bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract A163: Development of Grb2 SH3 domain antagonists
Authors: Giubellino Alessio , Liu Fa , Burke Terrence , Bottaro Donald P.
Published: June 2012

Src-homology 3 (SH3) domains are small modules of about 60 amino acids residues found in proteins that participate in many signaling pathways. As such, SH3 domains are involved in the regulation of several important cellular processes, including cell growth and differentiation, cell movement, protein trafficking and degradation, and immune responses. The adaptor protein Grb2 contains two SH3 domains. The canonical model of Grb2 function relies on the widely confirmed observation that Grb2 SH3 domains are constitutively associated with Sos1, a guanine-nucleotide exchange factor that promotes GDP-GTP exchange on Ras. Upon growth factor receptor activation and tyrosyl phosphorylation, Grb2 brings Sos1 into close proximity of membrane-bound Ras, thereby activating Ras and the downstream MAPK cascade, a well-know oncogenic signaling convergence point. Thus, antagonism of Grb2-Sos interaction is a logical strategy for inhibiting tumor cell growth. Using a short synthetic peptide corresponding to the SH3 domain recognition motif of Sos1 as a starting point, and systematically introducing bridging carbonyl sequences and other modifications, novel antagonists of Sos1-SH3 domain interaction were developed.

The performance of these antagonists was systematically evaluated using a solid phase Grb2-Sos1 binding assay and cell lysates prepared from the pheochromocytoma cell line PC12, which has robust expression of both Grb2 and Sos1 proteins. Refinement of candidates identified in initial screens yielded a set of peptidomimetic antagonists with nanomolar IC50 values that were selected for further study. The potency and target selectivity of these compounds suggest that they may have utility as anti-cancer therapeutics for tumors where Grb2-Sos1 interactions are critical for oncogenesis and disease progression.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A163.
Abstract A17: The dual angiogenesis/heparanase inhibitor PG545 inhibits solid tumor progression in models of breast, prostate and liver cancer: A comparative assessment of once versus twice weekly administration schedules
Authors: Hammond Edward , Bytheway Ian , Handley Paul , Kappler Michelle , McGirr Crystal , Gonda Thomas J. , Smith Maree , Dredge Keith
Published: June 2012

PG545 is Progen's lead oncology candidate currently undergoing formal preclinical development. PG545 is a synthetic heparan sulfate (HS) mimetic that prevents neovascularization by inhibiting growth-factor heparan sulfate binding and metastasis through the inhibition of heparan sulfate cleavage by heparanase. PG545 was assessed for efficacy in a number of xenograft models, namely the MDA-MB-231 (breast), PC3 (prostate), HepG2 (liver) and the orthotopic model Hep3B (liver). In the Hep3B liver cancer model, a concurrent study dosed tumor-bearing mice with radiolabeled PG545 every 96 h for three doses in order to generate a pharmacokinetic (PK) profile of the compound in blood and tumor tissue. In the efficacy studies, once or twice weekly treatment was initiated once the tumors reached 100–200cm3 (depending on the study). Although not significantly different to twice weekly dosing, PG545 exhibited maximal antitumor efficacy when dosed once weekly in each of the four independent studies. Moreover, in the Hep3B liver cancer study, PG545 exhibited antitumor activity to a similar extent as the tyrosine kinase inhibitor sorafenib which is approved by the FDA for inoperable hepatocellular carcinoma. A preliminary pharmacokinetic profile using radiolabeled compound [3H]-PG545 was also obtained. Data generated using both compartmental and non-compartmental modeling indicate a favourable pharmacokinetic profile and significant uptake of [3H]-PG545 into the tumor from the bloodstream. Taken together, the tumor efficacy and pharmacokinetic data support the ongoing preclinical development of PG545 as a once weekly, subcutaneously administered injection for the treatment of cancer.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A17.
Abstract A175: Isolation and identification of compounds from the fruits of Kigelia pinnata with anti-proliferative activity towards human cancer cells
Authors: Higgins Catherine A. , McGrath Owen , Delbederi Zoicha , McGarel Kelly , Feutren-Burton Stephanie , Watters William , Armstrong Paul , Waugh David , van den Berg Hendrik
Published: June 2012

Kigelia pinnata DC. (Bignoniaceae also referred to as K. Africana or sausage tree), is a tree which is found widely in Africa and the tropics in general. Traditionally hot aqueous extracts of fruit pods from Kigelia pinnata have been claimed to have widespread ethnomedicinal importance. A preliminary study of the components of the aqueous extracts from the fruits of Kigelia pinnata was undertaken to identify fractions with potential anti-cancer activity. A bioactivity guided fractionation process of extracts from fruits of the tree was carried out yielding a number of crude fractions, which demonstrated cytotoxicity in vitro against human melanoma cells. A number of compounds were isolated and identified within purified fractions of several fruit extracts including the dihydroisocoumarins, demethylkigelin and kigelin, a number of fatty acids, and a furonaphthoquinone, as compounds at least in part responsible for the anti-proliferative activity observed in extracted material from the fruits. We tested a number of structurally related dihydroisocoumarins for their anti-proliferative activity in order to conduct a preliminary structure-activity relationship (SAR) study. The preliminary medicinal chemistry programme clearly identified structures with enhanced anti-proliferative activity relative to the isolated compounds. In conclusion, using a bioassay fractionation approach, we have isolated and characterized several classes of compounds that exhibit biological activity against human cancer cell lines. Structurally-related derivatives of these compounds have been synthesized to develop knowledge of the structure-activity relationship for these classes of compounds. Our data to date suggest that this class of molecule has structural features that appear to be of importance in determining its activity against human cancer cells.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A175.
Abstract A182: PI3K inhibitors overcome resistance to HER2-targeted agents caused by PIK3CA mutations in HER2-amplified breast cancer cell lines
Authors: Kataoka Yu , Minami Hironobu , Shimada Hiroyuki , Saijo Nagahiro , Hirai Midori , Mukohara Toru
Published: June 2012

Background: The mechanisms of resistance to HER2-targeted agents and the means to overcome them have not been fully understood. We investigated the influence of PIK3CA mutations on sensitivity to HER2-targeted agents in naturally derived breast cancer cells. We also tested potential usefulness of various inhibitors against molecules on PI3K signaling pathway.

