bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract A122: The tyrosine kinase inhibitor MP470 inhibits RAD51-mediated homologous recombination and increases tumor cell radio- and chemosensitivity
Authors: Bristow Robert G. , Zhao Helen , Fraser Michael 
Published: June 2012

Abstract
MP470 is a tyrosine multi-kinase inhibitor whose targets include PDGFR, c-Kit and c-Met and is being tested as a single agent in Phase I clinical trials. In pre-clinical drug testing in vitro, we noted a reduction in the expression of RAD51, a key protein involved in the homologous recombination (HR) pathway of DNA double strand break (DSB) repair. We therefore tested whether MP470 can actually decrease HR function and thereby act as a radio- and chemosensitizer through a novel mechanism of action. We conducted qRT-PCR, Western blots, flow cytometric, inter-chromosomal DNA-dsb rejoining assays, subnuclear DSB recruitment and clonogenic survival using H1299 lung carcinoma cells with and without MP470 treatment. These cells incorporate a DR-GFP system which directly assesses HR by quantitative flow cytometry. As a single agent, MP470 treatments of 0.1 to 25 uM (24h) reduced RAD51 protein expression in H1299 cells in a dose-dependent manner. The ICD50 based on clonogenic assays was 0.66 uM; 1–2.5uM treatments reduced RAD51 levels by 50–60% with little effect on cell cycle distribution. This rules out that reduced RAD51 expression was secondary to cell cycle redistribution and decreased S phase following MP470 treatment. The same treatments reduced functional HR by 50% based on the DR-GFP assay. Using whole cell treatments with ionizing radiation (IR; 6Gy) and Mitomycin C (MMC) or UV microbeam sub-nuclear irradiation, we observed decreased expression and formation of RAD51 complexes at sites of DNA damage in MP470-treated (2.5uM) cells. Consistent with this finding, treatment of H1299 cells with 1 or 2.5uM MP470 led to significantly increased cell killing to IR and MMC (a drug that preferentially kill HR-defective cells) based on clonogenic assay. Confirmatory studies are ongoing with other cancer cell lines. We conclude that MP470 may have an additional mode of action by interfering with HR in cancer cells. Given that many cancers acquire radio- and chemoresistance and over-express RAD51, MP470 may be a novel drug to overcome RAD51-mediated therapeutic resistance. MP470 warrants further testing alone, or in combination with radiotherapy and chemotherapy, in pre-clinical and clinical efficacy studies with the development of HR-associated biomarkers. (Supported by funds from SuperGen, a Terry Fox Hypoxia Project Program Grant and a CCS Reseach Scientist award to RGB.).
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A122.
Abstract A127: Combination therapy targeting EGFR/MET crosstalk using nanotechnology improves photodynamic therapy treatment of pancreatic cancer
Authors: Zheng Lei Z. , Rai Prakash , Spring Bryan , Mai Zhiming , Evans Conor , Hasan Tayyaba 
Published: June 2012

Abstract
Pancreatic cancer (PanCa) is very difficult to treat due to its inherent resistance to most therapies. First line chemotherapy only has a 5% response rate, yielding a median survival of 6 months and a 5-year survival rate of &lt; 5%. Combinations of chemotherapy with numerous targeted therapies only showed modest benefits. In a pilot clinical trial, Photodynamic Therapy (PDT) showed considerable promise as an emerging alternative treatment modality for PanCa in humans by improving median survival from 6 to 9 months, which led to our subsequent investigation of a rationally designed molecularly targeted combination therapy to enhance PDT treatment of PanCa in an orthotopic murine model.
Targeted biological therapies in PanCa include an EGF Receptor (EGFR) antibody, C225 which has shown no survival benefits in humans either alone or in combination with other modalities. One of the mechanisms involved in the development of resistance to EGFR targeted therapy is the crosstalk between EGFR and MET signaling pathways. MET is also a growth factor receptor that is frequently deregulated in pancreatic cancer. In some cancers, the EGFR and MET signaling pathways synergistically drive proliferative and metastatic growth. To achieve effective tumor control it is vital that both EGFR and MET pathways are targeted simultaneously. In this preclinical study, we have developed an innovative nanoscale multidrug delivery system that targets the EGFR/MET crosstalk in combination with PDT. To target EGFR we are using C225 antibody while the MET activation is suppressed using a small molecule inhibitor PHA-665752.
