bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cellular Cholesterol Modulates VEGFR-1 Function on Acute Leukemia Cells.
Authors: Fragoso Rita , Casalou Cristina , Dias Sergio 
Published: October 2019

Abstract
Vascular endothelial growth factor (VEGF) and its receptors play a crucial role in malignancy and in disease, regulating the survival, proliferation, and migration of several cell types, such as endothelium and also leukemia cells. Following our recent report on the role of VEGFR-1 (FLT-1) in ALL (Fragoso R et al, 2006), in the present study we analyzed the molecular mechanisms whereby it modulates acute leukemia cell migration in response to VEGF/Placental Growth Factor (PLGF). First, we observed the formation of cell protrusions on ALL cells after VEGF/PLGF stimulation, with evidence for polymerized actin and FLT-1 co-localization (as determined by phalloidin, immunofluorescence staining, and confocal microscopy). Western blot analysis revealed that PLGF/VEGF stimulation resulted in increased RhoA and Rac1 GTPases expression. Co-treatment with LY200942 significantly decreased RhoA and Rac1 induction and cell migration by PLGF/VEGF, demonstrating this effect is modulated via Pi3 kinase. Next, we investigated the mechanisms whereby FLT-1 and actin co-localize at the cell “leading edge” (protrusions), after VEGF/PLGF stimulation, and the relevance of such co-localization for cell migration. We addressed this question by impairing the formation of lipid rafts/caveolae using drugs that either sequester (nystatin) or deplete (methyl-β-ciclodextrin) total cholesterol. Accordingly, co-treatment of leukemia cells with nystatin or MβCD and PLGF/VEGF blocked cell migration, an effect that was associated with a decrease in FLT-1 polarization and co-localization with actin filaments. Instead, FLT-1 was now found mostly in the cell cytosol. Given that leukemia cells have an increased rate of cholesterol up-take we sought to understand if increased cholesterol levels affected FLT-1 function in leukemia cells. Cholesterol repletion in leukemia cells enhanced leukemia cells migration in response to VEGF/PlGF (about 3 folds). This significant increase was associated with an increase in FLT-1 protein expression that, very interestingly, was particularly concentrated intracellulary in the cytoplasm. At this time we are trying to understand if this increase in FLT-1 expression after cholesterol repletion is associated with increase protein translation or impairment in proteasome activity. Finally, our preliminary in vivo experiments using Nod-Scid mice subjected (n=3) or not (n=3) to high fat diet (that results in increased cholesterol levels in the BM and in the spleen), showed this metabolic condition worsens disease symptoms and significantly decreases mouse survival. These results reveal for the first time some of the molecular mechanisms involved in FLT-1-mediated leukemia migration, namely the involvement of cholesterol metabolism, which may be crucial for new therapeutics delineation.
SBDS Protein Plays a Role in Ribosome Biogenesis.
Authors: Ganapathi Karthik A. , Austin Karyn M. , Malsch Maggie , Shimamura Akiko 
Published: October 2019

Abstract
Shwachman-Diamond syndrome is an autosomal recessive disorder characterized by exocrine pancreatic insufficiency, bone marrow failure, and leukemia predisposition. The majority of patients with Shwachman-Diamond syndrome harbor mutations in the SBDS gene. SBDS is a novel gene of unknown function and is highly conserved throughout evolution. Studies of the yeast orthologue, YLR022c/SDO1, suggest that SBDS may play a role in ribosome biogenesis. In support of this hypothesis, we have found that the SBDS protein shuttles in and out of the nucleolus. Previously we have shown that SBDS nucleolar localization is regulated in a cell cycle-dependant manner. We now find that SBDS nucleolar localization is also lost following exposure to actinomycin D, suggesting that SBDS nucleolar localization is dependent on active ribosomal RNA (rRNA) transcription. In cell survival assays, SBDS−/− patient-derived cells are sensitive to actinomycin D treatment relative to normal control cells. Introduction of the wild-type SBDS cDNA into SBDS−/− cells corrects their actinomycin D sensitivity, confirming that the observed sensitivity is SBDS-dependent. In contrast, SBDS−/− cells do not exhibit increased sensitivity to cyclohexamide, a protein translation inhibitor. Consistent with this result, SBDS protein co-localizes with ribosomal precursor subunits but not with mature polysomes upon sucrose gradient sedimentation. No differences in polysome profiles are observed between SBDS−/− cells and wild type control cells. Gel filtration studies suggest that SBDS associates into a complex with other proteins. SBDS co-immunoprecipitates with other nucleolar proteins involved in rRNA biogenesis. RNA immunoprecipitation studies reveal that SBDS also associates with the 28S rRNA but not the 18S rRNA. These findings support the hypothesis that SBDS plays a role in ribosome biogenesis
Forodesine IV (Bcx-1777) Is Clinically Active in Relapsed/Refractory T-Cell Leukemia: Results of a Phase II Study (Interim Report).