Materials and Methods: We examined the effects of CL-387,785, HER2 tyrosine kinase inhibitor, and trastuzumab, humanized anti-HER2 monocloncal antibody, on cell growth and HER2 signaling in eight breast cancer cell lines showing HER2 amplification and trastuzumab-conditioned BT474 (BT474-TR). We also examined different PI3K pathway inhibitors that were PI3K inhibitor, m-TOR inhibitor, and PI3K/m-TOR dual inhibitor, on the same panel of cell lines.

Results: Four cell lines with PIK3CA mutations (E545K and H1047R) were more resistant to trastuzumab than the remaining four without mutations (mean percentage of control with 10 mg/ml trastuzumab: 58% versus 92%; p = 0.010). While PIK3CA-mutant cells were more resistant to CL-387,785 than PIK3CA-wild-type cells (mean percentage of control with 1 M CL-387,785: 21% versus 77%; P = 0.001), CL-387,785 retained activity against BT474-TR. Growth inhibition by trastuzumab and CL-387,785 was more closely correlated with changes in phosphorylation of S6K (correlation coefficient, 0.811) than those of HER2, Akt, or ERK1/2. All HER2-amplified cells showed detectable level of phosphorylated-Akt on serum-starved condition, while cell lines without PI3K pathway enhancement or HER2-amplification did not. Growth of all HER2-amplified cells was inhibited by PI3K pathway inhibitors regardless of PIK3CA genotype. PI3K/m-TOR dual inhibitor had much lower IC50 than the other PI3K pathway inhibitors, suggesting that complete blockade of phosphorylation of Akt and S6K may be required for maximal growth inhibition.

Conclusions: PIK3CA mutations are associated with resistance to HER2-targeted agents. S6K phosphorylation is a possibly useful pharmacodynamic marker in HER2-targeted therapy. PI3K inhibitors, especially PI3K/m-TOR dual inhibitor, are potentially effective in overcoming trastuzumab resistance caused by PIK3CA mutations.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A182.
Abstract A190: In vivo activity of SGI-110, a novel hypomethylating agent for treatment in hematology and solid malignancies
Authors: Scholl Jason , Vollmer David , Bearss Jared , Jones Carissa , McCarthy Virgil , Severson Paul , Redkar Sanjeev , Joshi-Hangal Rajashree , Inloes Roger , Shi Chongtie , Bearss David
Published: June 2012

SGI-110 is a second generation hypomethylating agent being developed for treatment in myelodysplastic syndrome (MDS) and solid tumor malignancies. In previous work, SGI-110 has demonstrated potent in vivo activity in a number of tumor types, including non-hematological cell lines. Current efforts are underway to optimize formulation and delivery of SGI-110 for first-in-human (FIH) studies.

In animals, SGI-110 is well-tolerated across multiple species utilizing multiple routes of drug delivery. Tolerability studies have been performed in mouse, rat, and rabbit models with multiple dose routes and schedules. Myelosuppression is an observed toxicity endpoint for hypomethylating agents. Hence, myelotoxic effects were investigated by comparing RBCs and bone marrow cellularity of mice treated with and without SGI-110. Mice dosed with SGI-110 for five consecutive days showed a significant decrease in RBCs at the end of the dosing period and a continued decrease one week after dosing. Bone marrow cellularity also showed a decrease at the end of dosing, but recovered to near normal levels one week later. Interestingly, RBCs from SGI-110 treated mice were elevated in the bone marrow after the dosing period. Pyrosequencing methylation analysis of colon samples was also evaluated in this study. A significant decrease in B1 methylation was observed in colon samples of treated mice, indicating global DNA methylation is being inhibited. Decreased levels in several hematology parameters and decreases in bone marrow cellularity were also observed in rat and rabbit studies after five consecutive days of SGI-110 dosing. Increased dosing frequency, while maintaining the same total dose per week, appears to result in increased toxicity.

Previous pharmacokinetic studies have shown that SGI-110 rapidly metabolizes to decitabine, an FDA-approved drug for MDS. Multiple formulations and different routes of delivery were examined to determine the optimal dose form to be used in FIH studies. Subcutaneous dosing results in bioavailability that is similar to that of intravenous dosing. Subcutaneous dosing appears to reduce the Cmax while maintaining similar AUC values when compared to intravenous dosing. Similar results in pharmacokinetic parameters are observed when the delivery vehicle is changed from an aqueous to non-aqueous formulation.

