bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preliminary Experience of the Spanish Compassionate Use Registry of Bendamustine in Patients with Relapsed and/or Refractory Multiple Myeloma
Authors: Bueno Beatriz Aguado , Andres Isabel VicuÑa , Entrena Laura , De Arriba Felipe , Krisnik Isabel , Navas BegoÑa , Callejas Marta , Teruel Anabel , Lopez Aurelio , Lopez Tomas Gonzalez , Castillo Inmaculada , De Oteyza Jaime Perez , De Miguel Dunia , Calvo Sara Rivas , Posada Raquel Rodriguez , Alegre Adrian 
Published: October 2019

Abstract
Abstract 4035

Introduction:
Bendamustine is a dual alkylating agent with demonstrated efficacy in de novo multiple myeloma (MM) and in relapsed/refractory (R/R MM). We present the preliminary results from the experience of Spanish compassionate use registry of this agent in different treatment schedules of R/R MM, promoted by the GEM/PETHEMA Group (Benda-MMRR-11). This study has been approved by local ethical committee, CEIC, HUP, Madrid, Spain.

Patients and Methods:
72 patients, 42 males and 30 females, with advanced R/R MM after several lines of previous treatment received a schedule containing Bendamustine (Levact®, Mundipharma, UK). Median age was 66 (35–86), with a median of 4 previous salvage lines (1–11). Bendamustine dose used ranged between 60 and 120 mg/m2 iv on days 1 and 2 for each 28 days cycle. The median of cycles was 2 (1–9). The combinations used were: Bendamustine + Prednisone in 27 patients, Bendamustine + Thalidomide + Prednisone in 11 cases, Bendamustine + Dexamethasone in 14 patients, Bendamustine + Bortezomib + Dexamethasone in 7 patients, Bendamustine + Bortezomib + Prednisone in 3 patients, Bendamustine + Thalidomide + Dexamethasone in 2 cases, Bendamustine monotherapy in 5 patients, Bendamustine + Thalidomide in 1 case, Bendamustine with Caelyx in 1 case and Bendamustine with Rituximab in 1 case.

Results:
In the 69 evaluable patients, the response was: overall response rate (ORR) 30.24%%, with complete response (CR) 11.5%, partial response (PR) 13.04%. Minimal response (MR) was 5.7%, and stable disease (SD) was 17.39%. Progression was documented in 52.1% of patients. In general, treatment was well tolerated; the most common adverse effect was hematological toxicity with grade 3–4 neutropenia in 31.8%, grade 3–4 thrombocytopenia in 30.4% and grade 3–4 anemia in 17.3%. Other toxicities included grade 3–4 infections in 27% of patients and grade 3–4 asthenia in 11.5%. Clinical results will be updated with more details regarding TTP, OS and efficacy and toxicity with each schedule.

Comments:
Bendamustine is an effective salvage therapy in patients with advanced R/R MM. Our results are consistent with previous published data in larger series of patients. More experience is needed with this agent to define the best combination and to assess its grade of efficacy that will be probably superior in earlier stages of myeloma evolution.

Disclosures:
Off Label Use: compassionate use.
Phagocytosis Is A Mechanism of Action for Daratumumab
Authors: Overdijk Marije B. , Verploegen Sandra , Marijn Bögels , van Egmond Marjolein , Groen Richard W.J. , Martens Anton C.M. , van Bueren Jeroen Lammerts , Bleeker Wim , Parren Paul W.H.I. 
Published: October 2019

