Angelika M Burger

Wayne State University, Detroit, Michigan, United States

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Publications (141)690.55 Total impact

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    ABSTRACT: Background: Poly (ADP-ribose) polymerase (PARP) is essential for recognition and repair of DNA damage. In preclinical models, PARP inhibitors modulate topoisomerase I inhibitormediated DNA damage. This Phase I study determined the maximum tolerated dose (MTD), dose-limiting toxicities (DLTs), pharmacokinetics (PK) and pharmacodynamics (PD) of veliparib, an orally-bioavailable PARP 1/2 inhibitor, in combination with irinotecan. Methods: Patients with advanced solid tumors were treated with 100 mg/m2 irinotecan on days 1 and 8 of a 21-day cycle. Twice-daily (BID) oral dosing of veliparib (10-50 mg) occurred days 3- 14 (Cycle 1) and days -1-14 (subsequent cycles) followed by a 6-day rest. PK studies were conducted with both agents alone and in combination. Paired tumor biopsies were obtained after irinotecan alone and veliparib/irinotecan to evaluate PARP1/2 inhibition and explore DNA damage signals (nuclear gamma-H2AX and pNBS1). Results: Thirty-five patients were treated. DLTs included fatigue, diarrhea, febrile neutropenia, and neutropenia. The MTD was 100 mg/m2 irinotecan (days 1, 8) combined with veliparib 40 mg BID (days-1-14) on a 21-day cycle. Of 31 response-evaluable patients there were 6 (19%) partial responses. Veliparib exhibited linear PK, and there were no apparent PK interactions between veliparib and irinotecan. At all dose levels, veliparib reduced tumor poly(ADP-ribose) (PAR) content in the presence of irinotecan. Several samples showed increases in gamma-H2AX and pNBS1 after veliparib/irinotecan compared to irinotecan alone. Conclusions: Veliparib can be safely combined with irinotecan at doses that inhibit PARP catalytic activity. Preliminary antitumor activity justifies further evaluation of the combination.
    No preview · Article · Feb 2016 · Clinical Cancer Research
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    ABSTRACT: Patients with metastatic triple-negative breast cancer (TNBC) have a poor prognosis. New approaches for the treatment of TNBC are needed to improve patient survival. The concept of synthetic lethality, brought about by inactivating complementary DNA repair pathways, has been proposed as a promising therapeutic option for these tumors. The TNBC tumor type has been associated with BRCA mutations, and inhibitors of Poly (ADP-ribose) polymerase (PARP), a family of proteins that facilitates DNA repair, have been shown to effectively kill BRCA defective tumors by preventing cells from repairing DNA damage, leading to a loss of cell viability and clonogenic survival. Here we present preclinical efficacy results of combining the PARP inhibitor, ABT-888, with CPT-11, a topoisomerase I inhibitor. CPT-11 binds to topoisomerase I at the replication fork, creating a bulky adduct that is recognized as damaged DNA. When DNA damage was stimulated with CPT-11, protein expression of the nucleotide excision repair enzyme ERCC1 inversely correlated with cell viability, but not clonogenic survival. However, 4 out of the 6 TNBC cells were synergistically responsive by cell viability and 5 out of the 6 TNBC cells were synergistically responsive by clonogenic survival to the combination of ABT-888 and CPT-11. In vivo, the BRCA mutant cell line MX-1 treated with CPT-11 alone demonstrated significant decreased tumor growth; this decrease was enhanced further with the addition of ABT-888. Decrease in tumor growth correlated with an increase in double strand DNA breaks as measured by γ-H2AX phosphorylation. In summary, inhibiting two arms of the DNA repair pathway simultaneously in TNBC cell lines, independent of BRCA mutation status, resulted in un-repairable DNA damage and subsequent cell death.
    Full-text · Article · Mar 2015 · PLoS ONE
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    Karri Stark · Angelika Burger · Jianmei Wu · Phillip Shelton · Lisa Polin · Jing Li
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    ABSTRACT: Aminoflavone (AF) acts as a ligand of the aryl hydrocarbon receptor (AhR). Expression of estrogen receptor α (ERα) and AhR-mediated transcriptional induction of CYP1A1 can sensitize breast cancer cells to AF. The objective of this study was to investigate the combined antitumor effect of AF and the histone deacetylase inhibitor vorinostat for treating mesenchymal-like triple-negative breast cancer (TNBC) as well as the underlying mechanisms of such treatment. In vitro antiproliferative activity of AFP464 (AF prodrug) in breast cancer cell lines was evaluated by MTS assay. In vitro, the combined effect of AFP464 and vorinostat on cell proliferation was assessed by the Chou-Talalay method. In vivo, antitumor activity of AFP464, given alone and in combination with vorinostat, was studied using TNBC xenograft models. Knockdown of ERα was performed using specific, small-interfering RNA. Western blot, quantitative RT-PCR, immunofluorescence, and immunohistochemical staining were performed to study the mechanisms underlying the combined antitumor effect. Luminal and basal A subtype breast cancer cell lines were sensitive to AFP464, whereas basal B subtype or mesenchymal-like TNBC cells were resistant. Vorinostat sensitized mesenchymal-like TNBC MDA-MB-231 and Hs578T cells to AFP464. It also potentiated the antitumor activity of AFP464 in a xenograft model using MDA-MB-231 cells. In vitro and in vivo mechanistic studies suggested that vorinostat reactivated ERα expression and restored AhR-mediated transcriptional induction of CYP1A1. The response of breast cancer cells to AF or AFP464 was associated with their gene expression profile. Vorinostat sensitized mesenchymal-like TNBC to AF, at least in part, by reactivating ERα expression and restoring the responsiveness of AhR to AF.
