bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low-Dose Alemtuzumab Is Uniquely Effective in Refractory Leukemic Cutaneous T Cell Lymphoma (L-CTCL).
Authors: Fisher David C. , Tawa Marianne , Walsh Michele , Clark Rachael A , Kupper Thomas S. 
Published: October 2019

Abstract
Abstract 3748
Poster Board III-684
Sezary Syndrome and other Cutaneous T Cell Lymphomas with peripheral blood involvement (collectively termed leukemic CTCL, or L-CTCL) are often refractory to multiple therapies. Alemtuzumab, an antibody directed against the pan-lymphocyte antigen CD52, has been used to treat multiple hematologic malignancies, including L-CTCL. However, conventional treatment regimens are associated with an increased risk of infections, and this is of particular concern in CTCL patients with compromised skin integrity. We have treated six L-CTCL patients with a modified regimen of alemtuzumab: 10mg/kg, subcutaneously, three times weekly for six weeks (1/3 of the conventional dose). All patients had had disease for >3 years duration, skin biopsies consistent with CTCL, elevated absolute CD4 counts, CD4/CD8 ratios of >10 and were refractory to at least two prior therapies, including extracorporeal photochemotherapy, interferon, and single and combination agent chemotherapy. In five of six patients, the malignant clone was identifiable using a Vb family specific monoclonal antibody; all cells of the malignant clonotype strongly expressed CD52. Within three weeks, all six patients achieved clearance of detectable T and B cells in peripheral blood, including loss of the malignant clone. In parallel, all patients developed clearing of erythroderma, relief of pruritus, and by the end of the six week treatment period, all patients had complete to near complete resolution of all clinical signs of disease. Isolation of T cells from a skin biopsy of one patient in complete remission revealed that <6% of T cells resident in skin expressed the malignant Vb subunit. At this reduced dose, no infectious complications were encountered. We conclude from that low-dose Aletuzumab is a well tolerated, safe, and highly effective therapy in a carefully selected population of patients with refractory L-CTCL.

Disclosures:
No relevant conflicts of interest to declare.
Cyclin A2 Plays a Critical Role Not Only in Self-Renewal of Hematopoietic Stem Cells, but Also in Non-Self-Renewing Proliferation of Lymphoid Progenitors.
Authors: Kohno Kentaro , Iino Tadafumi , Ito Kyoko , Mizuno Shin-ichi , Sicinski Piotr , Akashi Koichi 
Published: October 2019

Abstract
Abstract 381
Cyclins are regulatory subunits of cyclin-dependent kinase, and are important components of cell cycle engine. The A-type cyclin is generally the S-phase cyclin. Mammalian cells express two A-type cyclins, including cyclin A1 that is exclusively expressed in the testis, and cyclin A2 whose expression is ubiquitous. We have recently reported that cyclin A2 is not required for fibroblast proliferation but it is indispensable in maintenance of self-renewal of stem cells, including embryonic stem cells and hematopoietic stem cells (HSCs) (Cell 138 2009). The question is whether cyclin A2 plays a role in proliferation of hematopoietic progenitors downstream of the HSC. Here we further assessed the requirement of A-type cyclin in non-self-renewing hematopoietic progenitors. Quantitative RT-PCR analysis showed that cyclin A2 was expressed in hematopoietic stem and progenitor cells, but its expression level is highest in lymphoid-committed progenitor stages of both T and B cell lineages. Thus, in order to test the role of cylin A2 in early lymphopoiesis, we crossed cyclin A2 floxed mice with Rag1-Cre knock-in mice. Rag1 expression is initiated at the preproB to the proB stages, and the DN1-DN3 stages in the thymus, while their proliferation is dependent at least upon pre-BCR or pre-TCR signal at these stages. Interestingly, the Rag1-Cre cyclin A2 floxed/floxed mice were viable, and have normal numbers of HSCs and myeloid progenitors in the bone marrow. They, however, displayed severe reduction of T and B cell numbers that were only 1/100 - 1/10 of wild-type controls; the number of common lymphoid progenitor was unchanged, but there were almost complete loss of proB and preB cells. Similarly, all thymic T cell progenitor compartments such as CD4-CD8- double negative, and CD4+CD8+ double positive populations were severely reduced. These findings clearly demonstrate that cyclin A2 is indispensable not only for self-renewal of HSCs, but also for proliferation of T and B cell progenitors.

