bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract A62: A novel Eg5 inhibitor that causes mitotic arrest leading to rapid cancer cell death shows broad-spectrum antitumor activity in preclinical xenograft tumor models
Authors: Ye Xiang S. , Fan Li , Van Horn Robert , Yin Tinggui , Nakai Ryuichiro , Ohta Yoshihisa , Credille Kelly , Donoho Gregory , Akinaga Shiro , Murakata Chikara , Perkins Everett , Ocheltree Scott , Yamashita Yoshinori , Blanchard Kerry , Westin Eric
Published: June 2012

Antitubulin agents including taxanes and vincas that target mitosis of rapidly dividing cancer cells are among the most effective cancer therapies in current clinical use. However, these antitubulin agents also have debilitating side effects that are dose-limiting, such as neuropathy, due to their disruption of the normal microtubule functions in resting cells including neuronal cells. Eg5 is an evolutionarily conserved mitosis-specific kinesin essential for bipolar mitotic spindle formation and has no roles in microtubule functions of resting cells. Inactivation of Eg5 causes mitotic arrest of proliferating cells, resulting in formation of monopolar spindles. Targeting Eg5 for cancer treatment thus represents an attractive strategy that has the potential to maximize the anticancer efficacy by inhibiting cancer cell mitosis while minimizing debilitating side effects associated with antitubulins. Here we describe a selective ATP-non competitive small molecule inhibitor of human Eg5 kinesin. The Eg5 inhibitor shows no effects on microtubule dynamics in cell-free assays and arrests cells specifically at mitosis with monopolar spindles, resulting in rapid cancer cell death. Growth inhibition assays against a panel of 21 cancer cell lines shows that the Eg5 inhibitor has potent and broad-spectrum activity with IC50 values ranged from 0.55 nM to 14.2 nM. Quantitative live cell imaging and high content imaging reveal that the Eg5 inhibitor has a threshold concentration activity and kills cancer cells specifically at mitosis in a time/cell cycle, but not concentration above the threshold,-dependent manner. Consistent with the in vitro activities, the Eg5 inhibitor shows broad-spectrum antitumor activity in preclinical xenograft tumor models representing major human cancer histologies also including drug resistant tumors and demonstrates superiority as compared to several chemotherapeutic agents targeting G2/M. Furthermore, its in vivo antitumor activity is highly schedule-dependent with a clear threshold dose effect, as expected from in vitro observations. Indeed, the Eg5 inhibitor exhibits a robust PK/PD relationship in antitumor activity and its antitumor activity is associated with mitotic arrest of cancer cells and subsequent cell death. The Eg5 inhibitor is currently being evaluated in Phase I studies.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A62.
Abstract A67: Molecular evidence of increased antitumor activity of gemcitabine in combination with a Cdk inhibitor, P276 in pancreatic cancer
Authors: Joshi Kalpana S. , Rathos Maggie J. , Joshi Kavita , Khanwalkar Harshal , Sharma Somesh
Published: June 2012

Purpose: Gemcitabine is an inhibitor of ribonucleotide reductase and DNA synthesis and is a standard of care for the treatment of pancreatic cancer. The present study investigates whether the cdk inhibitor P276 would be synergistic with gemcitabine in pancreatic cancers.

Experimental design: Various pancreatic cancer cell lines were treated with gemcitabine and P276 and the cytotoxicity was assessed using the combination index. The effect of gemcitabine and P276 on cell cycle and apoptosis was analyzed by flow cytometry. Several genes that are known to inhibit apoptosis and contribute to chemoresistance were analyzed using western blot analysis and RT-PCR. Finally, in vivo efficacy of the combination was studied in Panc-1 xenograft model in SCID mice.

Results: The combination of gemcitabine followed by P276 was found to be synergistic in various pancreatic cancer cell lines Panc-1, Capan-1, BxPc-3, AsPc-1 and MiaPaca-2 as assessed by the combination index using the Compusyn software. Mechanistic studies indicated enhancement of apoptosis in Panc-1 cells as seen by flow cytometry and increase in the antiapoptotic Bcl-2 protein by western blot analysis. Several genes that are known to inhibit apoptosis and contribute to chemoresistance such as p8, cox-2 and survivin were assessed to investigate the basis for the observed chemosensitizing effects of P276. P276 potentiated the gemcitabine induced cytotoxicity by downregulation of p8, cox-2 and survivin. In contrast, cox-2 was found to be significantly up regulated when the cells were exposed to gemcitabine alone, while there was no effect on p8 or survivin as compared to control, suggesting the potential mechanism of acquired chemoresistance to gemcitabine. BNIP3 the tumor suppressor is also downregulated in most pancreatic cancer cell lines and is associated with chemoresistance to gemcitabine. Interestingly BNIP3 was significantly up regulated in the combination and P276 alone but not by gemcitabine alone. In addition to in vitro results, we show here that gemcitabine in combination with P276 is much more effective as an antitumor agent compared with either agent alone in our Panc-1 xenograft tumor model in SCID mice.

