Rare Germline Mutations in Complement Regulatory Genes Make the Antiphospholipid Syndrome Catastrophic

Introduction: The antiphospholipid syndrome (APS) is characterized by thrombosis and/or pregnancy morbidity along with persistent antiphospholipid antibodies (aPL). Despite adequate anticoagulation, 10-30% of patients have recurrent thrombosis. Catastrophic APS (CAPS) is associated with approximately 40% mortality despite treatment. The pathogenesis of APS complications is incompletely understood. Recent animal studies indicate that complement is required for aPL-associated thrombosis, and complement has emerged as an attractive therapeutic target for refractory thrombotic APS and CAPS. Methods: We first evaluated complement activation in sera of patients with thrombotic APS by ISTH criteria (N=53), catastrophic APS (CAPS; N=8, sera available for 6), and systemic lupus erythematosus (SLE; N=74) who presented to our institution from June 2015 to June 2019 (and four patients with CAPS from other institutions). We used the modified Ham (mHam) test, a functional assay for complement activation as described previously (Gavriilaki et al. Blood 2015). The mHam assay is based on the principle that a PNH cell line (PIGA-null TF-1 cells) lacking the cell surface complement regulators CD55 and CD59 undergoes lysis in serum containing activated complement. Cell death (measured by a cell viability assay) is a measure of complement activation. Cell surface deposition of complement products (C3c, C5b-9) is also detected by flow cytometry. We then evaluated whether adding purified patient-derived aPL (anti-β2 glycoprotein IgG) to normal serum induced complement activation. Finally, we performed targeted sequencing of 15 complement genes in the study subjects, as well as 22 patients with aHUS and 36 healthy individuals as positive and negative controls, respectively. Results: (A) Complement activation is associated with thrombotic APS. A positive mHam assay (>20% cell killing) was detected in 32.1% (17 of 53) patients with thrombotic APS and 100% (6 of 6 with available sera) of CAPS compared with 6.8% (5 of 74) with SLE, (P <0.001) (Fig. 1A). A history of thrombosis was present in 79.3% patients with a positive mHam and 38.4% with a negative mHam test. Among APS patients, mHam positivity was associated with triple positivity (lupus anticoagulant, anti-β2-glycoprotein-1 Ab and anti-cardiolipin Ab), which is associated with higher thrombotic risk (60%), than double (23%) or single positivity (10%) (P = 0.002) (Fig. 1B). APS patients were more likely to have a positive mHam closer to a thrombotic event (Fig. 1C). (B) aPL from patients activate complement in vitro. Patient-derived anti- β2 glycoprotein IgG from all four patients induced complement activation in the mHam assay (Fig 2A). Flow cytometry confirmed cell surface deposition of complement activation products (C4d, C5b-9), which was inhibited by adding anti-C5 monoclonal Ab or a factor D inhibitor (representative sample in fig. 1B). (C) Catastrophic APS is associated with complement mutations. Rare (minor allele frequency <0.01) germline mutations in complement genes were present in 62.5% (5 of 8) patients with CAPS, 22.6% (12 of 53) patients with thrombotic APS, and 23.8% (5 of 21) of SLE compared with 50% (11 of 22) of aHUS, and 19.4% (7 of 36) of normal individuals. The mutation rate in CAPS was significantly higher than in APS (P=0.019), SLE (P=0.051), and normal controls and similar to that seen in aHUS (P=0.36). Rare variants in CAPS included: (i) homozygous CFHR1-CFHR3 deletion, (ii) THBD P501L, (iii) CR1 S1982G and homozygous CFHR1-CFHR3 deletion, (iv) CFHR4 R287H, and (v) CR1 V2125L. Conclusions: APS serum activates complement in vitro shown by a functional assay (mHam) and increased C5b-9 deposition on the cell surface. A positive mHam test strongly associates with both recent thrombosis and triple positive APS. Purified human anti-B2GPI antibody from APS patients activates complement when added to normal human serum, suggesting that complement activation plays a pathophysiologic role in APS associated thrombosis. Finally, CAPS patients have a high rate of mutations in complement genes, which likely serves as a 'second-hit' (in addition to aPL) leading to uncontrolled complement activation and a more severe phenotype (Figure 3). Taken together, our results provide a rationale for complement inhibition as a therapeutic strategy in patients with CAPS and refractory thrombotic APS. Disclosures Chaturvedi: Shire/Takeda: Research Funding; Sanofi: Consultancy; Alexion: Consultancy. Streiff:Pfizer: Consultancy, Honoraria; Bayer: Consultancy, Honoraria; Portola: Consultancy, Honoraria; Roche: Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Daiichi-Sankyo: Consultancy, Honoraria. Petri:Astellas: Consultancy; Novartis: Consultancy; Exagen: Consultancy, Research Funding; Glenmark Pharmaceuticals: Consultancy; EMD Serono: Consultancy; Bristol-Myers Squibb: Consultancy; IQVIA: Consultancy; Janssen Pharmaceuticals: Consultancy; Aleon Pharmaceuticals: Consultancy; Momenta Pharmaceuticals: Consultancy; Blackrock Pharmaceuticals: Consultancy; Astrazeneca: Consultancy, Research Funding; UCB Pharmaceuticals: Consultancy; GSK: Consultancy; Qiagen: Consultancy; Abbive: Consultancy; Amgen: Consultancy; Decision Resources: Consultancy; Principia Biopharma: Consultancy; Eli Lilly: Consultancy; Kezaar Life Sciences: Consultancy. McCrae:Dova Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Pfizer Pharmaceutical: Membership on an entity's Board of Directors or advisory committees; Rigel Pharmaceutical: Membership on an entity's Board of Directors or advisory committees; Sanofi Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Brodsky:Alexion: Membership on an entity's Board of Directors or advisory committees, Other: Grant funding; Achillion: Research Funding.

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FLT3 Splice Variant (FLT3Va) As a Potential Immunotherapeutic Target in Patients with Acute Myeloid Leukemia (AML)

Blood ◽

10.1182/blood.v128.22.1681.1681 ◽

2016 ◽

Vol 128 (22) ◽

pp. 1681-1681

Author(s):

Sophia Adamia ◽

Jeffrey Nemeth ◽

Shruti Bhatt ◽

Sarah R Walker ◽

Natalie I Voeks ◽

...