SGI-110 is a novel hypomethylating agent that is well-tolerated in rodent models, provides excellent PK exposure, and demonstrates inhibition of DNA methylation in a mouse model.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A190.
Abstract A194: Epigenetic modification of RXRα in human colon carcinomas by the green tea polyphenol, EGCG
Authors: Morris Jay , Brown Vondina R. , Coleman Kathleen V. , Wargovich Michal J.
Published: June 2012

Silencing of regulatory genes through hypermethylation of CpG islands is an important mechanism in tumorigenesis of numerous cancers. In colon cancer, one such gene which undergoes this type of silencing is Retinoid X Receptor alpha (RXRα) an important dimerization partner with other nuclear transcription factors. Previous studies have shown that ApcMin/+ mice treated with the carcinogen azoxymethane (AOM) will develop colonic tumors and when treated with green tea a reduction in tumor numbers was found. AOM treated mice also have reduced RXRα protein levels which is restored by treatment with green tea, reducing the amount of promoter methylation. We examined human colonic tumor microarrays by immunohistochemcial staining and found a marked decrease in RXRα a expression in tumor tissue compared to normal matched tissues, inversely β-Catenin levels increased. To determine how RXRα loss is reversed in human cancers by green tea, we treated HT-29 (methylation insensitive) and HCT116 (methylation sensitive) human colon cancer cell lines with Epigallocatechin gallate (EGCG - major polyphenolic compound in green tea for 48, 72 & 96 hr; 2, 3 & 4 doubling times). We found EGCG to restore RXRα activity levels in HCT116 cells treated with EGCG, in a dose dependant manner. We also found that EGCG treatments reduce the amount of promoter methlyation in 2 CpG island in the RXR promoter in HCT116 cells in a dose dependant manner. Numerous epidemiological reports have shown the benefits of green tea consumption in reducing colon cancer risks but to date no known studies have shown direct genetic effects of green tea on human colon cancer cells. Our results here show that EGCG, a common dietary compound, can modulate the reversal of gene-silencing involved colon carcinogenesis and maybe a possible avenue for colon cancer treatment.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A194.
Abstract A200: Differential kinase requirements of human cell lines pertaining to metastasis and c-Met signaling
Authors: Li Wenliang , Bhattacharya Nandita , Boyce Frederick M. , Gupta Piyush , Watnick Randolph S. , Harlow Edward E.
Published: June 2012

Metastasis accounts for over 90% of cancer death, but its mechanisms are still poorly understood. One valuable approach that has been commonly used to study metastasis was to compare paired poorly and highly metastatic cell lines, either for roles of a few genes of interest or global gene expression differences. Our work involved in using shRNA screen to identify global key functional differences between these matched cell lines. We postulated that the distinct in vivo phenotypes of these paired cell lines are a consequence of alterations in their cellular signaling networks during tumor progression. To characterize these functional differences, we performed arrayed shRNA screens against the human kinome to examine kinase requirements for survival and proliferation on several pairs of melanoma, colon or prostate cancer cell lines. From these screens, we have identified a set of kinases that become essential for multiple highly metastatic cells, some of which have been linked to metastasis (such as c-Met) but more have not. Several of these genes were shown to be amplified or mutated in human cancers. In vivo metastatic experiments are underway to prioritize these kinases by evaluating which kinases can promote metastasis when ectopically expressed. Since inhibition of these kinases phenocopied c-Met inhibition, we also sought to test if any of these kinases are functionally linked to c-Met signaling. Indeed, several of the identified kinases became essential when immortalized melanocytes were made tumorigenic and metastatic by introduction of activated c-Met. Biochemical and genetic rescue experiments are currently ongoing to further examine the links between these genes and c-Met. These studies offer new insights into the cellular signaling pathways operating in metastatic cancer cells and also suggest potential targets to treat metastatic cancers.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A200.
Abstract A21: Preclinical bioanalytical development to optimize drug treatment regimens using orthotopic models of human gastric cancer
Authors: Wick Michael J. , Cooper Joshua D. , Kelly Scott G. , Nieves Francis E. , Patnaik Amita , Tolcher Anthony W. , Kuhn John G. , Papadopoulos Kyriakos P.
Published: June 2012

Gastric cancer remains the second leading cause of cancer deaths worldwide and while gains have been made its treatment including neo- and post- adjuvant chemotherapy response rates are variable with limited survival benefit. Recent identification of molecular markers important in the pathogenesis of gastric cancer has spurred development of standard and targeted therapies to treat gastric cancer; however, lack of validated models has hindered this effort.

Preclinical development of anticancer agents can be accelerated with better tools to optimize a treatment regimen for in vivo studies. Identifying a useful drug concentration, route of administration and treatment schedule is costly and time consuming and often the decided regimen is suboptimal for efficacy experiments.

To address these issues, we have developed and characterized two cell-based orthotopic gastric tumor xenograft models (MKN-45 and 23132-87) in nude mice and rats. Using the mouse models we compared efficacy of several relevant anticancer agents including cisplatin, trastuzumab, docetaxel, ixabepilone, capecitabine and lapatinib. Bioanalytical methods using a UPLC-MS/MS system were developed for the latter four agents. Drug plasma concentrations were analyzed using blood collected at multiple in study timepoints from each animal (<30 l plasma per timepoint) and at study completion. In the capecitabine and lapatinib groups, tumors were also collected and analyzed. Docetaxel was active towards both models with tumor growth inhibition (%TGI) values >85% versus control. However, 23132-87 was insensitive to cisplatin and ixabepilone as well as trastuzumab and lapatinib but not capecitabine (TGI=79%) which was ineffective towards the MKN-45 model (T/C=19%). Bioanalytical analysis yielded Cmax values for each agent and steady state concentrations and plasma to tumor concentration ratios determined for capecitabine and lapatinib.