Major findings of this work include: 1) Our nanoscale multidrug delivery system enabled higher payloads of the PDT agent and PHA-665752 to be delivered with reduced systemic toxicity. In our nano-construct, the C225 is now delivered intracellularly into cancer cells thus allowing the targeting of both intracellular and membrane EGFR, as opposed to carrier-free C225 delivery which only down-regulates the cell surface EGFR level. 2) Intracellular targeting of EGFR by encapsulated C225 sensitized the cancer cells to PDT treatment. This combination showed greater efficacy in reducing the EGFR levels and improved PDT treatment effect by showing a greater reduction of the local tumor burden, compared to using carrier-free C225 extracellularly. 3) Blocking the EGFR/MET crosstalk with both C225 and PHA-665752 further enhanced PDT treatment by reducing the local tumor burden. We are further investigating if this combination treatment regimen reduces tumor metastasis to distal organs and the optimal scheduling of individual biological treatments.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A127.
Abstract A129: Targeted delivery of therapeutics to tumor cells and the tumor microenvironment
Authors: Moura Vera , Lacerda Manuela , Figueiredo Paulo , Corvo Maria Luisa , Cruz Maria Eugénia , Pedroso de Lima Maria C. , Simões Sérgio , Moreira João Nuno 
Published: June 2012

Abstract
Human cancer is a complex disease caused by genetic instability and accumulation of multiple molecular alterations. Tumor growth and metastasis depend on the development of a neovasculature by a process called angiogenesis, which is controlled by numerous pro- and antiangiogenic factors. Therefore, vascular targeting emerges as an attractive therapeutic approach, since angiogenic blood vessels express distinctive molecular markers with direct access by the therapeutic agent. Moreover, ablation of immature angiogenic vessels causes reduction of the interstitial pressure gradient in the tumor periphery, improving drug delivery through the highly permeabilized vessel wall. Hence, additional therapeutic gains will be expected by “starving” tumor cells to death and by increasing the concentration of the therapeutic agent in the target cell.
The present work, is aimed at investigating the ability of a system consisting of a ligand coupled to the extremity of poly(ethylene glycol)-grafted liposomes, containing doxorubicin (DXR), to simultaneously target human tumor cells and endothelial cells of tumor blood vessels. Cellular association studies were conducted by flow cytometry, fluorimetry and confocal microscopy with rhodamine-labeled liposomes. Competitive inhibition and mechanistic assays were also performed by fluorimetry. Cytotoxicity was evaluated with the MTT assay and biodistribution performed on Balb/c nude female mice bearing orthotopic implanted tumors was analyzed by radioactivity counts of a lipid and a drug tracer ([3H]CHE and [14C]DXR, respectively).
Our results show a substantial increase in the levels of association for ligand-targeted liposomes, in vitro as well as ex vivo, in tumor cells removed from patients, after mastectomy or tumorectomy. These results suggest that internalization occurs, most likely through the clathrin-mediated endocytic pathway. Cytotoxicity studies show that ligand-targeted liposomes are more cytotoxic than the control formulation (4 to 180-fold), against tumor and endothelial cells, indicating that binding and internalization of the system are contributing to a more efficient delivery of the payload to the target cells. In vivo experiments report a higher tumor accumulation of the radiolabeled targeted system over non-targeted liposomes (approximately 18-fold). The observed improved tumor targeting is likely due to a strong vascular targeting component that is taking place in vivo. The data generated so far indicate that the same technological platform is able to target two distinct cell populations within the tumor niche. Overall, these results represent a novel and a valuable contribution for delivery strategies to the tumor and its microenvironment.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A129.