Disclosures:
No relevant conflicts of interest to declare.
Modulation of ER Stress/Unfolded Protein Response (UPR) Pathways in Multiple Myeloma Cells by Inhibition of Hsp90 and Serine-Threonine Kinase CK2.
Authors: Piazza Francesco , Manni Sabrina , Gurrieri Carmela , Colpo Anna , Tubi Laura Quotti , Cabrelle Anna , Trentin Livio , Semenzato Gianpietro 
Published: October 2019

Abstract
Abstract 3840
Poster Board III-776
Hsp90 is an essential chaperone molecule that helps in the maturation and folding of a number of cellular client proteins. Hsp90 function is essential for malignant plasma cell survival, since its inhibition in multiple myeloma (MM) cells results in cell death and activation of apoptosis. Clinical trials using Hsp90 inhibitors are currently ongoing in MM patients.
Hsp90 inactivation in MM cells causes perturbation of the endoplasmic reticulum (ER) stress/unfolded protein response (UPR), eventually triggering the apoptotic cascades. Protein kinase CK2 critically regulates the activity of the chaperone complex formed by the Cdc37 and Hsp90 proteins. We already described that CK2 is over-expressed in a fraction of MM patients and is an essential MM pro-survival molecule. We have here investigated its role in the ER stress/UPR pathways and in Hsp90 inhibition-induced apoptosis in MM cells.
Down-regulation of the catalytic CK2 alpha subunit with selective chemical inhibitors or RNA interference resulted in significant modifications of the main UPR regulating signaling cascades: 1) a marked reduction of IRE1alpha protein levels; 2) a reduction of BiP/GRP78 and Hsp70 chaperone protein levels; 3) an increase of PERK activity and phospho eIF2alpha levels. When UPR was triggered by thapsigargin in CK2-inactivated cells, we observed that the IRE1alpha-dependent axis of the UPR was greatly impaired, as XBP-1short isoform generation and the levels of some induced chaperones were reduced. Interestingly, thapsigargin was able to induce CK2 kinase activity. Remarkably, treatment of CK2-silenced MM cells with Hsp90 inhibitors geldanamycin or its derivative 17-AAG (17-(demethoxy)-17-allylamino geldanamycin) resulted in 1) an even more pronounced reduction of IRE1 alpha protein levels; 2) a marked inhibition of GA or 17-AAG-triggered BiP/GRP78 protein level raise; 3) a more evident increase of eIF2 alpha phosphorylation. Of note, CK2 plus Hsp90 inhibition was followed by apoptotic cell death to a much greater extent than that obtained with the single inhibition of the two molecules. Noteworthy, these effects were also reproduced upon modelling the MM bone marrow (BM) microenvironment by co-culturing MM cells with BM stromal cells.
These data suggest that CK2-mediated signaling regulates the ER stress/UPR pathways and modulates the threshold to apoptosis of ER stressed MM cells. CK2 interacts with Hsp90, since its inhibition synergizes with GA or 17-AAG treatments in terms of induction of apoptosis and shift of the ER stress/UPR pathways towards the terminal phase. These results might be useful to set the groundwork in designing novel combination treatments for MM patients.

Disclosures:
No relevant conflicts of interest to declare.
Pomalidomide Monotherapy for Relapsed Myeloma Is Associated with Excellent Responses and Prolonged Progression Free and Overall Survival.
Authors: Streetly Matthew , Stewart Orla , Gyertson Kylie , Kazmi Majid A. , Schey Steve 
Published: October 2019

Abstract
Abstract 3878
Poster Board III-814

Introduction
Despite recent therapeutic improvements in the management of myeloma it remains an incurable disease. New therapies are therefore required. Pomalidomide (POM, Celgene) is a thalidomide derived immunomodulatory agent with similar preclinical spectrum of activity as lenalidomide. In Phase 1 studies we have previously demonstrated that POM monotherapy is well tolerated by patients with relapsed myeloma determining a maximum tolerated dose of 2mg od or 5mg on alternate days (Schey et al. JCO 2004; Streetly et al. BJHaem 2008). The toxicity profile was acceptable and overall response rates of 54 and 50% were observed with daily and alternate day dosing respectively. The current study examines long term responses, progression and survival outcomes. Patients were entered into the POM daily dosing or alternate day dosing Phase 1 studies between March 2001 and September 2003 and continued to receive treatment with POM until progressive disease (PD) or Grade 3 or greater non-haematological toxicity. Patients with PD were eligible to receive dexamethasone in addition to POM. POM became unavailable in May 2005 and patients still receiving drug were switched to receive lenalidomide. All patients gave informed consent.