Authors: Furman Richard R. , Gore Lia , Ravandi Farhad , Hoelzer Dieter 
Published: October 2019

Abstract
Background: Forodesine, a potent, rationally designed purine nucleoside phosphorylase inhibitor, has shown clinical activity in T-cell leukemia following IV administration. This phase II study was undertaken to evaluate further the efficacy and safety of IV forodesine in patients with relapsed/refractory T-cell acute lymphoblastic leukemia (T-ALL).
Methods: In this open-label, single-arm, multicenter, ongoing study, patients received forodesine, 40 mg/m2 IV, 5 days each week (1 cycle) for a total of 6 cycles. The dose was escalated to 90 mg/m2 in patients who were not responding after cycle 2. The primary end point was objective response (OR), which included complete response (CR), CR with incomplete recovery of peripheral blood cell counts (CRi), and partial response (PR).
Results: In total, 34 T-ALL patients (median age, 31 yr; range, 3–76 yr) with relapsed/refractory T-ALL (median, 3 prior treatments) received forodesine IV. The OR rate was 32.4% (11 patients; 7 [20.6%] CR, 0 CRi [0%] and 4 [11.8%] PR). Patient demographics and response for the 7 CR patients are shown in the Table. One CR patient has continued to receive treatment for almost 1 year. Two patients with CR proceeded to hematopoietic stem cell transplantation following remission. The restoration of normal hematopoiesis observed in patients while receiving therapy indicates a specificity of forodesine for leukemic cell populations. A total of 18 patients were dose escalated to 90 mg/m2 of forodesine after cycle 2 due to a lack of response. None of these patients demonstrated an improved response with dose escalation. The most frequently reported possibly drug-related AEs without regard to grade were nausea (22%), headache (16%), thrombocytopenia (14%), leukopenia (14%), asthenia (14%), and anemia (11%). Possibly drug-related AEs of grade 3 and higher occurring in ≥2 patients were thrombocytopenia (3 patients; 8%) and leukopenia and lymphopenia (2 patients each; 5%).
Conclusions: IV forodesine is effective as a single agent in the treatment of patients with relapsed or refractory T-ALL and is safe and well tolerated. Additionally, 40 mg/m2 has been confirmed as the dose for subsequent phase II development in T-ALL.
T-ALL Patients With Complete Response Patient No. No. of Previous Treatments Age/Gender Relapsed/Refractory Weeks of Tx Time to CR Time to Progression(Days) Overall Survival (Days) #Patient died in CR due to a cardiovascular event *Patient discontinued treatment and then progressed †Patient underwent transplantation following remission 1# 9 23/M Relapsed 9 2 weeks 77 77 2 1 60/M Relapsed 31 6 weeks 238 238+ 3* 4 28/F Relapsed 10 2 weeks 119 459+ 4 2 3/F Relapsed 51 2 weeks 398+ 398+ 5† 2 20/F Refractory 7 6 weeks 207 224 6 2 76/M Refractory 12 2 weeks 91 91+ 7† 3 27/M Refractory 6 2 weeks 180+ 180+
Phase II Study of Forodesine, a PNP Inhibitor, in Patients with Relapsed or Refractory B-Lineage Acute Lymphoblastic Leukemia.