Abstract
Abstract 4054
Daratumumab (DARA) is a human IgG1 CD38 antibody with broad-spectrum killing activity. DARA induces killing of CD38-expressing tumor cells, including fresh cells from multiple myeloma (MM) patient samples, via diverse mechanisms. These prominently include the Fc-dependent effector mechanisms complement-dependent cytotoxicity (CDC) and antibody-dependent cell-mediated cytotoxicity (ADCC) (de Weers et al. J. Immunol. 2011). In this study we show that DARA is also able to induce tumor cell killing via antibody-dependent cellular phagocytosis (ADCP) as an additional Fc-dependent effector mechanism.
In a first set of experiments, we studied ADCP with human macrophages as effector cells. Calcein-AM-labeled Daudi tumor cells, a Burkitt's lymphoma cell line, were mixed with human macrophages in the absence or presence of DARA. Specific DARA-induced phagocytosis was analyzed in flow cytometry by measuring the percentage of calcein-AM+/CD11b+ double-positive (DP) macrophages. Both classical GM-CSF activated and alternative M-CSF activated macrophages mediated DARA-specific ADCP of the Burkitt's lymphoma cells. To further explore the in vivo contribution of ADCP in the mechanism of action (MoA) of DARA, we studied DARA mediated phagocytosis with murine macrophages. In vitro ADCP with M-CSF-stimulated bone marrow-derived murine macrophages showed a dose-dependent DARA-specific effect on the Burkitt's lymphoma cell lines Ramos and Daudi, resulting in up to 24% and 43% DP macrophages and a 25% and 50% tumor cell reduction, respectively. Furthermore, dose-dependent DARA-specific phagocytosis was observed with patient-derived MM cell lines L363 and UM9, which were transduced with CD38 to obtain levels CD38 expression as they are generally observed in primary MM patient samples. With life-cell imaging we found that ADCP of Daudi and Ramos cells occurred very rapid and efficiently. Interestingly, our recordings document that single macrophages could engage multiple target cells and that they were able to engulf up to six tumor cells sequentially in a 30 min period. This suggests that ADCP might be a very potent MoA of DARA in vivo, which we are currently studying in a mouse xenograft model.
In conclusion, in addition to CDC and ADCC, we now show that DARA can also induce killing of CD38 expressing tumor cells via phagocytosis. This very fast and potent MoA might contribute to the treatment efficacy of DARA in hematological tumors, especially at sites where high numbers of macrophages reside, such as the bone marrow.

Disclosures:
Overdijk: Genmab BV: Employment. Verploegen:Genmab BV: Employment. Groen:Genmab BV: Research Funding. Martens:Genmab BV: Research Funding. Lammerts van Bueren:Genmab BV: Employment. Bleeker:Genmab BV: Employment. Parren:Genmab BV: Employment.
The Novel Anti-Myeloma Agent Chaetocin Enhances Tumor-Specific Dendritic Cell Response Via the Induction of Heat Shock Protein and Cancer Testis Antigens On Myeloma Cells
Authors: Nguyen-Pham Thanh-Nhan , Lee Hyun Ju , Tran Huong Thi Thanh , Vo Manh-cuong , Hoang My-Dung , Choi Nuri , Kim Hyeoung-Joon , Lee Je-Jung 
Published: October 2019

Abstract
Abstract 4066

Background:
Dendritic cell (DC) based immunotherapy is emerging as a useful tool to treat multiple myeloma (MM). Although several tumor target antigens have been used, the clinical effectiveness of the vaccination is still limited. Chaetocin is a small molecule thiodioxopiperazine natural-product produced by Chaetomium species fungi currently in development as a candidate antimyeloma therapeutic, and has potent in vitro and in vivo activity conveyed by its ability to impose increased levels of cellular oxidative stress. Chaetocin has also been found to be used as histone methyl-transferase inhibitor with interest in the compound sufficient to kill various cancer cells. We investigated whether chaetocin could be used to induce apoptotic bodies for loading into DCs to enhance myeloma specific antitumor responses.

Methods:
Chaetocin was used to induce the apoptotic U266 myeloma cells, which were used as the sources of tumor antigens to loading onto DCs to generate myeloma-specific cytotoxic T lymphocytes (CTLs).