Results from these studies confirm two useful orthotopic models of gastric cancer with variable drug sensitivity. We have developed a platform for testing new drugs which can be tailored to optimize treatment regimen parameters and correlate with efficacy in a single study.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A21.
Abstract A215: Hsp90 inhibitor IPI-504 demonstrates antitumor activity against a panel of neuroendocrine/carcinoid cell lines in vitro and in vivo
Authors: Lim Alice R. , Slocum Kelly , Denyeko Igor , West Kip A. , Palombella Vito J. , Fritz Christian C. , Vosburgh Evan , Normant Emmanuel Y.
Published: June 2012

Heat shock protein 90 (Hsp90), an emerging target in cancer, is a chaperone protein that contributes to tumorigenesis by maintaining the stability and activity of multiple oncogenic proteins. Infinity Pharmaceuticals is currently developing two Hsp90 inhibitors: IPI-504 (retaspimycin hydrochloride), an intravenous agent that has entered several phase II clinical trials, and IPI-493, an orally administered compound that is currently being tested in a phase I dose-escalation trial. In pre-clinical animal models, IPI-504 and IPI-493 have demonstrated anti-tumor activity against a wide variety of tumor types.

Neuroendocrine tumors form a heterogeneous group of malignancies, which differ from each other in their biology, prognosis, and genetics. They mainly occur in the gastrointestinal tract and bronchopulmonary system. Conventional cytotoxic therapy has failed to demonstrate effective treatment of neuroendocrine/carcinoid cancers over the past 4 decades, resulting in an unmet need for improved pharmacological treatment of these tumors. To date, no data have been reported on the activity of Hsp90 inhibitors against carcinoid cancer cells.

Herein we describe the activity of the Hsp90 inhibitors IPI-504 and IPI-493 against a panel of neuroendocrine tumors including: BON-1, a cell line derived from a metastasis of a primary pancreatic neuroendocrine tumor, NCI-H720, a lung carcinoid, QGP-1, a pancreatic carcinoma of islet cells and HC-45, an ileal carcinoid. In vitro, most of the carcinoid cell lines are sensitive to the Hsp90 inhibitors with EC50 values between 10 and 189 nM for IPI-493 and 49 and 930 nM for IPI-504. In vivo, IPI-504 dosed twice weekly inhibits the tumor growth of BON-1 cells in mice.

To identify the potential mechanism of action of IPI-504 in BON-1 cells we have determined that IGF-1R, a tyrosine kinase receptor and an Hsp90 client protein, is constitutively activated in these cells suggesting that it could participate in the unregulated growth of these tumor cells. Upon treatment of BON-1 cells with IPI-504, phospho-IGF-1R is degraded in a dose-dependent manner. The EC50 of the protein degradation and the in vitro growth inhibitory activity of IPI-504 are similar (∼50 nM), suggesting that the anti-tumor activity of IPI-504 could be due, in part, to the inactivation of this growth factor receptor.

In conclusion, we demonstrated that the Hsp90 inhibitors IPI-504 and IPI-493 potently inhibit the growth of neuroendocrine tumor cell lines both in vitro and in vivo and identified IGF-1R as a potential client protein. These data suggest further exploring IPI-504 for the possible treatment of neuroendocrine tumors in the clinic.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A215.
Abstract A217: Comparison of long-term pharmacodynamic actions of the synthetic small molecule HSP90 inhibitor AT13387 in multiple xenograft models
Authors: Lyons John , Curry Jayne , Smyth Tomoko , Harada Isobel , Fazal Lynsey , Reule Matthias , Graham Brent , Thompson Neil
Published: June 2012

AT13387 is a novel small molecule inhibitor of HSP90. a member of a family of molecular chaperones. Previously we highlighted an association between the high affinity binding of AT13387 to the N-terminal ATPase domain of HSP90 and the duration of target inhibition in tumor cell lines in vitro. Further, AT13387 was shown to inhibit HSP90 and deplete client proteins in tumor xenografts longer than other, lower affinity inhibitors in the class. Here we have expanded the investigation to a wider number of tumor cell lines and to in vivo xenograft models and demonstrate that AT13387 has an extended pharmacodynamic action in tumors compared to other HSP90 inhibitors. We reason that the cumulative effects of these properties allow for less frequent dosing thus maximising efficacy whilst minimising systemic exposure and the potential for side effects.

This study reports extended inhibition of HSP90 by AT13387 in a wider range of tumor cell lines in vitro. A 24hr exposure of A375 (melanoma) cells to AT13387 suppressed the expression of client proteins for 72 hrs or more. However in other cell lines such as NCI-H1975 (lung) and BT474 (breast), the suppression of client proteins by AT13387 was found to last in excess of 7 days.