Conclusion: These data demonstrate that the gemcitabine and a Cdk inhibitor, P276 combination displays synergistic cytotoxic activity, induces apoptosis and sensitizes the pancreatic cells to gemcitabine by modulating the pro- and anti apoptotic proteins. In vivo evidence of the synergistic combination is also demonstrated in Panc-1 xenograft model. The chemosensitzation of pancreatic tumors to gemcitabine would likely be an important and novel strategy for treatment of pancreatic cancer and enable the use of lower and safer concentrations, to pave the way for a more effective treatment in this devastating disease.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A67.
Abstract A73: The Bcl-2/BclXL inhibitor, ABT263, enhances paclitaxel-induced apoptosis in NSCLC models
Authors: Belmont Lisa D. , Yue Peng , Tan Nguyen , Malek Mehnaz
Published: June 2012

The anti-apoptotic protein, BclXL, is thought to be an important chemo-resistance factor (Amundsen et al, 2000), and the combination of a BclXL inhibitor and paclitaxel exhibits increased NSCLC cancer cell killing in culture and in xenograft models (Shoemaker et al, 2006). ABT263 is a small molecule inhibitor of Bcl-2, BclXL and Bcl-w, that is currently in clinical trials (Tse et al, 2008). We set out to address the following questions 1) is ABT-263 broadly synergistic with paclitaxel in NSCLC cells, 2) what is the mechanism of the synergistic interaction and 3) can we identify biomarkers to guide the selection of patients that are likely to respond to the combination of ABT263 and taxane based chemotherapy regimens? We screened a panel of 26 NSCLC cell lines for synergy with ABT263. All 26 cell lines exhibited a synergistic response to the combination, as evaluated by Bliss additivity, and 20 cell lines had Bliss sum values in excess of 100, considered to be a robust synergy response in this assay. In order to address the mechanism of synergy, we performed time-lapse microscopy on GFP-H2b expressing A549 cells. We find that the addition of ABT263 alters the timing and fate of cells that enter mitosis in the presence of paclitaxel. Paclitaxel alone caused prolonged mitotic arrest usually followed by mitotic slippage. ABT263 as a single agent had little effect on mitosis, but caused cells to die rapidly from a mitotic arrest state when added to paclitaxel. This resulted in an increase in the rate and percentage of cell death compared to either single agent. To identify biomarkers that might influence synergy between ABT263 and paclitaxel, we identified genes whose mRNA levels had significant correlations with the Bliss score. Together these data suggest that the combination of ABT263 and paclitaxel has the potential to have improved efficacy in cancers that are refractory to paclitaxel.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A73.
Abstract A78: Role of PTEN and ionizing radiation in underpinning differential activation of interleukin-8 in prostate cancer cells
Authors: Berlingeri Silvia , Gallagher Rebecca , Maxwell Pamela , O'Sullivan Joe , Waugh David
Published: June 2012

Prostate cancer (CaP) cells exhibit varying sensitivity to radiotherapy. Previous studies of our group showed that the synthesis of the CXC-chemokine Interleukin-8 (CXCL8) is linked to resistance of cancer cells to environmental and chemical stresses. Accordingly, we wished to explore the impact of ionizing radiation in modulating Interleukin-8 expression in Prostate Cancer cells (PC) in vitro. IR (3Gy) induced rapid time-dependent, NF¡B transcriptional activity in PC3 and LNCaP cells that co-incided with the detection of increased mRNA transcript levels for CXCL8 in both cell lines. However, although a same rapid increase in IL-8 mRNA was observed in Du145 and 22Rv1 cells, they show a more pronounced AP-1 activation, suggesting that in this prostate cancer cell lines signalling cascade to IL-8 mRNA synthesis is mainly driven by AP-1. Immunoblotting also confirmed that expression of CXCL8 increased rapidly in PC3 and LNCaP cells in response to IR (30 min to 2 hours). Subsequently, we investigated the importance of the tumor suppressor gene Phosphate and Tensin Homolog (PTEN) in underpinning this differential response of PC3 and LNCaP (PTEN-null) compared to Du145 and 22Rv1 (PTEN-wt) cells to IR. Moreover we sought to clarify the link between the PTEN-status in our in vitro model and the activation of PI3K, MAPKs and PKC pro-survival pathways after exposure of cells to Ionizing Radiation. Accordingly, we will continue to explore our hypothesis that PTEN acts as a master regulator of radiosensitivity in CaP cells by activating signal transduction pathways in irradiated cells.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A78.
Abstract A81: Synergistic antitumor efficacy of the multikinase inhibitor, sorafenib and paclitaxel combination in NSCLC tumor model
Authors: Jeon Eun Kyoung , Zhang Xiang-Hua , Shin Jung-Young , Yoon Seong-Ae , Kang Jin-Hyoung
Published: June 2012

Background: Sorafenib (BAY 43-9006) is a multi-kinase inhibitor that targets a serine-threonine kinase, B-Raf as well as several tyrosine kinases. Given the numerous molecular targets of sorafenib, several potential mechanisms of its inhibitory activity on tumor cell proliferation, angiogenesis and anti-apoptosis have been proposed. Paclitaxel exhibits unique and potent anti-cancer activity in the treatment of non-small cell lung cancer (NSCLC). Our aim of this study, is to examine the anti-proliferative, anti-angiogenesis effect and apoptosis induction when sorafenib combined with paclitaxel in NSCLC tumor model.

Methods: We investigated sorafenib's effect on cell proliferation, cell cycle distribution, ERK phosphorylation in A549 NSCLC cell line using SRB assay, flow cytometry, and Western blot analysis, respectively. In vivo, A549 tumor cells were implanted in the Balb/c nu/nu mice. Five different combination schedules of sorafenib and paclitaxel were applied with their single treatment. PPS and PSS combination therapy. Tumor volume and body weight was measured at two times per week. Intratumoral molecular changes were studied on paraffin-embedded tumor tissue block from xenograft mice using immunohistochemistry and the apoptotic change was measured with TUNEL assay.