Results:
Chaetocin showed to induce apoptotic cells mostly from tumor cells and led to increase the expression of heat shock protein 90 (HSP90) at a level comparable to bortezomib. The transfer of activating signal from chaetocin-induced tumor cells to induce DCs maturation is mediated by the exposure of HSP90 on the surface of apoptotic cells. The HSP90 inhibitor geldanamycin can block this immunogenicity. Chaetocin up-regulate the expression of cancer testis antigens MAGEA3 and MAGEC1/CT7, which are commonly expressed in MM and the potent targets for active immunotherapies. The cytokines production during uptake tumor antigens and maturation was comparable in DCs loaded with either irradiated MM cells or chaetocin-induced MM cells. However, DCs loaded with chaetocin-induced MM cells can reduce the production of an inhibitory cytokine (IL-10) after stimulation with CD40 ligand. CTLs stimulated by chaetocin-induced MM cells-loaded DCs showed the increasing of CD8+T cells and displayed a greater number of IFN-g-secreting cells than did those stimulated by other DCs loaded with MM cell made by other conditions.

Conclusion:
These results indicate that anti-myeloma drug-induced apoptotic cells can be used as the source of myeloma antigens to loading onto DCs that could elicit potent anti-myeloma activity of CTLs due to the expression of heat shock proteins and cancer testis antigens as a mechanism of immunogenic death of human MM cells.

Disclosures:
No relevant conflicts of interest to declare.
Alcam Mediated Interaction Regulates Normal Hematopoietic Stem Cell Function and Cbfβ-SMMHC Induced Leukemogenesis
Authors: Jeannet Robin , Cai Qi , Liu Hongjun , Vu Hieu , Kuo Ya-Huei 
Published: October 2019

Abstract
Abstract 4091
The inv(16) acute myeloid leukemia (AML)-associated CBFβ-SMMHC fusion protein impairs hematopoietic differentiation and predisposes to leukemic transformation. Alcam, which encodes the activated leukocyte cell adhesion molecule (CD166), is a cell surface immunoglobulin superfamily member mediating homophilic adhesion as well as heterotypic interactions with CD6. We found that Alcam expression marks long-term repopulating HSCs (LT-HSC), multipotent progenitors (MPP), a subset of granulocyte-macrophage progenitors (GMP), and that Alcam expression is lost or reduced in subsets of pre-leukemic and leukemic progenitors expressing the Cbfβ-SMMHC fusion protein. We characterized the role of Alcam in HSC differentiation and self-renewal using an Alcam-null (Alcam−/−) mouse model (Weiner et al. 2004 Mol Cell Neurosci 27:1, 59–69). We show that Alcam is highly expressed in LT-HSCs where its level progressively increases with age. Young adult Alcam−/− mice had normal homeostatic hematopoiesis, and normal numbers of phenotypic HSCs. However, Alcam−/− HSCs had reduced long-term replating capacity in vitro and reduced long-term engraftment potential upon transplantation. We show that Alcam−/− BM contain a markedly lower frequency of long-term repopulating cells than wild type (WT). Further, the long-term repopulating potential and engraftment efficiency of Alcam−/− LT-HSCs was greatly compromised despite a progressive increase in phenotypic LT-HSC numbers during long-term serial transplantation. In addition, an age-associated increase in phenotypic LT-HSC cellularity was observed in Alcam−/− mice. This increase was predominately within the CD150hi fraction, and was accompanied by significantly reduced leukocyte output. Moreover, Alcam−/− LT-HSCs display premature elevation of Selp expression, a hallmark of HSC aging. To understand the role of Alcam in leukemic transformation, we generated conditional Cbfb-MYH11 knock-in (Cbfb56M/+/Mx1-Cre), Alcam-deficient (Alcam−/−) mice. Interestingly, we found that loss of Alcam drastically delayed or reduced leukemia incidence. Transplantation of Alcam−/−/Cbfb56M/+/Mx1-Cre pre-leukemic bone marrow cells into WT recipients also led to delayed and reduced incidence of leukemia development. These results suggest that Alcam contributes to leukemia transformation in a cell-intrinsic manner. Collectively, our study reveals that Alcam regulates the functional integrity and self-renewal of LT-HSCs, and contributes to leukemia initiation induced by CBFβ-SMMHC.