Authors: Ritchie Ellen , Gore Lia , Roboz Gail J. , Feldman Eric , Ravandi Farhad , Furman Richard 
Published: October 2019

Abstract
Background: Forodesine is a potent, rationally designed purine nucleoside phosphorylase (PNP) inhibitor that has shown activity in acute lymphoblastic leukemia (ALL). Although the drug was thought to be most active in T-cell malignancies, preclinical data and results of a phase I/II trial showed clinical activity in B-lineage ALL (B-ALL).
Methods: Twelve patients with relapsed/refractory B-ALL were enrolled (median age of 10 adults, 48.5 yr; median age of 2 children, 10 yr). Three patients had relapsed after allogeneic bone marrow transplantation (BMT), and 9 patients relapsed after a median of two prior regimens. The patients were treated with a 30-minute infusion of forodesine, 80 mg/m2 for 5 days/wk for a 4-week period. If the patient showed clinical improvement at 4 weeks, the drug was continued for additional cycles.
Results: Two of 12 patients achieved a complete response. One of these patients had relapsed after allogeneic BMT and restored complete donor chimerism after 16 weeks of forodesine treatment. As restoration of donor chimerism was achieved, the patient developed hepatic graft-versus-host disease (GVHD) and was treated simultaneously with dexamethasone beginning at 4 weeks; this was tapered off and restarted when GVHD again worsened. The second patient failed one prior regimen and had no leukemic blasts in the bone marrow after 4 weeks of treatment. Both these patients continue to receive therapy (5+ and 2+ months respectively). There were no patients with a partial response. Four patients presented with high white blood cell (WBC) counts; each demonstrated an initial decrease in WBCs without an increase in neutrophils while they were receiving forodesine but then developed persistent pancytopenia with residual bone marrow disease at 4 weeks. Dexamethasone was added to the treatment of 3 nonresponders, with no clinical benefit. Three patients with Ph+ B-ALL were treated on the study. Two rapidly progressed on the medication and were taken off the study before the end of 2 weeks; one had persistent pancytopenia and bone pain with residual marrow disease at 4 weeks and was taken off the study. Adverse events included increases in liver transaminase (grade ≥ 2, 2 patients) and alkaline phosphatase levels (grade 2,3, 2 patients), hyperkalemia (grade 2,3, 2 patients), and hypomagnesemia (grade 1, 1 patient). Two patients with increased liver transaminase levels underwent liver biopsies: 1 showed leukemic infiltration and the other GVHD. Patient accrual continues for this study.
Conclusions: Forodesine is a safe, well-tolerated drug with preliminary evidence of activity as a single agent in B-ALL.
PKCδ Regulates Eukaryotic Initiation Factor eIF2α through PKR during Retinoic Acid-Induced Myeloid Cell Differentiation.
