Publications by authors named "Stephen Keir"

122 Publications

MTAP Loss Promotes Stemness in Glioblastoma and Confers Unique Susceptibility to Purine Starvation.

Cancer Res 2019 07 30;79(13):3383-3394. Epub 2019 Apr 30.

The Preston Robert Tisch Brain Tumor Center, Duke University Medical Center, Durham, North Carolina.

Homozygous deletion of methylthioadenosine phosphorylase () is one of the most frequent genetic alterations in glioblastoma (GBM), but its pathologic consequences remain unclear. In this study, we report that loss of MTAP results in profound epigenetic reprogramming characterized by hypomethylation of /CD133-associated stem cell regulatory pathways. MTAP deficiency promotes glioma stem-like cell (GSC) formation with increased expression of /CD133 and enhanced tumorigenicity of GBM cells and is associated with poor prognosis in patients with GBM. As a combined consequence of purine production deficiency in -null GBM and the critical dependence of GSCs on purines, the enriched subset of CD133 cells in -null GBM can be effectively depleted by inhibition of purine synthesis. These findings suggest that MTAP loss promotes the pathogenesis of GBM by shaping the epigenetic landscape and stemness of GBM cells while simultaneously providing a unique opportunity for GBM therapeutics. SIGNIFICANCE: This study links the frequently mutated metabolic enzyme MTAP to dysregulated epigenetics and cancer cell stemness and establishes MTAP status as a factor for consideration in characterizing GBM and developing therapeutic strategies.
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http://dx.doi.org/10.1158/0008-5472.CAN-18-1010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6810595PMC
July 2019

Synergistic antitumor effects of 9.2.27-PE38KDEL and ABT-737 in primary and metastatic brain tumors.

PLoS One 2019 9;14(1):e0210608. Epub 2019 Jan 9.

Department of Pathology, Duke University Medical Center, Durham, NC, United States of America.

Standard treatment, unfortunately, yields a poor prognosis for patients with primary or metastatic cancers in the central nervous system, indicating a necessity for novel therapeutic agents. Immunotoxins (ITs) are a class of promising therapeutic candidates produced by fusing antibody fragments with toxin moieties. In this study, we investigated if inherent resistance to IT cytotoxicity can be overcome by rational combination with pro-apoptotic enhancers. Therefore, we combined ITs (9.2.27-PE38KDEL or Mel-14-PE38KDEL) targeting chondroitin sulfate proteoglycan 4 (CSPG4) with a panel of Bcl-2 family inhibitors (ABT-737, ABT-263, ABT-199 [Venetoclax], A-1155463, and S63845) against patient-derived glioblastoma, melanoma, and breast cancer cells/cell lines. In vitro cytotoxicity assays demonstrated that the addition of the ABT compounds, specifically ABT-737, sensitized the different tumors to IT treatment, and improved the IC50 values of 9.2.27-PE38KDEL up to >1,000-fold. Mechanistic studies using 9.2.27-PE38KDEL and ABT-737 revealed that increased levels of intracellular IT, processed (active) exotoxin, and PARP cleavage correlated with the enhanced sensitivity to the combination treatment. Furthermore, we confirmed the synergistic effect of 9.2.27-PE38KDEL and ABT-737 combination therapy in orthotopic GBM xenograft and cerebral melanoma metastasis models in nude mice. Our study defines strategies for overcoming IT resistance and enhancing specific antitumor cytotoxicity in primary and metastatic brain tumors.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0210608PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6326518PMC
October 2019

Bevacizumab, irinotecan, temozolomide, tyrosine kinase inhibition, and MEK inhibition are effective against pleomorphic xanthoastrocytoma regardless of V600E status.

J Neurooncol 2018 Nov 17;140(2):261-268. Epub 2018 Aug 17.

Department of Neurosurgery, Duke University, Durham, NC, USA.

Introduction: Pleomorphic xanthoastrocytoma (PXA) is a rare Grade II and III glioma. Surgical resection is the mainstay of treatment, however, adjuvant therapy is sometimes necessary. Given the rarity of PXA, chemotherapeutic efficacy data is limited. The importance of the BRAF V600E mutation in the context of MAP kinase pathway inhibition is unknown. The purpose of this study was to perform an in vivo screen of a variety to agents to determine efficacy against both V600E mutant and non-mutant PXA.

Methods: The efficacy of bevacizumab, temozolomide, lomustine (CCNU), irinotecan (CPT 11), a tyrosine kinase inhibitor (sorafenib), a selective MEK1/2 inhibitor (cobimetinib), and a BRAF inhibitor (vemurafenib) were assessed in two subcutaneous xenografts: D645 PXA (V600E-mutant) and D2363 PXA (V600E-non-mutant) (n = 5-10 mice). Select agents were also assessed in an intracranial model of D2363 PXA (n = 6-9). Subcutaneous tumor growth and survival were the endpoints.

Results: Temozolomide, bevacizumab, CPT 11, and sorafenib significantly inhibited subcutaneous tumor growth in both V600E-mutant and V600E-non-mutant models (P < 0.05). MEK inhibition (cobimetinib) but not BRAF inhibition (vemurafenib) also inhibited tumor growth regardless of V600E mutation (P < 0.05). Temozolomide, CPT 11, and bevacizumab also prolonged survival in a V600E-non-mutant intracranial model (median overall survival (OS) 68.5, 62.5, and 42.5 days, respectively) in contrast to controls (31.5 days, P < 0.001).

Conclusions: These findings suggest that when adjuvant treatment is clinically indicated for PXA, temozolomide, CPT 11, or bevacizumab may be considered. Additionally, a trial of a MEK inhibitor or tyrosine kinase inhibitor could be considered for PXA regardless of V600E mutation status.
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http://dx.doi.org/10.1007/s11060-018-2975-5DOI Listing
November 2018

A Rationally Designed Fully Human EGFRvIII:CD3-Targeted Bispecific Antibody Redirects Human T Cells to Treat Patient-derived Intracerebral Malignant Glioma.

Clin Cancer Res 2018 08 27;24(15):3611-3631. Epub 2018 Apr 27.

Duke Brain Tumor Immunotherapy Program, Department of Neurosurgery, Duke University Medical Center, Durham, North Carolina.