Keyword(s):

Flow Cytometry ◽

Cell Surface ◽

Board Of Directors ◽

Research Funding ◽

Leukemic Cells ◽

Advisory Committees ◽

Gm Csf ◽

Nsg Mice ◽

Blocking Antibodies ◽

Pdx Models

Abstract Alternative pre-mRNA splicing (AS) is a normal epigenetic phenomenon, a key regulator of gene expression, yields multiple transcripts and thus a variety of proteins from a single gene. Mutations in the spliceosome components resulting in aberrant splicing isoforms are common in AML, and other myeloid neoplasms, and may generate leukemia-specific neoantigens targetable with an antibody-drug conjugates (ADCs) or blocking antibodies. Our previous studies revealed that the FLT3 cell surface receptor is one of the most commonly misspliced genes in AML (54-63% of ~400 AML patients). We conducted cloning and sequencing analyses in AML cells and identified multiple aberrant splice-variants of FLT3 that resulted from either skipping of one or more exons or activation of cryptic splicing sites. Transfection of cDNA with three of these variants in TF-1 (AML cell line) cells resulted in expression of Flt3 variant proteins on the cell surface. We successfully generated rabbit polyclonal antiserum against a unique peptide sequence present in the most commonly expressed abnormal splice variant, which we termed Flt3Va. Immunoblots performed with the polyclonal antibody identified a ~160 kDa protein expressed by TF-1 cells transfected with FLT3Va, and the antibody did not react with untransfected TF-1 cell lysate. Using standard techniques, we generated rabbit hybridomas and evaluated the clones by flow cytometry and western blotting experiments. Based on these data, we selected one antibody clone (15-7) for further experiments. The 15-7 anti-Flt3Va rabbit monoclonal antibody identified Flt3Va protein expressed on the cell surface and within the cytoplasm of transfected TF-1 cells by flow cytometry and western blotting. However, no Flt3Va protein was detected in untransfected TF-1 cells or normal CD34+ bone marrow cells. The 15-7 antibody bound to 26 of 52 primary AML samples and 5 of 10 primagraft samples (PDX models) of human AML. Immunoblotting analyses of PDX models and patient samples confirmed binding to a protein of the expected size (130-160 kDa). Additionally, multi-parameter flow cytometry in 10 PDX models and 52 primary demonstrated that putative AML stem cells (as defined by the CD45dim, CD34, CD38, CD33, c-Kit cell surface expression) co-expressed Flt3Va antigen in 50% samples evaluated. An analysis of Flt3Va protein localization by live cell imaging showed a punctate distribution of Flt3Va on the cell surface. Furthermore, we observed that overexpression of Flt3Va in TF-1 cells led to GM-CSF growth factor independence. Analysis of TF-1 cells in the absence of GM-CSF and Flt3 ligand demonstrated constitutive activation of STAT5, an important mediator of Flt3 signaling, in Flt3Va overexpressing cells. In addition, Erk1/2 phosphorylation was also increased in Flt3Va overexpressing cells, another downstream effector of Flt3. In an effort to determine if Flt3Va+ cells had tumor repopulating ability, we sorted 0.3X10^6 Flt3Va+ and Flt3Va- cells from a PDX sample and injected the sorted populations or unsorted bulk tumor cells into NSG mice. The human cell engraftment in the mice was detected by the expression of human CD45, CD33, CD34, CD38, and c-kit antigens in the peripheral blood. In two experiments, mice injected with Flt3Va+ cells had detectable circulating leukemic cells by ~18 days after injection, while those injected with Flt3Va- cells had detectable circulating leukemic cells after the 4th week. These results suggest both Flt3Va+ and Flt3Va- cell populations are able to reconstitute leukemia after transplantation in NSG mice. However, Flt3Va+ may be expressed by an aggressive AML clone that facilitate early tumor engraftment. Overall, these studies suggest that Flt3Va is a leukemia-specific neoantigen and is an attractive potential immunotherapeutic target in AML. Proteins such as Flt3Va generated by alternative splicing are common in AML and may be targets for of novel blocking antibodies or ADCs, minimizing effects on normal tissues. Disclosures Adamia: Janssen: Research Funding. Nemeth:Janssen: Employment. Attar:Janssen: Employment. Letai:AbbVie: Consultancy, Research Funding; Tetralogic: Consultancy, Research Funding; Astra-Zeneca: Consultancy, Research Funding. Steensma:Millenium/Takeda: Consultancy; Celgene: Consultancy; Amgen: Consultancy; Janssen: Consultancy; Ariad: Equity Ownership; Genoptix: Consultancy. Weinstock:Novartis: Consultancy, Research Funding. DeAngelo:Novartis: Consultancy; Ariad: Consultancy; Pfizer: Consultancy; Baxter: Consultancy; Celgene: Consultancy; Incyte: Consultancy; Amgen: Consultancy. Stone:Agios: Consultancy; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celator: Consultancy; Juno Therapeutics: Consultancy; Roche: Consultancy; Jansen: Consultancy; Pfizer: Consultancy; ONO: Consultancy; Sunesis Pharmaceuticals: Consultancy; Merck: Consultancy; Xenetic Biosciences: Consultancy; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy; Amgen: Consultancy; Karyopharm: Consultancy; Seattle Genetics: Consultancy. Griffin:Janssen: Research Funding; Novartis: Consultancy, Research Funding.

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Secreted Mutant Calreticulins As Rogue Cytokines Trigger Thrombopoietin Receptor Activation Specifically in CALR Mutated Cells: Perspectives for MPN Therapy

Blood ◽

10.1182/blood-2018-99-118348 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 4-4 ◽

Cited By ~ 15

Author(s):

Christian Pecquet ◽

Thomas Balligand ◽

Ilyas Chachoua ◽

Anita Roy ◽

Gaelle Vertenoeil ◽

...

Keyword(s):

