment differs significantly between PP and UH. Time to first treatment was significantly shorter in pts from UH. Overall survival was excellent, and better than reported previously.

Disclosures:
Hensel: Roche: Honoraria, Research Funding; Mundipharma: Research Funding.