Conventional therapy for malignant glioma fails to specifically target tumor cells. In contrast, substantial evidence indicates that if appropriately redirected, T cells can precisely eradicate tumors. Here we report the rational development of a fully human bispecific antibody (hEGFRvIII-CD3 bi-scFv) that redirects human T cells to lyse malignant glioma expressing a tumor-specific mutation of the EGFR (EGFRvIII). We generated a panel of bispecific single-chain variable fragments and optimized design through successive rounds of screening and refinement. We tested the ability of our lead construct to redirect naïve T cells and induce target cell-specific lysis. To test for efficacy, we evaluated tumor growth and survival in xenogeneic and syngeneic models of glioma. Tumor penetrance following intravenous drug administration was assessed in highly invasive, orthotopic glioma models. A highly expressed bispecific antibody with specificity to CD3 and EGFRvIII was generated (hEGFRvIII-CD3 bi-scFv). Antibody-induced T-cell activation, secretion of proinflammatory cytokines, and proliferation was robust and occurred exclusively in the presence of target antigen. hEGFRvIII-CD3 bi-scFv was potent and target-specific, mediating significant lysis of multiple malignant glioma cell lines and patient-derived malignant glioma samples that heterogeneously express EGFRvIII. In both subcutaneous and orthotopic models, well-engrafted, patient-derived malignant glioma was effectively treated despite heterogeneity of EGFRvIII expression; intravenous hEGFRvIII-CD3 bi-scFv administration caused significant regression of tumor burden ( < 0.0001) and significantly extended survival ( < 0.0001). Similar efficacy was obtained in highly infiltrative, syngeneic glioma models, and intravenously administered hEGFRvIII-CD3 bi-scFv localized to these orthotopic tumors. We have developed a clinically translatable bispecific antibody that redirects human T cells to safely and effectively treat malignant glioma. On the basis of these results, we have developed a clinical study of hEGFRvIII-CD3 bi-scFv for patients with EGFRvIII-positive malignant glioma. .
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http://dx.doi.org/10.1158/1078-0432.CCR-17-0126DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6103776PMC
August 2018

Sym004-induced EGFR elimination is associated with profound anti-tumor activity in EGFRvIII patient-derived glioblastoma models.

J Neurooncol 2018 Jul 21;138(3):489-498. Epub 2018 Mar 21.

Preston Robert Tisch Brain Tumor Center at Duke, Department of Neurosurgery, Duke University Medical Center, 3624 DUMC, Baker House, Durham, NC, 27710, USA.

Background: Sym004 is a mixture of two monoclonal antibodies (mAbs), futuximab and modotuximab, targeting non-overlapping epitopes on the epidermal growth factor receptor (EGFR). Previous studies have shown that Sym004 is more efficient at inducing internalization and degradation of EGFR than individual components, which translates into superior cancer cell inhibition. We investigated whether Sym004 induces removal of EGFRvIII and if this removal translates into tumor growth inhibition in hard-to-treat glioblastomas (GBMs) harboring the mutated, constitutively active EGFR variant III (EGFRvIII).

Methods: To address this question, we tested the effect of Sym004 versus cetuximab in eight patient-derived GBM xenograft models expressing either wild-type EGFR (EGFRwt) and/or mutant EGFRvIII. All models were tested as both subcutaneous and orthotopic intracranial xenograft models.

Results: In vitro studies demonstrated that Sym004 internalized and removed EGFRvIII more efficiently than mAbs, futuximab, modotuximab, and cetuximab. Removal of EGFRvIII by Sym004 translated into significant in vivo anti-tumor activity in all six EGFRvIII xenograft models. Furthermore, the anti-tumor activity of Sym004 in vivo was superior to that of its individual components, futuximab and modotuximab, suggesting a clear synergistic effect of the mAbs in the mixture.

Conclusion: These results demonstrate the broad activity of Sym004 in patient-derived EGFRvIII-expressing GBM xenograft models and provide a clear rationale for clinical evaluation of Sym004 in EGFRvIII-positive adult GBM patients.
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http://dx.doi.org/10.1007/s11060-018-2832-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5999169PMC
July 2018

Therapeutic targeting of ependymoma as informed by oncogenic enhancer profiling.

Nature 2018 01 20;553(7686):101-105. Epub 2017 Dec 20.

Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA.

Genomic sequencing has driven precision-based oncology therapy; however, the genetic drivers of many malignancies remain unknown or non-targetable, so alternative approaches to the identification of therapeutic leads are necessary. Ependymomas are chemotherapy-resistant brain tumours, which, despite genomic sequencing, lack effective molecular targets. Intracranial ependymomas are segregated on the basis of anatomical location (supratentorial region or posterior fossa) and further divided into distinct molecular subgroups that reflect differences in the age of onset, gender predominance and response to therapy. The most common and aggressive subgroup, posterior fossa ependymoma group A (PF-EPN-A), occurs in young children and appears to lack recurrent somatic mutations. Conversely, posterior fossa ependymoma group B (PF-EPN-B) tumours display frequent large-scale copy number gains and losses but have favourable clinical outcomes. More than 70% of supratentorial ependymomas are defined by highly recurrent gene fusions in the NF-κB subunit gene RELA (ST-EPN-RELA), and a smaller number involve fusion of the gene encoding the transcriptional activator YAP1 (ST-EPN-YAP1). Subependymomas, a distinct histologic variant, can also be found within the supratetorial and posterior fossa compartments, and account for the majority of tumours in the molecular subgroups ST-EPN-SE and PF-EPN-SE. Here we describe mapping of active chromatin landscapes in 42 primary ependymomas in two non-overlapping primary ependymoma cohorts, with the goal of identifying essential super-enhancer-associated genes on which tumour cells depend. Enhancer regions revealed putative oncogenes, molecular targets and pathways; inhibition of these targets with small molecule inhibitors or short hairpin RNA diminished the proliferation of patient-derived neurospheres and increased survival in mouse models of ependymomas. Through profiling of transcriptional enhancers, our study provides a framework for target and drug discovery in other cancers that lack known genetic drivers and are therefore difficult to treat.
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http://dx.doi.org/10.1038/nature25169DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5993422PMC
January 2018

Validation of an Immunohistochemistry Assay for Detection of CD155, the Poliovirus Receptor, in Malignant Gliomas.

Arch Pathol Lab Med 2017 Dec 22;141(12):1697-1704. Epub 2017 Aug 22.

Context: - The oncolytic polio-rhinovirus recombinant (PVSRIPO) has demonstrated promise in currently ongoing phase I/II clinical trials against recurrent glioblastoma and was granted breakthrough therapy designation by the Food and Drug Administration/Center for Biologics Evaluation and Research. A reliable clinical assay to document expression of the poliovirus receptor, CD155, in routinely available patient tumor samples is needed for continued clinical development of PVSRIPO oncolytic immunotherapy in primary brain tumors and beyond.