The pharmacodynamic action of AT13387 in vivo has been compared with that of 17-AAG and SNX-5422 in A375 and NCI-H1975 xenografts in nude mice. Following a single dose of each agent, we have investigated and compared the time course of the suppression of levels of several client proteins (e.g. AKT, CDK4) and the phosphorylation of key growth/survival signalling components (e.g. pERK, pS6, pAKT). These effects were rapidly induced in tumors following treatment with AT13387 and levels remained suppressed for up to 96 hrs. The durability of the AT13387 effects was significantly greater than for the other competitor compounds. Investigation of tumor growth in these models demonstrated that the longer pharmacodynamic action of AT13387 ensured that efficacy could be maintained on a once weekly schedule, whereas such a schedule for the other agents resulted in a significant loss of their anti-tumor effects. These data provide further support for the potential benefit of long acting HSP90 inhibitors as a way of maintaining anti-tumor effects whilst minimising potential for undesirable effects associated with systemic exposure.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A217.
Abstract A221: Results of preclinical and clinical phase I/II open-label dose-ranging trial with HE3235, a synthetic adrenal hormone, in castrate-resistant prostate cancer
Authors: Montgomery Bruce , Morris Michael , Ryan Charles , Corey Eva , Stickney Dwight , Frincke James , Reading Chris , Scher Howard
Published: June 2012

Background: HE3235 (17α-ethynyl-5α-androstane-3α, 17β-diol) is an androstenediol analog, which shows activity in preclinical CRPC and breast cancer models. HE3235 decreased AR expression in LNCaP cells in vitro, in the CRPC LuCaP 35V xenograft, and suppressed ER-a expression in MNU-induced breast tumors in rats. HE3235 also decreased intra-tumoral androgen synthesis (both T and DHT) in the LuCaP 35V tumors. In toxicology studies, it decreased steroidogenesis (DHEA and T in male dogs and sex steroids in female rats). HE3235 did not inhibit CYP17 in H295R adrenal tumor cells, but inhibited the conversion of d-cholesterol to d-pregnenolone. We are therefore conducting a Phase I/II clinical study in CRPC patients to determine safety, tolerance, pharmacokinetics, maximum tolerated dose and activity of this compound.

Methods: Men with CRPC and an ECOG PS of <2 who progressed either radiographically or biochemically through at least one taxane-containing chemotherapy regimen are eligible. HE3235 is given orally, twice daily in cohorts of 3–6 pts. Cohorts were defined by doses of 10 mg, 20 mg, 30 mg, 50 mg or higher until MTD is observed. Cohorts may be expanded based on dose limiting toxicity, activity or pharmacokinetics demonstrating adequate blood concentrations of drug to deliver a therapeutic effect. Subjects were treated on 28-day cycles until toxicity or disease progression. Scans were obtained every 2 cycles. The Prostate Cancer Consortium Clinical Trials consortium sites were supported by a grant form the Department of Defense.

Results: 22 subjects have been treated to date at doses of 10 mg/day (n=7), 20 mg/day (n=9) and 30 mg/day (n=6). Dose escalation continues to determine the MTD. Pharmacokinetics was dose proportional with a drug half-life of 11–14 hours. HE3235 was well tolerated. Nine of 22 subjects experienced a drop in PSA during treatment with 6 of 22 equal to or greater than 20%. No patient had a 50% decline in PSA. Eight of 17 (47%) subjects who were evaluable for response had stable disease. Median time to progression was 56 days (IQR 55, 224) for 10 mg/day, 112 days (IQR 56, 168) for 20 mg/days, 112 days (IQR 56, >122) for 30 mg/day and 112 days (IQR 56, 168) for all 22 subjects.

Conclusion: HE3235 is a novel, small orally delivered compound with preclinical activity for CRPC. It is well tolerated through a dose of 30 mg, and has a T1/2 linear to dose in cohorts tested to date. The trial continues to accrue, and a cohort of patients with chemotherapy-naïve CRPC will be enrolled into the ongoing Phase I/II Study.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A221.
Abstract A229: Novel in vivo imaging of chemotherapy-induced gonadotoxicity
Authors: Bar-Joseph Hadas , Ben-Aharon Irit , Tzarfaty Galia , Tzabari Moran , Stemmer Salomon M. , Shalgi Ruth
Published: June 2012

Introduction: Advances in cancer therapy have improved the long-term survival of cancer patients who may then face infertility and premature gonadal failure due to chemotherapy. It has been demonstrated that the chemotherapeutic agent doxorubicin (DXR) induces apoptosis in germ cells, though its role in inflicting potential gonadal failure remains obscure. We had previously shown ovarian damage in mice following DXR treatment, manifested by reduced ovarian size and weight and by apoptosis. We aimed at establishing a real-time in vivo molecular imaging platform in mice designated to evaluate chemotherapy-induced toxicity and to assess potential vascular insult in both ovaries and testes.

Methods: The volume of both ovaries and testes was measured in vivo by ultrasound biomicroscopy (Vevo2100) and by high resolution MRI, over a period of one month after adminstration of 10mg/kg intraperitoneal DXR. Ovaries were imaged by ultrasound using microbubbles as a contrast agent for evaluating the effect of DXR on ovarian blood flow.

Results: We have established a platform of visualizing the gonads by innovative high resolution ultrasound biomicroscopy and MRI that enabled in vivo detection of chemotherapy-induced effects in the same individuals over time. We observed a constant, significant reduction in gonadal volume, evident by both MRI and ultrasound. The ovary volume was reduced to 52% (N=10, p<0.05) of baseline values over one month. A similar trend was observed in the testes (reduced to 38% of baseline values over one month; N=6 p<0.05)). The use of bubbles as contrast media depicted a 30% reduction in ovarian blood flow already 15 min after DXR administration.

