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  • 1
    In: Neoplasia, Elsevier BV, Vol. 16, No. 5 ( 2014-05), p. 403-412
    Type of Medium: Online Resource
    ISSN: 1476-5586
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2014
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  • 2
    In: Blood, American Society of Hematology, Vol. 112, No. 11 ( 2008-11-16), p. 2629-2629
    Abstract: Discovery of somatic mutation of JAK-2 (G1849T that produces JAK-2V617F) in the hematopoietic cells of patients with Philadelphia chromosome negative myeloproliferative disorders (Ph−MPDs) was a watershed event that not only provided new insights into the pathobiology of polycythemia vera, essential thrombocytosis and primary myelofibrosis but also identified a potential target for therapy. Herein we report the results of preclinical studies designed to characterize the activity of a novel inhibitor of JAK-2. The compound, SGI-1252, developed by SuperGen (Dublin, CA) incorporates with high affinity into the ATP-binding site of JAK-2. SGI-1252 was tested against a panel of 75 kinases and was found to have significant activity against only FLT-3, TYK-2 and the SRC family members, ABL, LCK, YES, in addition to JAK-2 and JAK-1. SGI-1252 has an IC50 for JAK-2 of 5.4 nM with an IC50 for JAK-2V617F of 19.7 nM. The inhibitor also effectively blocks the activity of JAK-1 (IC50 14.8 nM) but has little JAK-3 inhibitory activity (IC50 1,700 nM). SGI-1252 is a potent inhibitor of STAT-5 phosphorylation (EC50 76.2 nM) and was also found to block the JAK-2 dependent expression of the anti-apoptotic protein, BCL-XL (EC50 778 nM). Drug treatment of a murine cell line (FDCP) transfected with either human wild-type JAK-2 or JAK-2G1849Tgenerated IC50 values of 83 nM and 108 nM, respectively, and SGI-1252 treatment of human cell lines, HEL, UKE-1 and SET-2, that express mutant JAK2 in different copy numbers, gave IC50 values of 472 nM, 83 nM and 63 nM, repectively. When tested in ex-vivo expanded native human erythroid progenitor cells from 17 patients with Ph−MPDs (10 PV and 7 MF), SGI-1252 showed an IC50 of ~100 nM, regardless of the JAK-2V617F allele burden. Using a flow cytometric assay, SGI-1252 was shown to induce apoptotic cell death in a concentration dependent manner. Luminex technology allows for concurrent quantitative analysis of multiple proteins from the same tissue source, and this technology was used to investigate simultaneously the effects of SGI-1252 on total and phospho ERK1/2, total and phospho STAT3, phospho STAT5, caspase 3, cleaved PARP and GAPDH (control) in untreated and drug treated cells at IC50 and IC80 concentrations. Significant in vivo efficacy of SGI-1252 was also observed using HEL and MV-4-11 xenograft models when compared to treatment with vehicle or daunorubicin. Using a murine model, we found that SGI-1252 has high oral bioavailability and is well tolerated with a five-day repeat maximum dose of at least 900 mg/kg. Together, these studies demonstrate that SGI-1252 is a potent inhibitor of JAK-2 dependent proliferation in both JAK-2V617F positive cell lines and in ex vivo expanded erythroid progenitors derived from patients with JAK-2V617F positive Ph−MPDs. Moreover, our studies show that the effects of SGI-1252 are mediated by blocking both JAK-2 dependent anti-apoptoic pathways and JAK-2 dependent proliferative pathways. Using the orally available form of the compound, pharmacokinetic, pharmacodynamic and toxicity studies in mice suggest that serum concentration of the drug well above the predicted therapeutic range can be achieved without significant hematological toxicity. Based on these preclinical experiments, SGI-1252 appears to be an excellent candidate for phase I/II studies in patients with Ph−MPDs.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
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    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2008
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  • 3
    Online Resource
    Online Resource
    American Association for Cancer Research (AACR) ; 2013
    In:  Cancer Research Vol. 73, No. 8_Supplement ( 2013-04-15), p. 2174-2174
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 73, No. 8_Supplement ( 2013-04-15), p. 2174-2174