Objectives: - To validate a novel anti-CD155 antibody for immunohistochemistry and develop a robust, reliable, and specific protocol for detecting CD155 expression in glioblastoma formalin-fixed, paraffin-embedded (FFPE) tissue samples. To characterize the expression of CD155 in human glioblastoma cells as well as to evaluate the influence of CD155 expression levels on tumor cell susceptibility to PVSRIPO infection and killing.

Design: - Immunohistochemical staining on glioblastoma FFPE tissue sections and immunoblot of corresponding frozen tissues were performed. Positive controls were confirmed sites of poliovirus propagation, spinal cord anterior horn, and tonsils; negative controls were vascular smooth muscle in patient samples and FFPE sections from a confirmed CD155-negative Burkitt lymphoma line (Raji).

Results: - We succeeded in developing a reliable assay to specifically detect CD155 by immunohistochemistry in glioblastoma FFPE sections. Our data suggest widespread, virtually universal expression of CD155 in glioblastoma cells at levels commensurate with susceptibility to PVSRIPO infection and killing.

Conclusions: - Anti-CD155 antibody D3G7H achieves monospecific detection of CD155 in immunoblots of tumor homogenates and immunohistochemistry of tumor FFPE sections. Our assay has utility in defining appropriate use of PVSRIPO in oncolytic immunotherapy against malignant glioma and other cancer histotypes.
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http://dx.doi.org/10.5858/arpa.2016-0580-OADOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6051547PMC
December 2017

A cross sectional analysis from a single institution's experience of psychosocial distress and health-related quality of life in the primary brain tumor population.

J Neurooncol 2017 Sep 1;134(2):363-369. Epub 2017 Jul 1.

Department of Neurology, Duke University Medical Center, Durham, NC, 27710, USA.

Primary brain tumor patients experience high levels of distress. The purpose of this cross-sectional, retrospective study is to evaluate the level and different sources of psychosocial distress and how these pertain to health-related quality of life (HRQoL). The Primary and Recurrent Glioma registry at Duke's The Preston Robert Tisch Brain Tumor Center was queried retrospectively for demographic and clinical information on patients seen between December 2013 and February 2014. Data also included the National Comprehensive Cancer Network's Distress Thermometer (NCCN-DT), Functional Assessment of Cancer Therapy-Brain Cancer (FACT-Br), and Functional Assessment of Chronic Illness Therapy- Fatigue (FACIT-F). 829 subjects completed questionnaires. 54% were male; 96% completed the NCCN-DT; 33.3% had a DT score ≥4 (moderate/severe distress). Women reported DT ≥ 4 more often than men (38.6 vs 29.0%; p = 0.005). Patients within 1 year of diagnosis reported DT ≥ 4 more often than those 1+ years after diagnosis (38.8 vs 30.9%; p = 0.034). 73.0% reported physical problems; the most frequent being fatigue (43.2%) and memory/concentration (40.9%). 42.0% complained of emotional problems with worry (29.4%) and nervousness (22.4%) being the most common. Patients who reported at least one practical, family, emotional or physical problem had significantly lower HRQoL scores (p < 0.001). Primary brain tumor patients experience memory dysfunction, fatigue, nervousness, worry, and financial concerns, which have a negative effect on the patient's HRQoL. By identifying and addressing these stressors, it may be possible to improve patient HRQoL.
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http://dx.doi.org/10.1007/s11060-017-2535-4DOI Listing
September 2017

The role of angiogenesis in Group 3 medulloblastoma pathogenesis and survival.

Neuro Oncol 2017 Sep;19(9):1217-1227

Department of Neurosurgery, Duke University, Durham, North Carolina; Preston Robert Tisch Brain Tumor Center, Duke University, Durham, North Carolina; Brain Imaging and Analysis Center, Duke University, Durham, North Carolina; Department of Radiology, Duke University, Durham, North Carolina; Department of Radiology, Stanford University, Palo Alto, California; Department of Medicine, Duke University, Durham, North Carolina; Department of Pediatric Oncology, Hematology, and Clinical Immunology, Medical Faculty, University Hospital Düsseldorf, Düsseldorf, Germany; and Department of Pediatric Neuro-Oncogenomics, German Cancer Consortium and German Cancer Research Center, Heidelberg, Germany; Department of Pathology, Duke University, Durham, North Carolina; Division of Haematology/Oncology, the Arthur and Sonia Labatt Brain Tumour Research Centre, Developmental & Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada; Division of Neurosurgery, the Arthur and Sonia Labatt Brain Tumour Research Centre, Developmental & Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.

Background: Of the 4 medulloblastoma subgroups, Group 3 is the most aggressive but the importance of angiogenesis is unknown. This study sought to determine the role of angiogenesis and identify clinically relevant biomarkers of tumor vascularity and survival in Group 3 medulloblastoma.

Methods: VEGFA mRNA expression and survival from several patient cohorts were analyzed. Group 3 xenografts were implanted intracranially in nude rats. Dynamic susceptibility weighted (DSC) MRI and susceptibility weighted imaging (SWI) were obtained. DSC MRI was used to calculate relative cerebral blood volume (rCBV) and flow (rCBF). Tumor vessel density and rat vascular endothelial growth factor alpha (VEGFA) expression were determined.

Results: Patient VEGFA mRNA levels were significantly elevated in Group 3 compared with the other subgroups (P < 0.001) and associated with survival. Xenografts D283, D341, and D425 were identified as Group 3 by RNA hierarchical clustering and MYC amplification. The D283 group had the lowest rCBV and rCBF, followed by D341 and D425 (P < 0.05). These values corresponded to histological vessel density (P < 0.05), rat VEGFA expression (P < 0.05), and survival (P = 0.002). Gene set enrichment analysis identified 5 putative genes with expression profiles corresponding with these findings: RNH1, SCG2, VEGFA, AGGF1, and PROK2. SWI identified 3 xenograft-independent categories of intratumoral vascular architecture with distinct survival (P = 0.004): organized, diffuse microvascular, and heterogeneous.

Conclusions: Angiogenesis plays an important role in Group 3 medulloblastoma pathogenesis and survival. DSC MRI and SWI are clinically relevant biomarkers for tumor vascularity and overall survival and can be used to direct the use of antivascular therapies for patients with Group 3 medulloblastoma.
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http://dx.doi.org/10.1093/neuonc/nox033DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5570262PMC
September 2017

Initial testing of VS-4718, a novel inhibitor of focal adhesion kinase (FAK), against pediatric tumor models by the Pediatric Preclinical Testing Program.

Pediatr Blood Cancer 2017 04 27;64(4). Epub 2016 Oct 27.

Cancer Therapy Evaluation Program, NCI, Bethesda, Maryland.

