bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract B256: A novel targeted oral insulin-like growth factor 1 (IGF-1) receptor inhibitor in clinical phase I/II testing
Authors: Harmenberg Johan , Ekman Simon , Bergqvist Michael , Frödin Jan-Erik , Larsson Olle , Axelson Magnus
Published: June 2012

The overall objective was to identify a novel compound targeting the Insulin-Like Growth Factor 1 receptor (IGF-1R) without influencing the closely related insulin receptor and to test such a compound in cancer patients with solid tumors.

IGF-1R belongs to a family of related receptors also including the insulin receptor (IR). The IGF-1R signaling pathway is crucial for the survival and growth of most types of cancer cells, but not of normal cells. The concept has general applicability with respect to many different cancers.

AXL1717 is a compound that has been optimized to inhibit the IGF-1R without inhibiting closely related receptors including IR. AXL1717 demonstrates strong and unique anti-tumor efficacy, including complete regression of established tumors in animals xenografted with human malignant cells, including breast cancer, prostate cancer, glioblastoma (intracerebral implants), malignant melanoma, sarcoma and multiple myeloma. AXL1717 did not show any effect in animals with IGF-1R negative xenografts. Preclinical testing showed excellent tolerability together with good oral bioavailability.

AXL1717 is presently studied in a Phase I/II clinical trial on advanced-stage cancer patients with progressive solid tumors and no remaining treatment options. The primary objective of the study is to identify and confirm a recommended Phase II dose. AXL1717 has been administered every third week as a single-day BID oral treatment in consecutively increasing doses as the only treatment with anti-tumor efficacy. Doses have been increased both within and between patients. The single-day oral dosing part of the ongoing Phase I/II clinical trial on cancer patients with AXL1717 has successfully been concluded. The results show that AXL1717 can be administered as a single-day BID treatment in very high doses with excellent tolerability. Dose-limiting toxicity has not been reported. The second part of the study is ongoing where consecutive cohorts of advanced-stage cancer patients are given 7–28 days of increasing BID doses of AXL1717. The preliminary results as of September 3rd 2009 have identified possible Phase II dosages. Even though the study was not designed to evaluate tumor or biomarker response, 4 out of 6 patients have shown decreased density of IGF-1R on granulocytes. Two patients, with progressive non-small cell lung cancer, treated with AXL1717 as 3rd and 4th line treatment, respectively, were reported to have documented tumor necrosis.

The preliminary results from the Phase I/II clinical trial indicate a recommended phase II dose with good tolerability and with an oral bioavailability resulting in an exposure several fold higher than the exposure resulting in complete regression of tumors in animals.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B256.
Abstract C224: A novel validated quantitative pharmacodynamic topoisomerase I covalent-complex immunoassay
Authors: Pfister Thomas D. , Khin Sonny A. , Agama Keli , Hollingshead Melinda , Sooryakumar Dhriti , Pommier Yves , Parchment Ralph E. , Tomaszewski Joseph E. , Doroshow James H. , Kinders Robert J.
Published: June 2012

Topoisomerase I (Top1) is an established molecular target for anti-cancer therapeutics. Top1 inhibitors function by trapping the catalytic intermediate of Top1 covalently attached to the DNA substrate, termed the Top1 covalent complex (Top1cc). We have developed and validated an immunoassay to measure Top1cc directly, in support of Phase 0 clinical trials for experimental Top1 inhibiting drugs. A simple Top1cc isolation step which separates Top1cc from free Top1 is followed by a quantitative infrared immunoblotting detection technique. Recombinant Top1 is used as the standard for quantification. The assay was used to measure Top1cc in cell lines that exhibit varied growth inhibitory responsiveness to topotecan (A375, HCT-116, HT-29 and SKMEL28). Cells were treated with single doses of Top1 inhibitors, topotecan and indenoisoquinoline and Top1cc levels were found to be dose dependent with a maximal response at/or before 30 min to 1h of exposure. To establish fitness-for-purpose for clinical applications the assay was tested on samples of human tumor xenografts from mice treated with topotecan and indenoisoquinolines. These results demonstrate the potential to quantify Top1cc levels as a pharmacodynamic maker for Top1 inhibitors in solid tumor extracts. Funded by NCI Contract No. HHSN261200800001E.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C224.
Abstract C226: Clinical evidence of mechanism-based activity in voreloxin-treated AML patients
Authors: Conroy Andrew , Tan Nguyen , Wong Oi Kwan , Fox Judith A. , Hawtin Rachael E.
Published: June 2012