Disclosures:
No relevant conflicts of interest to declare.
Prophylactic Use of Enoxaparin in Morbidly Obese Adolescents During Bariatric Surgery
Authors: Mushtaq Alvina , Vaughns Janelle D , Verdun Nicole , Williams Elaine , Ziesenitz Victoria , Nadler Evan P , van den Anker John 
Published: October 2019

Abstract
Abstract 4367

Introduction:
Obesity has increased exponentially in recent years and currently a substantial number of children and adolescents are morbidly obese. This development has resulted in the need for bariatric surgery in adolescents. Therefore, a bariatric surgery program has been initiated at Children's National Medical Center (CNMC) and enoxaparin has been used as prophylaxis for venous thromboembolism (VTE). Enoxaparin is the drug of choice for prevention and treatment of VTE in children and adults. The standard of care at CNMC is to dose enoxaparin 40 mg SC q 12 hrs in patients with a BMI < 50 and 60 mg SC q 12 hrs for patients with a BMI > 50 with no routine use of anti-FXa monitoring. Nationally and internationally there are no well defined guidelines for prophylactic doses of enoxaparin and the approach varies among different institutions. This study was therefore designed and conducted to investigate if the current dosing regimens are indeed appropriate.

Patients and Methods:
Four morbidly obese adolescents aged 16 to 18 years and with a body weight ranging between 118 and 174 kg were studied. Anti-FXa assay concentrations were collected before (predose) and at 1, 2, 4, 6, and 12 hrs after the administration of the first dose of enoxaparin. In addition, after an extensive literature search, two pharmacokinetic (PK) studies were found that investigated comparable doses of enoxaparin in adult lean healthy volunteers with a mean age of 24 years.

Results:
The results are shown in Figure 1 and Table 1. The peak anti-FXa level (Cmax) ranged from 0.2–0.23 IU/ml in the 4 studied adolescents and these values are significantly lower as compared to the range of concentrations (0.38–0.5 IU/ml) detected in the two control groups from the literature. The time to reach Cmax (T max) was delayed, along with a lower area under the time vs concentration curve and the mean residence time.

Conclusions:
We conclude, based on our results, that the use of 40–60 mg enoxaparin as the current standard of care for VTE prophylaxis in morbidly obese adolescents results in different and probably insufficient anti-FXa levels as compared to those found in lean patients of comparable age. The clinical significance of this finding still needs to be determined.

Disclosures:
No relevant conflicts of interest to declare.
Galactorrhea and Acute Lymphoblastic T-Cell Leukemia: A Case Presentation and Evaluation of the Role of Prolactin
Authors: Grimes Allison C 
Published: October 2019

Abstract
Abstract 4828
Acute lymphoblastic T-cell leukemia (T-ALL) accounts for nearly 15% of newly diagnosed cases of childhood acute lymphoblastic leukemia (ALL). Historically, T-ALL has conferred a worse prognosis than other forms of ALL. Although multi-agent pulse chemotherapy has improved EFS over the past several decades, the lack of clinical or laboratory based prognosticators as well as high rate of relapse have remained barriers in management. Described is a case of acute lymphoblastic T-cell leukemia in a previously healthy sixteen-year-old girl initially presenting with galactorrhea and hyperprolactinemia without evidence of CNS infiltrate. Although galactorrhea has been described in a few adults as an initial presentation of acute myeloginous leukemia (AML) and a single adult case of T-cell lymphoma, to date there has been no association with childhood cancers or T-ALL in particular. Hypothesized in AML cases as a rare paraneoplastic phenomenon, this case explores this theory and employs direct prolactin staining of tumor cell cytoplasm, serial prolactin monitoring throughout treatment, and investigation into underlying causes for hyperprolactinemia in the context of T-ALL. The possibilities for prolactin as a novel tumor marker are explored.