    Abstract: The proto-oncogene PIM kinases (PIM-1, PIM-2, PIM-3) are serine/threonine kinases that have been shown to be involved in a number of signaling pathways important to cancer cells. PIM kinases act as downstream effectors as inhibitors of apoptosis and as positive regulators of G1-S phase progression through the cell cycle. PIM kinases are upregulated in multiple cancer indications, including lymphoma, leukemia, multiple myeloma, prostate, gastric, and head & neck cancers. Overexpression of one or more PIM family members in patient tumors frequently correlates with poor prognosis. The aim of this investigation was to evaluate PIM expression in low- and high-grade urothelial carcinoma, and to assess for expression that may contribute to disease progression and serve as a potential site for targeted therapy. Seventy-two cases of urothelial carcinoma were included in this retrospective study of surgical biopsy and resection specimens from the University of Utah Department of Pathology (retrieved from 2008-2011). Tissue was stained with commercially available antibodies against PIM-1, PIM-2, and PIM-3. Cases were divided into three groups (invasive high grade urothelial carcinoma (n=49), non-invasive urothelial carcinoma/carcinoma in situ (n=16), and non-invasive low grade urothelial carcinoma (n=7)). Individual cases were then given a score (0-4) based upon a percentage of cells staining positive for each antibody ( & lt;5%=0; 5-25%=1; 26-50%=2; 51-75%=3; & gt;75%=4). A score of 2 or greater was considered expressed. PIM-1, PIM-2 and PIM-3 expression was noted in 29% (2/7), 43% (3/7) and 86% (6/7) cases of non-invasive low-grade urothelial carcinoma; 44% (7/16), 50% (8/16), 44% (7/16) cases of non-invasive high-grade urothelial carcinoma; 10% (5/49), 27% (13/49), and 18% (9/49) cases of invasive high-grade urothelial carcinoma, respectively. These results suggest that expression of PIM-1, PIM-2 and PIM-3 is present in a significant percentage of urothelial carcinomas and may serve as a source for targeted PIM-kinase inhibition. We have developed PIM inhibitors exhibiting 4-10 fold improved potency against the PIM kinase family compared to our original PIM inhibitor SGI-1776. Our PIM inhibitors display sub-μM activity in pharmacodynamic marker modulation, proliferation and 2D colony formation assays using the UM-UC-3 bladder cancer cell line. These PIM kinase inhibitors also are potent inducers of apoptosis in T24, RT4, and UM-UC-3 bladder cancer cell lines. These compounds have favorable hERG and CYP inhibition profiles compared with SGI-1776, and demonstrate excellent oral bioavailability. In vivo xenograft studies using bladder cancer cell line models show that PIM kinase inhibition can reduce the tumor growth of these tumor models suggesting that PIM kinase inhibitors may be active in human urothelial carcinomas. Citation Format: Kent J. Carpenter, Rachel Brog, Christopher Moreno, Daniel J. Albertson, Jared J. Bearss, Ting Liu, Steven Warner, David J. Bearss. Small molecule iInhibitors of PIM kinases as potential treatments for urothelial carcinomas. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2174. doi:10.1158/1538-7445.AM2013-2174
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2013
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  • 4
    In: ACS Medicinal Chemistry Letters, American Chemical Society (ACS), Vol. 4, No. 12 ( 2013-12-12), p. 1142-1147
    Type of Medium: Online Resource
    ISSN: 1948-5875 , 1948-5875
    Language: English
    Publisher: American Chemical Society (ACS)
    Publication Date: 2013
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  • 5
    Online Resource
    Online Resource
    Ovid Technologies (Wolters Kluwer Health) ; 2015
    In:  Applied Immunohistochemistry & Molecular Morphology Vol. 23, No. 10 ( 2015-11), p. 717-723
    In: Applied Immunohistochemistry & Molecular Morphology, Ovid Technologies (Wolters Kluwer Health), Vol. 23, No. 10 ( 2015-11), p. 717-723
    Type of Medium: Online Resource
    ISSN: 1541-2016
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2015
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  • 6
    In: Blood, American Society of Hematology, Vol. 126, No. 23 ( 2015-12-03), p. 3799-3799