Result: In vitro study, single treatment of sorafenib or paclitaxel inhibited cell proliferation in A549 cells with dose-dependent manner. Sorafenib effectively inhibited the phosphorylation of ERK and induced G0/G1 arrest of cell cycle. When these two agents were combined with different schedules, schedule-dependent cytotoxicity and cell cycle arrest were observed. In A549 xenograft model, combination of sorafenib and paclitaxel more significantly suppressed tumor growth than their single treatment. However, PSS combination caused profound body weight loss compared with other treatment schedules. In immunohistochemistry study, greater inhibition of Ki-67 as well as pAKT and pERK, and CD31 were observed in PPS combination compared with single treatment. In TUNEL assay, significant apoptosis was observed in combination treatment.

Conclusion: Taken together, sorafenib, paclitaxel, and their combination effectivity inhibited tumor growth and angiogenesis via down regulation of pAKT and pERK signaling and apoptosis induction in NSCLC tumor model. The PPS and PSS combination schedule demonstrated more potent antitumor activity including anti-proliferation, anti-angiogenesis, and apoptosis compared to other combination schedules.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A81.
Abstract A91: Identification of nuclear hormone receptors critical for rexiniod-mediated growth suppression of normal human breast cells
Authors: Rodenberg Jennifer M. , Uray Ivan P. , Bissonnette Reid P. , Brown Powel H.
Published: June 2012

Background: Drugs targeting estrogen signaling or production have successfully prevented or treated estrogen receptor-positive breast cancers, but not estrogen receptor-negative (ER-negative) breast cancers. Our laboratory has demonstrated that rexinoids prevent ER-negative breast cancer in transgenic mice by 90% at high-doses. Since the prevention is not 100% effective, it is imperative to develop more efficacious prevention strategies by determining the mechanism of rexinoids. We hypothesized that rexinoids are specifically able to prevent breast cancer by suppressing growth though interactions with key nuclear hormone receptors. To test this hypothesis we conducted high-throughput screens to determine which nuclear hormone receptors are critical to the growth suppressive effects of rexinoids.

Methods: We used quantitative RT-PCR to determine the quantity of mRNA transcripts for all 48 nuclear hormone receptors in human mammary epithelial cells (HMECs). To identify nuclear hormone receptors that when knocked-down reverse the effects of rexiniod treatment, a final concentration of 30nM of pools of three independent siRNAs specific to each nuclear hormone receptor was used. High-throughput microscopy of the siRNA-treated HMECs stained with DAPI (1ug/mL) and EdU (10mM) was used to analyze cell number and percent S-phase. Those nuclear receptors whose corresponding siRNA reversed the growth inhibitory effects of the rexinoid 75% or greater, were considered for further investigation. Co-immunoprecipitation (coIP) and GST pull-down assays are being conducted to investigate whether the identified nuclear hormone receptors form a complex with RXR proteins.

Results: qRT-PCR analysis confirmed that many of known RXR-binding nuclear hormone receptors are expressed in HMECs. High-throughput screens indicate that knockdown of most receptors alone affect growth of HMECs, but do not reverse the effects of rexinoid treatment. Receptors that did reverse the growth suppressive effect of rexiniods include RXRα, VDR, PNR and PPARγ. Currently, we are further investigating the function of these receptors in HMECs and other normal, premalignant, and malignant breast cells.

Conclusions: These experiments identified nuclear hormone receptors that are critical for the growth suppressive effects of rexinoids in normal human breast cells. Such studies identify possible targets for preventative therapy, alone or in combination with rexinoids to increase the efficacy of drugs for more effective prevention of estrogen receptor-negative breast cancer. Support: NCI R01 CA78480 (PHB, IPU) and NIH/NCI T32 CA90221 (JMR)

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A91.
Abstract A95: Epigenetic changes in colon cancer cell lines treated with the green tea polyphenolic, EGCG
Authors: Brown Vondina R. , Morris Jay , Wargovich Michael J.
Published: June 2012

Retinoids are known for their role in regulating cell growth and proliferation and for activating tumor suppressor genes. We have previously shown that Retinoid X Receptor alpha (RXRα) is silenced in tumors of the colon cancer AOM-APCMin/+ mouse model. Upon treatment with green tea, RXR expression was restored and intestinal tumorigenesis was inhibited. We hypothesize that tea polyphenols, especially epigallocatechin gallate (EGCG), induce modification of gene expression through effects of DNA methyltransferases (DNMTs) as well as Histone Deacetylases (HDACs). We treated HT-29 and HCT116 colon cancer cells with EGCG concentrations of 0, 50, 100 or 150µM or 5µM of the DNMT inhibitor 5-aza-2dC for 48, 72 and 96 hours as well as for two, three and four doubling times. The cell lines were chosen based on their methylation status. HCT116 cells are more sensitive to promoter region methylation compared to HT-29 cells. Using nuclear fractions of the cell lysates, we probed for presence of the most common DNMTs and HDACs using western blotting. We found that expression of DNMTs as well as HDACs was inhibited in a dose dependent manner following treatment with EGCG. We also found that treatments according to doubling times showed a more profound difference in expression levels when compared to traditional time points. We can conclude that the silencing of RXRα may be due in part to by repressing effects of EGCG on DNMT as well as HDAC activity. This could be one potential mechanism of cancer chemoprevention in green tea that outlines a new epigenetic pathway.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A95.
Abstract A96: Melanoma chemoprevention using topical PBISe
Authors: Chung Chinying , Madhunapantula SubbaRao V. , Meyers Craig , Desai Dhimant , Amin Shantu , Robertson Gavin P.
Published: June 2012