Disclosures:
No relevant conflicts of interest to declare.
Pilot Study of Sorafenib for Myelodysplastic Syndrome
Authors: Rao Arati , Rizzieri David A. , Vanegas Eduardo , Moore Joseph O. , Gockerman Jon P. , Diehl Louis F. , Adams Donna , Warzecho Julie , Decastro Carlos 
Published: October 2019

Abstract
Abstract 4948

Background:
MDS (Myelodysplastic syndrome) is a hematologic malignancy in which one or multiple conditions affects the fabrication (or dysplasia) of the myeloid class of blood cells. While treatable, therapies provide short term benefit and are not considered curable, short of an allogeneic stem cell transplant. The RAS pathway has been noted to be abnormally regulated in many malignancies, including MDS and AML. Thus, we performed a phase 2 efficacy study using sorafenib, a RAS inhibitor, for patients with MDS by WHO criterion.

Methods:
Adults with primary or secondary MDS, estimated CrCl >30 ml/min, and liver function tests 2 2. 5 × ULN were eligible. Patients of all IPSS risk categories were included. Patients received Sorafenib 400mg po bid daily for 28 days for a 28 day cycle (continuous therapy) and continued till progression or withdrawal for toxicity. Patients were evaluated after the first 2 cycles for response and then every 3 cycles thereafter until an endpoint was reached (up to five years).

Results:
Patient and disease characteristics are noted in the table below. Sixteen evaluable patients were treated on study: median 71 (range 56–88 years), median time from diagnosis to starting this study was 34 months (range 9–103 months), median number of prior therapies was 2 (range 0–6), median number of cycles on study was 1. 5 (range 1–7). Responses lasted for 4 months in 4 and a year in 1.
The agent was tolerated in this population though some toxicities were notable: 2 (12%) had grade 2 rash (though many with grade 1), 5 with grade 2 (31%) and 1 (6%) grade 3 nausea, vomiting or diarrhea, 2 (12% with grade 2 and 1 (6%) with grade 3 liver function abnormalities, and 1 (6%) grade 4 myositis likely related to the agent. Unfortunately, many of the toxicities occurred shortly after initiating therapy, leading to early withdrawal from therapy before a full cycle and evaluation for response could be performed.

Conclusions:
Sorafenib was tolerated and provided some responses in this difficult to treat group of unselected patients. Due to many early withdrawals, the study was terminated early. Utility would be enhanced in future studies by devising methods to apriori select this targeted therapy for those most likely to respond.

Disclosures:
No relevant conflicts of interest to declare.
Drp1 Activation Overcomes Diffuse Large B-Cell Lymphoma Cells Radioresistance
Authors: Pang Qingsong , Liu Ningbo , Liu Fengting , Agrawal Samir , Wang Ping 
Published: October 2019