VS-4718, a novel inhibitor of focal adhesion kinase (FAK), was tested against the Pediatric Preclinical Testing Program's (PPTP's) in vitro cell line panel and showed a median relative IC of 1.22 μM. VS-4718 was tested in vivo against the PPTP xenograft models using a dose of 50 mg/kg administered by the oral route twice daily for 21 days. VS-4718 induced significant differences in an event-free survival distribution compared with control in 18 of 36 of the evaluable solid tumor xenografts and in 0 of 8 acute lymphoblastic leukemia (ALL) xenografts, but no xenograft lines showed tumor regression. Future plans include further evaluation of the role of FAK inhibition in combination with ABL kinase inhibitors for Ph ALL.
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http://dx.doi.org/10.1002/pbc.26304DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5578428PMC
April 2017

Initial testing (stage 1) of the curaxin CBL0137 by the pediatric preclinical testing program.

Pediatr Blood Cancer 2017 04 21;64(4). Epub 2016 Sep 21.

Cancer Therapy Evaluation Program, NCI, Bethesda, Maryland.

Background: CBL0137 is a novel drug that modulates FAcilitates Chromatin Transcription (FACT), resulting in simultaneous nuclear factor-κB suppression, heat shock factor 1 suppression and p53 activation. CBL0137 has demonstrated antitumor effects in animal models of several adult cancers and neuroblastoma.

Procedures: CBL0137 was tested against the Pediatric Preclinical Testing Program (PPTP) in vitro cell line panel at concentrations ranging from 1.0 nM to 10.0 μM and against the PPTP in vivo solid tumor xenograft and acute lymphocytic leukemia (ALL) panels at 50 mg/kg administered intravenously weekly for 4 weeks.

Results: The median relative IC (rIC ) value for the PPTP cell lines was 0.28 μM (range: 0.13-0.80 μM). There were no significant differences in rIC values by histotype. CBL0137 induced significant differences in event-free survival (EFS) distribution compared to control in 10 of 31 (32%) evaluable solid tumor xenografts and in eight of eight (100%) evaluable ALL xenografts. Significance differences in EFS distribution were observed in four of six osteosarcoma lines, three of three rhabdoid tumor lines and two of six rhabdomyosarcoma lines. No objective responses were observed among the solid tumor xenografts. For the ALL panel, one xenograft achieved complete response and four achieved partial response.

Conclusions: The most consistent in vivo activity for CBL0137 was observed against ALL xenografts, with some solid tumor xenograft lines showing tumor growth delay. It will be important to relate the drug levels in mice at 50 mg/kg to those in humans at the recommended phase 2 dose.
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http://dx.doi.org/10.1002/pbc.26263DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5587189PMC
April 2017

Evaluation of Alternative In Vivo Drug Screening Methodology: A Single Mouse Analysis.

Cancer Res 2016 10 5;76(19):5798-5809. Epub 2016 Aug 5.

Center for Childhood Cancer and Blood Diseases, The Research Institute, Nationwide Children's Hospital, Columbus, Ohio.

Traditional approaches to evaluating antitumor agents using human tumor xenograft models have generally used cohorts of 8 to 10 mice against a limited panel of tumor models. An alternative approach is to use fewer animals per tumor line, allowing a greater number of models that capture greater molecular/genetic heterogeneity of the cancer type. We retrospectively analyzed 67 agents evaluated by the Pediatric Preclinical Testing Program to determine whether a single mouse, chosen randomly from each group of a study, predicted the median response for groups of mice using 83 xenograft models. The individual tumor response from a randomly chosen mouse was compared with the group median response using established response criteria. A total of 2,134 comparisons were made. The single tumor response accurately predicted the group median response in 1,604 comparisons (75.16%). The mean tumor response correct prediction rate for 1,000 single mouse random samples was 78.09%. Models had a range for correct prediction (60%-87.5%). Allowing for misprediction of ± one response category, the overall mean correct single mouse prediction rate was 95.28%, and predicted overall objective response rates for group data in 66 of 67 drug studies. For molecularly targeted agents, occasional exceptional responder models were identified and the activity of that agent confirmed in additional models with the same genotype. Assuming that large treatment effects are targeted, this alternate experimental design has similar predictive value as traditional approaches, allowing for far greater numbers of models to be used that more fully encompass the heterogeneity of disease types. Cancer Res; 76(19); 5798-809. ©2016 AACR.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5050128PMC
http://dx.doi.org/10.1158/0008-5472.CAN-16-0122DOI Listing
October 2016

Initial Testing (Stage 1) of MK-8242-A Novel MDM2 Inhibitor-by the Pediatric Preclinical Testing Program.

Pediatr Blood Cancer 2016 10 30;63(10):1744-52. Epub 2016 May 30.

Cancer Therapy Evaluation Program, NCI, Bethesda, Maryland.

Background: MK-8242 is an inhibitor of MDM2 that stabilizes the tumor suppressor TP53 and induces growth arrest or apoptosis downstream of TP53 induction.

Procedures: MK-8242 was tested against the Pediatric Preclinical Testing Program (PPTP) in vitro cell line panel at concentrations from 1.0 nM to 10.0 μM and against the PPTP in vivo xenograft panels using oral gavage on Days 1-5 and Day 15-19 at a dose of 125 mg/kg (solid tumors) or 75 mg/kg (acute lymphoblastic leukemia [ALL] models).

Results: The median IC50 for MK-8242 was 0.07 μM for TP53 wild-type cell lines versus >10 μM for TP53 mutant cell lines. MK-8242 induced a twofold or greater delay in time to event in 10 of 17 (59%) of TP53 wild-type solid tumor xenografts, excluding osteosarcoma xenografts that have very low TP53 expression. Objective responses were observed in seven solid tumor xenografts representing multiple histotypes. For the systemic-disease ALL panel, among eight xenografts there were two complete responses (CRs) and six partial responses (PRs). Two additional MLL-rearranged xenografts (MV4;11 and RS4;11) grown subcutaneously showed maintained CR and PR, respectively. The expected pharmacodynamic responses to TP53 activation were observed in TP53 wild-type models treated with MK-8242. Pharmacokinetic analysis showed that MK-8242 drug exposure in SCID mice appears to exceed that was observed in adult phase 1 trials.

Conclusions: MK-8242-induced tumor regressions across multiple solid tumor histotypes and induced CRs or PRs for most ALL xenografts. This activity was observed at MK-8242 drug exposures that appear to exceed those observed in human phase 1 trials.
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http://dx.doi.org/10.1002/pbc.26064DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5657425PMC
October 2016

A Therapeutic Antibody for Cancer, Derived from Single Human B Cells.

Cell Rep 2016 05 5;15(7):1505-1513. Epub 2016 May 5.

Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA; Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA. Electronic address:

Some patients with cancer never develop metastasis, and their host response might provide cues for innovative treatment strategies. We previously reported an association between autoantibodies against complement factor H (CFH) and early-stage lung cancer. CFH prevents complement-mediated cytotoxicity (CDC) by inhibiting formation of cell-lytic membrane attack complexes on self-surfaces. In an effort to translate these findings into a biologic therapy for cancer, we isolated and expressed DNA sequences encoding high-affinity human CFH antibodies directly from single, sorted B cells obtained from patients with the antibody. The co-crystal structure of a CFH antibody-target complex shows a conformational change in the target relative to the native structure. This recombinant CFH antibody causes complement activation and release of anaphylatoxins, promotes CDC of tumor cell lines, and inhibits tumor growth in vivo. The isolation of anti-tumor antibodies derived from single human B cells represents an alternative paradigm in antibody drug discovery.
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http://dx.doi.org/10.1016/j.celrep.2016.04.038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4871760PMC
May 2016

Initial Testing of NSC 750854, a Novel Purine Analog, Against Pediatric Tumor Models by the Pediatric Preclinical Testing Program.

Pediatr Blood Cancer 2016 Mar 24;63(3):443-50. Epub 2015 Nov 24.

NCI, Cancer Therapy Evaluation Program, Bethesda, Maryland.

Background: NSC 750854 is a purine analog with an antitumor activity profile distinctive from that of other anticancer purines. It has shown significant activity against adult cancer preclinical models.

Procedure: NSC 750854 was tested against the Pediatric Preclinical Testing Program (PPTP) in vitro cell line panel at concentrations from 1.0 nM to 10 μM and against the PPTP in vivo xenograft panels administered intraperitoneally at a dose of 5 mg/kg daily for 5 days repeated at day 15.

Results: The median relative IC50 (rIC50 ) value for the PPTP cell lines was 32 nM (range from 11 to 124 nM), with consistent cytotoxicity across all cell lines. Acute lymphoblastic leukemia (ALL) cell lines were more sensitive to NSC 750854 than non-ALL cell lines. NSC 750854 induced significant differences in EFS distribution compared to control in 31 of 35 (89%) solid tumor xenografts. It induced tumor growth inhibition meeting criteria for intermediate or high event free survival (EFS) T/C activity in 17 of 32 (53%) evaluable solid tumor xenografts (most consistently in the rhabdomyosarcoma panel). Objective responses were observed in 15 of 37 (41%) solid tumor xenografts and in all eight leukemia models with complete response (CR) or maintained complete response (MCR) in seven of eight leukemia models.

Conclusions: NSC 750854 has a unique spectrum of antitumor activity compared with other agents tested by the PPTP as it induces regression in tumor models with limited sensitivity to most agents tested to date. Given the promising level of activity observed for NSC 750854 against PPTP preclinical models, further exploration of its mechanism of action is warranted.
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http://dx.doi.org/10.1002/pbc.25826DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4724638PMC
March 2016

MiR-215 Is Induced Post-transcriptionally via HIF-Drosha Complex and Mediates Glioma-Initiating Cell Adaptation to Hypoxia by Targeting KDM1B.

Cancer Cell 2016 Jan;29(1):49-60

Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA. Electronic address:

The hypoxic tumor microenvironment serves as a niche for maintaining the glioma-initiating cells (GICs) that are critical for glioblastoma (GBM) occurrence and recurrence. Here, we report that hypoxia-induced miR-215 is vital for reprograming GICs to fit the hypoxic microenvironment via suppressing the expression of an epigenetic regulator KDM1B and modulating activities of multiple pathways. Interestingly, biogenesis of miR-215 and several miRNAs is accelerated post-transcriptionally by hypoxia-inducible factors (HIFs) through HIF-Drosha interaction. Moreover, miR-215 expression correlates inversely with KDM1B while correlating positively with HIF1α and GBM progression in patients. These findings reveal a direct role of HIF in regulating miRNA biogenesis and consequently activating the miR-215-KDM1B-mediated signaling required for GIC adaptation to hypoxia.
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http://dx.doi.org/10.1016/j.ccell.2015.12.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4871949PMC
January 2016

Phosphorylation of Glutathione S-Transferase P1 (GSTP1) by Epidermal Growth Factor Receptor (EGFR) Promotes Formation of the GSTP1-c-Jun N-terminal kinase (JNK) Complex and Suppresses JNK Downstream Signaling and Apoptosis in Brain Tumor Cells.

J Biol Chem 2015 Dec 1;290(52):30866-78. Epub 2015 Oct 1.

From the Departments of Neurosurgery and the Preston Robert Tisch Brain Tumor Center, Duke Cancer Institute and Duke University School of Medicine, Durham, North Carolina 27710 Pathology and

Under normal physiologic conditions, the glutathione S-transferase P1 (GSTP1) protein exists intracellularly as a dimer in reversible equilibrium with its monomeric subunits. In the latter form, GSTP1 binds to the mitogen-activated protein kinase, JNK, and inhibits JNK downstream signaling. In tumor cells, which frequently are characterized by constitutively high GSTP1 expression, GSTP1 undergoes phosphorylation by epidermal growth factor receptor (EGFR) at tyrosine residues 3, 7, and 198. Here we report on the effect of this EGFR-dependent GSTP1 tyrosine phosphorylation on the interaction of GSTP1 with JNK, on the regulation of JNK downstream signaling by GSTP1, and on tumor cell survival. Using in vitro and in vivo growing human brain tumors, we show that tyrosine phosphorylation shifts the GSTP1 dimer-monomer equilibrium to the monomeric state and facilitates the formation of the GSTP1-JNK complex, in which JNK is functionally inhibited. Targeted mutagenesis and functional analysis demonstrated that the increased GSTP1 binding to JNK results from phosphorylation of the GSTP1 C-terminal Tyr-198 by EGFR and is associated with a >2.5-fold decrease in JNK downstream signaling and a significant suppression of both spontaneous and drug-induced apoptosis in the tumor cells. The findings define a novel mechanism of regulatory control of JNK signaling that is mediated by the EGFR/GSTP1 cross-talk and provides a survival advantage for tumors with activated EGFR and high GSTP1 expression. The results lay the foundation for a novel strategy of dual EGFR/GSTP1 for treating EGFR+ve, GSTP1 expressing GBMs.
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http://dx.doi.org/10.1074/jbc.M115.656140DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4692215PMC
December 2015

Pharmacodynamic and genomic markers associated with response to the XPO1/CRM1 inhibitor selinexor (KPT-330): A report from the pediatric preclinical testing program.