Voreloxin is a first-in-class anticancer quinolone derivative that intercalates DNA and poisons topoisomerase II (Stockett et al. and Hawtin et al., AACR 2008). This leads to replication-dependent, site-selective DNA double strand breaks (DSB) targeting G/C-rich sequences that are characteristic sites of quinolone-induced DNA cleavage (Noble et al, 2003, Richter et al 2007, Stockett et al, AACR 2008). A consequence of this DNA damage is G2 arrest and cell death by apoptosis. Voreloxin is under clinical investigation in acute myeloid leukemia (AML) and ovarian cancer. Clinical responses have been observed in these indications (Lancet et al., ASCO 2009; Maris et al., ASCO 2009; McGuire et al., SGO 2008), as well as in NSCLC and SCLC (Burris et al., ECCO 2007).

The current analysis was performed in support of the ongoing phase 1b/2 study clinical study (SPO-0012) of voreloxin in combination with cytarabine in relapsed or refractory AML. The purposes were to; (1) characterize voreloxin-induced biomarkers of mechanism-based pharmacodynamic (PD) activity in cell lines and peripheral blood mononuclear cells (PBMC) from AML patients; (2) differentiate between the cellular PD DNA damage responses to voreloxin and cytarabine; (3) profile patient PBMC before and following the combination treatment with voreloxin and cytarabine in SPO-0012, to evaluate PD markers of cellular response; (4) investigate potential correlations between cellular PD markers of DNA damage and clinical outcome.

Based on our understanding of voreloxin's mechanism of action, pharmacodynamic (PD) markers of S phase delay, G2 arrest and DNA damage following treatment with voreloxin were profiled in cell lines and then evaluated in primary AML cells. These included markers of stalled replication forks (pRPA-32, pCHK1) and DNA DSB (DNA-PKcs, p53, and pCHK2). Cellular response to cytarabine was also characterized in these in vitro model systems. Cytarabine is a mainstay of treatment in AML, administered for 7 days per treatment cycle in combination with daunorubicin on days 1–3 (the “7+3” treatment schedule). Cytarabine is incorporated into DNA and causes inhibition of DNA polymerase resulting in decreased DNA synthesis and repair. DNA damage responses were observed with cytarabine, but these occurred later than with voreloxin treatment. Voreloxin induction of pDNA-PKcs and pCHK2 were chosen for PD assessments in the ongoing phase 1b/2 study of voreloxin in combination with cytarabine in relapsed or refractory AML. PBMC were purified from blood samples collected from patients at time points pre- and post-dosing. Upregulation of pDNA-PKcs and pCHK2 was detected within 2 hours post-dose, providing evidence of mechanism-based PD responses to voreloxin. Inconsistent quality of PBMC preparation at individual sites precluded correlation of PD response with clinical outcome.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C226.
Abstract C229: BAL27862: A novel anticancer agent which dissociates microtubules and creates a distinct cellular phenotype
Authors: Bachmann Felix , Burger Karin , Pohlmann Jens , Kellenberger Laurenz , Lane Heidi
Published: June 2012

Background: BAL27862 is a synthetic small molecule potently inducing apoptosis in cancer cells due to tubulin depolymerization. BAL27862 has a broad in vitro anti-proliferative activity against a range of human tumor lines (low nM IC50s) and elicits significant antitumor responses in animal models of human cancer, including multidrug-resistant tumors, after oral or intravenous administration.

Materials and Methods: Anti-proliferative activity was analyzed with monolayer (crystal violet) or soft agar (clonogenic) assays. Effects on microtubules (MTs) were assessed by immunofluorescence (IF) or immunoblotting (IB) for -tubulin; centrosome maturation by IF for -tubulin.

