bluuebunny/crossref_metadata_2025_split huggingface dataset:
Therapeutic Potential of Anti-CD137 Antibody in Lymphoma.
Authors: Houot Roch , Goldstein Matthew J , Kohrt Holbrook E , Myklebust June H , Alizadeh Ash A , Lin Jack T , Irish Jonathan M , Torchia James A , Kolstad Arne , Chen Lieping , Levy Ronald 
Published: October 2019

Abstract
Abstract 722

Immunomodulating monoclonal antibodies (mAb) directed against immune cell targets can be used to enhance antitumor immune responses. CD137 (4-1BB) is a costimulatory molecule expressed on a variety of activated immune cells, including T and NK cells. Anti-CD137 agonistic mAb has demonstrated antitumor activity in various tumor models and has now entered clinical trials for the treatment of solid tumors (BMS-663513). Here, we investigate the therapeutic potential of anti-CD137 mAb in lymphoma.
Using microarray gene expression data, we compared CD137 mRNA expression across 17 different types of cancer. We found that lymphoma tumor specimens significantly over-expressed CD137 mRNA compared to other tumors (p<0.0001). Single cell analysis of primary lymphoma samples of various histologies (follicular lymphoma [n=29], mantle cell lymphoma [n=14], and diffuse large B cell lymphoma [n=11]) revealed that CD137 was expressed by a significant proportion of tumor-infiltrating T cells, particularly in the CD8 subset (mean[range]=6.1%[2.5-11.5], 15.4%[2.7-40.9] and 18.7%[6.7-51.7], respectively). In contrast, CD137 was not expressed by the tumor cells. These results suggest that the target of anti-CD137 mAb is present and selectively expressed on cells with potential antitumor activity in patients with lymphoma.
Using a murine model, we then investigated the anti-lymphoma activity of anti-CD137 agonistic mAb in vivo. BALB/c mice, bearing large and established A20 lymphoma tumors, were treated with anti-CD137 mAb or other immunomodulating mAbs (anti-OX40, anti-CTLA4, anti-GITR) for comparison. The mAbs were given i.p. on days 5 and 10 post tumor inoculation. Anti-CD137 mAb demonstrated potent anti-lymphoma activity in vivo, and appeared to be significantly superior to the other immunomodulating mAbs tested (Figure 1). The antitumor effect of anti-CD137 mAb was not due to direct targeting of the malignant cells as A20 tumor cells do not express CD137.
Depletion experiments revealed that anti-CD137 therapy required both NK and CD8 T cells. Analysis of tumor-bearing mice showed that anti-CD137 therapy increased the number of CD8 T cells and reduced the number of Tregs at the tumor site. Anti-CD137 therapy also induced long-lasting antitumor immunity as cured mice harbored antitumor IFN-g producing memory CD8 T cells and were protected from tumor re-challenge more than 100 days after initial therapy.
In conclusion, this study demonstrates for the first time that anti-CD137 agonistic mAb has potent antitumor activity in lymphoma. These results support the evaluation of anti-CD137 mAb in clinical trials for patients with lymphoma.

Disclosures:
No relevant conflicts of interest to declare.
Dissecting the Activation Pathway of Pro-Apoptotic BAX: Mechanistic Insights and Pharmacologic Opportunities.
Authors: Gavathiotis Evripidis , Davis Marguerite , Ruiz Denis Reyna , Bird Gregory H. , Walensky Loren D. 
Published: October 2019

Abstract
Abstract 768
BAX is a pro-apoptotic BCL-2 family member that lies dormant in the cytosol until converted into a killer protein in response to cellular stress. We previously identified an elusive trigger site that mediates BH3-induced direct BAX activation. The continuum of conformational changes that transforms ligand-triggered BAX into a lethal mitochondrial homooligomer remains undefined. Here, we apply NMR and chemical biology methodologies to characterize the key structural alterations and corresponding functional consequences that comprise the direct BAX activation mechanism. Our structure-function analysis reveals a cascade of dynamic changes involving the N-terminal loop, C-terminal helix, and BH3 domain, which convert BAX from an inactive monomer into a toxic oligomer. Our dissection of this seminal pro-apoptotic process highlights new pharmacologic opportunities to modulate cell death in hematologic malignancy by influencing key steps of the BAX activation pathway.