Conclusions: Using high resolution, state of the art imaging modules enabled us to trace chemotherapy-induce gonadotoxicity by in vivo imaging of the same individuals throughout an extended period of time. The acute reduction of ovarian blood flow following chemotherapy treatment may suggest a role for vascular injury in inflicting ovarian damage.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A229.
Abstract A23: A collection of patient-derived pancreatic adenocarcinoma xenograft models: Chemosensitivity in vitro and in vivo and molecular characterization
Authors: Beckers Thomas , Maier Armin , Schüler Julia , Hofmann Michael , Giesemann Torsten , Hopt Ulrich , Keck Tobias , Fiebig Heinz-Herbert , Küsters Simon
Published: June 2012

Pancreatic cancer is a devasting disease with an incidence of 0.1% and - in most cases - only palliative treatment options. The standard 1st line chemotherapy in inoperable, locally advanced (stage II and III) and metastatic (stage V) pancreas adenocarcinoma is Gemcitabine as a single agent with a median survival of about 6 month. In addition, Gemcitabine is indicated as adjuvant chemotherapy after surgery. Although the antimetabolite 5-Flourouracil (5-FU) and the EGF-R inhibitor Tarceva (Erlotinib) have been approved for 2nd line treatment, new and more efficacious treatments are urgently needed. In the present study, more than 60 primary pancreatic carcinoma samples from patients were transplanted subcutaneously (s.c.) into NMRI nude mice. In most cases, tumor material from chemonaive patients with defined histology and staging was used for implantation. Up to now, 14 pancreatic carcinoma models named PAXF and passaged in nude mice have been established and characterized comprehensively. Tumor bearing animals were treated in-vivo with 5-FU (100 or 75mg/kg, q7dx3, i.p.), Gemcitabine (240mg/kg, q7dx3, i.v.) and Tarceva (25 and 50mg/kg, qdx21, p.o.). In most studies, tumor growth was inhibited with best T/C values > 50%, highlighting the general chemoresistance of pancreatic cancer. Only for PAXF1872 and PAXF1998, a high sensitivity towards Gemcitabine was evident with best T/C values of 8% and 3.8%, respectively. In general, there was no correlation of response to Tarceva with EGFR expression status and best T/C values ranging from 89.6% (PAXF1876) to 38.5% (PAXF1982). A more broad chemosensitivity profile was established with Gemcitabine, 5-FU, Tarceva, Taxol, Cisplatin, Rapamycin, Sorafenib and Sunitinib in the ex-vivo clonogenic assay. Interestingly, 2 out of 12 pancreatic cancer models responded with high sensitivity towards treatment with Rapamycin (IC50 <= 10nM) with a mean IC50 = 0.18 µM over all models. Finally, the established tumor models were characterized by using Affymetrix HG U133 plus2.0 gene expression arrays, exon sequencing (Ki-ras, B-raf, p53) and the Sequenom MassARRAY® System - OncoCarta(TM) panel. In all tumors analysed so far, an activating Ki-ras (H-ras, B-raf) mutation was identified. Mutational analysis of p53 (exons 4 to 10) revealed only 4 out of 13 models as p53 wild-type. For the PAXF1998 tumor model with animals cured by Gemcitabine therapy, mutations in Ki-ras (G12V, heterozygous) and p53 (V274A, homozygous) have been identified.

In summary, a unique collection of patient-derived xenograft models of high clinical relevance has been established. These pancreatic carcinoma models are available for translational research studies including in-vivo efficacy testing of new investigational drugs.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A23.
Abstract A232: Optical imaging of tumors using a near-infrared probe for cell death
Authors: Smith Bryan A. , Akers Walter J. , Leevy W. Matthew , Lampkins Andrew J. , Xiao Shuzhang , Wolter William , Suckow Mark A. , Achilefu Samuel , Smith Bradley D.
Published: June 2012

Imaging probes that can determine, non-invasively, the amount of cell death in a specific tumor may have utility in clinical prognosis, as there is evidence that some highly malignant tumors have high rates of cell death, and in measuring anti-cancer treatment efficacy.i,ii Annexin V, a protein that binds exposed phosphatidylserine (PS) during cell death, is commonly used to determine drug efficacy and cell viability in vitro, and has been investigated for use in vivo. It is often challenging to optimize the formulation and pharmaceutical properties of proteins; therefore, we have developed a fluorescent small molecule mimic of Annexin V. Our near-infrared probe contains a carbocyanine dye conjugated to a zinc (II)-2,2-dipicolylamine (Zn(II)-DPA) coordination complex, which binds to anionic phospholipids on apoptotic and necrotic cells. Using tumor-bearing mouse and rat models, the probe (PSS794) was easily visualized at the site of the tumor. Ex vivo analysis revealed heterogeneity of probe localization in the tumor, with most of the probe concentrated in the necrotic core. Small molecules that can selectively target tumor anionic membrane surfaces and distinguish them from the near-neutral membrane surfaces of normal human cells have promising potential as imaging probes,iii drug delivery agents,iv and targeted molecular therapeutics.v

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A232.
Abstract A252: KRAS mutant lung cancer cells are differentially responsive to MEK inhibition due to AKT or STAT3 activation: Implication for combinatorial approach
Authors: Yoon Young-Kwang , Kim Hwang-Phill , Han Sae-Won , Im Seock-Ah , Oh Do Youn , Bang Yung-Jue , Kim Tae-You
Published: June 2012