Results: BAL27862 showed potent anti-proliferative activity in vitro on 8 NSCLC cell lines (IC50 range 8.5–17nM). Significant activity was also observed on 3 patient-derived NSCLC lines, highly resistant to paclitaxel (clonogenic IC50s: paclitaxel >3.5 M; BAL27862 15nM, 29nM, 300nM). In all tumor histotypes analyzed, BAL27862 elicited a unique MT phenotype, distinct from that observed with conventional MT-targeting agents (paclitaxel, vinblastine, colchicine) or other mitotic inhibitors. In proliferating A549 NSCLC cells (anti-proliferative IC50: 16±2nM; MT depolymerization IC50: 10–20nM) BAL27862 caused a concentration-dependent effect on MTs. In interphase cells, at concentrations ≥15nM the MT network collapsed towards the MT-organizing center, with an absence of peripheral MTs. In dividing cells, an apparent fragmentation of the mitotic spindle occurred at 15nM, associated with the appearance of tiny MT asters. The asters decreased in size as concentrations increased (15–100nM), and were co-localized with condensed chromatin. A comparative titration (5–100nM) with the clinically used MT destabilizer vinblastine (VBL) indicated no phenotypic overlap. VBL-treated interphase cells had a mesh-like MT network with peripheral MTs intact, while in dividing cells aberrant, spindle-like structures were observed at concentrations ≥15nM. Using non-immortalized HS68 human fibroblasts, no obvious effects of BAL27862 (10–20nM) on centrosome number or size were observed, as defined by -tubulin staining; in contrast to an increase in size and decrease in apparent resolution of the centrosomes after treatment with VBL at the same concentrations. BAL27862 treatment also converted the abnormal spindle structures induced by the MT destabilizers VBL or colchicine into the distinct and dominant BAL27862 MT phenotype, further highlighting it's novel mechanism of MT disruption.

Conclusions: BAL27862 is a new tubulin-interacting agent with a novel mechanism of action leading to a unique MT phenotype. These observations, together with a broad antitumor activity targeting refractory tumors, strongly support further development of BAL27862 as an anticancer agent.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C229.
Abstract C230: MPC-6827 is safely combined with temozolomide for the treatment of patients with metastatic melanoma
Authors: Hamid Omid , Akerley Wallace , Stephenson Joseph , Yu Margaret K. , Evans Brent A. , Mather Gary , Swabb Edward A. , Hwu Wen-Jen
Published: June 2012

Purpose: MPC-6827 (4-arylaminoquinazoline) is a microtubule destabilizing agent with in vitro cytotoxic and in vivo vascular disrupting characteristics. We determined the dose-limiting toxicity (DLT) and the most tolerable doses of MPC-6827 in combination with daily administration of temozolomide.

Experimental Design: Metastatic melanoma patients were treated weekly with a 2-hour intravenous infusion of MPC-6827 for 6 or 3 consecutive weeks during 8- or 4-week cycles, respectively. Temozolomide was administered orally either at 75 mg/m2 daily during the first 6 weeks of an 8-week cycle or at 85 mg/m2 daily during the first 3 weeks of a 4-week cycle. Therapy was repeated every 56 days in the 8-week cycle and every 28 days in the 4-week cycle. Three pre-selected doses of MPC-6827 were tested: 2.1, 2.7, and 3.3 mg/m2. Patients in the 2.1 mg/m2 dose level were treated at 8-week cycles. Due to the inconveniences of 8-week cycles, patients enrolled in the 2.7 and 3.3 mg/m2 dose levels were treated at 4-week cycles. Patients were observed for DLTs during the first cycle. Plasma samples were obtained at various timepoints after MPC-6827 infusion to evaluate concentrations of MPC-6827 and temozolomide. A conventional “3+3” design was used for dose escalation.