Disclosures:
Walensky: Aileron Therapeutics: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees.
Fox-2A Modulates Protein 4.1R Exon 16 5' Splice Site Activation.
Authors: Huang Shu-Ching , Yang Guang , Park Jennie , Ou Alexander , Benz Edward J. 
Published: October 2019

Abstract
Abstract 778
Erythroid differentiation-induced Fox-2A is an important regulator for the differentiation-specific exon 16 splicing switch in protein 4.1R. Up-regulation of Fox-2A in late erythroid differentiation is critical for inclusion of exon 16, which encodes a portion of the spectrin/actin binding domain vital for maintaining the mechanical stability of red blood cell membranes. Fox-2A exerts its splicing enhancing activity in a motif-dependent manner, binding to UGCAUGs located downstream of exon 16. In this study, we investigated the mechanism by which Fox-2A modulates the expression of exon 16. The excision of introns and the joining of exons depends on the recognition and usage of 5' and 3' splice sites (5' ss and 3' ss, respectively) by the splicing machinery. Exon 16 possesses a relatively strong 3' ss but a weak 5' ss. Mutation of the weak 5' ss (GAGIGTTTGT) to a strong consensus 5' ss (GAGIGTAAGT) led to nearly total exon 16 inclusion. While mutations impairing Fox-2A binding drastically reduced exon 16 inclusion in the presence of the weak 5' ss, no effect on exon 16 inclusion was observed when the strong 5' ss was presented with these mutations. These results suggest that Fox-2A facilitates exon 16 splicing by supporting the weak 5' ss. Early recognition of the 5' ss involves base-pairing interaction with the 5' end of U1 snRNA and stabilization by U1 snRNP. Psoralen-mediated UV cross-linking assays revealed a reduction in U1 snRNA recruitment to the weak 5' ss when Fox-2A binding sites were impaired, suggesting that binding of Fox-2A could promote recruitment and stabilization of U1 snRNP to the weak 5' ss. In support for a role of Fox-2A in modulating the activation of the weak 5' ss by recruiting U1 snRNP, we demonstrated that Fox-2A directly interacts with U1 specific protein U1C in an RNA-independent manner. The C-terminal domain of Fox-2A is responsible for its association with U1C. These data suggest a novel mode for exon 16 5' ss activation in which the binding of Fox-2A to an intronic splicing enhancer element UGCAUG may stabilize the pre-mRNA-U1 snRNP complex through interactions with U1C. These could then result in spliceosome commitment complex formation and exon 16 inclusion.

Disclosures:
No relevant conflicts of interest to declare.
Association Between Genetic Variants in the Base Excision Repair Pathway and Outcomes After Hematopoietic Cell Transplant.
Authors: Arora Mukta , Lindgren Bruce , Basu Saonli , Nagaraj Sriharsha , Gross Myron , Weisdorf Daniel J , Thyagarajan Bharat 
Published: October 2019

Abstract
Abstract 870

Introduction:
Despite recent advances in technology and supportive care, hematopoietic cell transplant (HCT) continues to be associated with high morbidity and mortality. Since the therapies used in HCT induce DNA damage that is repaired by the base excision repair (BER) pathway we hypothesized that single nucleotide polymorphisms (SNPs) in BER genes may influence HCT outcomes.

Methods:
We evaluated the association between tagSNPs and functionally important SNPs (n= 179) in the BER pathway with transplant related mortality at one year (TRM) and disease relapse in a cohort of 470 recipients of allogeneic HCT for hematologic malignancies at the University of Minnesota between 1998 and 2007 from a HLA-identical sibling donor, HLA-matched or mismatched unrelated donor (URD) or single umbilical cord graft.

Results:
After adjustment for age at transplant, donor type, race, and conditioning regimen, four SNPs in OGGI, LIG3 and MUTYH1 genes (rs159153, rs3135974, rs3219463, rs3219476) were associated with increased risk of TRM whereas two SNPs in TDG gene (rs167715, rs2374327) were associated with decreased risk of TRM at one year (p≤0.01). Patients with increasing numbers of deleterious alleles in the BER pathway showed an increased cumulative incidence of TRM at one year (14% for ≤ 1 deleterious allele vs. 51% for ≥ 4 deleterious alleles; p<0.001). One SNP, rs3135974, in LIG3 gene was associated with decreased risk of disease relapse (p<0.001) post HCT.