Abstract
Abstract 5121
Mitochondria undergo fusion and fission in response to physiological or pathological changes. Mitochondrial fusion is regulated by mitofusin-1 and 2 (MFN-1/2) and optic atrophy 1(OPA-1), whereas, mitochondrial fission (or fragmentation) is controlled by a Dynamin-related protein 1 (Drp1). Drp1 activation is triggered by dephosphorylation of Drp1 on its serine 637 site. Recent studies demonstrated that Drp1 activation plays an important role in mitochondrial fragmentation-induced cell death. The phosphorylation of Drp1 by serine kinase inhibits its GTPase activity and prevents mitochondrial fragmentation. Inhibition of Drp1 activation or loss of Drp1 function leads to slow down apoptosis and necrosis.
Recent reports showed that patients who received consolidative radiotherapy (RT) combine R-CHOP had significant better 5-year event-free and overall survival rates than patients with diffuse large B-cell lymphoma who did not receive RT combination therapy. Although RT combination therapy significant increased survival of DLBCL, the mechanisms of RT induced cell death are reminded unclear.
In this study, we investigated the roles of Drp1 activation in the sensitivity of DLBCL cells to radiotherapy. Radiation causes damage in both nuclear and mitochondrial DNAs and generation of reactive oxygen species (ROS) followed by caspase activation. In the radio-resistant DLBCL cells, radiation induced activation of Drp1, and led to mitochondrial fragmentation, caspase-3 activation and cell death. However, the sensitive DLBCL cells underwent cytochrome c release, caspase-3 activation and PARP cleavage but not the activation of Drip1. To confirm the role of Drp1 activation in radiation-induced cell death on radio-resistant cells, Drp1 was dephosphorylated by a serine kinase inhibitor STS. Co-treatment of radio-resistant DLBCL cells with STS and radiation greatly enhanced mitochondrial fragmentation and significantly increased the sensitivity of radio-resistant DLBCL cells to radiation-induced caspase-3 activation, PARP cleavage and apoptotic cell death. However, co-treatment with STS did not further increase the sensitivity of radio-sensitive cells to caspsase-3 activation and cell death. Our data indicate that radiation-induced cell death in radio-resistant DLBCL cells is regulated by Drp1. We therefore propose that Drp1 could be a potential target for overcoming radio-resistance.

Disclosures:
No relevant conflicts of interest to declare.
SF3B1 Mutations in CLL Are Equivalent to p53/ATM Dysfunction and Cause Defective Puma Upregulation in Response to Chemotherapy
Authors: te Raa Doreen , Derks Ingrid AM , Luijks Dieuwertje M , van Laar Jacoline , Monsuur Hanneke , Oldreive Ceri , Jethwa Alexander , Hüllein Jennifer , Stankovic Tatjana , Zenz Thorsten , Van Oers Marinus H.J. , Kater Arnon P. , Eldering Eric 
Published: October 2019

Abstract
Abstract 711
Mutations or deletions of the tumor suppressor p53 or its upstream kinase ATM are well-known determinants of poor prognosis in Chronic Lymphocytic Leukemia (CLL). In recent years, genome wide sequencing has uncovered novel gene mutations that correspond with poor prognosis. Specifically, recurrent mutations in the splicing factor SF3B1 and the Notch and NRAS/KRAS oncogenes have been found. These mutations were (in part) mutually exclusive with p53 and/or ATM mutations, which suggested overlap in biological function.
Here, we report results of a comparative analysis of p53 target genes and in vitro drug responses in CLL samples with either p53 (n=9), ATM (n=10), SF3B1 (n=11), Notch (n=6), or NRAS/KRAS (n=4) gene deletions/mutations. We found that upon irradiation, mRNA induction of all tested p53 targets genes (p21, Puma, CD95, Bax, PCNA, FXDR) was clearly decreased in all SF3B1 mutated CLL samples (overall p<0.001). SF3B1 samples resembled ATM mutated/11q− CLL in displaying a defective but not absent p53 response. In contrast, Notch and KRAS/NRAS mutations did not affect RNA induction of apoptosis inducers Puma and Bax. At the protein level, Puma and p21 induction were defective or absent in SF3B1 mutated CLL. This corresponded with decreased apoptosis after in vitro treatment with fludarabine. Treatment with nutlin, either alone or in combination with fludarabine, restored cell death induction, again indicating an overlap with ATM dysfunction. To establish possible causality between SF3B1 mutation and ATM dysfunction, more genetic and functional studies are ongoing and will be reported.
In conclusion, the recently described mutations in a splicing factor in CLL can be linked at the functional level to defective ATM and/or p53 target gene responses, providing an explanation for the poor clinical prognosis of CLL patients with SF3B1 mutations.

Disclosures:
No relevant conflicts of interest to declare.