Abstract A130: Effects of a novel liposomal formulation of fenretinide on human neuroblastoma cell growth, apoptosis and angiogenesis
Authors: Di Paolo Daniela , Caffa Irene , Pastorino Fabio , Loi Monica , Marimpietri Danilo , Brignole Chiara , Perri Patrizia , Cilli Michele , Nico Beatrice , Ribatti Domenico , Ponzoni Mirco , Pagnan Gabriella 
Published: June 2012

Abstract
Neuroblastoma (NB) is an embryonal tumor originating from the simpatico-adrenal lineage of the neural crest and developing virtually at any site of the sympathetic nervous system. It approximately accounts for about 15% of all paediatric oncology deaths. NB is characterized by different clinical presentations and courses. Metastatic tumors at diagnosis remains a clinical challenge, despite advances in multimodal therapy. Retinoids are a class of compounds known to induce both terminal differentiation and apoptosis/necrosis of NB cells. Among them, fenretinide (HPR), thanks to its good safety profile in humans, has been considered one of the most promising synthetic retinoids tested as chemopreventive agent but it is only partially efficacious due to both a scanty oral delivery and a rapid methabolism. Here, we have developed a novel liposomal HPR by which the drug was encapsulated into sterically stabilized liposomes [SL-(HPR)] according to the reverse-phase evaporation method. This procedure led to a higher drug encapsulation and to better size and stability in organic fluids when compared to our previously HPR-entrapped liposome preparation (Pagnan et al., Int.J.Cancer 1999;81:268). Moreover, liposomes were coupled with NGR peptides that target the tumor endothelial cell marker, the aminopeptidase N [NGR-SL-(HPR)] (Pastorino et al, Cancer Res 2006;66:10073). The in vivo sensitivity of NB to the HPR liposomal preparations was tested against an established orthotopic NB xenograft animal model. Tumor-bearing mice treated with NGR-SL-(HPR) lived statistically longer than mice un-treated or treated with free HPR [NGR-SL-(HPR) vs both control and HPR: P&lt;0.0001]. SL-(HPR) resulted in a statistically improved survival [SL-(HPR) vs both control and HPR: P&lt;0.0001] but with a less extent if compared with that obtained with NGR-SL-(HPR) [SL-(HPR) vs NGR-SL-(HPR): P=0.01]. Double staining of primary tumor sections with TUNEL and with antibodies against the NB specific antigen, NB84a, and against either factor VIII or smooth muscle antigens evidenced that HPR reduced NB growth through both antitumor and angiostatic effects, mainly when delivered by NGR-SL-(HPR). These results were confirmed by a marked reduction of intratumoral vessel counts together with a down-modulation of both matrix metalloproteinases MMP2 and MMP9.
The use of this novel targeted delivery system for the apoptotic and anti-angiogenic drug, fenretinide, could be considered as an adjuvant tool in the future treatment of NB patients.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A130.
Abstract A132: Development of efficient macromolecular prodrugs derived from dendritic polyglycerol
Authors: Calderon Marcelo , Welker Pia , Licha Kai , Graeser Ralph , Kratz Felix , Haag Rainer 
Published: June 2012

Abstract
Introduction: Utilizing the Enhanced Permeation Retention Effect (EPR) for passive targeting is one of the novel approaches for tumor-selective drug delivery. Polymer-based nanocarriers, especially those of dendritic architecture, have gained increasing interest for encapsulating or coupling diagnostic or therapeutic agents. Chemical conjugation to a dendritic scaffold, thereby exploiting the high multivalency, allows for the covalent attachment of different kinds of bioactive molecules (imaging agents, drugs, targeting moieties, or biocompatible molecules) in a controlled ratio. (1) Hyperbranched polyglycerol is a potent alternative to perfect dendrimers for biomedical applications because of its ease of preparation, non-immunogenicity, tuneable molecular weight, high water-solubility and structural flexibility through end group modification. (2)
Here we present a comprehensive study for the development of macromolecular doxorubicin-polyglycerol prodrugs. The effects of the conjugation approach, the polymeric architecture, the cleavable linker and the drug loading over the final properties are analyzed.