Pediatr Blood Cancer 2016 Feb 23;63(2):276-86. Epub 2015 Sep 23.

Cancer Therapy Evaluation Program, NCI, Bethesda, Maryland.

Background: Selinexor (KPT-330) is an inhibitor of the major nuclear export receptor, exportin 1 (XPO1, also termed chromosome region maintenance 1, CRM1) that has demonstrated activity in preclinical models and clinical activity against several solid and hematological cancers.

Procedures: Selinexor was tested against the Pediatric Preclinical Testing Program (PPTP) in vitro cell line panel at concentrations from 1.0 nM to 10 μM and against the PPTP in vivo xenograft panels administered orally at a dose of 10 mg/kg thrice weekly for 4 weeks.

Results: Selinexor demonstrated cytotoxic activity in vitro, with a median relative IC50 value of 123 nM (range 13.0 nM to >10 μM). Selinexor induced significant differences in event-free survival (EFS) distribution in 29 of 38 (76%) of the evaluable solid tumor xenografts and in five of eight (63%) of the evaluable ALL xenografts. Objective responses (partial or complete responses, PR/CR) were observed for 4 of 38 solid tumor xenografts including Wilms tumor, medulloblastoma (n = 2), and ependymoma models. For the ALL panel, two of eight (25%) xenografts achieved either CR or maintained CR. Two responding xenografts had FBXW7 mutations at R465 and two had SMARCA4 mutations. Selinexor induced p53, p21, and cleaved PARP in several solid tumor models.

Conclusions: Selinexor induced regression against several solid tumor and ALL xenografts and slowed tumor growth in a larger number of models. Pharmacodynamic effects for XPO1 inhibition were noted. Defining the relationship between selinexor systemic exposures in mice and humans will be important in assessing the clinical relevance of these results.
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http://dx.doi.org/10.1002/pbc.25727DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4722540PMC
February 2016

Dynamic treatment effect (DTE) curves reveal the mode of action for standard and experimental cancer therapies.

Oncotarget 2015 Jun;6(16):14656-68

Department of Radiation Oncology, Duke University Medical Center, NC, USA.

We present a method for estimating the empirical dynamic treatment effect (DTE) curves from tumor growth delay (TGD) studies. This improves on current common methods of TGD analysis, such as T/C ratio and doubling times, by providing a more detailed treatment effect and overcomes their lack of reproducibility. The methodology doesn't presuppose any prior form for the treatment effect dynamics and is shown to give consistent estimates with missing data. The method is illustrated by application to real data from TGD studies involving three types of therapy. Firstly, we demonstrate that radiotherapy induces a sharp peak in inhibition in a FaDu model. The height, duration and timing of the peak increase linearly with radiation dose. Second, we demonstrate that a combination of temozolomide and an experimental therapy in a glioma PDX model yields an effect, similar to an additive version of the DTE curves for the mono-therapies, except that there is a 30 day delay in peak inhibition. In the third study, we consider the DTE of anti-angiogenic therapy in glioma. We show that resulting DTE curves are flat. We discuss how features of the DTE curves should be interpreted and potentially used to improve therapy.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4546495PMC
http://dx.doi.org/10.18632/oncotarget.4141DOI Listing
June 2015

Proteomic profiling of patient-derived glioblastoma xenografts identifies a subset with activated EGFR: implications for drug development.

J Neurochem 2015 Jun 12;133(5):730-8. Epub 2015 Feb 12.

School of Medicine, Wake Forest University, Winston-Salem, North Carolina, USA.

The development of drugs to inhibit glioblastoma (GBM) growth requires reliable pre-clinical models. To date, proteomic level validation of widely used patient-derived glioblastoma xenografts (PDGX) has not been performed. In the present study, we characterized 20 PDGX models according to subtype classification based on The Cancer Genome Atlas criteria, TP53, PTEN, IDH 1/2, and TERT promoter genetic analysis, EGFR amplification status, and examined their proteomic profiles against those of their parent tumors. The 20 PDGXs belonged to three of four The Cancer Genome Atlas subtypes: eight classical, eight mesenchymal, and four proneural; none neural. Amplification of EGFR gene was observed in 9 of 20 xenografts, and of these, 3 harbored the EGFRvIII mutation. We then performed proteomic profiling of PDGX, analyzing expression/activity of several proteins including EGFR. Levels of EGFR phosphorylated at Y1068 vary considerably between PDGX samples, and this pattern was also seen in primary GBM. Partitioning of 20 PDGX into high (n = 5) and low (n = 15) groups identified a panel of proteins associated with high EGFR activity. Thus, PDGX with high EGFR activity represent an excellent pre-clinical model to develop therapies for a subset of GBM patients whose tumors are characterized by high EGFR activity. Further, the proteins found to be associated with high EGFR activity can be monitored to assess the effectiveness of targeting EGFR. The development of drugs to inhibit glioblastoma (GBM) growth requires reliable pre-clinical models. We validated proteomic profiles using patient-derived glioblastoma xenografts (PDGX), characterizing 20 PDGX models according to subtype classification based on The Cancer Genome Atlas (TCGA) criteria, TP53, PTEN, IDH 1/2, and TERT promoter genetic analysis, EGFR amplification status, and examined their proteomic profiles against those of their parent tumors. Proteins found to be associated with high EGFR activity represent potential biomarkers for GBM monitoring.
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http://dx.doi.org/10.1111/jnc.13032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4514443PMC
June 2015

Synergistic activity of PARP inhibition by talazoparib (BMN 673) with temozolomide in pediatric cancer models in the pediatric preclinical testing program.

Clin Cancer Res 2015 Feb 10;21(4):819-32. Epub 2014 Dec 10.

Nationwide Children's Hospital, Columbus, Ohio.

Purpose: Inhibitors of PARP, an enzyme involved in base excision repair, have demonstrated single-agent activity against tumors deficient in homologous repair processes. Ewing sarcoma cells are also sensitive to PARP inhibitors, although the mechanism is not understood. Here, we evaluated the stereo-selective PARP inhibitor, talazoparib (BMN 673), combined with temozolomide or topotecan.

Experimental Design: Talazoparib was tested in vitro in combination with temozolomide (0.3-1,000 μmol/L) or topotecan (0.03-100 nmol/L) and in vivo at a dose of 0.1 mg/kg administered twice daily for 5 days combined with temozolomide (30 mg/kg/daily x 5; combination A) or 0.25 mg/kg administered twice daily for 5 days combined with temozolomide (12 mg/kg/daily x 5; combination B). Pharmacodynamic studies were undertaken after 1 or 5 days of treatment.