KRAS is frequently mutated in non-small cell lung cancer (NSCLC), resulting in the activation of the MEK/ERK pathway. High-throughput mutation profile has shown that lung cancer frequently harbors co-mutation of cancer related genes. Therefore, given that cancer cells have multiple genetic alterations, combinatorial therapeutic strategy is demanded for effective cancer therapy. To address this, we first characterized MEK dependence in four NSCLC cells. Two cells (H358, A549) carried KRAS mutation only, and the other two (H23, H157) harbored co-mutation of KRAS/PTEN. H358 cells with KRAS mutation only were sensitive to MEK inhibition. However, the other KRAS mutant A549 cells were resistant to MEK inhibition. Previously, we have shown that dual inhibition of EGFR and MEK signaling shows a synergistic effect on KRAS mutant gastric cancer cells by suppressing compensatory activation of AKT. Here we also observed that this combination was effective in KRAS mutant A549 cells. However, the combination was ineffective in H23 and 157 cells with co-mutation of KRAS/PTEN. Compared to KRAS mutant/PTEN wild-type cells, STAT3 was significantly activated following MEK inhibition in KRAS/PTEN co-mutant cells. Combined STAT3 inhibition by a JAK2 inhibitor or gene knockdown with MEK inhibition blocked STAT3 activation, synergistically suppressed cell growth, and induced apoptosis in co-mutant cells. Taken together, our study provides molecular insights that help explain the heterogeneous response to MEK inhibition in KRAS mutant lung cancers, and presents a rationale for the clinical investigation of combination of MEK and EGFR inhibitor or MEK and STAT3 inhibitor depending on PTEN status.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A252.
Abstract A39: Development and validation of an integrated genomic classifier to predict sensitivity to the IGF-1R/IR tyrosine kinase inhibitor, OSI-906, in colorectal cancer
Authors: Pitts Todd M. , Tan Aik Choon , Kulikowski Gillian N. , Tentler John J. , Flanigan Sara A. , Leong Stephen , Brown Amy , Coldren Chris D. , Varella-Garcia Marileila , Hirsch Fred R. , Eckhardt S. Gail
Published: June 2012

Background: The role of the IGF-1 receptor (IGF-1R) pathway in mediating proliferative, invasive and pro-survival responses in cancer has led to a plethora of agents targeting this pathway, including antibodies and small molecule tyrosine kinase inhibitors. In order to maximize the clinical utility of such agents, it is imperative that patient selection strategies be applied. The goal of this study was to develop and characterize predictive biomarkers for the small molecule IGF-1R/IR tyrosine kinase inhibitor, OSI-906, in colorectal cancer (CRC).

Methods and Results: Twenty-seven human CRC cell lines were exposed in vitro to OSI-906 and classified according to the IC50 value as sensitive (< 1.5 mol/L) or resistant (> 1.5 mol/L). Immunoblotting and immuno-histochemistry for effector proteins was performed on all CRC cell lines as well as fluorescent in-situ hybridization (FISH) to assess IGF-1R gene amplification and KRAS/BRAF/PI3K mutation sequencing. Baseline expression levels of effector proteins were not predictive of OSI-906 sensitivity. Although IGF-IR FISH did not reveal amplification, the OSI-906 sensitive CRC cell lines displayed an “unbalanced gain” of IGF-IR based upon ploidy. Likewise, there was a trend toward KRAS wildtype status and sensitivity to OSI-906. Next, the baseline gene expression of selected in vitro and in vivo sensitive or resistant cell lines was analyzed using Affymetrix U133 Plus 2.0 gene arrays. These transcriptional profiling data led to the development of a k-Top Scoring Pair (k-TSP) classifier which identified three gene pairs as the final classifier: (PROM1>MT1E), (LY75> OXCT1) and (HSD17B2>CALD1). Pathway analysis at baseline indicated IGF-IR signaling and insulin pathways were among the top 20 up regulated BioCarta pathways whereas in the resistant cells, the ErbB, MAPK, VEGF, and multiple cell adhesion/motility signaling pathways were prominently represented. From these data an integrated genomic classifier of FISH, KRAS status, and the k-TSP was developed and tested against 5 human CRC explants in vivo. The classifier was able to predict with 100% accuracy the responsiveness of these explants to OSI-906.

Conclusions: These results indicate that an integrated approach to the development of individualized therapy is feasible and should be applied early in the development of this and other novel classes of anticancer agents. Additionally, such data may be used to develop rationale combination partners, such as VEGF or MEK inhibitors, to enhance responsiveness to OSI-906.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A39.
Abstract A41: The preanalytic impact of simulated ischemia on PI3K biomarkers
Authors: Ostrom Lance , Mosher Rebecca , Loda Massisimo
Published: June 2012

Introduction: Pharmacodynamic (PD) measurements in patient tissues following administration of cancer drugs may be used to determine a drug's activity and calculate dosing schedules. Biomarker selection for these tests must evaluate the most pertinent proteins in the pathway, but must also take into account biomarker stability in the tissue being tested. Constitutive expression of the PI3K pathway occurs with a high frequency in a variety of human malignancies. We sought to determine whether improper handling of tumor tissue can lead to inaccurate analysis of PI3K-AKT pathway activation when using immunohistochemistry (IHC).

Methods: 23 human cancer xenograft tumors were grown in nude mice (n=3/line) and allowed to stay at room temperature for fixed lengths of time to simulate handling of human specimens following surgery. Uniform sized tissue fragments (600–1000 mg) were kept in PBS for 0, 15, 30 and 120 minutes following resection prior to fixation in formalin and paraffin embedding. Four of these tumor lines were also frozen and analyzed by Western blot. IHC was preformed utilizing two pAKT antibodies and one pP70S6K (pS6) antibody. Following IHC, staining intensity was quantified using the Aperio image analysis system.