Results
44 patients received treatment with POM at a dose of 1mg alternate days – 10mg od. A median of 3 (range 1 – 8) prior lines of therapy had been received. POM was received for a median of 9.3 months (1 – 53). Following POM withdrawal 8/44 patients who had not developed PD subsequently received lenalidomide from a median of 30 months after starting POM. Overall responses by IMWG criteria to POM monotherapy were: CR 13.6%, VGPR 4.5%, PR 34%, MR 9%, SD 29.5% and PD 7% giving an overall response rate (>PR) of 52%. Dexamethasone was introduced for PD for 10 patients and prolonged SD for 1 patient. 5/10 of these patients had >MR response to the addition of dexamethasone. With a median follow-up of 28 months the median PFS was 13.7 months and median OS was 28 months. Patients who had a PR response or better received POM for a median of 17.5 months and had improved PFS (median 19.8 months) and OS (median 42 months). 8/44 patients subsequently received lenalidomide. 7/8 of these patients have now developed PD at a median 26 months from commencing lenalidomide and 74 months from starting POM.

Conclusions
POM is a very well tolerated drug with excellent long term responses observed in this Phase 1/2 setting predominantly as monotherapy. Phase 2 studies are ongoing and results of these are awaited with interest.

Disclosures:
Streetly: Celgene: Honoraria. Schey:Celgene: Honoraria.
AML-1/RUNX-1 Is Overexpressed in Patients with Myeloproliferative Neoplasms and Mediates JAK2 V617F-Independent Overexpression of NF-E2.
Authors: Wang Wei , Schwemmers Sven , Pahl Heike L 
Published: October 2019

Abstract
Abstract 3893
Poster Board III-829
The transcription factor nuclear factor erythroid-2 (NF-E2) plays an essential role in both erythropoiesis and megakaryopoiesis. In addition to erythroid, megakaryocytic and granulocytic progenitors, NF-E2 is expressed in hematopoietic stem cells and in mature granulocytes. We have previously shown that NF-E2 is overexpressed in the vast majority of patients with polycythemia vera (PV). Concomitantly, 90 – 95% of these patients carry the JAK2V617F point mutation. Even though NF-E2 levels correlated with JAK2V671F allele burden in some PV cohorts, the molecular mechanism causing aberrant NF-E2 expression in PV patients has not been described. Here we show that NF-E2 expression is also increased in patients with Essential Thrombocythemia (ET) and that this is independent of the presence of the JAK2V617F mutation. Characterization of the NF-E2 promoter revealed multiple binding sites for Acute Myeloid Leukemia-1 (AML-1/RUNX-1), which were shown to be functional by deletion analysis and site directed mutagenesis. Chromatin Immunoprecipitation (ChIP) demonstrated AML-1 binding to the NF-E2 promoter in vivo. Moreover, AML-1 binding to the NF-E2 promoter in vivo is significantly increased in primary granulocytes from PV patients compared to healthy controls. Subsequently, we demonstrated that mRNA and protein expression of AML-1 is elevated in PV and ET patients, both in the presence and absence of JAK2V617F. In addition, AML-1 and NF-E2 expression are highly correlated. RNAi-mediated suppression of AML-1 levels significantly decreased NF-E2 expression. In summary, our data identify NF-E2 as a novel AML-1 target gene and point to a role of aberrant AML-1 expression in mediating elevated NF-E2 expression in MPN patients.

Disclosures:
No relevant conflicts of interest to declare.
Generation and Characterization of Transgenic Mice Expressing MplW515L.
Authors: Zhao Wanming , Xing Shu , Gao Rufei , Al-Kali Aref , Ho Wanting Tina , Zhao Zhizhuang Joe 
Published: October 2019