    Full-text · Article · Sep 2013 · PLoS ONE
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    ABSTRACT: Intravenously (i.v.) administered nanomedicines have the potential for tumour targeting due to the enhanced permeability and retention (EPR) effect, but in vivo tumour models are rarely calibrated with respect to functional vascular permeability and/or mechanisms controlling intratumoural drug release. Here the effect of tumour type and tumour size on EPR-mediated tumour localisation and cathepsin B-mediated drug release was studied. Evans Blue (10 mg/kg) and an N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-doxorubicin (Dox) conjugate (FCE28068) (5 mg/kg Dox-equiv) were used as probes and tumour levels (and Dox release) measured at 1 h after i.v. administration in a panel of murine and human xenograft tumours. Evans Blue and FCE28068 displayed similar tumour levels in the range of 2-18 % dose/g at 1 h for B16F10 and L1210. Approximately half of the tumour models evaluated exhibited tumour size-dependent accumulation of FCE28068; smaller tumours had the highest accumulation. Administration of free Dox (5 mg/kg) produced tumour levels of <2.5 % dose/g independent of tumour size. Whereas the degree of EPR-mediated targeting showed ~12-fold difference across the tumour models evaluated, Dox release from FCE28068 at 1 h displayed ~200-fold variation. Marked heterogeneity was seen in terms of EPR effect and Dox release rate, underlining the need to carefully calibrate tumour models used to benchmark nanomedicines against known relevant standard agents and for optimal development of strategies for late pre-clinical and clinical development.
    Preview · Article · Jun 2013 · Cancer Chemotherapy and Pharmacology
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    ABSTRACT: BCA2 is an E3 ligase linked with hormone responsive breast cancers. We have demonstrated previously that the RING E3 ligase BCA2 has autoubiquitination activity and is a very unstable protein. Previously, only Rab7, tetherin, ubiquitin and UBC9 were known to directly interact with BCA2. Here, additional BCA2 binding proteins were found using yeast two-hybrid and bacterial-II-hybrid screening techniques with Human breast and HeLa cDNA libraries. Co-expression of these proteins was analyzed through IHC of TMAs. Investigation of the molecular interactions and effects were examined through a series of in vivo and in vitro assays. Ten unique BCA2 interacting proteins were identified, two of which were hHR23a and 14-3-3sigma. Both hHR23a and 14-3-3sigma are co-expressed with BCA2 in breast cancer cell lines and patient breast tumors (n = 105). hHR23a and BCA2 expression was significantly correlated (P = < 0.0001 and P = 0.0113) in both nucleus and cytoplasm. BCA2 expression showed a statistically significant correlation with tumor grade. High cytoplasmic hHR23a trended towards negative nodal status. Binding to BCA2 by hHR23a and 14-3-3sigma was confirmed in vitro using tagged partner proteins and BCA2. hHR23a and 14-3-3sigma effect the autoubiquitination and auto-degradation activity of BCA2. Ubiquitination of hHR23a-bound BCA2 was found to be dramatically lower than that of free BCA2, suggesting that hHR23a promotes the stabilization of BCA2 by inactivating its autoubiquitination activity, without degradation of hHR23a. On the other hand, phosphorylated BCA2 protein is stabilized by interaction with 14-3-3sigma both with and without proteasome inhibitor MG-132 suggesting that BCA2 is regulated by multiple degradation pathways. The interaction between BCA2 and hHR23a in breast cancer cells stabilizes BCA2. High expression of BCA2 is correlated with grade in breast cancer, suggesting regulation of this E3 ligase is important to cancer progression.
    Full-text · Article · Feb 2012 · BMC Cancer
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    ABSTRACT: Mammalian target of rapamycin (mTOR) inhibitors mediate AKT activation through a type 1 insulin-like growth factor receptor (IGF-1R)-dependent mechanism. Combining the mTOR inhibitor temsirolimus with cixutumumab, a fully human immunoglobulin G1 monoclonal antibody directed against IGF-1R, was expected to enhance mTOR-targeted anticancer activity by modulating resistance to mTOR inhibition. The objectives of this phase I study were to evaluate the tolerability and activity of temsirolimus and cixutumumab. Patients in sequential cohorts ("3 + 3" design) received escalating doses of temsirolimus with cixutumumab weekly for 28 days. At the maximum tolerated dose (MTD), 21 patients were randomized into three separate drug sequence treatment groups for serial blood draws and 2[18F]fluoro-2-deoxy-d-glucose positron emission tomography combined with X-ray computed tomography (FDG-PET/CT) scans for pharmacodynamic analyses (PD). Forty-two patients with advanced cancer (19 male/23 female, median age = 53, median number of prior therapies = 4) were enrolled. MTD was reached at cixutumumab, 6 mg/kg IV and temsirolimus, 25 mg IV. Dose-limiting toxicities included grade 3 mucositis, febrile neutropenia, and grade 4 thrombocytopenia. The most frequent toxicities were hypercholesterolemia, hypertriglyceridemia, hyperglycemia, thrombocytopenia, and mucositis. Tumor reduction was observed in 2 of 3 patients with Ewing's sarcoma and in 4 of 10 patients with adrenocortical carcinoma. PD data suggest that cixutumumab alone or combined with temsirolimus increased plasma IGF-1 and IGF binding protein 3. FDG-PET/CT showed the odds of achieving stable disease decreased by 58% (P = 0.1213) with a one-unit increase in absolute change of standard uptake value from baseline to day 3. Temsirolimus combined with cixutumumab was well tolerated. We are currently enrolling expansion cohorts at the MTD for Ewing's sarcoma and adrenocortical carcinoma.
    Preview · Article · Jul 2011 · Clinical Cancer Research