Authors: Ozpolat Bulent , Akar Ugur , Barria Magaly , Lopez-Berestein Gabriel 
Published: October 2019

Abstract
Dysregulation of mRNA translation can contribute to malignant transformation. Translation initiation is a rate limiting step of mRNA translation and protein synthesis and plays a critical role in regulation of cell growth, proliferation and differentiation. We previously reported that ATRA induces translational suppression through multiple posttranscriptional mechanisms during terminal cell differentiation detected by proteomic analysis (Harris et al, Blood, 104 (5) 2004). Here we investigated the regulation of translation initiation and the role of eIF2α during terminal differentiation of myeloid leukemia cells. We found that ATRA and other granulocytic differentiation inducing agents, such as dimethyl sulfoxide (DMSO), arsenic trioxide (ATO) induce phosphorylation of eIF2α on serine 51 in promyelocytic leukemia (NB4) cells, indicating the suppression of translation initiation. However, monocytic/macrophagic differentiation of NB4 cells by phorbol 12-myristate 13-acetate (phorbol ester, PMA), or by ATRA in U937 and THP-1 myelomonoblastic myeloid leukemia (AML) cells, was not accompanied with induction of eIF2α phosphorylation. ATRA, ATO or DMSO-induced granulocytic differentiation closely correlated with induction of expression and phosphorylation/activation of protein kinase C-delta (PKCδ) on threonin 505 and serine 643 in NB4 cells. The specific PKCδ inhibitor, rottlerin, markedly inhibited ATRA-induced expression and phosphorylation (serin 51) of eIF2a in NB4 cells. Rottlerin reduced phosphorylation of eIF2α expression not only in the leukemia cells but also in solid tumor cells such as breast (MCF7) and pancreatic (Panc28) cancer cells. Because protein kinase R (PKR) has been shown to inhibit mRNA translation by inducing phosphorylation of eIF2α, we also examined whether this pathway is involved in ATRA-induced phosphorylation of eIF2α and whether it is downstream of PKCδ. We observed that ATRA induces expression and phosphorylation/activation of PKR in NB4 cells. Rottlerin inhibited ATRA-induced expression and activity of PKR , suggesting that activity of PKR is regulated by PKCδ in response to ATRA in NB4 cells. Overall, our data suggest that retinoic acid suppresses translation initiation through PKCδ/PKR/eIF2α pathway during granulocytic but not monocytic differentiation of acute myeloid leukemia cells. These results revealed a novel role of ATRA in granulocytic cell differentiation of myeloid cells. Because malignant cells usually have hyperactivated mRNA translation, targeting translational factors/regulators of initiation may offer new strategies for the treatment of myeloid leukemia cells.
Development of a Novel Xenotransplantation System for Studying Human Acute Myeloid Leukemia.
Authors: Park Christopher Y. , Majeti Ravindra , Tan Brenton T. , Weissman Irving L. 
Published: October 2019

Abstract
The formal demonstration of leukemia stem cells (LSC) relies on the ability of primary human leukemias to engraft in transplanted xenohosts with the subsequent demonstration of serially transplantable tumors to establish the presence of a self-renewing population. Several immunodeficient and transgenic mouse strains have been utilized as xenohosts for human AML (e.g. NOD, NOD/SCID, NOD/SCID,β2m); however, robust engraftment frequently requires that the mouse recipients be pre-treated with antibodies against mouse immune cells or that leukemic blasts and/or mouse hosts are treated with exogenous hematopoietic growth factors before and/or during transplantation. While such treatments result in a higher percentage of engrafting AML’s, the overall effect on leukemic blasts, particularly the leukemic stem cell population, is unknown. In order to avoid these confounding factors as well as to potentially develop a more robust model of xenotransplantation, we have evaluated the use of the RAG2/gamma common chain double knockout mouse model to xenotransplant human AML’s. Using primary human samples (n=32, patient age range 1–86, median 55), we have determined that newborn pups intravenously injected via the facial vein efficiently engraft human AML’s without the use of additional growth factors or depleting antibody therapy. Among the AML’s tested, 65.6% (21/32) engrafted in mice as assessed by >5% human chimerism in either the peripheral blood, spleen, or bone marrow at 12 weeks post-transplant. In contrast to other xenotransplantation mouse models, circulating leukemic cells were typically identified in the circulation by 4 weeks post-transplant and were present in stable or increasing numbers in the circulation until engraftment was assessed (12 weeks) or until recipient mouse demise. Engrafting AML’s were composed of both CD34+ and CD34- AML’s and included all WHO/FAB subtypes except for acute promyelocytic leukemia. These AML’s included de novo and relapsed AML, as well as therapy-related AML and AML arising from pre-existing MDS or CMPD. While the number of samples tested was limited, there was no statistically significant association between engraftment and WBC at diagnosis, cytogenetic risk group, MLL or FLT3 status, age, or achievement of CR following induction therapy; however, among CD34+ AML’s the percentage of putative leukemic stem cells (defined as CD34+CD38- leukemic blasts), showed a statistically significant correlation with engraftment (student T-test p < 0.05). All CD34+AML’s containing >18% CD34+/CD38− leukemic blasts engrafted in the transplanted hosts. Overall, these findings demonstrate that the RAG2/gamma common chain double knockout mouse is a robust system for studying human AML and will be a useful model for future functional studies of human AML LSC’s.