    Abstract: Alvocidib has demonstrated a significant improvement in the complete response rates of newly diagnosed acute myeloid leukemia (AML) patients when administered before cytarabine and mitoxantrone (FLAM regimen) in a randomized Phase 2 study compared to 7+3, the current standard of care. Although the mechanism of action of alvocidib as a single agent is documented, the mechanism underlying synergy found in the FLAM regimen is still not fully understood. The FLAM regimen was originally developed based on the perceived benefit of time-sequential cell cycle arrest (alvocidib) followed by release of the cells from cell cycle arrest and inhibition of DNA replication (cytarabine) during S-phase. However, recent reports suggest that the transcriptional repression of key anti-apoptotic proteins (eg., MCL-1) mediated by alvocidib's CDK9 inhibition, drive the activity in the FLAM regimen. We, therefore, hypothesized that MCL-1 transcriptional repression constitutes the primary mechanism for the synergism observed with the treatment of the FLAM regimen. Here, we demonstrate that treatment with alvocidib, followed by treatment with cytarabine and mitoxantrone, is synergistic in vitro and correlates with the downregulation of MCL-1 expression. The FLAM regimen results in significant increases in caspase activity in comparison to any single agent within the combination. As has been previously reported, we also observe that increased activity of cytarabine in alvocidib-treated cells corresponds with progression into the S-phase of the cell cycle, following the washout of alvocidib. However, this observation accounts for only a small portion of the inhibition of cell proliferation. This is further confirmed by the observation that CDK4/6 (cell cycle) specific inhibitors, such as palbociclib, do not show synergistic increases in caspase activity following treatment in the same setting. In various AML cell lines treated with MCL-1 siRNA, followed by cytarabine and mitoxantrone treatment, we also observe a synergistic increase in the inhibition of cell proliferation. Therefore, considering our earlier work showing that MCL-1 dependence predicts AML patient response to the FLAM regimen, we propose that MCL-1 repression is the primary mechanism of alvocidib's biological activity and also a primary mechanism conferring resistance to cytarabine. We also conclude that the FLAM regimen is an effective regimen, clinically, in treating patients with high-risk AML, as a consequence of its inhibition of transcription via CDK9. Disclosures Kim: Tolero Pharmaceuticals: Employment. Bahr:Tolero Pharmaceuticals: Employment. Soh:Tolero Pharmaceuticals: Employment. Bearss:Tolero Pharmaceuticals: Employment. Lee:Tolero Pharmaceuticals: Employment. Peterson:Tolero Pharmaceuticals: Employment. Whatcott:Tolero Pharmaceuticals: Employment. Siddiqui-Jain:Tolero Pharmaceuticals: Employment. Weitman:Tolero Pharmaceuticals: Employment. Bearss:Tolero Pharmaceuticals: Employment. Warner:Tolero Pharmaceuticals: Employment.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
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    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2015
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  • 7
    In: Clinical Lymphoma Myeloma and Leukemia, Elsevier BV, Vol. 15 ( 2015-09), p. S18-
    Type of Medium: Online Resource
    ISSN: 2152-2650
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2015
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  • 8
    In: Blood, American Society of Hematology, Vol. 126, No. 23 ( 2015-12-03), p. 3253-3253
    Abstract: Mesenchymal stem cells (MSCs) contribute to the regeneration of mesenchymal tissues, and are essential in providing support for the growth and differentiation of primitive hemopoietic cells within the bone marrow microenvironment. It is becoming increasingly clear that the tumor microenvironment plays a very important role in tumor progression and drug resistance, and the selection of cancer cells possessing the mesenchymal phenotype leads to drug resistance in many different tumor types. We have been exploring the role of the protein Axl in promoting the mesenchymal phenotype in both myeloid and lymphoid malignancies, and the role of Axl in promoting drug resistance in these malignancies. The signaling