  • No preview · Article · Apr 2011 · Cancer Research
  • F R Kona · D Buac · A. M. Burger
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    ABSTRACT: Disulfiram is a FDA approved drug for the treatment of alcoholism and available for clinical use since over 5 decades. Despite data from the 1970s and 80s that showed that disulfiram and analogs are able to enhance the activity of anticancer cytotoxic drugs and might be useful chemopreventative agents, the underlying molecular mechanisms remained unknown until recently. Large scale screening efforts for agents that can inhibit the proteasome and be used as novel anticancer drugs, revealed that disulfiram has proteasome inhibitory activity. Moreover, disulfiram was also found to have specific activity against zinc fingers and RING-finger ubiquitin E3 ligases that play an important role in cancer development. Here, we review the preclinical and clinical studies exploring disulfiram as an anticancer agent as well as research programs that focus on the development of disulfiram derivatives as inhibitors of the ubiquitin-proteasome system.
    No preview · Article · Mar 2011 · Current cancer drug targets
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    ABSTRACT: Pemetrexed has emerged as one of the most active agents for the treatment of patients with advanced non-small cell lung cancer (NSCLC). We conducted a phase II study to assess the efficacy and feasibility of integrating pemetrexed in a concurrent therapy plan for patients with stage III NSCLC. Patients with stage III NSCLC with performance status 0 to 1, adequate organ function including pulmonary function, and V20 less than 40% were eligible. Patients were treated with cisplatin 75 mg/m² (first five patients 60 mg/m²) and pemetrexed 500 mg/m² every 21 days for three cycles with chest radiotherapy to 66 Gy. Patients then received three cycles of docetaxel 75 mg/m² every 21 days. Tumors were analyzed for Excision Repair Cross Complementation Group 1 and thymidylate synthase. Patient characteristics (N = 28) were median age, 60; males, 68%; stage IIIB, 64%; and squamous cell, 43%. Twenty-four patients (86%) completed all three cycles of cisplatin/pemetrexed. Of the 24 patients eligible for docetaxel, 21 (87%) received it. Grade 3/4 toxicities were neutropenia (39%), febrile neutropenia (14%), esophagitis (14%), and pneumonitis (4%). Median survival was 34 months, and 1-year survival was 66%. Survival was not significantly different in squamous and other histology patients. Tumor analysis in 16 patients showed that moderate/strong expression of thymidylate synthase was significantly associated with progression-free survival and overall survival. Integrating pemetrexed in a concurrent therapy regimen for patients with stage III NSCLC is feasible and was associated with a median survival of 34 months.
    No preview · Article · Mar 2011 · Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer
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    ABSTRACT: Breast ultrasound tomography is a rapidly developing imaging modality that has the potential to impact breast cancer screening and diagnosis. Double difference (DD) tomography utilizes more accurate differential time-of-flight (ToF) data to reconstruct the sound speed structure of the breast. It can produce more precise and better resolution sound speed images than standard tomography that uses absolute ToF data. We apply DD tomography to phantom data and excised mouse mammary glands data. DD tomograms demonstrate sharper sound speed contrast than the standard tomograms.
    No preview · Article · Mar 2011 · Proceedings of SPIE - The International Society for Optical Engineering