Results: Twenty-two patients (median age, 59 years; range, 35–81; median number of prior therapies,2; range 1–5) with stage IV melanoma (3 M1b, 19 M1c) were enrolled, two patients are still receiving therapy. Twenty patients (91 %) had an ECOG score 0–1 and ten (45%) patients had brain metastases. Eight patients (36%) received temozolomide/dacarbazine therapy previously. Four patients (18%) experienced a grade 3 or greater MPC-6827-related SAE, which include an increased Troponin I level (n=1), cerebral hemorrhage (n=2), and cerebral infarction associated with a brain metastasis (n=1). One of the cerebral hemorrhages was deemed a DLT. Median MPC-6827 half-life ranged from 2.9–4.0 hours. Cmax and AUC increased proportionally with dose. The highest dose tested was 3.3 mg/m2 once weekly with temozolomide 85 mg/m2 daily for 3 weeks of a 4-week cycle. Employing modified RECIST criteria, two patients achieved partial response (durations of 6 and 4 months). Another nine patients achieved stable disease (duration range: 1 – 6 months).

Conclusion: The combination of MPC-6827 and temozolomide is safe and well tolerated in patients with refractory metastatic melanoma, including brain metastases. Responses are durable. A dose reduction of MPC-6827 is not required when combined with temozolomide. Incidences of cerebral hemorrhage, deep venous thrombosis and/or pulmonary emboli were similar to those in previous reports.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C230.
Abstract C246: nab®-paclitaxel targets tumor stroma and results, combined with gemcitabine, in high efficacy against pancreatic cancer models
Authors: Maitra Anirban , Rajeshkumar N.V. , Rudek Michelle , Garrido-Laguna Ignacio , Laheru Daniel , Iglesias Jose , Desai Neil , Von Hoff Daniel D. , Hidalgo Manuel
Published: June 2012

nab®-paclitaxel (Abraxane ™, Abraxis Bioscience, Los Angeles, CA) is an albumin-bound nano particle formulation of paclitaxel that may target SPARC (secreted protein acid-rich in cysteine). In a phase I/II study in patients with advanced pancreatic cancer, the combination of nab®-paclitaxel and gemcitabine resulted in impressive clinical activity with an objective response rate of 40%, 10.3 months median survival and 78 % of patients having a decrement of CA199 > 50 % (Von Hoff et al, ASCO 2009). To gain insight into the mechanisms underlying the high efficacy of this combination, we treated 11 freshly generated pancreatic cancer xenografts from the Johns Hopkins PancXenoBank collection. nab®-paclitaxel, in combination with gemcitabine, doubled the response rate of either agent alone and resulted in a 57% response rate, mimicking the results obtained in the clinical trial. Tumors treated with nab®-paclitaxel showed a marked decrement in the otherwise abundant fibrotic stroma characteristic of pancreatic cancer and present in control and gemcitabine only treated animals. The elimination of the stroma resulted in marked cellular tumors and increased tumor vascularization and cell-vessel proximity. Consequently, the intratumoral concentration of gemcitabine increased by 3.7 fold in mice treated with nabR-paclitaxel and gemcitabine versus those receiving gemcitabine alone. We conclude that nab®-paclitaxel effectively eliminates pancreatic cancer stroma resulting in increased delivery of gemcitabine and high antitumor effects. Targeting tumor stroma appears a promising strategy in pancreatic cancer.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C246.
Abstract C63: Biological characterization of GSK2126458, a novel and potent inhibitor of phosphoinositide 3-kinase and the mammalian target of rapamycin (mTOR)
Authors: Hardwicke Mary Ann , Lu Hong , Luo Lusong , Diamond Melody , Sung Chiu-Mei , Carson Jeffrey D. , Plant Ramona , Gardiner Christine , Wang Jamin , Oleykowski Catherine A. , Gontarek Richard , Van Aller Glenn , Gilbert Seth , Sutton David S. , Tummino Peter J. , Wooster Richard F. , Knight Steven D. , Jackson Jeffrey R. , Dhanak Dashyant , Auger Kurt R.
Published: June 2012