Despite public awareness and availability of sunscreen, incidence and mortality rates for malignant melanoma continue to increase every year. Novel strategies are required to prevent melanoma development as the causes for ∼60% of cases remaining unknown. While sunscreen is effective at protecting skin from UV radiation induced damage, inhibiting melanocytic lesion development using body creams or sunscreens containing chemopreventive agents could be a novel approach to fight this disease. Hence, the chemopreventive efficacy of PBISe, a selenium containing isosteric analogue of PBIT, has been examined in laboratory generated skin reconstructs and melanoma tumor xenograft models. The data demonstrate that PBISe treated skin reconstructs containing melanocytic lesion cells had 60–70% smaller tumor lesions compared to control treated skins. Furthermore, mice topically treated with PBISe had ∼50% fewer tumors compared to PBIT or acetone vehicle treated control groups. Mechanistically, PBISe elevated MAP kinase pathway activity as indicated by increased pErk1/2 levels to amounts that induced cellular senescence. Furthermore, PBISe treatment down-regulated cyclin-D1, upregulated the expression of cell cycle inhibitors p21 and p27 as well as apoptotic markers cleaved caspase-3 and PARP to inhibit cell proliferation and induce apoptosis. In conclusion, the results demonstrate the potential utility of topical PBISe application for preventing melanoma leision development.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A96.
Abstract A97: Combination of a bifunctional alkylating agent and arsenic trioxide is effectively against the drug resistant tumor cells
Authors: Pei-Chih Lee , Kakadiya Rajesh , Su Tsann-Long , Lee Te-Chang
Published: June 2012

Inherited or acquired resistance to therapeutic agents is a crucial factor causing the failure of cancer chemotherapy. In this study, we explored the combination effect of a synthetic bifunctional alkylating agent, BO-1012, and arsenic trioxide (ATO) on killing H460 cells, derived from human large cell lung carcinoma and more resistant to BO-1012 and ATO as compared to several other cancer cell lines used, such as H1299, PC3, U87, MCF7, and OECM1 cells. We observed a synergistic enhancement of cell killing effects by treatment of H460 cells with BO-1012 for 1 h and followed with ATO for 72 h as compared to individual agents. By aid of modified comet assay, the repair of BO-1012-induced DNA interstrand crosslinks was significantly inhibited by ATO. Consequently, the protein levels as well as the nuclei foci of H2AX, a marker for DNA double strand breaks, was remarkably increased in H460 cells treated with in combination of BO-1012 and ATO. Accompanied with increased DNA damage, combined treatment resulted in severe G2/M accumulation as well as apoptosis. We further demonstrated that combination treatment with BO-1012 and ATO synergistically reduced tumor volumes of H460 cells subcutaneously inoculated into nude mice, indicating the effectiveness of combined treatment with BO-1012 and ATO against the inherited resistant H460 cells in xenograft mice model. Similar findings were demonstrated by using NTUB1/P cells, cisplatin resistant human bladder carcinoma cells derived from NTUB1 cells. These present results suggest that combination of bifunctional alkylating agents and ATO may be a rationale strategy for treatment of inherited or acquired drug-resistant cancers.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A97.
Abstract B10: A phase I, dose-escalation and PK study of IV aflibercept (VEGF Trap) in combination with docetaxel (D), cisplatin (C), and 5-fluorouracil (F) administered every 3 weeks in patients with advanced solid malignancies
Authors: Massard C. , Bahleda R. , Khan A. , Ajan J. , Soria J. C.
Published: June 2012

Background: Aflibercept (AF) is a recombinant fusion protein of the human vascular endothelial growth factor (VEGF) receptor combining the Fc portion of human IgG1 with the extracellular ligand-binding domains of human VEGFR1 and VEGFR2. AF binds and neutralizes all VEGF-A isoforms plus placental growth factor. This study was designed to assess the safety, dose-limiting toxicities (DLTs)/ recommended dose (RD), and PK of AF + DCF.

Methods: This phase I combination trial explored escalating IV doses of AF given on day 1 followed by DCF (fixed dose of D 75mg/m2, C 75mg/m2 both on day 1 and F 750 mg/m2/day from day 1 to 5), every 3 weeks. G-CSF and fluoroquinolone were given as primary prophylaxis.

Patient characteristics: 44 pts (M/F 29/15, median age 53 [range: 33–74], baseline ECOG-PS 0/1/2: 16/27/1) were enrolled in 3 AF dose cohorts: 2 (n = 9), 4 (n = 14) and 6 (n = 21) mg/kg. Primary tumors were mostly gastro-intestinal (28, including 22 gastro-esophageal, 3 pancreas, 2 liver, 1 cholangiocarcinoma), 4 breast, 3 lung, 3 utero-vaginal, 2 thyroid, and 4 others. Sixteen (36%) pts received prior chemotherapy, median number of lines 2 (range 1–6).

Preliminary Results: Pts received a median number of 6, 4, and 7 cycles respectively for each dose group of 2, 4, and 6 mg/kg (range 1–19). One AF-related DLT of pulmonary embolism was observed at the 6 mg/kg AF dose level. Most common Gr ≥ 3 adverse events included: fatigue/asthenia (46%), mucosal inflammation/stomatitis (41%), anorexia (18%), and febrile neutropenia (16%). Mild to moderate arterial hypertension and proteinuria were reported. Grade 1 or 2 epistaxis (61%) and dysphonia (41%) also were reported. Two fatal events were observed: gastrointestinal haemorrhage after C2 (cholangiocarcinoma, AF 6 mg/kg), pulmonary haemorrhage with bronchial necrosis after C12 (NSCL cancer, AF 6 mg/kg). Thirteen (35%) partial responses (PR) in various tumor types, and 20 stable disease (SD) including 14 pts with SD≥2 months were noted. PK analysis will be presented once available.