  • No preview · Article · Jan 2011 · Cancer Research

  • No preview · Article · Jan 2011 · Cancer Research
  • S. Chumsri · A.M. Burger
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    ABSTRACT: Emerging evidence suggests that cancers contain a rare and biologically distinct subpopulation of cells with the ability to self-renew and to sustain tumor growth, termed "cancer stem cells". Cancer stem cells share many characteristics with normal stem cells including self-renewal, asymmetric division, indefinite proliferative capacity, and self-protection mechanisms. The cancer stem cell concept is best understood in hematologic malignancies. In solid tumors, breast cancer stem cells have been the most explored. Several techniques have been described, allowing the identification or isolation of cancer stem cells by either expression of specific cell surface markers, their differential ability to efflux dyes, or by a distinct enzymatic activity. More recent studies also established the crucial role of cancer stem cells in multistage cancer progression and metastasis which has important implications for the design of novel targeted therapies. Since most of the conventional chemotherapies only affect differentiated cancer cells, initial reduction in tumor mass is often followed by a rapid relapse. In order to achieve durable remissions, it will be imperative to eradicate cancer stem cells.
    No preview · Article · Jan 2011

  • No preview · Chapter · Jan 2011

  • No preview · Chapter · Jan 2011
  • Heinz-Herbert Fiebig · Angelika M. Burger
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    ABSTRACT: Since the first report of the successful xenografting of a human tumor into nude mice in 1969, there have been numerous studies conducted throughout the world using the nude moue as a tool to answer a variety of questions regarding the cause, prevention, and therapy of cancer. Thus, the role of immunodeficient animals in oncology has continuously increased and the athymic nude mouse has proven to be an outstanding host for many human solid tumor xenografts [1, 2]. The latter are now extensively used in the development of potential anticancer drugs, new antineoplastic treatment modalities, and studies on tumor biology [3–7]. Moreover, mice with severe combined immunodeficiency (SCID) and nonobese diabetic (NOD)/SCID mice have enlarged the spectrum of possible applications in cancer research. SCID mice have enabled engraftments of human tumors which were previously difficult to explant such as those of the hematopoietic system [8]. The NOD/SCID mouse tumor repopulation model has become the gold standard for the analysis of self-renewal properties of putative cancer stem cells and is critical to the emerging field of cancer stem cell biology [9]. KeywordsHuman Xenografts-Patient derived tumor models-Molecular characterization-Drug sensitivity testing-Gene signature
    No preview · Chapter · Dec 2010

  • No preview · Article · Nov 2010 · EJC Supplements
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    ABSTRACT: Aminoflavone (AF), the active component of a novel anticancer agent (AFP464) in phase I clinical trials, is a ligand of the aryl hydrocarbon receptor (AhR). AhR dimerizes with HIF-1beta/AhR, which is shared with HIF-1alpha, a transcription factor critical for the response of cells to oxygen deprivation. To address whether pharmacologic activation of the AhR pathway might be a potential mechanism for inhibition of HIF-1, we tested the effects of AF on HIF-1 expression. AF inhibited HIF-1alpha transcriptional activity and protein accumulation in MCF-7 cells. However, inhibition of HIF-1alpha by AF was independent from a functional AhR pathway. Indeed, AF inhibited HIF-1alpha expression in Ah(R100) cells, in which the AhR pathway is functionally impaired, yet did not induce cytotoxicity, providing evidence that these effects are mediated by distinct signaling pathways. Moreover, AF was inactive in MDA-MB-231 cells, yet inhibited HIF-1alpha in MDA-MB-231 cells transfected with the SULT1A1 gene. AF inhibited HIF-1alpha mRNA expression by approximately 50%. Notably, actinomycin-D completely abrogated the ability of AF to downregulate HIF-1alpha mRNA, indicating that active transcription was required for the inhibition of HIF-1alpha expression. Finally, AF inhibited HIF-1alpha protein accumulation and the expression of HIF-1 target genes in MCF-7 xenografts. These results show that AF inhibits HIF-1alpha in an AhR-independent fashion, and they unveil additional activities of AF that may be relevant for its further clinical development.