The phosphoinositide 3-kinase (PI3K) pathway is among the most commonly activated pathways in human cancer. The biological role of PI3K in growth and survival of cancer cells and the prevalence of activating mutations in human cancers are well documented and a significant proportion of tumors would be predicted to benefit from inhibition of this pathway. Here we report on the characterization of the pan-PI3K pyridylsulfonamide inhibitor GSK2126458: a very potent (PI3K app Ki = 19 pM), reversible, ATP-competitive inhibitor of wild-type PI3K and the ‘hotspot’ activating mutants of p110 found in human cancer. GSK2126458 demonstrated good selectivity for the PI3K family of enzymes including the mTORC1 and mTORC2 complexes, when evaluated in a large panel of protein kinases. Consistent with potent PI3K enzyme inhibition, GSK2126458 decreased the cellular levels of phosphorylated AKT, p70S6K, PRAS40 and ERK in a concentration and time dependent manner, the IC50 for pAKT in the HCC1954 breast carcinoma cell line was 2 nM. GSK2126458 induced the nuclear translocation of the FOXO3a transcription factor in a concentration dependent manner that mechanistically appeared bimodal. Growth inhibition was time and concentration dependent with a 3 day exposure resulting in a growth IC50 (gIC50) of 9 nM in HCC1954 cells with evidence of cell death. Cell death correlated with induction of caspase 3 and 7 activity suggesting apoptosis was the mechanism of cell death. GSK2126458 had a breadth of activity for potent cell growth inhibition and induction of cell death in a variety of human cancer cells. GSK2126458 demonstrated robust, dose dependent in vivo pharmacodynamic activity as measured by inhibition of phospho-AKT in advanced BT474 breast cancer cell xenograft tumors. Inhibition of AKT phosphorylation was rapid and lasted for several hours after a single oral administration of GSK2126458. Transient increases in plasma insulin and blood glucose were observed. Evaluation of in vivo tumor growth effects of GSK2126458 in xenograft models demonstrated dose dependent tumor growth delay in several models of diverse tumor lineage and tumor regression in a breast cancer xenograft. The biological profile of GSK2126458 supports the clinical advancement of this compound and GSK2126458 has entered Phase I human clinical trials.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C63.
Abstract A10: Combined blockade of VEGF and Ang2 promotes dramatic tumor necrosis and growth inhibition of colorectal cancer xenografts.
Authors: Lalani Alshad S. , Castanaro Carla , Kyle Alastair H. , Minchinton Andrew I. , Thurston Gavin , Daly Christopher
Published: June 2012

Background: VEGF and Angiopoietin-2 (Ang2) are secreted growth factors that are elevated in many human malignancies and function to regulate critical yet distinct aspects of tumor angiogenesis. While blockade of VEGF in combination with standard chemotherapy regimens has been demonstrated to improve survival in patients with metastatic colorectal cancer, the clinical benefit is transient, with most patients experiencing disease progression. We hypothesized that a combination treatment with agents that block the VEGF and Ang2 signaling pathways would provide more potent inhibition of tumor angiogenesis than single agent therapies, thereby resulting in more pronounced and/or durable effects on tumor growth.

Methods: We assessed the antitumor effects of aflibercept (VEGF Trap) as a single agent or in combination with REGN910, a fully-human monoclonal antibody that specifically binds and potently inhibits Ang2 (each agent dosed at 15 mg/kg q4dx3). We employed whole tissue section mapping and multiplexed immunostaining techniques in Colo205 human tumor xenografts to assess changes in vessel density (CD31), hypoxia (pimonidazole) and tumor cell death (TUNEL).

Results: The combination treatment of REGN910 plus aflibercept provided significantly greater tumor regression than single agent aflibercept treatment. No additive gross toxicities or body weight loss were observed following the combination treatment. Consistent with a more potent effect on tumor growth, the combination treatment caused a more pronounced decrease in tumor vessel density and a greater increase in tumor hypoxia at 24 hr post-treatment than either single agent. Finally, the combination treatment promoted much more dramatic tumor cell death at 72 hr than either single agent.