Abstract
Abstract 3901
Poster Board III-837
Myeloproliferative neoplasias (MPNs) are a group of conditions characterized by chronic increases in some or all of the blood cells (platelets, white blood cells, and red blood cells). JAK2V617F, a gain-of-function mutation of tyrosine kinase JAK2, is found in over 90% of patients with polycythemia vera (PV) and about 50% of patients with essential thrombocythemia (ET) and primary myelofibrosis (PMF). Attempt to identify other signaling components involving the JAK2 signaling pathways has led to discovery of acquired mutations of Mpl, the receptor of thrombopoietin, in 5-10% patients with PMF and ET. To prove the pathogenesis of Mpl mutants, we have generated transgenic mice expressing the most frequently occurred Mpl mutant designated MplW515L by using the vav gene promoter which drives expression of transgenes in the hematopoietic system. We obtained three lines of MplW515L transgenic mice which all displayed similar hematological abnormalities. As expected, the mice developed ET- and PMF-like phenotypes with much elevated platelet counts, severe splenomegaly/hepatomegaly, and bone marrow/spleen myelofibrosis. Interestingly, these mice also had markedly increased white blood cells in the peripheral blood, majority of which are IgD-positive mature B-cells. Histochemical staining and flow cytometric analyses revealed infiltrations of megkaryocytes and B cells into the spleen, the presence of megkaryocytes and erythroid blast cells in the liver, and infiltrations of the bone marrow with B-cells. Reticulin staining revealed that MplW515L transgenic mice developed profound myelofibrosis in the bone marrow and spleen. In vitro hematopoietic colony assays demonstrated increased numbers of hematopoietic progenitor cells including BFU-E, CFU-GM, CFU-Mk, and CFU-Pre-B in the bone marrow, mobilization of these stem/progenitor cells to peripheral blood and spleen, and their autonomous growth in the absence of growth factors and cytokines. Finally, transplantation of bone marrow cells from MplW515L mice into irradiated normal mice installed the aforementioned phenotypes into the recipient mice, indicating that expression of MplW515L altered the activity of hematopoietic stem cells. Together, our data demonstrated that transgenic expression of MplW515L not only causes PMF- and ET-like phenotypes but also lymphoproliferative disorders. Considering that Mpl is expressed in hematopoietic stem cells and that oncogenic gene mutations are often associated with alteration of gene expression, we believe that MplW515L may be involved in a wider spectrum of human hematological diseases than MPNs.

Disclosures:
No relevant conflicts of interest to declare.
Weight Loss, Splenomegaly, and Hypocholesterolemia in Myeloproliferative Neoplasms: Patterns and Relevance from the Pre JAK2 Inhibitor Era.
Authors: Mesa Ruben A. , Schwager Susan , Huang Jocelin , Pardanani Animesh D. , Hussein Kebede , Camoriano John , Tefferi Ayalew 
Published: October 2019

Abstract
Abstract 3918
Poster Board III-854

BACK GROUND
We have previously demonstrated that the myeloproliferative neoplasms (MPNs) of primary myelofibrosis (PMF), polycythemia vera (PV), and essential thrombocythemia (ET) can lead to weight loss, splenomegaly and constitutional symptoms (Cancer 2007;109:68–76). Additionally we have demonstrated that hypocholesterolemia in MPN patients is associated with decreased survival (Blood 2007;110:a2548). Given that current JAK2 inhibitor trials are demonstrating the ability to reverse MPN associated splenomegaly (Haematologica 2009;94(Suppl 2)439 a1088) and cachexia (Blood 2008;112(11):a1760) we sought to determine the baseline natural history for these variables in patients treated prior to the JAK2 inhibitor era.

METHODS
We analyzed the Mayo MPN database for patients (not treated with JAK2 inhibitors) with information on disease prognosis, presentation, therapies, height and weight at diagnosis, and outcomes. Additionally, when available, we analyzed additional weights during the clinical course, the body mass index (BMI- (weight/(height*height)), spleen size, and peripheral blood studies including lipids.

Results: Patients
783 patients with MPNs (followed for a median of 51 months (range 1-871 months); 60% having expired) were identified for the analysis (PV=158, ET=255, PMF=370) with 541 (69%) having a weight at the time of diagnosis, the remainder had a weight obtained a median of 7.8 months after diagnosis. Additionally, 508 patients (65%) had a weight value available from 1–3 additional time points during the course of their disease. Corresponding measurements of splenomegaly, or absence thereof, were noted in 766 cases (98%). Lipid panels (obtained within 18 months of diagnosis) were available in 264 patients. Results by MPN disease type are listed in the Table.

Impact on prognosis
Univariate analysis of variables discussed which negatively impacted survival included the subtype of MPN (not surprisingly worse for PMF p<0.001), weight loss of greater than 10% during the course of follow-up (P<0.001), or development of splenomegaly of >10 cm below the left costal margin (p=0.004) whereas hypocholesterolemia was significant only for the subset of PMF patients (P=0.03). The IWG-MRT International Prognostic Score (IPSS - Cervantes et. al. Blood 2009) was the only variable prognostically relevant in multivariate analysis (P<0.001).

Conclusions
Progressive splenomegaly, weight loss, and hypocholesterolemia are common across all MPNs but are most prognostically detrimental in PMF. Ongoing and future trials of JAK2 inhibitors will answer whether reversal of these latter hypercatabolic and proliferative manifestations of disease will improve outcomes for MPN patients.