Results and Discussion: Hyperbranched polyglycerols partially modified with azido, propargyl, amine or polyethylene glycol were prepared with overall yields higher than 60%. Different reactions, e.g click coupling and Michael addition, were evaluated for the conjugation of several doxorubicin derivates to the polyglycerol scaffolds. UV-Visible, 1H-NMR, GPC and HPLC were used to demonstrate the obtention of macromolecular prodrugs with several molecular weights, architectures and different cleavable linkers. The conjugates showed rapid and selective release of doxorubicin after being triggered by a change in pH or in presence of enzymes, accordingly to the nature of conjugated prodrugs.
The antiproliferative activity assessed against two human tumor cell lines AsPC1 LN (pancreatic carcinoma) and MDA-MB-231 LN (mamma carcinoma) showed less (2- to 10-fold) cytotoxicity than the corresponding free drugs. Cellular uptake was confirmed by fluorescence microscopy. In all cases, the conjugates showed to be active in the low micromolar range that is relevant for further preclinical studies of anticancer prodrugs.
The in vivo efficacy was tested in ovarian carcinoma A2780 xenograft model. With respect to antitumor efficacy, some of the conjugates manifested excellent antitumor effects with complete tumor remissions up to day 30. No significant changes in body weight were observed even after administration of 3-fold the maximal tolerated dose for free doxorubicin.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A132.
Abstract A161: Acquired resistance to combination treatment with TMZ and ABT-888 is mediated by both BER and HR DNA repair pathways
Authors: Liu Xuesong , Han Edward K. , Anderson Mark G. , Shi Yan , Semizarov Dimitri , Wang Gang , McGonigal Thomas , Roberts Lisa , Iasko Ioren , Palma Joann , Zhu Gui-Dong , Penning Thomas , Rosenberg Saul , Giranda Vincent , Luo Yan , Leverson Joel , Johnson Eric F. , Shoemaker Alexander R. 
Published: June 2012

Abstract
Many established cancer therapies involve DNA-damaging chemotherapy or radiotherapy. Gain of DNA repair capacity of the tumor represents a common mechanism employed by cancer cells to survive DNA-damaging therapy. Poly (ADP-ribose) polymerase-1 (PARP-1) is a nuclear enzyme that is activated by DNA-damage and plays a critical role in base excision repair (BER). Inhibition of PARP represents an attractive approach for the treatment of cancer. Previously, we have described the discovery and characterization of a potent PARP inhibitor, ABT-888. ABT-888 potentiates the activity of DNA-damaging agents such as temozolomide (TMZ) in a variety of preclinical models. Previously, we demonstrated that ABT-888 potentiated the cytotoxic effect of TMZ by converting TMZ-induced single strand DNA breaks (SSB) to double strand breaks (DSB). We report here the generation of HCT116 cells resistant to treatment with TMZ and ABT-888 (HCT116R cells). HCT116R cells exhibit decreased H2AX phosphorylation in response to the treatment with TMZ and ABT-888 relative to parental HCT116 cells. Microarray and western blot studies indicate that HCT116R cells have decreased PARP-1 and elevated Rad51 expression levels. HCT116R cells are dependent on Rad51 for proliferation and survival, as demonstrated by inhibition of proliferation and induction of apoptosis upon treatment with Rad51 siRNA. In addition, HCT116R cells are more resistant to radiation than the parental HCT116 cells. Our study suggests that cancer cells up-regulate the homologous recombination DNA repair pathway to compensate for the loss of BER, which may account for the observed resistance to the treatment with TMZ and ABT-888.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A161.
Abstract A168: Quantitative high-throughput screening for inhibitors of human apurinic/apyrimidinic endonuclease APE1
Authors: Dorjsuren Dorjbal , Jadhav Ajit , Kulkarni Avanti , McNeill Daniel , Austin Christopher P. , Wilson David M. , Shen Min , Simeonov Anton 
Published: June 2012

Abstract
The major human apurinic/apyrimidinic endonuclease APE1 plays a pivotal role in the repair of spontaneous hydrolytic, oxidative, and non-enzymatic alkylation base damage via the DNA base excision repair (BER) pathway. The increased activity of APE1, often observed in tumor cells, is thought to contribute to the development of resistance to various anticancer drugs; conversely, its down-regulation sensitizes tumor cells to DNA damaging agents via induction of apoptosis. Therefore, inhibiting APE1 within the BER pathway in cancer cells is an attractive strategy in the attempts to overcome chemotherapeutic resistance. Despite ongoing efforts, potent specific inhibitors of APE1 have yet to be discovered.