Conclusions:
Single nucleotide polymorphisms in the BER pathway are significantly associated with both TRM and disease relapse, thus supporting the hypothesis that genetic polymorphisms in the BER pathway are involved in the pathophysiology of TRM and disease relapse. If confirmed in independent cohorts, these SNPs may indicate patients who might benefit from altered or less DNA damaging conditioning regimens.

Disclosures:
No relevant conflicts of interest to declare.
MicroRNAs Characterize Genetic Diversity and Drug Sensitivity in Pediatric Acute Lymphoblastic Leukemia.
Authors: Schotte Diana , de Menezes Renee X , Moqadam Farhad Akbari , Lange-Turenhout Ellen , Chen Caifu , Pieters Rob , Den Boer Monique L. 
Published: October 2019

Abstract
Abstract 89
MicroRNAs (miRNAs) are a new class of small non-coding RNAs that regulate the activity of protein-coding genes, including those involved in cancer. The function of a miRNA depends on the cellular context and hence prominent miRNAs in lymphoma may not be important in acute lymphoblastic leukemia (ALL). To understand which miRNAs may be relevant in pediatric ALL, the expression levels of 397 miRNAs including seven newly cloned miRNAs were measured in seven genetic subtypes of ALL and normal hematopoietic cells. Except for BCR-ABL-positive and B-other ALL all major subtypes, i.e. T-ALL, MLL-rearranged, TEL-AML1-positive, E2A-PBX1-positive and hyperdiploid ALL, have unique miRNA signatures that differ from each other and from those in healthy hematopoietic cells. The expression of miR-383, miR-125b, miR-99a, miR-100 and let-7c was increased by a five to 1700-fold (P < 0.001) in TEL-AML1-positive cases. Hyperdiploid patients demonstrated a three to 24-fold upregulation (P < 0.001) of miR-222/222*, miR-223, miR-511 and miR-660, encoded on either chromosome X or 10 which is often duplicated in hyperdiploid cases. Some ALL subtypes shared similarities in their miRNA expression signature suggesting a common underlying biology e.g. both E2A-PBX1 and T-ALL cases demonstrated a downregulation of eight miRNAs (P ≤ 0.02) and within the TEL-AML1-positive subtype, two distinct groups were identified of which one showed an overlapping miRNA expression profile with hyperdiploid cases. Aberrant miRNA expression may result in dysregulated expression of their targeted proteins. Here we observed that the 70-fold downregulation of let-7b in MLL-rearranged ALL was associated with a 2-fold upregulation of oncoprotein c-Myc (P< 0.0001). Furthermore, a classifier built with a selection of 28 miRNAs predicted the MLL-rearranged, TEL-AML1-positive, E2A-PBX-positive and T-ALL subtypes with 100% sensitivity and specificity. Besides the genetic subtype, cellular drug resistance determines outcome of ALL. In vitro resistance of patients to vincristine, daunorubicin and L-asparginase was characterized by abnormal expression of 27 miRNAs (P < 0.05) whereas no discriminative miRNAs were found for resistance to prednisolone. Most striking was the 14- to 25-fold upregulation (P ≤ 0.002) of miR-125b, miR-99a and miR-100 in cases resistant to vincristine or daunorubicin. In conclusion, genetic subtypes and drug resistant leukemic cells display characteristic miRNA expression levels. Functional studies are indicated for discriminative miRNAs and may provide new insights into leukemogenesis.

Disclosures:
No relevant conflicts of interest to declare.
Thienopyridine-Associated Thrombotic Thrombocytopenia Purpura: Updated Antibody Results From the SERF-TTP Study.
Authors: Zakarija Anaadriana , Luu Thanh Ha , Kwaan Hau C. , McKoy June , Weiss Ivy , Yarnold Paul , Bandarenko Nicholas , Bennett Charles L. 
Published: October 2019

Abstract
Abstract 892

Background:
The thienopyridines, ticlopidine and clopidogrel, have been associated with thrombotic thrombocytopenia purpura (TTP). However, few studies have reported information on antibodies to ADAMTS13 among patients with thienopyridine-associated TTP. We previously reported on two mechanistic pathways of thienopyridine-associated TTP with some overlapping features. Evaluation of ADAMTS13 autoantibodies was undertaken to improve understanding of these syndromes.

Methods:
Clinical and laboratory findings were evaluated for 30 ticlopidine-, 10 clopidogrel-associated TTP cases, and 54 cases of idiopathic TTP.