downstream of Axl that leads to the acquisition of the mesenchymal phenotype has not been well elucidated. Following results from a genetic screen using a zebrafish model, we have discovered a role for retinoic acid (RA) signaling which is regulated by Axl and controls the mesenchymal phenotype in leukemic cells. In addition, recent reports have shown an interaction between a retinoic acid regulated gene, RARRES1, and Axl, leading our group to seek to understand the role of retinoic acid signaling in the control of AXL. We hypothesized that treatment with our AXL inhibitor, TP-0903, would disrupt RA signaling and lead to a reversal of the mesenchymal phenotype in leukemia cells. Following TP-0903 treatment, we interrogated changes in mRNA expression using RT-PCR, protein expression using standard immunoblotting, and endogenous RA levels using a competitive ELISA. We also assessed the effect of TP-0903 on tumor growth in an in vivo model, assessing efficacy of TP-0903 in an MV4-11 xenograft mouse model. One of the genes that we detected being dramatically changed by treatment with TP-0903 was the RA metabolizing protein CYP26A1, suggesting that Axl inhibition indeed leads to changes in RA metabolism. We observed a strong induction of CYP26 mRNA expression following RA treatment in MV4-11 leukemia cells which was also observed in treatment with our AXL inhibitor, TP-0903, at levels as low as 100 nM. We also assessed TP-0903 activity in additional cell lines (HL60, A549, and H1650), and with an alternative AXL inhibitor, R428. Importantly, TP-0903 treatment correlated with increased CYP26 expression and reduced levels of endogenous RA. In vivo, TP-0903 strongly inhibited xenograft tumor volumes by up to 100% with multiple dose levels and treatment schedules. CYP26 expression in fixed tissues correlated well with mRNA levels observed in xenograft tumors following treatment. Taken together, our observations support our hypothesis that inhibition of AXL kinase by TP-0903 can disrupt RA metabolism by inducing CYP26 expression and this disruption of RA metabolism leads to reversal of the mesenchymal phenotype in leukemic cells. Disclosures Soh: Tolero Pharmaceuticals: Employment. Bahr:Tolero Pharmaceuticals: Employment. Bearss:Tolero Pharmaceuticals: Employment. Kim:Tolero Pharmaceuticals: Employment. Peterson:Tolero Pharmaceuticals: Employment. Whatcott:Tolero Pharmaceuticals: Employment. Siddiqui-Jain:Tolero Pharmaceuticals: Employment. Bearss:Tolero Pharmaceuticals: Employment. Warner:Tolero Pharmaceuticals: Employment.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
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    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2015
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  • 9
    In: Blood, American Society of Hematology, Vol. 126, No. 23 ( 2015-12-03), p. 1343-1343
    Abstract: Despite significant efforts, the clinical mechanism of action of hypomethylating agents such as 5-azacytidine (5-aza) is still poorly understood. 5-aza is currently indicated for the treatment of patients with myelodysplastic syndrome (MDS). While 5-aza has achieved good single-agent activity in acute myeloid leukemia (AML), complete response rates remain low when used as a single agent. In a recent report aimed at identifying rational therapeutic combinations with 5-aza, Bogenberger and colleagues identified multiple BCL-2 family member/BH3-containing therapeutic targets, which synergize with 5-aza when inhibited genetically or pharmacologically. The CDK9 inhibitor, alvocidib, has achieved significant improvement in complete response rates of newly diagnosed AML patients when administered before cytarabine and mitoxantrone (FLAM regimen) in a randomized multi-center Phase 2 trial when compared to 7+3 standard of care treatment. Recent reports suggest that the transcriptional repression of key anti-apoptotic proteins (eg., MCL-1) mediated by alvocidib's CDK9 inhibition, drive the pro-apoptotic activity of alvocidib in the FLAM regimen. We, therefore, hypothesized that alvocidib and 5-aza would synergize therapeutically in the treatment of AML by means of transcriptional repression of MCL-1 and sensitization to 5-aza. In this report, we demonstrate that treatment of AML cell lines with