Results: In vitro talazoparib potentiated the toxicity of temozolomide up to 85-fold, with marked potentiation in Ewing sarcoma and leukemia lines (30-50-fold). There was less potentiation for topotecan. In vivo, talazoparib potentiated the toxicity of temozolomide, and combination A and combination B represent the MTDs when combined with low-dose or high-dose talazoparib, respectively. Both combinations demonstrated significant synergism against 5 of 10 Ewing sarcoma xenografts. The combination demonstrated modest activity against most other xenograft models. Pharmacodynamic studies showed a treatment-induced complete loss of PARP only in tumor models sensitive to either talazoparib alone or talazoparib plus temozolomide.

Conclusions: The high level of activity observed for talazoparib plus temozolomide in Ewing sarcoma xenografts makes this an interesting combination to consider for pediatric evaluation.
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http://dx.doi.org/10.1158/1078-0432.CCR-14-2572DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4587665PMC
February 2015

Initial testing (stage 1) of BAL101553, a novel tubulin binding agent, by the pediatric preclinical testing program.

Pediatr Blood Cancer 2015 Jun 18;62(6):1106-9. Epub 2014 Nov 18.

Nemours/A.I. duPont Hospital for Children, Wilmington, Delaware.

BAL101553 is a highly water soluble prodrug of BAL27862 that arrests tumor cell proliferation and induces cell death in cancer cells through disruption of the microtubule network. In vitro BAL27862 demonstrated potent activity, with the median relative IC50 (rIC50 ) of 13.8 nM (range 5.4-25.2 nM). The in vitro activity of BAL27862 against the PPTP cell lines is distinctive from that previously described for vincristine. BAL101553 induced significant differences in EFS distribution compared to control in 16 of 30 (53%) solid tumor xenografts and in two of four (67%) of the evaluable ALL xenografts. No objective responses were observed.
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http://dx.doi.org/10.1002/pbc.25329DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4405429PMC
June 2015

Initial testing (stage 1) of the PARP inhibitor BMN 673 by the pediatric preclinical testing program: PALB2 mutation predicts exceptional in vivo response to BMN 673.

Pediatr Blood Cancer 2015 Jan 27;62(1):91-8. Epub 2014 Sep 27.

Cancer Therapy Evaluation Program, NCI, Bethesda, Maryland.

Background: BMN 673 is a potent inhibitor of poly-ADP ribose polymerase (PARP) that is in clinical testing with a primary focus on BRCA-mutated cancers. BMN 673 is active both through inhibiting PARP catalytic activity and by tightly trapping PARP to DNA at sites of single strand breaks.

Procedure: BMN 673 was tested in vitro at concentrations ranging from 0.1 nM to 1 μM and in vivo at a daily dose of 0.33 mg/kg administered orally twice daily (Mon-Fri) and once daily on weekends (solid tumors) for 28 days.

Results: The median relative IC50 (rIC50 ) concentration against the PPTP cell lines was 25.8 nM. The median rIC50 for the Ewing cell lines was lower than for the remaining cell lines (6.4 vs. 31.1 nM, respectively). In vivo BMN 673 induced statistically significant differences in EFS distribution in 17/43 (39.5%) xenograft models. Three objective regressions were observed: a complete response (CR) in a medulloblastoma line (BT-45), a maintained CR in a Wilms tumor line (KT-10), and a maintained CR in an ependymoma line (BT-41). BMN 673 maintained its high level of activity against KT-10 with a threefold reduction in dose. KT-10 possesses a truncating mutation in PALB2 analogous to PALB2 mutations associated with hereditary breast and ovarian cancer that abrogate homologous recombination (HR) repair.

Conclusions: The PPTP results suggest that single agent BMN 673 may have limited clinical activity against pediatric cancers. Single agent activity is more likely for patients whose tumors have defects in HR repair.
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http://dx.doi.org/10.1002/pbc.25201DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4456187PMC
January 2015

miR-33a promotes glioma-initiating cell self-renewal via PKA and NOTCH pathways.

J Clin Invest 2014 Oct 9;124(10):4489-502. Epub 2014 Sep 9.

Glioblastoma (GBM) is the most common and lethal brain tumor in adults. Glioma-initiating cells (GICs) are stem-like cells that have been implicated in glioblastoma progression and recurrence; however, the distinct properties of GICs and non-GICs within GBM tumors are largely uncharacterized. Here, we evaluated stem cell-associated microRNA (miR) expression in GICs from GBM patients and GICs derived from xenografted human glioma cell lines and determined that miR-33a promotes GIC growth and self-renewal. Moreover, evaluation of a GBM tissue array revealed that higher miR-33a expression was associated with poor prognosis of GBM patients. Antagonizing miR-33a function in GICs reduced self-renewal and tumor progression in immune-compromised mice, whereas overexpression of miR-33a in non-GICs promoted the display of features associated with GICs. We identified the mRNAs encoding phosphodiesterase 8A (PDE8A) and UV radiation resistance-associated gene (UVRAG) as direct miR-33a targets. PDE8A and UVRAG negatively regulated the cAMP/PKA and NOTCH pathways, respectively; therefore, miR-33a-dependent reduction of these proteins promoted growth and self-renewal of GICs by enhancing PKA and NOTCH activity. Furthermore, in GBM specimens, there was an inverse correlation between the expression levels of miR-33a and PDE8A and UVRAG expression. These findings reveal a miR-33a-centered signaling network that promotes GIC maintenance and has potential as a therapeutic target for GBM treatment.
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http://dx.doi.org/10.1172/JCI75284DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4191031PMC
October 2014

Initial solid tumor testing (stage 1) of AZD1480, an inhibitor of Janus kinases 1 and 2 by the pediatric preclinical testing program.

Pediatr Blood Cancer 2014 Nov 17;61(11):1972-9. Epub 2014 Aug 17.

Nationwide Children's Hospital, Columbus, Ohio.

Background: AZD1480 is an ATP competitive inhibitor of Janus kinases 1 and 2 (JAK1, 2) that has been shown to inhibit the growth of solid tumor models. This agent was selected for testing the putative role of JAK/STAT signaling in the standard PPTP solid tumor models.

Procedures: AZD1480 was tested against the PPTP in vitro cell line panel at concentrations from 1.0 nM to 10 μM and against the PPTP in vivo solid tumor xenograft panels at (60 mg/kg once daily (SID) × 5) for three consecutive weeks. Additional studies evaluated 5 to 20 mg/kg BID × 5 with SID dosing at 7-30 mg/kg at weekends for three consecutive weeks.