Disclosures:
No relevant conflicts of interest to declare.
High Incidence of Hepatitis B or C Virus Infection in Lymphoma.
Authors: Tajima Katsushi 
Published: October 2019

Abstract
Abstract 3934
Poster Board III-870

Introduction
In lymphoma, several reports from different countries have shown that patients with lymphoma have a higher prevalence of HCV or HBV infection. The infection rates were very different even in virus endemic areas as Asia-Pacific countries including Japan. However, an association between virus infection and lymphoma should be evaluated and discussed with the background of virus prevalence in the community. This study aimed to investigate the prevalence of HBV or HCV infection status in lymphoma patients in Tohoku distinct in Japan.

Patients and Methods
The study, designed by the Tohoku Hematology Forum Group, was conducted in 9 clinical centers in Tohoku Distinct in Japan. This study included 1331 newly diagnosed consecutive series of lymphoma patients admitted in Tohoku Hematology Forum Group Hospital (Japan) and 848 non-lymphoma control patients enrolled from January 2005 to October 2008. We evaluated the prevalence of HBV (as indicated by hepatitis B surface antigen) or HCV infection in both group patients and compared the clinic-pathological characteristics of HBV- or HCV-positive and its negative lymphoma cases.

Results
The carrier rate of HBsAg was higher in lymphoma patients (57 of 1331, 4.3%) than control group (1.7%, p <0.001) The higher prevalence was observed in both sexes and especially diffuse large B cell lymphoma. Compared with HBV negative lymphoma group, the positive group displayed more liver or spleen involvement (p=0.002). The rate of HCV infection was higher than those in control group In HCV-infected case, more liver involvement was indicated (p<0.004). No difference in HBV or HCV prevalence was found between B-cell and T/NK-cell lymphoma.

Conclusions
The present study, so far the largest trial of incidence of HBV or HCV infection in lymphoma patients, demonstrated that patients with lymphoma in Japan had higher prevalence of HBV and HCV infection. These appears to be a possible role for HBV or HCV in the induction of malignant transformation, resulting in the development of lymphoma. However, the precise role of HBV or HCV in the pathogenesis of lymphoma remains to be elucidated and warrants further research.

Disclosures:
No relevant conflicts of interest to declare.
Divergent Effects of Notch Signaling On Leukemia Stem Cells and Hematopoietic Stem Cells.
Authors: Chiang Mark Y , Shestova Olga , Childs M. Eden , Romany Candice , Aster Jon , Pear Warren S. 
Published: October 2019

Abstract
Abstract 395
The Leukemia Stem Cell (LSC) hypothesis proposes that a subset of the cells in the bulk tumor cell population is responsible for leukemia maintenance and propagation. We tested the LSC hypothesis in murine T-cell acute lymphoblastic leukemia/lymphoma (T-ALL) induced by retroviruses expressing strong gain-of-function Notch1 alleles. This model is relevant to human disease, as Notch1 is activated in ∼70% of human T-ALLs. By transferring sorted leukemia cells to syngeneic secondary recipients at limiting dilution, we found that LSC activity was enriched in the CD8+CD4-HSAhi (Immature Single Positive or “ISP”) T-cell subset. The LSC frequency was ∼1 in 1000 cells, two orders of magnitude higher than in the CD8+CD4+ (Double positive or “DP”) T-cell subset. We found similar results in a KrasG12D-driven T-ALL mouse model where activating Notch mutations occur spontaneously in ∼80% cases. Surprisingly, we were unable to isolate Notch-activated hematopoietic stem and progenitor cells (HSPCs) to test for LSC activity. Upon further analysis, we observed that activation of Notch in HSPCs caused loss of stem cell quiescence and progressive, complete loss of long-term hematopoietic stem cells (LT-HSCs) over several weeks. Notch signals had no significant effects on stem cell homing, apoptosis, or senescence. Similar results were obtained in both noncompetitive and competitive secondary transplants as well as in a mouse model in which Notch activation is conditionally induced in HSCs by Cre recombinase. We conclude that while Notch signaling promotes LSC activity, it extinguishes HSCs. These results provide a rationale for therapeutic targeting of the ISP-like T-cell subset in Notch-activated T-ALL while underscoring the potential difficulty of manipulating Notch signaling to expand normal, long-term stem cell populations for clinical applications.

Disclosures:
No relevant conflicts of interest to declare.