Results:
Among patients with thienopyridine-induced TTP, those with a history of ticlopidine versus clopidogrel use were more likely to present with severe thrombocytopenia (platelet < 20,000) (90% versus 13%), severe ADAMTS13-deficiency (80% versus 0%), and neutralizing antibodies to ADAMTS13 (100% versus 0%), and were less likely to have less than a two week history of thienopyridine exposure (0% versus 50%) (p<0.05 for each comparison). They were also more likely to survive following therapeutic plasma exchange (TPE) (85% versus 50%). 2 patients exposed to clopidogrel later relapsed and had similar characteristics to idiopathic TTP patients with non-deficient ADAMTS13 activity.

Conclusion:
Ticlopidine causes TTP by a pathway involving a neutralizing autoantibody to ADAMTS13 while clopidogrel causes TTP by an ADAMTS13-independent pathway. Although ADAMTS13 autoantibodies are present in both idiopathic and ticlopidine-associated TTP, spontaneous relapses are not seen in ticlopidine-associaated TTP, suggesting that drug-dependent antibodies are present. Clopidogrel associated TTP is distinct from idiopathic TTP in that ADAMTS13 autoantibodies are absent and response to TPE is poor.

Disclosures:
No relevant conflicts of interest to declare.
HIV-Related Hodgkin Lymphoma in the Era of Highly Active Antiretroviral Therapy: Incidence and Survival in a Prospective European Multi-Cohort Study On Behalf of the Collaboration of Observational HIV Epidemiological Research in Europe (COHERE) Study Group.
Authors: Bohlius Julia , Boue Francois 
Published: October 2019

Abstract
Abstract 895

Introduction:
HIV-infected patients are at increased risk to develop Hodgkin Lymphoma (HL). We examined the incidence and risk factors for HL, and the prognosis of patients with HIV-related HL in the era of highly active antiretroviral therapy (HAART) in the Collaboration of Observational HIV Epidemiological Research Europe (COHERE).

Patients and Methods:
40,168 adult HIV-1 infected patients who started HAART in one of 16 prospective cohort studies in Europe were included in the present analysis. Incidence rates per 100,000 person-years, Kaplan-Meier estimates of cumulative incidence and survival, and adjusted hazard ratios (HRs) from Weibull random-effects models, with 95% confidence intervals (CIs), were calculated.

Results:
During 159,133 person-years of follow-up, 78 patients were diagnosed with HL. The crude incidence rate of HL was 50.4 per 100,000 person-years for patients who developed HL before starting HAART (17 cases) and 48.7 per 100,000 person-years in patients who were already on HAART (61 cases). Age, gender, CDC clinical stage, CD4 cell counts and HIV-1 RNA viral load at baseline (start of observation) were not significantly associated with the risk of HL. At HL diagnosis median age was 38.9 years (inter quartile range (IQR) 35.3 - 45.9 years) and the median CD4 cell count was 158 cells/μL (IQR 54 – 281 cells/μL). During a median follow-up of 18 months (IQR 4.8 - 34.8 months) 12 of 78 patients with HL died (15%), six of them during the first 6 months after diagnosis. Survival was 88% (95% CI 77% - 94%) at one year and 81% (95% CI 68% - 89%) at two years. Restricting the analysis to patients aged 16-44 years, one year survival in our population (86%, 95% CI 73% - 93%) was less compared to a European population of male Hodgkin patients of similar age (97.7%) [1]. The figure shows Kaplan-Meier plots of cumulative incidence (upper panel) and survival (lower panel).

Conclusions:
HL incidence rates were similar in HAART treated and untreated patients. In contrast to HIV-related Non-Hodgkin's Lymphoma no clear association with baseline CD4 cell count was observed.

Disclosures:
No relevant conflicts of interest to declare.
Mutation and Single-Nucleotide Polymorphism (rs16754) in Wilms Tumor-1 Gene Are Independent Prognostic Factors in Acute Myeloid Leukemia.
Authors: Ma Wanlong , Kantarjian Hagop , Zhang XI , Wang Xiuqiang , Zhang Zhong , Yeh Chen-Hsiung , Sferruzza Anthony , O'Brien Susan , Albitar Maher 
Published: October 2019