Results: In vitro the median relative IC50 (rIC50 ) for the PPTP cell lines was 1.5 µM, with a range from 0.3 µM to 5.9 µM. The two cell lines with rIC50 values of 0.3 µM both had ALK activating genomic alterations. AZD1480 demonstrated statistically significant differences (P < 0.05) in EFS distribution compared to control in 89% of the solid tumor xenografts. AZD1480 induced intermediate (EFS T/C > 2) or high-level growth inhibition in 15 of 30 (50%) solid tumor xenografts. Tumor regressions were observed in three of six Wilms tumor models at doses that induced inhibition of Stat3(Y705) phosphorylation.

Conclusions: AZD1480 demonstrated significant tumor growth inhibition against most PPTP solid tumor xenografts, similar to that observed for antiangiogenic agents tested by the PPTP. Tumor regressing activity was noted for Wilms tumor xenografts.
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http://dx.doi.org/10.1002/pbc.25175DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4201390PMC
November 2014

Profiling Hsp90 differential expression and the molecular effects of the Hsp90 inhibitor IPI-504 in high-grade glioma models.

J Neurooncol 2014 Dec 13;120(3):473-81. Epub 2014 Aug 13.

Department of Neurological Surgery, UC Irvine School of Medicine, Sprague Hall, Irvine, CA, 92697, USA.

Retaspimycin hydrochloride (IPI-504), an Hsp90 (heat shock protein 90) inhibitor, has shown activity in multiple preclinical cancer models, such as lung, breast and ovarian cancers. However, its biological effects in gliomas and normal brain derived cellular populations remain unknown. In this study, we profiled the expression pattern of Hsp90α/β mRNA in stable glioma cell lines, multiple glioma-derived primary cultures and human neural stem/progenitor cells. The effects of IPI-504 on cell proliferation, apoptosis, motility and expression of Hsp90 client proteins were evaluated in glioma cell lines. In vivo activity of IPI-504 was investigated in subcutaneous glioma xenografts. Our results showed Hsp90α and Hsp90β expression levels to be patient-specific, higher in high-grade glioma-derived primary cells than in low-grade glioma-derived primary cells, and strongly correlated with CD133 expression and differentiation status of cells. Hsp90 inhibition by IPI-504 induced apoptosis, blocked migration and invasion, and significantly decreased epidermal growth factor receptor levels, mitogen-activated protein kinase and/or Akt activities, and secretion of vascular endothelial growth factor in glioma cell lines. In vivo study showed that IPI-504 could mildly attenuate tumor growth in immunocompromised mice. These findings suggest that targeting Hsp90 by IPI-504 has the potential to become an active therapeutic strategy in gliomas in a selective group of patients, but further research into combination therapies is still needed.
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http://dx.doi.org/10.1007/s11060-014-1579-yDOI Listing
December 2014

Mutations in IDH1, IDH2, and in the TERT promoter define clinically distinct subgroups of adult malignant gliomas.

Oncotarget 2014 Mar;5(6):1515-25

Department of Pathology, Duke University Medical Center, The Preston Robert Tisch Brain Tumor Center at Duke, and Pediatric Brain Tumor Foundation Institute at Duke, Durham, NC, USA.

Frequent mutations in isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) and the promoter of telomerase reverse transcriptase (TERT) represent two significant discoveries in glioma genomics. Understanding the degree to which these two mutations co-occur or occur exclusively of one another in glioma subtypes presents a unique opportunity to guide glioma classification and prognosis. We analyzed the relationship between overall survival (OS) and the presence of IDH1/2 and TERT promoter mutations in a panel of 473 adult gliomas. We hypothesized and show that genetic signatures capable of distinguishing among several types of gliomas could be established providing clinically relevant information that can serve as an adjunct to histopathological diagnosis. We found that mutations in the TERT promoter occurred in 74.2% of glioblastomas (GBM), but occurred in a minority of Grade II-III astrocytomas (18.2%). In contrast, IDH1/2 mutations were observed in 78.4% of Grade II-III astrocytomas, but were uncommon in primary GBM. In oligodendrogliomas, TERT promoter and IDH1/2 mutations co-occurred in 79% of cases. Patients whose Grade III-IV gliomas exhibit TERT promoter mutations alone predominately have primary GBMs associated with poor median OS (11.5 months). Patients whose Grade III-IV gliomas exhibit IDH1/2 mutations alone predominately have astrocytic morphologies and exhibit a median OS of 57 months while patients whose tumors exhibit both TERT promoter and IDH1/2 mutations predominately exhibit oligodendroglial morphologies and exhibit median OS of 125 months. Analyzing gliomas based on their genetic signatures allows for the stratification of these patients into distinct cohorts, with unique prognosis and survival.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4039228PMC
http://dx.doi.org/10.18632/oncotarget.1765DOI Listing
March 2014

Initial testing (stage 1) of the notch inhibitor PF-03084014, by the pediatric preclinical testing program.

Pediatr Blood Cancer 2014 Aug 24;61(8):1493-6. Epub 2014 Mar 24.

Children's Cancer Institute Australia for Medical Research, Randwick, NSW, Australia.

PF-03084014, a γ-secretase inhibitor, was tested against the PPTP in vitro cell line panel (1.0 nM to 10 μM) and against the in vivo xenograft panels (administered orally twice daily on Days 1-7 and 15-21). PF-03084014 demonstrated limited in vitro activity, with no cell line achieving ≥50% inhibition. PF-03084014 induced significant differences in EFS distribution in 14 of 35 (40%) solid tumor xenografts, and 1 of 9 ALL xenografts (which lacked a NOTCH1 mutation), but objective responses were not observed. PF-03084014 demonstrated limited single agent activity in vitro and in vivo against the pediatric preclinical models studied.
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http://dx.doi.org/10.1002/pbc.25026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4225044PMC
August 2014

Initial testing (stage 1) of the investigational mTOR kinase inhibitor MLN0128 by the pediatric preclinical testing program.

Pediatr Blood Cancer 2014 Aug 20;61(8):1486-9. Epub 2014 Feb 20.

Texas Tech University Health Sciences Center, Lubbock, Texas.

MLN0128 is an investigational small molecule ATP-competitive inhibitor of the serine/threonine kinase mTOR. MLN0128 was tested against the in vitro panel at concentrations ranging from 0.1 nM to 1 μM and against the PPTP in vivo panels at a dose of 1 mg/kg administered orally daily × 28. In vitro the median relative IC(50) concentration was 19 nM. In vivo MLN0128 induced significant differences in EFS in 24/31 (77%) solid tumor models, but 0/7 ALL xenografts. The modest activity observed for MLN0128 against the PPTP preclinical models is similar to that previously reported for another TOR kinase inhibitor.
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http://dx.doi.org/10.1002/pbc.24989DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4248662PMC
August 2014