    Full-text · Article · Sep 2010 · Cancer Research
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    ABSTRACT: Drug resistance remains a clinical challenge in cancer treatment due to poor understanding of underlying mechanisms. We have established several drug-resistant prostate cancer cell lines by long-term culture in medium containing chemotherapeutic drugs. These resistant lines displayed a significant increase in side population cells due to overexpression of drug efflux pumps including ABCG2/BCRP and MDR1/Pgp. To uncover potential mechanisms underlying drug resistance, we performed microarray analysis to identify differentially expressed genes in 2 drug-resistant lines. We observed that POU5F1/OCT4, a transcription factor key to regulating pluripotency in embryonic stem cells, was upregulated in drug-resistant lines and accompanied by transcriptional activation of a set of its known target genes. Upregulation of OCT4 in drug-resistant cells was validated by RT-PCR and sequencing of PCR products as well as confirmation by Western blot and specific shRNA knockdown. Analysis of the regulatory region of POU5F1/OCT4 revealed a reduction of methylation in drug-resistant cell lines. Furthermore, these drug-resistant cells exhibited a significant increase in tumorigenicity in vivo. Subcutaneous inoculation of as few as 10 drug-resistant cells could initiate tumor formation in SCID mice, whereas no detectable tumors were observed from the parental line under similar conditions, suggesting that these drug-resistant cells may be enriched for tumor-initiating cells. Knocking down OCT4 expression by specific shRNAs attenuated growth of drug-resistant cells. Our data suggest that OCT4 re-expression in cancer cells may play an important role in carcinogenesis and provide one possible mechanism by which cancer cells acquire/maintain a drug-resistant phenotype.
    Full-text · Article · Sep 2010 · Genes & cancer
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    ABSTRACT: Heat shock protein (Hsp) 90 inhibition affects the Raf kinase signaling pathway and could enhance antitumor effects of sorafenib, a Raf kinase inhibitor. The combination of sorafenib and tanespimycin [17-allyl-amino-geldanamycin (17-AAG); NSC 330507/KOS-953] was evaluated in a phase I trial with the primary objective of defining a phase II dose. Patients and Methods: The dose cohorts consisted of fixed continuous oral dosing of 400 mg sorafenib twice daily, starting at 14 days before tanespimycin, which was administered intravenously at escalating doses (starting at 300 mg/m,(2) with 50 mg/m(2) increments), on days 1, 8, and 15 in a 28-day cycle. Toxicity was assessed weekly, and response was evaluated every two cycles. Twenty-seven toxicity-evaluable patients were enrolled and treated at four dose levels. Predominant primary malignancies were renal cancer (12), melanoma (6), and colorectal cancer (4). Dose-limiting toxicities of grade 4 transaminitis and grade 3 hand-foot syndrome in one patient each were observed at 450 mg/m(2) of tanespimycin. One hundred fourteen cycles were administered with a median of four cycles (range 1-17 cycles). Plasma concentrations of sorafenib and metabolites reached steady state after 7 days. Tanespimycin did not alter sorafenib concentrations. Pharmacodynamics showed a decrease in Hsp90 levels and induction of Hsp70. Clinical efficacy was observed in 9 of 12 renal cancer patients and 4 of 6 melanoma patients Recommended phase II doses of this combination are 400 mg sorafenib twice daily and 400 mg/m(2) tanespimycin on days 1, 8, and 15, every 28 days. Clinical and pharmacodynamic activity was observed in kidney cancer and melanoma.
    Full-text · Article · Jul 2010 · Clinical Cancer Research