We developed a fluorogenic substrate operating in the red-shifted fluorescence spectral region to configure a highly robust kinetic assay for use in 1536-well based automated high-throughput screening (HTS). The assay was used in a titration-based screen of the LOPAC1280 library to identify potential APE1 inhibitors which were further validated and profiled in a panel of assays including radiotracer-based incision assay, Thiazole Orange fluorophore displacement test for promiscuous DNA binders, and E. coli Endo IV counterscreen. Select compounds which passed the above validation steps were progressed to studies of increased biochemical complexity and were shown to inhibit abasic-site incision activity in whole cell protein extracts and to potentiate the genotoxic effect of methyl methanesulfonate (MMS), consistent with suppression of BER on a cellular level. Subsequently, a fully automated HTS was conducted against a collection of 241,291 diverse compounds tested as 7-concentration series at a 4 uL reaction volume in 1536-well plate format. To our knowledge, this represents the first large-scale HTS to identify inhibitors of APE1, and provides a key first step in the development of novel agents targeting BER for cancer treatment.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A168.
Abstract A184: A phase I study of 5-azacytidine (AZA) and erlotinib (E) for patients (pt) with advanced solid tumors
Authors: Verschraegen Claire , Muller Carolyn , Bauman Julie , Rutledge Teresa , Jones Dennie 
Published: June 2012

Abstract
Background: Erlotinib (E), a tyrosine kinase inhibitor of EGFR, is approved for non-small cell lung cancer. 5-Azacytidine (AZA) is approved for leukemia. AZA traps DNA methyltransferase (DMT) in a covalent complex with DNA resulting in a progressive loss of DNA methylation, at concentrations that do not cause major suppression of DNA synthesis. Hypomethylation reactivates previously quiescent genes and may restore the function of genes that control cell proliferation and differentiation, such as EGFR.
Methods: A standard 3+3 phase I study of the combination of E and AZA was planned in patients with incurable solid tumors. E was given at full dose (150 mg/day continuously). Vidaza was given intravenously every 2 weeks at a starting dose of 75 mg/m2/day ×1 day. Increments were by number of AZA days: The second cohort received 2 consecutive days of Vidaza, the third, 3 days, the fourth, 4 days. One course was 4 weeks. Standard grade 3 and 4 DLTs (CTCAE version 3) were recorded on the first course of treatment. RECIST criteria were used to determine response.
Results: 18 adult patients (pt) have been enrolled. Cohort 1: 6 pt; cohort 2, 3 pt; cohort 3, 6 pt; cohort 4, 3 pt. DLTs included eye infection (1 pt in cohort 1) and a neutropenic sepsis in cohort 3. Both cohorts were expanded. Overall AEs were: grade 3 rash, diarrhea, and hypokalemia (1 each (5%)); grade 1–2 rash (60%), nausea/vomiting (38%), diarrhea (38%), fatigue (33%), mouth sores and dysgeusia (22% each), hypokalemia (16%), transaminase increase (11%), neutropenia (5%), pneumonitis (5%), urticaria (5%). The maximum tolerated dose has not been reached at 75 mg/m2/day × 4 days every 2 weeks. Enrollment will continue until AZA 100 mg/m2/day × 4 days is reached. ORR is 5% with a clinical benefit rate of 40%, and the median number of courses given is 2 (range 1–6).
Conclusions: The combination of E and AZA is well tolerated with no synergistic toxicities. The main AEs are rash and gastrointestinal. E+AZA has modest but definite activity in patients with refractory tumors, and long disease stabilization are observed in selected patients.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A184.