Electron Microscopy ◽

Flow Cytometry ◽

Cell Surface ◽

Board Of Directors ◽

Research Funding ◽

Advisory Committees ◽

Allele Burden ◽

In Trans ◽

Equity Ownership ◽

In Cells

Abstract Background Mutant calreticulins carrying the sequence translated after a +1 frameshift at the C-terminus are major drivers of myeloproliferative neoplasms (MPNs). These mutant CALRs bind and activate TpoR/MPL in cells co-expressing TpoR and mutant CALRs, resulting in persistent JAK2-STAT5 signaling. Whether mutant CALR proteins are secreted, thus acting in trans on other cells, is not known. Aims Our objectives were to: 1) assess the direct TpoR-mutant CALR interaction both when expressed in the same or in different cells; 2) determine whether mutant CALRs are secreted; and 3) determine whether mutant CALR can act as extracellular cytokines. Methods Engineered CALR and TpoR mutants were analyzed by a combination of biochemical approaches (bioluminescence resonance energy transfer, recombinant protein production), functional assays (cell growth and transcriptional assays, flow cytometry, primary megakaryocytic clonogenic assay, analysis of CALR del52 knock-in mice) and cell imaging (confocal microscopy, flow cytometry and immuno-gold electron microscopy). Secreted CALRs were determined by ELISA using mutant specific antibodies. Results 1) Two systems provided evidence that mutant CALRs and TpoR directly interact. First, using Nano-BRET in cells co-expressing N-terminally fused TpoR or EpoR with Nano-luciferase and mutant or WT CALR C-terminally tagged with HaloTag that is bound to the 618-ligand fluorophore, we show that TpoR and mutant CALRs interact in a complex whether the two proteins are within 10 nm. The interaction does not occur between TpoR and WT CALR, or between EpoR and mutant or WT CALRs. Second, expressing mutant CALR and TpoR extracellular domain in S2 Drosophila Schneider cells showed that stable complex formation requires immature high mannose structure on TpoR. Lastly, we could detect surface expression of the TpoR/CALRdel52 complex using proximity ligation assay with anti-TpoR and anti-mutant CALR antibodies in CRISPR/Cas9 engineered UT7/Tpo cells that express endogenous mutant CALR and TpoR levels. 2) We used flow cytometry, confocal immunofluorescence and immunogold electron microscopy and could show that mutant CALRs are trafficking via cis-, medial- and trans-Golgi to the cell-surface and are secreted, independently from TpoR expression. Importantly, mutant CALRs are also secreted in CALR mutated MPN patients as determined by mutant CALR-specific ELISA assay in patient plasma (mean plasma level 24.6 ng/ml, range 0-156.5 ng/ml). In the 113 evaluated CALR mutated patients from different centers the plasma mutant CALR levels correlated with CALR mutant allele burden (P<0.001). Secreted mutant CALR can also be found in plasma from knock-in CALR del52 mice. 3) We show that recombinant mutant CALR can act as a cytokine and specifically stimulate JAK2-STAT5 pathway in cells that carry the TpoR at the surface. Using Nano-BRET, we could demonstrate that extracellular mutant Halo-tagged CALR can specifically bind in trans to the cell-surface TpoR fused with Nano-luciferase, but not to EpoR fused with Nano-luciferase. This binding and the subsequent JAK2 activation were obtained at levels of around 100-150 ng/ml only in cells exposing at the cell-surface TpoR with at least one immature N-linked sugar. This can be accomplished by co-expressing in the reporter cells non-tagged mutant CALR, which will promote cell-surface localization of partially immature TpoR. The effect of exogenous mutant CALR could involve both stabilization of the endogenous cell-surface mutant CALR-TpoR complexes and binding to unoccupied immature TpoRs. Conclusion We show that mutant CALRs directly interact with TpoR and also are secreted and can act as rogue cytokines, leading to activation of cells carrying TpoR. Activation of TpoR in trans is efficient at mutant CALR levels similar to those detected in patients when target cells co-express heterozygous mutant CALR and TpoR, where endogenous mutant CALR transports to the surface TpoR with immature glycosylation. Thus, secreted mutant CALRs is predicted to expand the MPN clone. Given that cell-surface mutant CALR in TpoR expressing cells is crucial for oncogenicity, and that mutant CALRs are also secreted correlating with allele burden, we discuss how antibodies and other immunotherapy approaches could specifically target the mutant CALR MPN clone. Disclosures Xu: MyeloPro Research and Diagnostics GmBH: Employment. Hug:MyeloPro Diagnostics and Research GmbH: Employment. Gisslinger:Janssen: Consultancy, Honoraria; AOP Orphan: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Shire: Honoraria; Novartis: Consultancy, Honoraria, Research Funding. Kralovics:MyeloPro Diagnostics and Research GmbH: Equity Ownership. Constantinescu:Personal Genetics: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy; Novartis: Membership on an entity's Board of Directors or advisory committees; AlsaTECH: Equity Ownership; Novartis: Honoraria; MyeloPro Research and Diagnostics GmbH: Equity Ownership.

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Venetoclax Enhances Anti-Leukemia Activity of CD123-Specific BiTE-Secreting T-Cells in AML

Blood ◽

10.1182/blood-2020-139625 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 12-13

Author(s):

Hong Mu-Mosley ◽

Lauren B Ostermann ◽

Ran Zhao ◽

Challice L. Bonifant ◽

Stephen Gottschalk ◽

...

Keyword(s):

Flow Cytometry ◽

T Cells ◽

T Cell ◽

Board Of Directors ◽

Research Funding ◽

Vehicle Control ◽

Advisory Committees ◽

Cellular Therapies

Background: CD123 is frequently expressed in hematologic malignancies including AML. CD123 has been a potential immunotherapeutic target in AML due to its association with leukemic stem cells that play an essential role in disease progression and relapse. Our previous study using T-cells secreting CD123/CD3-bispecific T-cell engagers (BiTEs) (CD123-ENG T-cells) has shown activity in preclinical studies, recognizing and killing acute myeloid leukemia (AML) blasts in vitro and in vivo. CD123-ENG T-cells secrete bispecific molecules that recognize CD3 (T-cells) and CD123 (AML blasts), and are able to direct transduced T-cells and recruit bystander T-cells to kill CD123-positive blasts. Venetoclax is a BCL-2 inhibitor that can restore functional apoptosis signaling in AML cells, and has been FDA approved for the treatment of AML patients in combination with hypomethylating agents. To improve the efficacy of CD123-ENG T-cells we explored efficacy in AML by combining targeted immunotherapy (CD123-ENG T cells) with targeted inhibition of anti-apoptotic BCL-2 (venetoclax) in vitro and in vivo models of AML. Methods : CD123-ENG T-cells were generated by retroviral transduction and in vitro expansion. Non-transduced (NT) T-cells served as control. In vitro, GFP+ MOLM-13 AML cells were pretreated with venetoclax (0, 10µM, and 20µM) for 24 hours prior to co-culture with CD123-ENG or NT T-cells at an effector/target ratio of 1:10. After 16 hours, MOLM-13 AML cells were analyzed by flow cytometry and quantitated using counting beads; cytotoxicity was calculated relative to untreated MOLM-13 control. The anti-AML activity of the combination was further evaluated in a MOLM-13-luciferase xenograft AML mouse model. Leukemia progression was assessed by bioluminescence imaging. The frequency of MOLM13 AML and human T cells in periphera blod (PB) was determined by flow cytometry. Results: In vitro, we demonstrated that pretreatment of Molm13 AML cells with venetoclax enhanced the cytolytic activity of CD123-ENG T-cells compared to NT- or no T-cell controls. Interestingly, venetoclax sensitized Molm13 to CD123-ENG T-cell killing in a dose-dependent manner (Fig.1; 50%/31% killing by CD123-ENG T-cells versus 27%/14% of killing by NT T cells post pretreatment with 10µM or 20µM ventoclax, p<0.001). In the Molm13 luciferase xenograft model, NSGS mice were randomized into 5 groups after AML engraftment was confirmed: 1) vehicle control, 2) Venetoclax (Ven) only, 3) CD123-ENG T-cells only, 4) Ven+CD123-ENG T-cells, 5) Ven+CD123-ENG T-cells/2-day-off Ven post T-cell infusion (Ven[2-day-off]+CD123-ENG). Venetoclax treatment (100 µg/kg daily via oral gavage) was started on day 4 post Molm13 injection, and on day 7, mice received one i.v. dose of CD123-ENG T-cells (5x106 cells/mouse). Venetoclax or CD123-ENG T-cell monotherapy reduced leukemia burden compared to the control group, and combinational treatments further inhibited leukemia progression as judged by BLI and circulating AML cells (%GFP+mCD45-/total live cells) by flow cytometry on day 15 post MOLM-13 injection: vehicle control: 19.6%; Ven+: 3.4%; CD123-ENG T-cells:1.2 %; Ven+CD123-ENG T-cells: 0.3%; Ven[2-day-off]+CD123-ENG T-cells (p<0.01 Ven+ or CD123-ENG T-cells versus control; p<0.001 Ven+CD123-ENG or Ven[2-day-off]+CD123-ENG T cells versus CD123-ENG T cells, n=5). The enhanced anti-AML activity of combining venetoclax and CD123-ENG T-cells translated into a significant survival benefit in comparison to single treatment alone (Fig. 2). However, while Ven+CD123-ENG and Ven[2-day-off]+CD123-ENG T-cell treated mice had a survival advantage, they had reduced circulating numbers of human CD3+ T cells on day 8 post T-cells infusion compared to mice that received CD123-ENG T-cells, indicative of potential adverse effect of venetoclax on T-cell survival in vivo. Conclusion: Our data support a concept of combining pro-apoptotic targeted and immune therapy using venetoclax and CD123-ENG T-cells in AML. While it has been reported that venetoclax does not impair T-cell functionality, more in-depth analysis of the effect of Bcl-2 inhibition on T-cell function and survival appears warranted, as it could diminish survival not only of AML blasts but also of immune cells. Disclosures Bonifant: Patents filed in the field of engineered cellular therapies: Patents & Royalties: Patents filed in the field of engineered cellular therapies. Gottschalk:Patents and patent applications in the fields of T-cell & Gene therapy for cancer: Patents & Royalties; Inmatics and Tidal: Membership on an entity's Board of Directors or advisory committees; Merck and ViraCyte: Consultancy; TESSA Therapeutics: Other: research collaboration. Velasquez:Rally! Foundation: Membership on an entity's Board of Directors or advisory committees; St. Jude: Patents & Royalties. Andreeff:Amgen: Research Funding; Daiichi-Sankyo; Jazz Pharmaceuticals; Celgene; Amgen; AstraZeneca; 6 Dimensions Capital: Consultancy; Daiichi-Sankyo; Breast Cancer Research Foundation; CPRIT; NIH/NCI; Amgen; AstraZeneca: Research Funding; Centre for Drug Research & Development; Cancer UK; NCI-CTEP; German Research Council; Leukemia Lymphoma Foundation (LLS); NCI-RDCRN (Rare Disease Clin Network); CLL Founcdation; BioLineRx; SentiBio; Aptose Biosciences, Inc: Membership on an entity's Board of Directors or advisory committees.