Publication Stats

4k Citations
690.55 Total Impact Points


  • 2008-2015
    • Wayne State University
      • • Barbara Ann Karmanos Cancer Institute
      • • Department of Pharmacology
      Detroit, Michigan, United States
    • American Society for Pharmacology and Experimental Therapeutics
      Baltimore, Maryland, United States
  • 2007-2013
    • Oncotest GmbH – Institute for Experimental Oncology
      Freiburg an der Elbe, Lower Saxony, Germany
  • 2008-2011
    • Karmanos Cancer Institute
      Detroit, Michigan, United States
  • 2006-2010
    • University of Maryland, Baltimore
      • • Department of Medicine
      • • Greenebaum Cancer Center
      Baltimore, Maryland, United States
    • University of Maryland Medical Center
      Baltimore, Maryland, United States
    • University of Nottingham
      • School of Pharmacy
      Nottingham, ENG, United Kingdom
  • 1996-2006
    • University of Toronto
      • • Department of Laboratory Medicine and Pathobiology
      • • Sunnybrook Health Sciences Centre
      Toronto, Ontario, Canada
  • 2005
    • Liverpool John Moores University
      Liverpool, England, United Kingdom
  • 2003-2005
    • Sunnybrook Health Sciences Centre
      • Division of Anatomic Pathology
      Toronto, Ontario, Canada
  • 2001-2005
    • Clinic for Tumor Biology Freiburg
      Freiburg, Baden-Württemberg, Germany
  • 1998-2005
    • University of Freiburg
      Freiburg, Baden-Württemberg, Germany
  • 1996-2005
    • University of Bradford
      • Bradford School of Medical Sciences
      Bradford, England, United Kingdom
  • 1997
    • National Cancer Institute (USA)
      • Developmental Therapeutics Program
      베서스다, Maryland, United States
  • 1995
    • Leidos Biomedical Research
      Фредерик, Maryland, United States