Abstract
Abstract 995
Poster Board I-17
Several reports have suggested that mutations in the Wilms tumor 1 gene (WT1) represent an adverse prognostic factor in acute myeloid leukemia (AML). Here we examined the associations of WT1 mutations in exons 7 and 9 and the silent R301 single-nucleotide polymorphism (SNP) in exon 7 (A903G; NCBI dbSNP reference ID: rs16754) with outcome in AML patients treated at a single institution. Peripheral blood plasma and bone marrow samples from 174 newly diagnosed AML patients were tested for WT1 mutations in exons 7 and 9 by sequencing and fragment-length analysis for the detection of small deletions/insertions. Sequencing provided information on the specific genotype of the rs16754 SNP. The findings were correlated with outcome and other laboratory findings. WT1 mutation was detected in 7 of 50 (14%) AML patients <50 years of age and in 5 of 124 (4%) patients >50. The silent R301 SNP was detected at frequencies of 4% for GG, 26% for GA, and 70% for AA genotypes, but there was no difference with age. A similar SNP genotype distribution was detected in normal control subjects. WT1 mutations were associated with higher white cell count (P=0.01) and higher percentage of blasts in bone marrow (P=0.03) and peripheral blood (P=0.009). In addition, WT1 mutation was significantly associated with FLT3 mutation (P=0.002) but not NPM1 mutation (P=0.8). WT1 mutation was also significantly associated with shorter survival (P=0.025), event-free survival (P=0.002), and complete remission duration (P=0.002) in patients <50 years of age, but not in older patients. The association with shorter survival persisted when only patients with intermediate cytogenetics were considered (P=0.03). There was no correlation between WT1 mutation and response to therapy. The most striking correlation was between the presence of the GG genotype at R301 and longer survival, irrespective of age (see survival chart below). There was no difference in survival between the AA and GA groups. To the best of our knowledge, this is the first report describing correlation between survival duration and an SNP in the WT1 gene. While we confirm that the presence of WT1 mutation is associated with poor outcome in young AML patients, our data suggest that there is no clinical value in testing patients older than 50 for WT1 mutation, but that there may be value in testing adult patients of all age groups for the SNP polymorphism at R301

Disclosures:
No relevant conflicts of interest to declare.
Platelets Play a Protective Role in Erythrocytic Stage Malaria Infection.
Authors: Foote Simon J. , McMorran Brendan J. , Drysdale Karen E. , de Graaf Carolyn , Smyth Gordon K. , Alexander Warren S. 
Published: October 2019

Abstract
Abstract MRG-1
Mpl-/- mice lack the thrombopoietin receptor (Mpl) and have 10% the platelet mass of normal, isogenic C57BL/6 animals. When infected with the murine malarial parasite, P. chabaudi, C57BL/6 mice survive the infection whereas Mpl-/- mice die. There is a previously, well-documented thrombocytopenia associated with infection by malarial parasites and, in mice, this is co-incidental with a rise in parasitaemia, not the onset of symptoms. We show that murine infected red cells are preferentially bound to platelets. Using the TUNEL staining technique to identify dead or dying cells we show more TUNEL positive cells in C57BL/6 mice than in the thrombocytopenic Mpl-/- mice. Parasites are more likely to be TUNEL positive if their red cell is bound by a platelet or is CD41 positive. This data provided circumstantial evidence that platelet were directly killing malarial parasites within the red cell in the mouse murine model. It was therefore predictable that aspirin should decrease the resistance to malaria and this proved to be the case. The evidence for the protective role of platelets was substantiated by experiments with human platelets and P.falciparum, the lethal human malarial parasite. Unlike the murine malarias, P.falciparum can be grown in culture (with human red cells). The addition of purified human platelets inhibits the growth of P. falciparum. This is associated with an increase in TUNEL-staining of parasites. It is inhibited by most platelet activation inhibitors (aspirin, Prostaglandin E1, sodium nitroprusside, and the P2Y1 antagonist, MRS2179 as well as administration of aspirin to the platelet donor prior to platelet isolation. Interestingly, inhibition of P2Y12 by MRS2395 does not abrogate the growth inhibitory effect of platelets. Again, infected red cells preferentially bind platelets and there is an excellent correlation between the binding of platelets in infected cells and TUNEL positivity of the resident parasite. This data points strongly to the ability of platelets to kill intraerythocytic malarial parasites. In association with the specificity of binding to infected erythrocytes, this provides a further mechanism of innate immunity, mediated by platelets aimed at controlling the growth of malarial parasites. We surmise that its major impact will be early in infection, prior to the onset of significant parasitaemia or thrombocytopenia, at which stage parasite numbers will greatly outnumber platelets and this will not be an effect strategy.

Disclosures
No relevant conflicts of interest to declare.