Results: Significant decrease in signal (p<.05) was seen as soon as fifteen minutes of ischemia with both pS6 and pAKT antibodies by IHC in some samples. In nearly all of the samples that had detectable levels of pAKT or pS6 at time zero, this was gone by 120 minutes. There was also considerable discordance between pS6 and pAKT staining in the control samples bringing into question pS6 as a relevant pAKT surrogate biomarker.

Conclusion: Significant care should be taken in the interpretation of phospho-specific antibodies since results are strongly dependent on the time of ischemia. Broader analysis of pre-analytic biomarkers not dependent on tissue ischemia may be utilized as surrogate for pathway activation.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A41.
Abstract A55: A first-in-human, phase I study of an oral hedgehog pathway antagonist, BMS-833923 (XL139), in subjects with advanced or metastatic solid tumors
Authors: Siu Lillian L. , Papadopoulos Kyriakos P. , Alberts Steven R. , Taylor Sara , Patnaik Amita , Chen Eric X. , Tolcher Anthony , Vakkalaguada Blisse , Lang Lixin , Ahlers Christoph , Bennett Kelly L. , Van Tornout Jan M.
Published: June 2012

Background: The hedgehog pathway is dysregulated in basal cell carcinoma, medulloblastoma, pancreatic, lung, gastric, and a variety of other cancers. BMS-833923 is a potent, oral, small molecule antagonist of hedgehog signaling.

Methods: Subjects with advanced or metastatic solid tumors were enrolled into a multiple ascending dose study to identify a maximum tolerated dose and evaluate safety, tolerability, pharmacokinetics (PK), and pharmacodynamics of BMS-833923. All subjects receive a single dose one week prior to continuous daily dosing. The single dose window allows for single dose PK collection for one week. To identify the pharmacologically active dose range surrogate tissue was collected prior to Day 1 and again on Day 22 of the first cycle.

Results: As of August 14, 2009 sixteen subjects have been treated at four dose levels: 30 mg (n=5), 60 mg (n=3), 120 mg (n=3), and 240 mg (n=5); with mean patient age of 56 (range 21–78) and ECOG performance 0–1. No subjects in the first three dose cohorts experienced drug-related CTCAE AEs greater than Grade 2. One subject with medulloblastoma in the 30 mg dose cohort continues on study for more than 10 months with stable disease. Treatment of patients in the fourth cohort at 240 mg continuous daily dosing is still on-going. In this cohort one subject experienced drug-related CTCAE Grade 2 lipase elevation and pancreatitis that quickly resolved when drug was withheld. This subject has a diagnosis of Gorlin Syndrome, which is caused by germline mutations in the hedgehog pathway genes Patched or Smoothened. This subject experienced a partial response (PR) that is still ongoing. BMS-833923 PK properties showed dose proportionality between the 30, 60, and 120 mg dose cohorts with a Cmax of 30 ng/ml, 56 ng/ml and 102 ng/ml respectively. The terminal half-life was greater than 7 days and drug accumulations were observed.

Conclusion: BMS-833923 is generally well tolerated at daily doses of 30, 60, 120 mg.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A55.
Abstract A59: Increased expression of ABC transporter genes in lung cancer CD133-positive cells
Authors: Gatti Laura , Cossa Giacomo , Bertolini Giulia , Tortoreto Monica , Tinelli Stella , Fontanella Enrico , Delia Domenico , Roz Luca , Sozzi Gabriella , Perego Paola
Published: June 2012

Drug resistance represents a major obstacle towards the cure of different tumor types including non-small cell lung cancer (NSCLC), being one of the main causes of failure of antitumor therapy. Tumor cells frequently exhibit simultaneous resistance to multiple structurally unrelated drugs, a phenotype known as multidrug resistance (MDR). A major cause of the MDR phenotype is the over-expression of members of a conserved family of transmembrane proteins (ABC transporters). Different structurally unrelated compounds, including conventional cytotoxic and target-specific agents are substrates for ABC transporters. Cancer stem cells (CSC) refer to a subset of tumor cells with the ability to self-renew and generate the diverse cells that comprise tumors. At present, the mechanisms contributing to the drug-resistant phenotype of CSC are poorly understood. Some lines of evidence support that specific ABC transporters may be expressed in CSC and may be relevant therapeutic targets. The aim of the present study was to examine the pattern of expression of ABC transporter genes in spheres derived from human lung tumors, which we found enriched for CD133 (prominin-1), a surface glycoprotein described as a marker of cancer-initiating cells in different tumor types. To better define the molecular features of cancer cells endowed with stem-like features with respect to cellular defence mechanisms, using TaqMan MicroFluidic cards we analyzed the mRNA levels of transporters of the ABC superfamily in CD133+ and CD133− cell populations sorted from lung tumor cell lines grown as spheres. With this approach, we found that around 70% of the 50 human ABC transporters were expressed at detectable levels in floating spheres obtained from human lung cancer A549 adherent cell line and in the corresponding sorted populations. When compared to the CD133− raction, CD133+ cells exhibited a marked increased expression of different components of the ABCC family which are known to be involved in the MDR phenotype (i.e., ABCC1). The level of ABCG2 mRNA was also enhanced. Similar results were obtained in CD133+ cells isolated from a cell line established from a human primary lung tumor growing as floating spheres. Thus, CD133+ cells expressed ABCG2 and additional ABC transporters that may contribute to determine a drug-resistant phenotype. A better knowledge of the pattern of expression of ABC transporters in lung cancer CD133+ cells may lead to develop approaches that will circumvent drug resistance in NSCLC and is expected to contribute to optimization of therapy, based on targeting of ABC transporters.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A59.