Azacitidine Plus Gemtuzumab Ozogamicin (GO): A Novel Combination in the Treatment of Acute Myeloid Leukemia (AML) and High-Risk Myelodysplastic Syndromes (MDS) in the Elderly.
Authors: Nand Sucha , Godwin John , Smith Scott , Barton Kevin , Germano Eliza , Stiff Patrick 
Published: October 2019

Abstract
AML and high-risk MDS in the elderly carry a poor prognosis. Only 46% of AML patients receiving standard chemotherapy achieve complete remission (CR) and treatment-related mortality approaches 30% above age 60. In 2005, we initiated a Phase II trial for elderly patients with newly diagnosed AML or MDS, using the following outpatient treatment schema: If white blood cell (WBC) count at presentation was >10,000/ul, pt was started on hydroxyurea 1500 mg twice daily by mouth. Leukapheresis was performed if WBC >100,000/ul. Once WBC count was <10,000/ul, the patient received azacitidine 75 mg/m2 s/cu D1–7 and GO 3 mg/m2 on D8. A bone marrow was performed on D14 and induction therapy repeated for residual disease. Those who achieved CR were given one consolidation treatment with azacitidine+GO in same doses after recovery of blood counts. A total of 13 pts have been treated to date. Eleven had AML by WHO classification and 2 MDS (both RAEB). The median age was 77 (62–83) and 7 were male. Ten patients required retreatment on D14. Ten patients (76%) achieved CR. Six patients developed grade 3 toxicities: 5 neutropenic fever and 1 typhlitis, all requiring hospitalization. There were no treatment-related deaths. Median follow up is 7 months (2–13 months) and eleven patients remain alive. Two patients have died from relapsed or refractory disease. Nine patients remain in CR with a median duration of remission of 7 months (2–13 months). The trial is ongoing with an accrual goal of 20. Our early experience with this novel combination is quite encouraging. Cytoreduction with hydroxyurea and leukapheresis followed by azacitidine and GO appears to be a safe and effective regimen for elderly patients with AML and the therapy can be given in the outpatient setting. These preliminary results need to be confirmed in a larger cohort of patients.
SGN-33 Modulates Cytokine and Chemokine Production by Activated Monocytes and Macrophages.
Authors: Sutherland May S.K. , Lewis Timothy S. , Yu Changpu , McEarchern Julie A. , Drachman Jonathan G. , Sievers Eric L. , Grewal Iqbal S. , Law Che-Leung 
Published: October 2019

Abstract
SGN-33, a humanized IgG1 anti-CD33 antibody that targets CD33, a sialoadhesion family member expressed on myeloid precursor cells, macrophages, and monocytes, is currently in Phase I clinical trials for acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). To further characterize and define the mechanism of action of SGN-33, we undertook a series of experiments in AML cell lines and in cultures of primary normal human monocytes and macrophages. SGN-33 has previously been shown to eliminate tumor cells through antibody-mediated effector functions including Antibody-Dependent Cellular Cytotoxicity (ADCC) and Complement Dependent Cytotoxicity (CDC). We have now demonstrated that SGN-33 binding also initiates Antibody-Dependent Cellular Phagocytosis (ADCP). Because CD33 has been hypothesized to mediate signal transduction, we explored the biochemical effects of SGN-33 binding on AML cell lines and normal monocytes and macrophages. SGN-33 binding stimulated tyrosine phosphorylation of CD33 and recruitment of SHP-1, with maximal effects between 5 to 30 minutes. Initiation of signaling by SGN-33 was not dependent upon antibody crosslinking. Furthermore, SGN-33 exposure significantly reduced the syntheses of pro-inflammatory cytokines (TNF-a, IL-6, IL-1b) and chemokines (RANTES, MCP-1, IL-8) by macrophages cultured in the presence of tumor cell conditioned media. Production of these cytokines by monocytes and macrophages activated in vitro by IFN-g and TGF-b were also blocked by SGN-33 binding (up to 100% reduction in TNF-a levels in vitro). These data demonstrate that the mechanisms of action of anti-CD33 immunotherapy may be broader than previously known. Because pro-inflammatory cytokines have been implicated in the growth and survival of tumor cells in patients, the capacity of SGN-33 to block these factors may yield clinical benefit. This hypothesis is currently being evaluated in clinical studies of SGN-33.