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Hypoxia Promotes Dissemination of Multiple Myeloma Through Acquisition of Endothelial to Mesenchymal Transition (EMT) Features

Blood ◽

10.1182/blood.v118.21.471.471 ◽

2011 ◽

Vol 118 (21) ◽

pp. 471-471

Author(s):

Abdel Kareem Azab ◽

Jinsong Hu ◽

Phong Quang ◽

Feda Azab ◽

Costas Pitsillides ◽

...

Keyword(s):

Flow Cytometry ◽

Tumor Progression ◽

Board Of Directors ◽

Research Funding ◽

Tumor Burden ◽

Advisory Committees ◽

Mesenchymal Transition ◽

E Cadherin

Abstract Abstract 471 Multiple myeloma (MM) is characterized by widespread dissemination of the MM cells at diagnosis associated with multiple focal bone lesions, implying (re)circulation of MM cells into the peripheral blood and (re)entrance or homing into new sites of the BM. However, the driving force for MM cells to leave the BM, egress, and home to new BM niches is still not well understood. Hypoxia (low oxygen) in solid tumors was shown to promote metastasis in solid tumors through activation of proteins involved in the endothelial to mesenchymal Transition (EMT). In this study, we hypothesized that MM tumor progression induces hypoxic conditions, which in turn activates EMT related proteins and promotes metastasis of MM cells. To test this hypothesis, we examined levels of hypoxia in MM cells at different stages of tumor progression in vivo in two animal models: the first by injecting MM1s cell to SCID mice, and the second by injecting 5T33MM cells to C57BL/KaLwRijHsd mice. Hypoxic markers were examined using flow cytometry and immunohistochemistry. We found that tumor progression induced hypoxia in both the MM cells and the tumor microenvironment. Similarly, hypoxia induced genes (HIF1a, HIF1b, HIF2b, CREBBP, HYOU1, VEGF1, HIF1a-inhibitory protein) were increased in MM patients (n=68) compared to plasma cells from healthy donors (n=14). Using flow cytometry we found that the number of circulating MM cells increased with the progression; however, the correlation was observed in late stages of the progression but not in the early stages. A better direct correlation was achieved with the hypoxic state of the MM cells in the BM. Circulating MM cells were more hypoxic that MM cells in the BM (especially at low tumor burden). Moreover, we found that the level of hypoxia in MM cells in the PB did not correlate with the hypoxia in the BM. Next, we tested the mechanism in which hypoxia induces cell egress. We found that MM cells isolated from MM patients have higher gene expression of EMT inducing proteins (E-cadherin, SNAIL, FOXC2, TGFb1) in parallel to a decrease of expression in E-cadherin, and we confirmed the downregulation of E-cadherin expression in correlation with the increase of hypoxia in MM cell and cells in the BM microenvironment in vivo. Culturing MM cells under hypoxic conditions increased the expression of HIF1a and HIF2a. In parallel, hypoxia induced acquisition of EMT related features including downregulation of E-cadherin, upregulation of SNAIL, and inhibition of GSK3b. In addition, hypoxia decreased the adhesion of MM cells to stromal cells. To complete the metastatic process after egress, MM cells need to home to new sites in the BM. Therefore we investigated the effect of hypoxia on expression of CXCR4, chemotaxis and homing of MM cells to the BM. Using flow cytometry we found a direct correlation between hypoxia and the expression of CXCR4 in MM cells in vivo using the SCID-MM1s model. These results were confirmed in vitro, where hypoxia increased the expression of CXCR4 at protein and mRNA levels in MM cells. Moreover, the expression of CXCR4 in MM cells isolated from the PB was higher than cells isolated from the BM especially at low tumor burden, correlating with higher hypoxic state of the circulating tumor cells. Functionally, hypoxia increased the chemotaxis of MM cells towards SDF1a in vitro and, using in vivo confocal microscopy, it was shown to accelerate the homing of MM cells to the BM in vivo. To demonstrate that the chemotaxis and homing were CXCR4 dependent, we treated the hypoxic MM cells with AMD3100 (a CXCR4 inhibitor) and showed that it inhibited chemotaxis in vitro and homing of MM to the BM in vivo. In conclusion, we demonstrate that tumor progression induces hypoxia in the MM cells and in the BM microenvironment. Hypoxia activates EMT-related machinery in MM cells, decreases expression of E-cadherin and consequently decreased the adhesion of MM cells to the BM, and enhance egress of MM cells to the circulation. In parallel, hypoxia increases the expression of CXCR4, and consequently increased the migration and homing of MM cells in from the peripheral blood to the BM. Further studies to manipulate hypoxia in order to regulate tumor dissemination as a therapeutic strategy are warranted. Disclosures: Roccaro: Roche: . Kung:Novartis Pharmaceuticals: Consultancy, Research Funding. Ghobrial:Novartis: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Millennium: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Research Funding; Noxxon: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.