alvocidib inhibits both mRNA and protein expression of MCL-1 in a time and concentration-dependent fashion. Pre-treatment of cells with alvocidib, to repress MCL-1 expression prior to 5-aza treatment, reduced the 5-aza cell viability EC50 more than 2.5-fold, from 1.8 µM to 0.6 µM in MV4-11 cells. The alvocidib/5-aza combination also resulted in synergistic increases in caspase activity relative to either single agent within the combination, at multiple dose levels. Therefore, following reports suggesting inhibition of BCL-2 family members including MCL-1, sensitizes cells to 5-aza, our data suggest that the alvocidib/5-aza combination may constitute a viable therapeutic regimen. We also conclude that a CDK9 inhibitor/5-aza combination may be an effective clinical approach for the treatment of AML. Disclosures Kim: Tolero Pharmaceuticals: Employment. Soh:Tolero Pharmaceuticals: Employment. Bearss:Tolero Pharmaceuticals: Employment. Lee:Tolero Pharmaceuticals: Employment. Peterson:Tolero Pharmaceuticals: Employment. Whatcott:Tolero Pharmaceuticals: Employment. Siddiqui-Jain:Tolero Pharmaceuticals: Employment. Weitman:Tolero Pharmaceuticals: Employment. Bearss:Tolero Pharmaceuticals: Employment. Warner:Tolero Pharmaceuticals: Employment.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2015
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  • 10
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 75, No. 15_Supplement ( 2015-08-01), p. 3604-3604
    Abstract: BTK inhibitors (e.g. ibrutinib) have significantly impacted the treatment of B-cell malignancies in a positive way. Single agent response rates with ibrutinib are 65% or higher in B-cell lymphomas and chronic lymphocytic leukaemia with the majority of patients enjoying a prolonged duration of response. Continued clinical development is needed, however, as most patients achieve only a partial response from their treatment and ultimately patients become refractory to ibrutinib leading to relapse and disease progression. Targeted combinations with ibrutinib could potentially increase the number of patients undergoing complete remission and combat emergent resistant mechanisms. The PIM family (1, 2, and 3) are serine/threonine kinases that have proven to be oncogenic in-part due to their ability to suppress c-Myc induced apoptosis. The PIM kinases have emerged as important regulators of drug resistance in multiple cancer types. Tolero Pharmaceutical's second generation PIM Kinase inhibitor, TP-3654 has exhibited favorable activity in preclinical models of prostate cancer, AML, and lymphoma. Due to the signaling crosstalk between BTK and PIM through the STAT transcription factors, we hypothesized that synergies may arise through the simultaneous targeting of both kinases. Here, we report a significant increase in drug activity when a BTK inhibitor (ibrutinib) was combined with TP-3654 in various lymphoma cell lines. In Granta-519 cells, the IC50 of ibrutinib decreased 3.5-fold, from 0.7 μM to 0.2 μM, when cultured in combination with a subtoxic concentration of TP-3654 (300 nM). Similarly, the IC50 of TP-3654 decreased 6-fold, from 2.4 μM to 0.4 μM, when cells were cultured in combination with a subtoxic concentration of ibrutinib (100 nM). BTK is known to attenuate the activity of the transcription factor STAT3, a major regulator of PIM kinase levels in cells. Due to this, mechanistic studies focused on analyzing the STAT3 pathway are ongoing to determine the downstream effects of using ibrutinib and TP-3654 in combination. Several lymphoma xenograft studies are also ongoing to further explore this combination in vivo. These results provide a strong rationale that inhibitors of PIM and BTK could be used in combination for the treatment of B-cell malignancies and other B-cell mediated diseases. Citation Format: Jeremiah J. Bearss, Brigham L. Bahr, Katie K. Soh, Peter W. Peterson, Clifford J. Whatcott, Adam Siddiqui-Jain, David J. Bearss, Steven L. Warner. Targeting the PIM kinases in combination with BTK inhibition is synergistic in preclinical models of B-cell malignancies. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3604. doi:10.1158/1538-7445.AM2015-3604
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2015
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