Farnesyl Transferase Inhibitor (Tipifarnib, Zarnestra; Z) in Combination with Standard Chemotherapy with Idarubicin (Ida) and Cytarabine (ara-C) for Patients (pts) with Newly Diagnosed Acute Myeloid Leukemia (AML) or High-Risk Myelodysplastic Syndrome (MDS).
Authors: Alvarez Ricardo H. , Kantarjian Hagop , Garcia-Manero Guillermo , Estrov Zeev , Ravandi-Kashani Farhad , Verstovsek Srdan , Giles Francis , O’Brien Susan , Asa Koller Charles , Faderl Stefan , Thomas Deborah , Wright John J. , Cortes Jorge 
Published: October 2019

Abstract
Tipifarnib is a non-peptidomimetic farnesyl transferase inhibitor (FTI) with clinical activity in hematologic malignancies, including AML, MDS and CML. Pre-clinical data suggests that tipifarnib may be synergistic with some chemotherapeutic agents. We designed a phase I/II study where pts age 15 to 70 years with previously untreated AML or high-risk MDS (blasts >10%) received induction with Ida 12 mg/m2/d on days 1–3, ara-C 1.5 g/m2 IV over 24 hours daily on days 1–4 (days 1–3 only if age ≥ 60 years) and Z with first cohort (6 pts) receiving 200mg orally twice daily (BID), and all others 300 mg BID x 21 days every 28 days. Pts achieving CR received consolidation (5 courses) with Ida 8 mg/m2/d, days 1–2, ara-C 0.75 g/m2/d, days 1–3, and Z 300 mg BID x14 days every 4–6 weeks. Maintenance was with Z 300 mg BID x 21 d every 4–6 wk for 6 months. We have treated 74 pts, median age 50 yrs (17–61 yrs). All pts are evaluable for response. Fifty seven pts (77%) responded: 48 (65%) achieved CR and 9 (12%) CRp. Overall response rate (CR+CRp) in a similar historical population treated with the same chemotherapy regimen (IA) without Z was 68% (p=0.29). Response by cytogenetics was: 26/30 (86%) for diploid, 12/16 (76%) with -5/-7, 1/2 with t(8;21), and 17/25 (68%) with other abnormalities. Response by Flt3 was 11/15 (73%) for unmutated Flt3, 39/46 (85%) for mutated Flt3. Response by age was 26/34 (76%) if ≤50yrs, 9/13 (69%) if >50yrs with diploid karyotype and 13/27 (48%) if >50yrs with abnormal karyotype. With median follow-up of 22 weeks, 34 pts are still on study. Of the 48 pts that achieved CR, 2 died in CR of unrelated causes and 9 pts have relapsed after 5, 11 13, 14, 16, 26, 29, 34, and 39 weeks, respectively. The most common grade 3 adverse events include diarrhea in 31 (42%) and hyperbilirrubinemia in 10 (14%), both transient. Thirty nine (53%) pts have required treatment interruptions/dose reductions during induction, 17 (16%), and 2 (7%) during consolidation and maintenance respectively. We conclude that Z combined with Ida and ara-C induces a high rate of CR in AML, with increased incidence of diarrhea and hyperbilirrrubinemia. Direct comparison with chemotherapy alone is warranted in a randomized trial.