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Mechanisms Underlying the Synergistic Interaction of Filanesib with Pomalidomide and Dexamethasone (FPD) in Multiple Myeloma

Blood ◽

10.1182/blood.v126.23.1801.1801 ◽

2015 ◽

Vol 126 (23) ◽

pp. 1801-1801 ◽

Cited By ~ 1

Author(s):

Susana Hernández-García ◽

Laura San-Segundo ◽

Lorena González-Méndez ◽

Montserrat Martín-Sánchez ◽

Luis A Corchete ◽

...

Keyword(s):

Cell Cycle ◽

Flow Cytometry ◽

Board Of Directors ◽

Research Funding ◽

Annexin V ◽

Triple Combination ◽

Advisory Committees ◽

Cell Cycle Profile

Abstract Introduction: Filanesib (ARRY-520) is a novel inhibitor of the "kinesin spindle protein" (KSP), which has demonstrated efficacy in heavily pretreated patients with refractory MM, (Lonial et al, ASH 2013). Our preliminary studies demonstrated synergy with standard anti-MM agents, especially with pomalidomide and dexamethasone. This set the stage for a recently activated trial being run by the Spanish MM group investigating FPD in relapsed MM patients. In this abstract we investigate the mechanisms underlying the synergy of the combination. Methods: In vitro action of FPD was evaluated in MM cell lines by MTT assay, bioluminescence, Annexin V staining, cell cycle profile analysis and TMRE staining by flow cytometry. Synergy was quantified with the Calcusyn software. In vivo efficacy was assessed in a subcutaneous plasmacytoma model of MM1S in CB17-SCID mice (The Jackson Laboratory, Bar Harbor, ME, USA). The mechanism of action was analyzed by Western blot, flow cytometry, genomic techniques, immunohistochemistry and immunofluorescence techniques. Results: The triple combination of FPD resulted in clear synergy in multiple myeloma cell lines (MM1S, OPM2, and RPMI8226) with combination indices between 0.4-0.7, and abrogated the effect of the soluble cytokines IL-6 and IGF-I and the protective effect of the adhesion of plasma cells to BMSCs, HS-5 and TERT cells. FPD caused cell cycle arrest in G2/M and specific apoptosis of cells arrested in these proliferative phases (with apoptosis percentage of 5, 23, 58 and 88 for control, poma+dexa, filanesib and FPD, respectively) demonstrated by flow cytometry with DRAQ5 and Annexin-V. Thus, FPD and filanesib in monotherapy treatments induced a similar effect on the cell cycle profile (arrest in G2/M) with a concordant increase of cyclin B1 and phosphorylated Histone H3. Although a secondary increase of KSP protein levels would be expected, pomalidomide and dexamethasone induced a decrease of the levels of this protein, which was still present in the triple combination (FPD). This fact could be contributing to the potentiation observed with the combination. Attending to apoptosis mechanism, proapoptotic stimulus from the extrinsic and intrinsic apoptotic pathways were promoted by pomalidomide and dexamethasone and filanesib, and converged in the triple combination. In this regard, a decrease of MCL-1 (antiapoptotic protein) and a significant increase of the proapoptotic BCL2 family members of the intrinsic pathway like NOXA and BIMEL BIML, BIMS(this last one being the most potent proapoptotic isoform), tBID (extrinsic pathway) and Bax protein were observed. We confirmed that all these proteins were translocated into the mitochondria, resulting in a decrease of the mitochondrial membrane potential by TMRE, increase of permeability and a release of cytochrome C and AIF. These results were confirmed in vivo in a model of subcutaneous plasmacytoma in small (70 mm3) and large (2000 mm3) tumors. In this model we observed a significant reduction of tumor growth, which was correlated with a statistically significant improvement in survival. Changes induced by FPD in the gene expression profile were concordant with the in vitro results as several overexpressed genes belonging to the previous pathways were identified, such as spindle assembly checkpoint (CENP-E and CENP-F) and apoptosis (BCL2L11, gene that codifies BIM protein). Furthermore, IHC of tumors treated with FPD showed more apoptosis by TUNEL and a significant increase of monopolar spindles (2, 0, 53 and 140 per 10 high-power fields, for control, poma+dexa, filanesib and FPD, respectively). Conclusions: The synergy observed with filanesib in combination with pomalidomide and dexamethasone is the result of several coincidental mechanisms: a potentiation of the KSP inhibition with a subsequent increase in monopolar spindle formation and a simultaneous activation of the intrinsic and extrinsic pathways of apoptosis. In this regard, NOXA, BIM, BAX and tBID are probably the central players that, through different mechanisms, inhibit antiapoptotic proteins (MCL-1, BCL2 and BCL-XL) and promote mitochondrial outer membrane permeabilization and the release of apoptogenic factors such us cytochrome C and AIF. This work was funded in part by the company Array BioPharma. Disclosures Tunquist: Array BioPharma: Employment. Mateos:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Onyx: Consultancy; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy. Ocio:Jassen: Honoraria; Celgene: Honoraria, Research Funding; Pharmamar: Consultancy, Research Funding; MSD: Research Funding; Novartis: Consultancy, Research Funding; Mundipharma: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy; Amgen/Onyx: Consultancy, Honoraria, Research Funding; Array BioPharma: Consultancy, Research Funding.

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Leukemic Cell Expressed CTLA-4 Suppresses T Cells Via Down-Modulation of CD80 By Trans-Endocytosis

Blood ◽

10.1182/blood.v128.22.3221.3221 ◽

2016 ◽

Vol 128 (22) ◽

pp. 3221-3221 ◽

Cited By ~ 1

Author(s):

Priscilla Do ◽

Kyle A. Beckwith ◽

Larry Beaver ◽

Brittany G. Griffin ◽

Xiaokui Mo ◽

...

Keyword(s):

Flow Cytometry ◽

T Cells ◽

T Cell ◽

B Cells ◽

Cell Surface ◽

Board Of Directors ◽

Tumor Cells ◽

Research Funding ◽

Leukemic Cell ◽

Advisory Committees

Abstract The function of CTLA-4 on non-T cells is largely ignored and currently ill defined despite rapidly growing interest in targeting this immune checkpoint protein in several cancers. While anti-CTLA-4 therapy is proposed to work through inhibition of the immunosuppressive effect of CTLA-4 on T cells, multiple examples of non-T cell expressed CTLA-4 have been reported. These cells include tumor cells of hematological and non-hematological origin and normal B cells. In this study, we have defined a novel immune suppressive role for non-T cell, tumor expressed CTLA-4 in Chronic Lymphocytic Leukemia (CLL). We have detected by microarray that CTLA-4 is in the top 5 most differentially expressed genes between pooled samples of healthy donor normal B cells (N=6) and pooled CLL leukemic B cells (N=5). Upregulation of CTLA-4 by CLL B cells compared to normal B cells was validated by RT-qPCR and flow cytometry. CTLA-4 was predominantly intracellular (42/46 CTLA-4+) and not on the cell surface (2/48 CTLA-4+) in primary CLL samples. B cell activating factors (CD40L, PMA/Ionomycin, LPS, IL4, LPS+IL4, CD40L+IL4, CpG, and anti-IgM) could not induce surface expression of CTLA-4; however, co-culture with anti-CD3/anti-CD28 or ConA activated T cells (autologous or allogeneic) resulted in detectable CTLA-4 on the cell surface of leukemic B cells. This induction did not occur with resting T cells. This finding suggests a role for CTLA-4+ tumor cells in sites of T cell activation, such as the lymph node, a site of leukemic cell proliferation in CLL. To mechanistically study leukemic B cell expressed CTLA-4, we generated CLL-derived Mec1 and OSU-CLL that inducibly express CTLA-4 upon doxycycline (dox) treatment. Mec1 and OSU-CLL cells highly express the ligands for CTLA-4, CD80 and CD86. Dox-induction of CTLA-4 resulted in decreased expression of Mec1 and OSU-CLL expressed CD80, a critical T cell co-stimulatory protein (N=3). Blockade of CTLA-4 using the anti-CTLA-4 therapeutic antibody, Ipilimumab, could restore CD80 on Mec1 and OSU-CLL cells (N=3). Because T cell-expressed CTLA-4 has been previously shown by others to down-modulate CD80 via trans-endocytosis, we co-cultured CTLA-4+ Mec1 and CTLA-4+ primary CLL cells with stably transfected CD80-GFP or CD86-GFP Hek293 cell lines to assess uptake of CD80/CD86 into CTLA-4 expressing tumor cells as the mechanism of CD80 down-modulation. Transfer of CD80-GFP and CD86-GFP was detected by flow cytometry in primary CLL cells and the Mec1 cell line, consistent with the ability of T cell expressed CTLA-4 to trans-endocytose CD80 and CD86. Furthermore, uptake of CD80-GFP or CD86-GFP by primary tumor cells was CTLA-4 dependent, demonstrated by inhibition of GFP uptake in the presence of Ipilimumab. Following determination of decreased CD80, we found that co-culture of primary T cells with Mec1 CTLA-4+ cells resulted in decreased IL2 production measured by Cytokine Bead Array. The loss of IL2 signified decreased co-stimulation as a result of tumor expressed CTLA-4. Studies are ongoing regarding dependence on CD80 or CD86. A minor subset of T cells, Tregs, are known to exert profound immunosuppressive effects through their expression of CTLA-4. Due to our results, tumor expressed CTLA-4 has an overlapping function with Treg CTLA-4, and it is imperative that we define the immunosuppressive effects as, in patients, the leukemic cells may comprise a much larger proportion of white blood cells than T cells. Efforts are now underway to address the effect of tumor expressed CTLA-4 in suppressing anti-tumor immunity in vivo utilizing a novel mouse model. Suppression of T cells by tumor expressed CTLA-4 is a novel finding that is broadly applicable to fields within and outside of cancer research as the pathway and mechanism described here are potentially applicable to CTLA-4 in diverse disease contexts and to the general biology of CTLA-4. [Funding: This work was supported by P01 CA95426. PD received the Pelotonia Graduate Fellowship. Any opinions, findings, and conclusions expressed in this material are those of the author(s) and do not necessarily reflect those of the Pelotonia Fellowship Program] Disclosures Jones: AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics, LLC, an AbbVie Company: Membership on an entity's Board of Directors or advisory committees, Research Funding.

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p53 Functional Assessment and Correlation with 17p Deletion and/or TP53 Mutation Status: Final Report of the ICLL001 Bomp Trial

Blood ◽

10.1182/blood-2018-99-116722 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 3127-3127

Author(s):

Magali Le Garff-Tavernier ◽

Claire Quiney ◽

Lauren Veronese ◽

Florence Nguyen-Khac ◽

Pauline Robbe ◽

...

Keyword(s):

Functional Status ◽

Clinical Response ◽

Board Of Directors ◽

Research Funding ◽

Gene Disruption ◽

Tp53 Mutation ◽

Tp53 Gene ◽

Functional Assay ◽

Type B ◽

Advisory Committees

Abstract Introduction: The 17p deletion (del(17p)) resulting in loss of the TP53 gene is associated with impaired response to genotoxic agents and has an impact on PFS following BTK inhibitor and possibly also venetoclax. The del(17p) usually coincides with TP53 mutation, leading to the impairment of the p53-associated pathway. Sole TP53 mutations appear also associated with poor outcome in prospective trials. The iwCLL guidelines recommend to look for del(17p) and TP53 mutation before each line of treatment. An original approach is the functional assay, which highlights the functional abnormalities of p53 whether it is a TP53 gene disruption (del(17p) and/or TP53 mutation) or a defect of another actor in the p53 pathway. We aim to validate this functional assay on a prospective trial and to study the impact of p53 status on the clinical response regardless of the biological method. Methods: Clinical and biological data were collected from 74 CLL patients (pts) enrolled in the BOMP phase II trial of the French Innovative Leukemia Organization (FILO) (NCT01612988) evaluating 6 monthly courses of BOMP including bendamustine, ofatumumab and high dose methylprednisolone in fit pts with relapsing CLL. In addition to conventional screening, we focused on p53 evaluation at time of inclusion. FISH analysis for del(17p) was done with a 5% cut-off for positive result. TP53 gene mutation screening was performed by Sanger sequencing of the coding region (exons 2-11). A targeted NGS screening (19 genes including TP53, Illumina MiSeq) was also performed. The p53 functional status was determined by a flow cytometry assay based on induction of p53 and p21 protein expression after etoposide and nutlin-3 exposition, as previously described (Le Garff-Tavernier M., 2011), which allows the detection of 3 types of p53 dysfunction (A, B and C), irrespective of an ATM default. Clinical response was evaluated by PFS, OS and TTNT Kaplan-Meier analyses (MedCalc stat). Results: Data from the whole cohort are available. Median age was 64 yrs. Pts had a median of 1 (1-3) lines of treatment previous to this trial, including FCR in >90%. Concerning p53 evaluation, a del(17p) was found in 30% of cases by FISH (22/73 pts with a median of 68% positive cells, range 10-98). The percentage of p53 abnormalities increased to 41% when TP53 mutations were screened (30/73 pts with 1 to 8 mutations, median VAF 10 %, range 1.6-90). Results from the p53 functional assay were available for 69 pts showing the highest level of p53 abnormalities. Indeed, p53 dysfunction was observed in 48% of pts (33/69) including type A (n=11), type B (n=17) and type C (n=5) dysfunction. Thus, the sensitivity and specificity of the p53 functional assay to detect pts with del(17p) and/or TP53 mutation were of 87% and 84% respectively (n=68 pts for which the 3 tests were available). Interestingly, discordant results were observed in 10 pts: 4 pts with a functional p53 despite a TP53 gene disruption (3 with TP53 mutation only and 1 with del(17p) only) and conversely 6 pts with a p53 dysfunction (all with type B dysfunction) but without any TP53 gene disruption, suggesting alternative alterations of the p53 pathway. The only similarity for those latter pts is the occurrence of at least one ATM abnormality (del(11q) and/or ATM mutation). The combination of the 3 assays defines 3 groups: (1) "intact p53" (no TP53 disruption and functional p53, n=32), (2) "altered p53" (TP53 disruption and p53 dysfunction, n=26) and (3) "discordant p53" (n=10). PFS and TTNT were higher in pts without (n=38) compared to those with TP53 gene disruption (n=30) (p=0.04 for both). The OS, even though not significant, presented a similar trend. When considering the functional status, a similar profile is observed but with a better discrimination between pts with normal p53 function (n=36) and pts with p53 dysfunction (n=32) (p=0.002 and 0.003, respectively). Combining the 3 assays, PFS and TTNT of the group 3 "discordant p53" profiles' appeared intermediate (Figure 1). Conclusion: This study shows that a p53 functional analysis can predict with an acceptable sensitivity the presence of a TP53 gene disruption. Interestingly, this functional assay coupled with cytogenetic and mutational screening could reveal a sub-group of pts with discordant results for which PFS and TTNT appeared intermediate. Evaluation of other discordant cases is mandatory to confirm these results and could lead to a wider use of this global functional approach. Figure 1. Figure 1. Disclosures Feugier: Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Sylvain:Gilead: Other: scientific advisor board. Schuh:Giles, Roche, Janssen, AbbVie: Honoraria. Guieze:abbvie: Honoraria; janssen: Honoraria; gilead: Honoraria. Leblond:Abbvie: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Speakers Bureau; Roche: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Speakers Bureau; Janssen: Consultancy, Honoraria, Speakers Bureau; Gilead: Honoraria, Speakers Bureau; Sandoz: Honoraria; Amgen: Honoraria.

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Response and Outcomes to Nilotinib at 24 Months in Imatinib-Resistant Chronic Myeloid Leukemia Patients in Chronic Phase (CML-CP) and Accelerated Phase (CML-AP) with and without BCR-ABL Mutations.

Blood ◽

10.1182/blood.v114.22.1130.1130 ◽

2009 ◽

Vol 114 (22) ◽

pp. 1130-1130 ◽

Cited By ~ 1

Author(s):

Jerald P. Radich ◽

Giovanni Martinelli ◽

Andreas Hochhaus ◽

Enrico Gottardi ◽

Simona Soverini ◽

...

Keyword(s):

Board Of Directors ◽

Median Time ◽

Research Funding ◽

Philadelphia Chromosome ◽

Chronic Phase ◽

Cytogenetic Response ◽

Molecular Response ◽

Advisory Committees ◽

Imatinib Resistant

Abstract Abstract 1130 Poster Board I-152 Background Nilotinib is a selective and potent BCR-ABL inhibitor, with in vitro activity against most BCR-ABL mutants (excluding T315I) indicated for the treatment of patients with Philadelphia chromosome positive (Ph+) CML in CPor AP resistant or -intolerant to prior therapy, including imatinib. In a previous analysis of nilotinib in patients with BCR-ABL mutations, mutations occurring at three specific amino acid residues (E255K/V, Y253H, and F359C/V) were shown to be associated with less favorable response to nilotinib. The current analysis is based on mature data with a minimum follow-up of 24-months for all patients. Outcomes of patients at 24 months were analyzed by mutation type. Methods Imatinib-resistant CML-CP (n = 200) and CML-AP (n = 93) patients were subdivided into the following mutational subsets: no mutation, sensitive mutations (including mutations with unknown in vitro IC50). or E255K/V, Y253H, or F359C/V mutations at baseline. Patients with mutations of unknown in vitro sensitivity were classified as sensitive in this analysis based on a previous finding that patients with these mutations responded similarly to nilotinib as patients with sensitive mutation. Patients with baseline T315I mutations were excluded from this analysis. Patient groups were analyzed for kinetics and durability of cytogenetic and molecular response to nilotinib, as well as event-free survival (EFS), defined as loss of hematologic or cytogenetic response, progression to AP/BC, discontinuation due to disease progression, or death, and overall survival (OS). Results In CML-CP and -AP patients with no mutation, sensitive mutations, or E255K/V, Y253H, or F359C/V mutations, hematologic, cytogenetic and molecular responses are provided in the Table. Overall, patients with no mutations responded similarly to patients with sensitive mutations, whereas patients with E255K/V, Y253H, or F359C/V mutations had less favorable responses. This correlation was observed in both CML-CP and CML-AP patients, respectively. Median time to CCyR was 3.3 months (range, 1.0–26.7) for CML-CP patients with no mutations, and 5.6 months (range, 0.9–22.1) for patients with sensitive mutations. At 24 months, CCyR was maintained in 74% of CML-CP patients with no mutation and in 84% of patients with sensitive mutations. One patient with CML-CP and an E255K mutation achieved CCyR at 25 months and maintained until last assessment at 30 months. Median time to MMR was similar at 5.6 months (range, 0.9–25.8) for CML-CP patients with no mutations and 5.6 months (range, 2.7–22.1) for patients with sensitive mutations. No patient with a less sensitive mutation achieved MMR. Median EFS and 24-month estimated OS rate are provided in the Table. Conclusions Imatinib-resistant CML-CP and CML-AP patients treated with nilotinib therapy with BCR-ABL mutations (excluding E255K/V, Y253H, or F359C/V) achieved rapid and durable cytogenetic responses, and estimated EFS and OS at 24 months similar to that of patients with no mutations, respectively. Patients with E255K/V, Y253H, or F359C/V mutations had lower and less-durable responses and shorter EFS than patients with sensitive mutations. Alternative therapies may be considered for patients with these uncommon mutations (E255K/V, Y253H, and F359C/V). Disclosures Radich: Novartis: Consultancy, Honoraria, Research Funding. Hochhaus:Novartis: Research Funding. Branford:Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding. Shou:Novartis: Employment. Haque:Novartis: Employment. Woodman:Novartis: Employment. Kantarjian:Novartis: Research Funding. Hughes:Bristol-Myers Squibb: Advisor, Honoraria, Research Funding; Novartis: Advisor, Honoraria, Research Funding. Kim:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Wyeth: Research Funding. Saglio:Novartis: Consultancy, Speakers Bureau; BMS: Consultancy, Speakers Bureau.

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Iron Overload Diminishes the Effectiveness of the Innate Immune Response in Thalassemia Major: a Possible Mechanism for Increased Infection Risk.

Blood ◽

10.1182/blood.v114.22.4071.4071 ◽

2009 ◽

Vol 114 (22) ◽

pp. 4071-4071

Author(s):

Patrick B Walter ◽

Paul R Harmatz ◽

Annie Higa ◽

David Killilea ◽

Nancy Sweeters ◽

...

Keyword(s):

Flow Cytometry ◽

Immune Response ◽

Iron Overload ◽

Board Of Directors ◽

Innate Immune Response ◽

Research Funding ◽

Innate Immune ◽

Healthy Controls ◽

Advisory Committees ◽

Fluorescent Intensity

Abstract Abstract 4071 Poster Board III-1006 Introduction Infection is the second most common cause of death in thalassemia. The innate immune system provides a first line of defense against infection and specificity depends on pattern recognition receptors (PRRs) specific to microbial pathogens. One class of PRR called the toll-like receptors (TLRs) are important for transducing the signal for bacterial Lipopolysaccharide (LPS), resulting not only in cytokine production, but also in the control of extracellular iron levels through production of neutrophil gelatinase associated Lipocalin (NGAL). However, the exact role that NGAL plays and the expression level of PRRs are unknown in thalassemia. Thus, the goal in these studies is to investigate the relationship of iron overload to the innate immune cell expression of PRRs and NGAL in thalassemia. Patients and Methods Fifteen transfusion dependent thalassemia patients (11 – 29 yrs old) participating in the combination trial of deferasirox (an oral iron chelator) and deferoxamine were enrolled (Novartis sponsored CICL670AUS24T). Fasting blood samples were obtained i) at baseline after a 72 hr washout of chelator, and ii) at 6 and 12 months on study. Five healthy controls (13 - 18 yrs old) were also enrolled. Fresh monocytes were isolated using antibody-linked magnetic microbeads (Miltenyi Biotec Inc). Highly enriched populations of CD14+ monocytes were verified by flow cytometry. The expression of TLR4, also examined by flow cytometry is reported as the mean fluorescent intensity (MFI). In patients with thalassemia, liver iron concentration (LIC) was analyzed by biomagnetic susceptibility (“SQUID”, Ferritometer®). The plasma levels of NGAL were analyzed by ELISA. Results At baseline the expression of monocyte TLR4 (mean 18.8 ± 3.5 MFI) was reduced 30% compared to the healthy controls (mean 26.9 ± 7.6 MFI, p<0.05). The expression of TLR4 over the follow-up period of 52 weeks in patients receiving intensive combination chelator therapy significantly increased 27% / year (7 MFI / year, p=0.005). Interestingly the expression of monocyte TLR4 was negatively correlated with LIC (r=-0.6, p=0.04). Finally, thalassemia patients at baseline have significantly higher levels of NGAL (80 ± 20 ng/ml) compared to controls (42 ± 15 ng/ml, p=0.01). Conclusions These preliminary studies support the hypothesis that iron burden has a negative impact on the innate immune response in thalassemia as demonstrated by the decreased expression of TLR4. After intensive chelation, the levels of TLR4 increased, indicating that decreased iron overload with chelation may improve innate immune responsiveness. Finally, the iron transport protein NGAL is significantly elevated in thalassemia possibly acting to prevent essential iron uptake by pathogenic bacteria. Disclosures: Harmatz: Novartis: Research Funding; Apotex : Membership on an entity's Board of Directors or advisory committees; Ferrokin: Membership on an entity's Board of Directors or advisory committees. Vichinsky:Novartis: Consultancy, Research Funding.

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Deregulation of TNFRSF18 (GITR) Through Promoter CpG Island Methylation Induces Tumor Proliferation in Multiple Myeloma

Blood ◽

10.1182/blood.v118.21.2424.2424 ◽

2011 ◽

Vol 118 (21) ◽

pp. 2424-2424

Author(s):

Yang Liu ◽

Yong Zhang ◽

Phong Quang ◽

Hai T Ngo ◽

Feda Azab ◽

...

Keyword(s):

Gene Expression ◽

Bone Marrow ◽

Flow Cytometry ◽

Board Of Directors ◽

Research Funding ◽

Plasma Cells ◽

Cpg Island ◽

Advisory Committees ◽

Brdu Assay

Abstract Abstract 2424 Introduction Tumor necrosis factor receptor super families (TNFRSFs) play an important role in activation of lymphocyte and cell apoptosis. However the function of TNFRSFs in multiple myeloma (MM) remains unknown. Loss of function mutation of Fas antigen (TNFRSF6) was identified in MM cells, thus suggesting the possible role of TNFRSFs in regulating MM pathogenesis. We therefore investigated the epigenetic mechanisms that may mediate inactivation of TNFRSFs and its functional role in MM. Methods Dchip software was utilized for analyzing gene expression dataset. DNA was extracted from both primary CD138+ MM plasma cells and MM cell lines using blood & tissue DNA isolation kit (Qiagen, Inc.). Expression of GITR in primary CD138+ plasma cells was detected by Imunohistochemistry (IHC) DNA methylation was analyzed by methylated DNA immunoprecipitation (Medip) assay and bisulfate sequencing. 5'azacytidine was used to demethylate genomic DNA. Gene expression was detected by qRT-PCR and confirmed at the protein level by flow cytometry and western-blot. Over-expression of GITR was obtained in MM1.S cells by using GITR recombinant plasmid and electroporation. Apoptosis was determined using Annexin/PI staining and flow cytometry analysis. Activation of apoptotic signaling was studied by western blot. Cell survival and proliferation were analyzed by MTT and BrdU assay, respectively. Recombinant GITR-lentivirus was obtained from the supernatant of culture medium after 72 hours transfection in 293 cells. GFP positive MM cells were sorted and analyzed by flow cytometry. In vivo effect of GITR on MM tumor growth was determined by injection of GITR over-expressing MM cells in null mice. Mice skull, femur and vertebrae were isolated after 4 weeks injection. Anti-human CD138+ mAb microbead was used to detect MM cells extracted from mice tissue by flow cytometry. Results Gene-expression profiling showed down-regulation of TNFRSFs, including TNFRSF11A, TNFRSF11B, TNFRSF8, TNFRSF10C, TNFRSF9, TNFRSF21, TNFRSF1B, TNFRSF1A and TNFRSF18, compared to normal plasma cells. Moreover, Our IHC results also showed that GITR expression was positive in primary CD138+ plasma cells from 9 normal bone marrow, but negative in 9 MM samples. Importantly, we found that low GITR expression significantly correlated with MM progression. Indeed, GITR gene levels were lower in smoldering and active MM patients compared to MGUS patients and normal donors. Promoter CpG island (CGI) methylation of GITR was indentified in 5 out of 7 MM primary bone marrow (BM)-derived CD138+ cells but not in normal BM-derived plasma cells. Bisulfate sequencing and Medip assay showed that methylation of GITR was significantly associated with GITR expression in 5 MM cell lines, including MM1.S, OPM1, U266, RPMI and INA6. Promoter CGI of GITR was highly methylated leading to complete silencing of GITR in MM1.S cell line. GITR expression was significantly up-regulated in MM cells upon treatment with the 5'azacytidine. MTT and BrdU assay revealed that the proliferation and survival of MM1.S cells was disrupted in the GITR over-expressing MM1.S cells, notably with inhibition of cell proliferation compared to control vector infected cells. Moreover induction of cytotoxicity in GITR over-expressing cells was confirmed by using GFP competition assay. GITR-induced apoptosis was supported by induction of caspase 8 and 3 cleavage. The inhibition of human CD138+ plasma cell growth in the bone marrow of SCID mice using a disseminated MM xenograft model was observed in the experimental group injected with GITR expressing cells compared to the control group after 4 weeks injection. Conclusion Our findings uncovered a novel epigenetic mechanism contributing to MM pathogenesis, showing the role of GITR methylation as a key regulator of MM cell survival. Disclosures: Roccaro: Roche:. Ghobrial:Novartis: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Millennium: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Research Funding; Noxxon: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding.

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