Conclusions: AF 6 mg/kg combined with DCF q3wks was selected for further investigation, based on DLTs and overall safety profile. This dose is consistent with results from other aflibercept phase 1 studies. Encouraging signs of anti-tumor activity and disease control have been seen.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B10.
Abstract B125: Antiproliferative and anti-invasive effect of the novel anti-IGF-1R monoclonal antibody R1507 in endocrine-responsive and -resistant breast cancer cell lines
Authors: Hutcheson Iain R. , Pumford Sara L. , Barrow Denise , Frankel Stanley R. , Nicholson Robert I.
Published: June 2012

R1507 is a novel insulin-like growth factor type 1 receptor (IGF-1R)-specific, human monoclonal antibody that binds the extracellular domain of the receptor to inhibit ligand binding and promote receptor internalization. IGF-1R signalling has been implicated in both endocrine-responsive and -resistant breast cancer and the IGF-1R identified as a potential therapeutic target to treat these disease states. In the present study we have examined the effect of R1507 in tamoxifen-resistant (Tam-R) and wild-type MCF-7 cells to determine the therapeutic potential of this agent in breast cancer. Both cell lines were exposed to R1507 (3–300 nM) for periods ranging from 1 to 7 days and effects on signalling, growth and invasive capacity were assessed. R1507 treatment of both MCF-7 and Tam-R cells for 24 hours reduced both expression and activity of IGF-1R and this effect was maintained through to 7 days treatment with this antibody. This effect of R1507 was observed both in the absence and presence of ligand (IGF-I and II) stimulation in the two cell lines. In MCF-7 cells the reduction in basal and ligand-stimulated IGF-1R activity was associated with reduced IRS-1 phosphorylation and inhibition of AKT and ERK1/2 activity at day 1 with the reduction in AKT phosphorylation being maintained through to day 7. However, basal and ligand-stimulated ERK1/2 phosphorylation demonstrated some evidence of recovery in the presence of R1507 although a small inhibitory effect was still apparent at day 7. This potent blockade of IGF-1R signalling by R1507 was associated with a significant inhibition of basal and ligand-stimulated cell growth. A similar effect of R1507 on signalling activity was also observed in Tam-R cells with reductions in basal and ligand-stimulated IRS-1 phosphorylation and AKT activity apparent at day 1 through to day 7. However, although prolonged exposure to R1507 also reduced basal and ligand-stimulated levels of phosphorylated EGFR and erbB2 in this cell line, there was no effect of this antibody on ERK1/2 activity at this time point. Indeed, there was evidence of an increase in basal and ligand-stimulated ERK1/2 activity at the higher concentrations of antibody used in this study. Although R1507 abolished ligand-stimulated Tam-R cell growth there was little effect of this antibody on basal growth of these cells. Interestingly, however, R1507 potently reduced the basal and ligand-stimulated invasive capacity of this cell line. In conclusion these studies would suggest that R1507 can potently inhibit IGF-1R signalling in both an endocrine-responsive and -resistant breast cancer cell line. In endocrine-responsive MCF-7 cells this action of R1507 is anti-proliferative, whereas, in Tam-R cells R1507 appears to have potent anti-invasive properties and only modest growth inhibitory activity.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B125.
Abstract B134: PIK3CA mutations in patients with advanced cancers treated in phase I clinical trials
Authors: Janku Filip , Garrido-Laguna Ignacio , Hong David S. , Tsimberidou Apostolia M. , Naing Aung , Falchook Gerald S. , Wheler Jennifer J. , Moulder Stacy L. , Fu Siqing , Piha-Paul Sarina , Kurzrock Razelle
Published: June 2012

Background: Phosphatidylinositol 3-kinase (PI3K) is thought to play an important role in tumorigenesis. Activating mutations of the p110 subunit of PI3K (PIK3CA) have been identified in a broad spectrum of tumors.

Methods: A mutational analysis (a PCR-based DNA sequencing) of exon 9 (helical domain) and exon 20 (kinase domain) of the PIK3CA was performed using DNA obtained from tumors of patients referred for clinical trials using targeted therapy. Patients with PIK3CA were preferably treated whenever possible with regimens containing PI3K-AKT-mTOR signaling pathway inhibitors.

Results: To date 146 samples from patients with various advanced cancers have been collected. At the time of submission 117 results from mutational analysis were available (ovarian cancer, n=23; colon cancer, n=13; cervical cancer, n=10; endometrial cancer, n=7; breast cancer, n=11; melanoma, n=7; head and neck cancer, n=10; soft tissue sarcoma [not including GIST] n=6; renal cancer, n=4; and other tumor types, n=26). PIK3CA mutations were detected in 14 (12%) patients (3 in exon 9-helical domain, 11 in exon 20-kinase domain). In tumor types with more than 5 patients tested, PIK3CA mutations were most frequent in endometrial cancer (43%, 3 out of 7 patients), ovarian cancer (22%, 5 out of 23 patients), squamous head and neck cancer (14%, 1 out of 7 patients), breast cancer 18% (2 out of 11 patients), and colon cancer (15%, 2 out of 13 patients). No mutations were identified in patients with melanoma or cervical cancer. The small number of patients at this point precludes statistical comparisons. Of the 14 patients with PIK3CA mutations, 10 were treated on a protocol that included a drug targeting the PI3K-AKT-mTOR pathway, and 4 (40%) responded (partial responses). Although numbers are small, in individual disease there were 2 (67%) responses in 3 endometrial cancers, 1 (25%) in 4 ovarian cancers, 1 (100%) in 1 breast cancer, and no response in 1 colorectal cancer patient.

Conclusion: PIK3CA mutations were detected in 12% of patients with various solid tumors. Although numbers are small, response rate appears high (40%) in tumors with PIK3CA mutations treated with PI3K-AKT-mTOR pathway inhibitors.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B134.
Abstract B137: Pharmacokinetics and pharmacodynamic biomarkers for the dual PI3K/mTOR inhibitor GDC-0980: Initial phase I evaluation
Authors: Wagner Andrew J. , Burris Howard A. , de Bono Johann S. , Jayson Gordon C. , Bendell Johanna C. , Gomez-Roca Carlos , Dolly Saoirse , Zee Ying-Kiat , Ware Joseph A. , Yan Yibing , Mazina Kathryn , Derynck Mika , Holden Scott , Soria Jean-Charles
Published: June 2012

Background: The PI3K-AKT-mTOR signaling pathway is deregulated in a wide variety of cancers. GDC-0980 is a potent, selective, dual inhibitor of class I PI3K and mTOR kinase with in vitro IC50 of 4.8 nM for p110α/p85 and apparent Ki of 17.3 nM for human mTOR. GDC-0980 potently inhibits tumor growth of xenografts and has demonstrated activity in preclinical models bearing PI3K mutant, PTEN-null, K-ras mutant, as well as PI3K pathway wild-type tumors in vitro and in vivo.

Methods: Two Phase I dose escalation studies were initiated using a 3+3 design in patients (pts) with solid tumors or non-Hodgkin's lymphoma who had progressed on, or were intolerant of, standard therapy. In study PIM4604g, GDC-0980 is administered as a single oral dose followed by a 1-week PK sampling period, and then administered daily (QD) on a 3-week on/1-week off schedule. Steady-state PK is evaluated after 1 week of continuous dosing. A second trial, PIM4605g, evaluating a once weekly (QW) dosing of GDC-0980 with a 4-week cycle was also initiated with a focus on PD evaluation using mandatory tumor biopsies and imaging. Immunohistochemical assays for pS6 PD marker evaluation were developed for clinical evaluation of pre- and post-dose tumor biopsies. Surrogate PD assays include an assessment of pAKT levels in platelet-rich plasma (PRP) coinciding with PK evaluation in both studies and an evaluation of tumor biopsies for marker modulation in PIM4605g.

Results: As of September 2009, a total of 15 patients have been treated in the two Phase I studies. Nine pts were treated in three successive cohorts of 2 mg, 4 mg, and 8 mg GDC-0980 QD in PIM4604g, and 6 pts were treated in the first cohort with 6 mg GDC-0980 QW in PIM4605g. GDC-0980 has been generally well tolerated. There have been no dose-limiting toxicities and no drug-related Grade ≥ 3 events reported in either study. Preliminary PK data suggests that GDC-0980 is rapidly absorbed with dose-appropriate increases in Cmax and AUC under fasting conditions. Preliminary surrogate PD data show decreases in pAKT levels in PRP reflective of drug levels in plasma. Preliminary data from comparison of tumor biopsies obtained at baseline and following administration of GDC-0980 demonstrate a > 50% decrease in pS6 staining by immunostaining consistent with downstream modulation of the PI3K pathway.

Conclusions: GDC-0980 is a potent, oral, dual PI3K/mTOR inhibitor with promising preclinical activity. No significant toxicities have been observed to date in these ongoing Phase I studies at exposures producing PD modulation in surrogate tissue and tumor. Favorable preliminary PK profiles have been observed at initial dose levels.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B137.
Abstract B147: Lack of an additive effect of radiation treatment on PI3K or mTOR inhibition in prostate cancer cell lines
Authors: Bubley Glenn , Huang Qiuying , Lee Mike , Floyd Scott , Jones Graham , Yaffe Michael
Published: June 2012

We assessed the effect of PI3-K inhibition, mTOR inhibition and combined PI3K/mTOR inhibition in combination with ionizing radiation in prostate cancer cell lines. The treatments were studied in a cell lines with wild type PTEN status (CWR Rv1–22) and PTEN deficiency (LNCaP). Initial experiments determined concentrations of rapamycin (an mTOR antagonist) and wortmanin (a PI3-K antagonist) that resulted in an approximate 50% in cell viability at 48 hours. Cells were then treated with these agents both alone, together, or in combination with 8 gray of ionizing radiation and cell viability was assessed at 24, 48 and 72 hours. Regardless of the treatment schedule, i.e either radiation before inhibitor treatment or inhibitor treatment before radiation, we did not observe any additive effects from combination radiation and inhibitor treatment. This was regardless of whether inhibtor treatment was PI3K inhibition, mTOR inhibition, or combined treatment. Flow sorting cell cycle analysis from these studies indicates that the lack of effect might be related to the findings that radiation and PI3K/mTOR inhibition have effects of different phases of the cell cycle. This is a cell based model only and animal model data may be quite different. However, at this time PI3K/mTOR inhibition does not appear to be a mechanism for enhancing radiation sensitivity in prostate cancer.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B147.
Abstract B15: Effect of axitinib (AG-013736) on thyroid function and biomarkers: Results from phase I studies in Japanese patients
Authors: Fujiwara Yutaka , Kiyota Naomi , Chayahara Naoko , Suzuki Akiyuki , Umeyama Yoshiko , Mukohara Toru , Minami Hironobu
Published: June 2012

Background: Axitinib is an oral, potent, and selective inhibitor of vascular endothelial growth factor receptors (VEGFRs) 1, 2, 3. In a phase I study previously conducted in 12 Japanese patients with solid tumors, fatigue and abnormal thyroid stimulating hormone (TSH) levels were frequently observed.1 An additional phase I study has been conducted in 6 Japanese patients with solid tumors to evaluate the pharmacokinetics (PK), safety, and biomarkers (VEGF, soluble [s]-VEGFRs, and s-KIT). Thyroglobulin was measured to evaluate the direct effects of axitinib on the thyroid in these patients.

Methods: Twelve patients received axitinib at a 5 mg single dose followed by 5 mg twice daily (BID). A further 6 patients received axitinib at 5, 7, and 10 mg single doses followed by 5 mg BID. Based on data obtained from all 18 phase I patients, safety and potential correlations between TSH or biomarkers and exposure to axitinib were investigated.

Results: The plasma PK following single dosing was generally linear with a geometric mean AUC0-∞ of 148, 185, and 292 ng·h/mL following 5, 7, and 10 mg axitinib single doses, respectively. Across both phase I studies, the common treatment-related adverse events were fatigue (83%), diarrhea, anorexia, hand-foot syndrome (67% each), and hypertension (61%). Fifteen patients (83%) experienced TSH elevation. In the first phase I study, grade (G) 3 fatigue was observed in 5 of 12 patients (42%). In the additional phase I study, thyroid hormone replacement therapy was proactively given to patients as appropriate according to TSH level measured at every visit; none of 6 patients experienced G3 fatigue. Elevation of thyroglobulin with peak levels of > 100 ng/mL was observed in 3 of 6 patients (50%) at approximately ≥3 months after initiating treatment. Three patients discontinued therapy during cycle 1 or 2 due to progressive disease; elevation of thyroglobulin was not observed in these patients. In the exploratory analysis, abnormal TSH was highly correlated with exposure to axitinib (r=0.72). Decrease in s-VEGFR2 levels was significantly correlated with exposure to axitinib (r=-0.95). Tumor size decreased in 11 of 17 patients (65%) who had target lesions.

Conclusions: Preliminary data suggest that fatigue may be manageable with thyroid hormone replacement therapy. Elevation of thyroglobulin was observed in all 3 patients who continued treatment with axitinib for longer than 3 months; this may indicate that hypothyroidism observed following axitinib treatment is potentially due to its direct effect on the thyroid. Results from two phase I studies demonstrated a significant correlation between change in s-VEGFR2 or TSH and exposure to axitinib. This suggests that s-VEGFR2 and TSH potentially act as biomarkers of axitinib plasma exposure.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B15.
Abstract B156: Augmenting sensitivity of cancer cells to novel antitumor fusicoccin derivative (ISIR-042) by hypoxia
Authors: Honma Yoshio , Akimoto Miho , Takenaga Keizo , Sassa Takeshi , Kato Nobuo
Published: June 2012

Some diterpene glucosides produced by the plant-pathogenic fungi are modulators of 14-3-3 proteins, and they induced the differentiation of human myeloid leukemia cells and apoptosis in human carcinoma cells in the presence of interferon-alpha (IFN). Combined treatment with IFN and cotylenin A significantly inhibited the growth of human lung cancer cells as xenografts without apparent adeverse effects.

We synthesized several fusicoccin derivatives with antitumor activity, and found that some effective derivatives exhibited antitumor effects in xenografts inoculated with several human cancer cell lines when treated alone or with IFN. Among the derivatives, ISIR-042 was the most effective in inhibition of the tumor growth in xenografts. This compound preferentially induced growth inhibition and apoptosis of some cancer cells under hypoxic conditions. The hypoxia-targeting effects were not observed in the parental compound (cotylenin A) or other fusicoccin derivatives, suggesting that ISIR-042 is the novel antitumor agent with a unique mode of action. Pancreatic cancer is highly aggressive and refractory to existing therapies.

Pancreatic ductal adenocarcinomas contain tumor cells that are at low oxygen tensions (hypoxic), and tumor hypoxia is known to induce the expression of a variety of genes associated with tumor progression and aggressiveness. Novel therapeutic strategies can be devised to improve treatment. Therefore, we examined the antitumor effect of ISIR-042 with IFN in xenografts inoculated with human pancreatic cancer MiaPaCa-2 cells. The combined treatment significantly inhibited the tumor growth in xenografts without appreciable adverse effects, suggesting that combined treatment with ISIR-042 and IFN may have therapeutic value in treating pancreatic cancer.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B156.
Abstract B157: Generation of “Natural Unnatural Product Library” and identification of small molecule XIAP inhibitors
Authors: Kawamura Tatsuro , Otaka Hitomi , Tashiro Etsu , Imoto Masaya
Published: June 2012

For the drug discovery, generation of chemical libraries has been required. Natural products are utilized for drug-lead discovery because of their structural diversity, and indeed, many natural products and their derivatives have been used as approved drugs historically. Here, we generated a natural product-derived chemical library named “Natural Unnatural Product (NUP) library”. To generate NUP library, chemical reagent was added in microbial broth extracts, and many microbial metabolites in the broths extracts were converted into their derivatives. After this reaction, newly synthesized components, NUPs, in the reaction mixtures were detected and isolated by LC-MS system to give a NUP library. On the other hand, X-linked inhibitor of apoptosis (XIAP) is an endogenous direct inhibitor of caspase-3, -7 and -9. Overexpression of XIAP is often seen in several types of human tumor, and it contributes tumor malignancy by inhibiting apoptosis. Therefore, XIAP is considered as a promising molecular target for cancer therapies, and we searched for the compound that inhibited anti-caspase activity of XIAP from our NUP library. As results, three compounds, C38OX3, C38OX6 and C38OX8, were found to restore XIAP-suppressed enzymatic activity of caspase-3 in a dose dependent manner in vitro. Next, we examined whether these XIAP inhibitors could accelerate apoptosis induced with death ligands or anticancer drugs. C38OX6 overcame XIAP-mediated resistance of HeLa cells against TRAIL and anticancer drugs. These findings suggest that our NUPs contain potential drug-leads for the development of new class of anticancer drugs such as XIAP inhibitors. In conclusion, we generated NUP library as source for drug-lead of anticancer drugs and identified three NUPs as XIAP inhibitors.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B157.
Abstract B158: Innovative design for a phase 1 trial with intra-patient dose escalation: The Crotoxin study
Authors: Medioni Jacques , Trinquart Ludovic , Benlhassan-Chahour Kadija , Ohnona Jessica , Reid Paul , Chatellier Gilles , Oudard Stephane , Bray Dorothy
Published: June 2012

Introduction: Crotoxin is a neurotoxic phospholipase isolated from the venom of a rattlesnake. It has proven to have significant and broad acting anti-tumor activity: in previous phase 1 clinical studies, comprising 60 enrolled patients, clinical benefit was observed in 26 patients (43%). Traditional designs were used, the dose-limiting toxicity (DLT) being neuromuscular toxicity. Preclinical animal data suggests that, by using a dose escalation protocol, the administration of very high doses can be achieved without adverse toxicity because the host becomes tolerant to the neurotoxic effects. Much higher doses could be administered without adverse toxicity, but maximizing treatment efficacy. Our aim was to develop an innovative design for a Phase 1 study with intra patient dose escalation to induce subject tolerance.

Methods: A new open label intra-patient dose escalation method was planned. The primary objective is to determine the Maximum Tolerated Dose (MTD). DLT was defined as the occurrence of two consecutive grade 2 or 3 neuromuscular events not recovered within 24 hours at a given dose. MTD was defined as the dose where no DLT was observed among three consecutive patients, or no more than one DLT among six patients. Dosing schedule, duration and highest dose was based on the previous clinical experience. Eight possible crotoxin doses will be administered using intrapatient dose escalation, starting from 0.04 and up to 0.32 mg/m2. Each dose will be initially administered for 5 consecutive days with 2 days break during week-end.

Results: Determination of MTD will be as follow: the first patient will be treated up to 0.32 mg/m2 or a lower tolerated dose. This dose is called the ith target ceiling dose (TCDi). Next two patients will be treated up to the TCDi.

→If no DLT is encountered, then TCDi is MTD. → If two or more DLT are encountered, then include 3 new patients up to the next lower dose (TCDi-1) and proceed similarly. →If one DLT encountered, then add 3 more patients up to TCDi. →If no DLT is encountered among those 3 new patients, then TCDi is MTD. →If one or more DLT is encountered among those 3 new patients, then include 3 new patients up to TCDi-1 and proceed similarly.

Conclusion: host could become tolerant with some products using dose escalation and avoid toxicity. This innovative design is expected to allow fast and simple determination of MTD in these situations. The study protocol was approved by our local ethics committee and will start at early November.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B158.
Abstract B185: Bench to bedside experience with TH-302: A tumor-selective hypoxia-activated prodrug as a promising treatment for prostate cancer
Authors: Hart Charles P. , Armstrong Andrew J. , Chiorean Elena G. , Sun Jessica D. , Langmuir Virginia K. , Meng Fanying , Eng Clarence , Kroll Stewart , Matteucci Mark D. , Curd John G.
Published: June 2012

Hypoxia is a defining feature of solid tumors, including prostate cancer. Metastases also exhibit subregional hypoxia and micrometastases may be severely hypoxic. Hypoxic cells are known to be resistant to standard chemotherapies and thus play a role in treatment failure and disease relapse. TH-302, a tumor-selective hypoxia-activated prodrug of the cytotoxic warhead bromo-isophosphoramide mustard (Br-IPM), is currently in clinical development for the treatment of advanced solid tumors. We explored the preclinical efficacy of TH-302 in both in vitro and in vivo models of prostate cancer. Based on these translational results, we identified prostate cancer as an indication for further clinical investigations.

Preclinically, TH-302 demonstrated hypoxia-selective cytotoxicity in the human prostate cancer cell lines PC-3, LNCaP, and DU-145. We explored in vivo prostate cancer efficacy in PC-3 xenograft models that included (1) an ectopic subcutaneous model, (2) an orthotopic model, and (3) a model of bone and soft tissue prostate cancer metastases. TH-302 demonstrated efficacy both as monotherapy and in combinations with taxanes in all three settings. The combination of TH-302 and docetaxel in the disseminated prostate cancer metastases model demonstrated 100% complete responses in the 8 of 10 animals surviving to the end of the study at approximately 8 weeks.

The TH-302 Phase 1 dose escalation clinical trial established the monotherapy maximum tolerated dose (MTD) of TH-302 dosed weekly for 3 weeks of a 4 week cycle at 575 mg/m2. Mucosal and skin toxicity were dose limiting, while hematologic toxicity was minimal. Evidence of anti-tumor activity was observed including four RECIST responses in patients with small cell lung cancer and metastatic melanoma. In the ongoing Phase 1/2 combination therapy clinical trials of TH-302, the MTD of TH-302 was established at 340 mg/m2 when dosed at days 1 and 8 with docetaxel 75 mg/m2 on day 1 every 3 weeks. Neutropenia was dose-limiting. In the first two patients with metastatic castration-resistant prostate cancer (CRPC) treated with the combination of TH-302 and docetaxel, PSA responses (a > 50% reduction from baseline) have been observed along with a marked reduction in cancer-related pain in one of the patients. An additional 12 CRPC patients will be enrolled.

These translational studies and early clinical findings indicate that the addition of TH-302 to docetaxel may be a promising new treatment option for prostate cancer.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B185.