Conclusions: Combined inhibition of VEGF and Ang2 using aflibercept plus REGN910 provides much more pronounced antitumor effects than either single agent, suggesting that combining these agents in the clinic is an attractive strategy to extend the benefit of anti-VEGF therapies.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A10.
Abstract A193: Assessment of effect of low- and high-fat diet on E7050 pharmacokinetics and characterization of E7050 pharmacokinetics after 100 mg, 200 mg, and 400 mg single oral doses in healthy subjects.
Authors: Mistry Bipin , Nishioka Yuki , Fan Jean , Verbel David
Published: June 2012

Purpose: E7050, an orally available c-MET tyrosyne kinase inhibitor is currently under evaluation for the treatment of advanced malignancies. The objectives of this study were to evaluate (1) effects of a standard high-fat and low-fat meal on the pharmacokinetics (PK) of 100 mg E7050; (2) E7050 PK following single doses of 100, 200 and 400 mg of E7050 in under fasted condition and (3) the safety of E7050 in healthy subjects.

Methods: This open label study consisted of two parts: Part A (Food Effect) and Part B (Rising dose PK). Part A was a randomized, single-dose, three-way crossover study with a 2-week wash out between treatments. In Part A, 18 subjects received a single dose of E7050 (100 mg) in a fasting state, following a high-fat meal or a low-fat meal. In Part B, 12 and 10 subjects sequentially received 200 and 400 mg E7050 doses, respectively in fasted state. Serial blood samples for E7050 PK analysis were taken up to 196 h post-dosing. Subjects were evaluated for adverse events (AEs).

Results: Study results are summarized in Table 1. Based on E7050 Cmax, AUC(0−t) and AUC(0−inf), the presence of food at the time of dosing reduces exposure by 21 to 28%. When administered with food (high-fat or low-fat), the lower 90% CI limit for E7050 is below 80% for Cmax and AUC. Thus the food effect is independent of the type of meal consumed. However, the magnitude of the observed food effect was modest and clinically insignificant. PK of E7050 was found to be linear following single doses of 100 to 400 mg E7050. In this study, a single dose of the 400-mg E7050 tablet was safe and well tolerated when administered under fed and fasted conditions. Most TEAEs were mild in severity; there were no treatment-related severe or serious AEs and no treatment-related AEs leading to study treatment withdrawal. There were no clinically significant changes in vital sign assessments, clinical laboratory analyzes or ECG parameters.

Conclusion: Consumption of a low- or high-fat meal had no clinically significant effect on E7050 PK and E7050 can be administered without regards to food. PK of E7050 was found to be linear following single doses of 100 to 400 mg E7050. This study demonstrated an acceptable safety/tolerability profile of E7050 in healthy subjects.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A193.
Abstract A78: Simvastatin synergistically potentiates tipifarnib cytotoxic and apoptotic effects and disrupts Ras membrane localization in human leukemia cells.
Authors: Ahmed Tamer , Hayslip John , Leggas Markos
Published: June 2012

Background: Tipifarnib, a farnesyl transferase inhibitor, was initially designed to prevent Ras farnesylation and its subsequent membrane localization, which is necessary for Ras mediated signaling. Although, the clinical effectiveness of tipifarnib as a single agent in solid tumors was limited, it was modest in hematologic malignancies. Alternative prenylation by geranylgeranyl transferase has been postulated as an escape mechanism by which Ras evades the effect of tipifarnib. Simvastatin, an anti-hyperlipidemic drug that inhibits 3-hydroxy 3-methylglutaryl coenzyme A (HMG-CoA) reductase, has been shown in several studies to induce apoptosis in cancer cells through blockade of the geranylgeranylation pathway of small GTPases. Thus, we hypothesized that simvastatin can augment the cytotoxic effect of tipifarnib by blocking the alternative Ras prenylation pathway. Our studies were carried out in a panel of leukemia cell lines. Methods: Studies were carried out using five cell lines of varied leukemic origin including HL60, K562, Molt4, Jurkat and HSB2. Cells were exposed to increasing drug concentrations for 72 hours either as a single or combination treatment with simvastatin and tipifarnib. Cell viability was measured using AlamarBlue (Invitrogen) and the combination index values were calculated based on the Chou-Talalay equations. Apoptosis was evaluated using Annexin V assay. Biochemical assays assessing the expression of caspases, c-PARP and Ras, in both membrane and cytosolic fractions, were also used. