bluuebunny/crossref_metadata_2025_split huggingface dataset:
PRT060318, a Novel Syk Inhibitor, Prevents Heparin-Induced Thrombocytopenia in a Transgenic Mouse Model
Authors: Reilly Michael P. , Sinha Uma , Andre Pierrette , Taylor Scott M. , Pak Yvonne , DeGuzman Francis R. , Nanda Nisha , Pandey Anjali , McKenzie Steven E. 
Published: April 2020

Abstract
Heparin-induced thrombocytopenia (HIT), in which patients develop antibodies to complexes formed by heparin and platelet factor 4 (PF4), is the most frequent drug-induced immune thrombocytopenia. Extensive studies in vitro and our previous studies in vivo using a transgenic mouse model of HIT have shown that antibodies reactive with heparin-PF4 complexes lead to FcgRIIa receptor-mediated platelet activation. In this study we investigated whether PRT060318 (PRT318), a novel Syk inhibitor, prevents HIT antibody-mediated platelet activation both in vitro and in vivo. PRT318 at concentrations of 0.3 to 3 μM completely inhibited HIT immune complex (IC)-induced aggregation in both human and transgenic mouse platelets. In the absence of the inhibitor, HIT IC-induced final aggregation was 50–60%. At concentrations of PRT318 less than 0.1 μM, or in the presence of vehicle only, there was no inhibition of aggregation. Aggregation was not inhibited by PRT318 at any concentration when platelets were stimulated by ADP (5–20 μM final concentration). We also show that PRT318 prevents HIT IC-induced thrombocytopenia in vivo using a transgenic mouse HIT model. All mice were treated with KKO, a mouse monoclonal HIT antibody. On days 1 to 4 following antibody injection, the experimental group (n = 13) received orally dosed PRT318 (30 mg/kg body weight) twice a day by gavage while the control group (n = 11) was similarly treated with vehicle only (water). Both experimental and control mice were injected with heparin (1600 U/kg body weight, SQ, once daily). Nadir platelet counts of PRT318-treated mice were significantly higher than control mice (89.8 ± 1.1% of baseline vs. 48.8 ± 6.7%; p = 0.00003). The PRT318 concentration, 2 hrs post dose, in mouse plasma from treated mice was measured as 7.1 μM, consistent with the concentration which blocked FcgRIIa-mediated platelet activation in vitro. These studies demonstrate that Syk inhibitor PRT318 is an active agent in HIT.
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Dynamic Contrast-Enhanced Magnetic Resonance Imaging Identifies a Subgroup of Patients with Asymptomatic Monoclonal Plasma Cell Disease and Pathological Microcirculation
Authors: Hillengass Jens , Zechmann Christian M , Bäuerle Tobias , Heiss Christiane , Benner Axel , Neben Kai , Ho Anthony D. , Goldschmidt Hartmut , Delorme Stefan , Moehler Thomas M. 
Published: April 2020

Abstract
The aim of the present study was to investigate whether dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) allows visualization of a change in microcirculation between healthy controls on the one side and early/advanced stages of plasma cell disease on the other. We examined a group of 222 individuals consisting of 60 patients with monoclonal gammopathy of undetermined significance (MGUS), 65 patients with asymptomatic multiple myeloma (aMM), 75 patients with newly diagnosed symptomatic MM (sMM) and 22 healthy controls with DCE-MRI of the lumbar spine. A continuous increase in the microcirculation parameter amplitude A reflecting vascular volume was detected from normal controls over MGUS and asymptomatic to symptomatic MM. Significant differences were found between controls and aMM (p = 0.03), controls and sMM (p = 0.001) and between asymptomatic and symptomatic MM (p = 0.02) respectively. While diffuse microcirculation patterns were found in healthy controls as well as MGUS and MM, a pattern with focal hot spots was exclusively detected in 42.6 % of sMM and in 3 patients with MGUS and 3 patients with aMM. Patients with MGUS and aMM with increased microcirculation patterns showed a significantly higher bone marrow plasmocytosis compared to patients with a low microcirculation pattern. Our investigations substantiate by means of a non invasive assessment of bone marrow microcirculation the concept of an angiogenic switch from early plasma cell disorders to symptomatic MM. Pathological DCE-MRI findings can be identified and correlate with an adverse prognostic parameter.
Inhibition of eIF2α Dephosphorylation Maximizes Bortezomib Efficiency and Eliminates Quiescent Multiple Myeloma Cells Surviving Therapy
Authors: Schewe Denis M , Aguirre-Ghiso Julio A 
Published: April 2020

Abstract
The proteasome inhibitor Bortezomib (Velcade®) effectively eradicates multiple myeloma (MM) cells, partly by activating endoplasmic reticulum (ER) stress apoptotic signaling. However, MM recurrences in Bortezomib-treated patients are invariable. We have shown that ER stress signaling can also induce growth arrest and survival in cancer cells. Thus, we hypothesized that Bortezomib therapy could induce quiescence and survival of residual MM cells, contributing to disease recurrence. Here we report that in MM cells, proteasome inhibition with MG-132 or Bortezomib results in a surviving cell fraction that enters a prolonged quiescent state (G0-G1 arrest). Mechanism analysis revealed that in Bortezomib-surviving quiescent cells eIF2α phosphorylation and induction of the ER stress pro-apoptotic gene, GADD153, were attenuated. In contrast, p38 and the ER-chaperone BiP/Grp78 were persistently activated and induced, respectively. The Bortezomib-surviving quiescent fraction could be eradicated by a simultaneous or sequential combination therapy with Salubrinal, an inhibitor of GADD34-PP1C phosphatase complex, and in consequence, eIF2α dephosphorylation. This effect was mimicked by expression of a phospho-mimetic eIF2α-S51D mutant. Our data indicate that Bortezomib can induce growth arrest in therapy-surviving MM cells and that attenuation of eIF2α phosphorylation and GADD153 induction contribute to this survival. Most importantly, this ability of MM cells to evade Bortezomib toxicity can be prevented by inhibiting eIF2a dephosphorylation. Thus, strategies that maintain eIF2α in a hyper-phosphorylated state may be a novel therapeutic approach to maximize Bortezomib-induced apoptosis and reduce recurrences in this type of cancer.
Parathyroid Hormones (PTH) Serum Variations Are Associated with Bortezomib Response in Multiple Myeloma Patients
Authors: Zangari Maurizio , Pappas Lisa , Zhan Fenghuang , kumar Naveen Sanath , Cavallo Federica , Suva Larry J , Tricot Guido , Esseltine Dixie-Lee , Yaccoby Shmuel 
Published: April 2020

Abstract
A correlation between increase in bone markers (alkaline phosphatase (ALP) and response to bortezomib in patients with multiple myeloma (MM) has been previously described. We now report results from a prospective study examining the relationship of serum PTH variation with skeletal effects and myeloma response to bortezomib treatment.
Methods: Single agent bortezomib (1.3 mg/m2 patients 1–10; 1mg/m2 patient 11–20), was administered to patients with relapsed/refractory MM on days 1, 4, 8 and 11 on a 21 day interval for a total of 3 cycles; patients were not allowed to receive concurrent bisphosphonates or any other anti-myeloma drugs during the study period. Dynamic indices of bone turnover were prospectively evaluated by high-resolution microCT. Architectural parameters such as bone volume/total volume (BVTV), trabecular number (TbN), and thickness (Tb.Th) was obtained. PTH along with bone markers (osteocalcin, calcium, magnesium, phosphorus and serum creatinine) were measured on days 1, 4, 8, 11 before and after each bortezomib dose and every 4 hours thereafter, daily for the other days of the treatment cycle.
Results: Seventeen patients were enrolled in the study with a median age of 63 years, 41 % were male and 3/4 of the patients previously failed high-dose chemotherapy. Histomorphometric microCT comparative analysis was completed (baseline and post-treatment) in 7 of the 17 patients enrolled in the trial. Baseline BV/TV values ranged from 13% to 90%. After 3 cycles of bortezomib treatment a statistically significant increase in BV/TV was recorded in 6 of 7 patients (P&lt;0.02).
Median serum osteocalcin values increased from 1.95 ng/ml at baseline to 7.16 ng/ml at the end of the third bortezomib cycle. Serial PTH levels were measured in all enrolled patients. Median PTH variation across cycle of the entire group of patients is shown in Fig. 1A. Comparing patients who achieved at least a PR (according to the European Group for Blood and Marrow Transplant criteria) versus the others, median PTH levels separate after the second Bortezomib injections and were statistically higher in responding patients on days 11 (p=0.04), 21 (p=0.04), and 33 (p=0.04) (Fig. 1b). No significant changes from baseline in PTH levels were observed in control patients (≤PR). No serum differences in calcium, magnesium, phosphorus, and creatinine levels were recorded between responders and non-responder individuals.
Conclusion: This Phase II study is the first to show that response to bortezomib in multiple myeloma treated patients is associated with changes in serum PTH level concentration, which appears to be independent from calcium metabolic regulation.
Figure Figure
A Phase I Study of XL019, a Selective JAK2 Inhibitor, in Patients with Polycythemia Vera
Authors: Paquette Ronald , Sokol Lubomir , Shah Neil P. , Silver Richard T. , List Alan F. , Clary Douglas O. , Bui Lynne A. , Talpaz Moshe 
Published: April 2020

Abstract
More than 98% of patients with polycythemia vera (PV) carry the activating JAK2 mutation V617F, which may play a role in the pathogenesis of PV by promoting hematopoetic cell proliferation and survival. PV is characterized by an increased red blood cell mass and is generally accompanied by increased myeloid and megakaryocytic production. Current therapy consists of supportive care measures including aspirin, phlebotomy, interferon and hydroxyurea to reduce the risk of complications of the disease such as thrombotic events. Such palliative therapy is often unsatisfactory due to side effects and the persistent susceptibility of the patients to development of thrombosis, and the failure to prevent transformation to myelofibrosis or acute leukemia. XL019 potently and selectively inhibits JAK2 (Ki of 2 nM); relative to other JAK family kinases (JAK1 Ki of 134 nM, JAK3 Ki of 195 nM and TYK2 Ki of 344 nM). Cellular selectivity of XL019 was confirmed in primary human cell assays; while EPO-stimulated pSTAT5 in primary erythroid cells was quite sensitive to XL019 treatment (IC50 of 64 nM), stimulation of T-cells with IL-2 or B-cells with IL-4 or IL-6 gave pSTAT IC50s of &gt;800 nM in each case. Potent effects on JAK2-STAT signaling were also demonstrated in single-dose pharmacodynamic studies in xenograft tumors, including HEL92.1.7, CFPAC-1 and DU 145. XL019 is being evaluated in a Phase 1 dose escalation study in subjects with PV who have failed or are intolerant of standard therapies defined as follows: symptomatic splenomegaly in spite of current therapy, thrombocytosis with a platelet count &gt;450K/μl, or non-controlled constitutional symptoms such as pruritus, night sweats, or weight loss. The primary objectives of this study are to determine the safety and tolerability of XL019 when administered orally either once daily, or every Monday, Wednesday, and Friday in 28-day cycles (starting doses 10 mg QD and 25 mg QMWF). Secondary objectives include determination of the pharmacokinetics and pharmacodynamics of XL019, and to evaluate clinical response using the following endpoints:
hematologic response; time to hematologic response; duration of hematologic response; phlebotomy independence; change in spleen and/or liver size; change in bone marrow morphology; impact on quality of life (QOL); and impact on functional exercise capacity.
Pharmacodynamic assessments for this study include JAK2 V617F allele burden, erythropoietin-independent colony formation, changes in cytokine levels and JAK2 signaling pathways in peripheral blood mononuclear cells, and changes in bone marrow histology. Our initial findings regarding the tolerability, pharmacokinetics, pharmacodynamics, and preliminary clinical activity of XL019 in PV patients will be presented.
CD74 Is a Regulator of Fas-Mediated Apoptotic Signaling
Authors: Berkova Zuzana , Wang Shu , Wise Jillian , Wang Suizhao , Tao Ronghua , Maeng Hoyoung , Hawke David , Kwak Larry W. , Samaniego Felipe 
Published: April 2020

Abstract
Resistance to Fas-mediated apoptosis in hematopoietic cancers interferes with the efficacy of currently available chemotherapy. Our prior studies of human herpesvirus 8 oncoprotein K1 showed that K1 binds to Fas and interferes with activation of Fas-mediated apoptotic signaling (Wang, W, et al, Blood2007; 109:5455–62). Herpesvirus proteins often mimic host proteins or their functions, we thus searched for cellular proteins associated with inactive Fas in order to identify potential regulators of Fas signaling. We identified CD74, the invariant light chain of the major histocompatibility class II complex, associated exclusively with inactive/activation resistant Fas in B-cell lymphoma-derived BJAB cell line. Interestingly, overexpression of CD74 has been previously reported in ~ 90% of hematopoietic cancers and derived cell lines (Stein, R, et al., Ciln Cancer Res.2007; 13: 5556s–63s), as well as in ~ 80% of non-small-cell lung carcinoma (Ioachim, H.L., Am J Surg Pathol.1996; 20: 64–71). The role of CD74 in carcinogenesis was thus suspected. Through siRNA suppression of CD74 expression in BJAB cells we have determined that CD74 positive cells are more resistant to agonistic antibody CH-11-induced Fas-mediated apoptosis then the CD74 siRNA transfected cells (38 ± 7.8 % vs. 54 ± 9.8 %; P = 0.045). In addition, a challenge with agonistic anti-Fas antibody showed a significant survival advantage of the mice expressing CD74 in their livers over the vector-transfected mice (83% vs. 0 %; P &lt; 0.016). We have mapped domain of CD74 required for its association with Fas and for significant protection of mice to a membrane-proximal extracellular region of CD74. Treatment of BJAB cells for 24 hours with humanized anti-CD74 antibody (hLL1 + crosslinking antibody), FasL-Fc, or anti-Fas antibody CH-11 induced apoptosis in 19%, 25% and 13% of cells, respectively. Combination of hLL1+crosslinking antibody with FasL-Fc or CH-11 increased apoptosis to ~ 45% of cells in both cases (P &lt; 0.01), while combination of FasL-Fc or CH-11 with hLL1 + irrelevant antibody had no significant effect on the extent of apoptosis. Our results support the idea of an endogenous regulatory system of Fas-mediated apoptosis that utilizes transmembrane proteins interacting with Fas. We anticipate that specific blocking of the CD74-Fas interaction will sensitize CD74 overexpressing cancer cells to Fas-mediated apoptosis and thus will lead to a more effective chemotherapy for hematopoietic cancers.
Rig-I Activates Expression of Interferon-Stimulated Genes (ISGs) and Inhibits the Proliferation of Acute Myeloid Leukemia Cells
Authors: Zhang Nan-Nan , Chen Lei , Zhang Wu , Li Xian-Yang , Jiang Lin-Jia , Ding Fei , Zhang Hong-Xin , Chen Sai-Juan , Wang Zhu-Gang , Chen Zhu , Zhu Jiang 
Published: April 2020

Abstract
Acute promyelocytic leukemia (APL) is initiated by the formation of PML/RARα oncogenic fusion protein, a potent transcriptional repressor. Retinoid acid (RA) at pharmacological dosage can physically bind to the PML/RARα protein, ushering in the unfolding of downstream programs normally regulated by the wild type RARα. However, through what particular regulatory pathways RA inhibits APL malignant hematopoiesis has remained largely obscured. Rig-I is one of the genes whose mRNA levels were highly up-regulated, along with all-trans-RA (ATRA)-induced terminal granulocytic differentiation of APL cell line NB4 cells in vitro. Based on the analysis of a Rig-I−/− mouse model, recently we have reported a critical regulatory role of Rig-I in normal granulopoiesis. To understand the functional contribution of Rig-I induction in RA-mediated leukemia cell differentiation, we converted a pair of previously reported Rig-I RNAi-duplex sequences into a miR30a-based small hairpin-encoding sequence, which was expressed under the CMV enhancer/promoter within a lentiviral vector. As expected, Rig-I shRNAmir30 infection induced a significant knockdown of Rig-I protein level, and accordingly its delivery into HL-60 cells partially inhibited ATRA-induced granulocytic differentiation, growth inhibition/cell cycle arrest and apoptosis induction, suggesting that Rig-I upregulation participates in RA-induced granulocytic differentiation of acute myeloid leukemia cells. In order to investigate the effect of Rig-I induction on the proliferation of APL cells in vivo, we transduced PML/RARα-harboring leukemic cells with vector or Rig-I-expressing retrovirus, and then transplanted these cells into the syngeneic mice. The vector-transduced APL cells readily expanded in vivo, but the proliferation of Rig-I-transduced cells was apparently prohibited. Moreover, we found that the forced expression of Rig-I induced the expression of numerous ISGs in APL cells, which was recapitulated by the transduction of the C terminal part of Rig-I, but not by the N terminal part. In line with this, during the in vitro short-term culture post-IFNγ or IFNα stimulation, Stat1 phosphorylation at p701 in Rig-I−/− granulocytes was significantly inhibited. In parallel, the induction of multiple ISGs by IFNs was also significantly impaired. In conclusion, our findings indicate that the Rig-I induction inhibited APL reconstitution potentially through up-regulating a number of ISGs via regulating Stat1Tyr701 phosphorylation.
The D816V Mutation of C-Kit Circumvents a Requirement for Src Family Kinases in C-Kit Mediated Signal Tranduction and Transformation
Authors: Sun Jianmin , Pedersen Malin , Rönnstrand Lars 
Published: April 2020

Abstract
The receptor tyrosine kinase c-Kit plays a critical role in hematopoiesis and gain-of-function mutations of the receptor are frequently seen in several malignancies, including acute myeloid leukemia (AML), mastocytoma and sinonasal NK/T cell lymphomas. The most common mutation of c-Kit in these disorders is a substitution of the aspartic acid residue in position 816 to a valine (D816V), leading to constitutive activation of the receptor. In this study we aimed to investigate the role of Src family kinases in c-Kit/D816V signaling. Src family kinases are necessary for the phosphorylation of wild-type c-Kit as well as for activation of downstream signaling pathways including receptor ubiquitination and the Ras/MEK/Erk pathway. Tyrosine 568 of c-Kit, that is important for Src activation by wild-type c-Kit, was mutated to phenylalanine in both wild-type c-Kit and c-Kit/D816V and stably transfected into the hematopoietic cell line Ba/F3. Our data demonstrate that, unlike wild-type c-Kit, the phosphorylation of c-Kit/D816V is not dependent on Src family kinases. In addition we found that neither receptor ubiquitination nor Erk activation by c-Kit/D816V required activation of Src family kinases. In vitro kinase assay using synthetic peptides revealed that c-Kit/D816V had an altered substrate specificity resembling Src and Abl tyrosine kinases. The serine/threonine kinases Akt and Erk play important roles in cell survival and proliferation mediated by receptor tyrosine kinases. We could show constitutive activation of both PI3-kinase pathway and Erk in Ba/F3 cells expressing c-Kit/D816V, although ligand stimulation induced even stronger activation. We further present evidence that, in contrast to wild-type c-Kit, Src family kinases are dispensible for c-Kit/D816V cell survival. Taken together, we demonstrate that the signal transduction pathways mediated by c-Kit/D816V are markedly different from those activated by wild-type c-Kit and that altered substrate substrate specificity of c-Kit circumvents a need for Src family kinases in signaling of growth and survival, thereby contributing to the transforming potential of c-Kit/D816V.
Leukemia Induced by Altered TRK-Signaling Is Sensitive to Rapamycin Treatment in a Preclinical Model
Authors: Rhein Mathias , Yang Min , Kaever Volkhard , Meyer Johann , Baum Christopher , Li Zhixiong 
Published: April 2020

Abstract
Neurotrophins (NTs) and their receptors play a key role in neurogenesis and survival. The TRK (tropomyosin-related kinase) receptor protein tyrosine kinases (TRKA, TRKB, TRKC) are high affinity NT-receptors that are expressed in a variety of human tissues. Their role in normal and malignant hematopoiesis is poorly understood. Recently, we and others have obtained evidence for potential involvement of this receptor system in leukemia. In a prospective study involving 94 adult patients, we demonstrated for the first time cell surface expression of the three TRKs and constitutive activation in blasts from patients with de novo or secondary acute leukemia. At least one TRK receptor was expressed in 55% of the analyzed cases (Li Z et al., ASH 2007). Altered TRK signaling efficiently transformed murine hematopoietic stem/progenitor cells (Meyer J et al., Leukemia 2007; Li Z et al., ASH 2007). We observed constitutive activation of mammalian target of rapamycin (mTOR) both in murine and human leukemic cells. Murine leukemic cells induced by altered TRK signaling were very sensitive to rapamycin treatment in vitro. We next tested the therapeutic effect of rapamycin on altered TRK-induced leukemia in a mouse model (C57Bl/6J). Leukemic cells isolated from #483 mouse transplanted with primary hematopoietic stem/progenitor cells modified with deltaTrkA, an active mutant of TRKA isolated from a patient with acute myeloid leukemia, grew factor-independently. Treatment of #483 cells with rapamycin (10–50nM) induced apoptosis and showed a dose-dependent growth inhibition (up to 100%) in colony forming assay. Consistently, mTOR was strongly dephosphorylated. In pilot studies, we found that
transplantation of 106 #483 cells into recipients constituted with sublethal irradiation (7.5Gy) gave rise to leukemia development in all animals after a latency of 8 weeks; Daily i.p. injection of 2mg/kg rapamycin in healthy animals mediated a high level of rapamycin in whole blood (around 50ng/ml).
Thus, after irradiation, 20 animals were transplanted with 106 #483 cells and randomized in two groups. One group was treated daily with rapamycin 2mg/kg i.p., the other group received only carrier (placebo). The treatment begun 3 weeks after transplantation and continued until the last animal succumbed to leukemia. Rapamycin treatment significantly prolonged the survival of animals compared with control group (mean survival 48.5 and 32 days, respectively, P=0.0087) (Figure 1). Concentration of rapamycin in whole blood at the time of end point analysis ranged 26–151ng/ml. Our findings suggest that mTOR plays an important role in leukemogenesis induced by altered TRK signaling. TRKs and mTOR might serve as therapeutic targets in acute leukemia.
Figure 1 Kaplan-Meier estimate of survival of animals after treatment. Figure 1. Kaplan-Meier estimate of survival of animals after treatment.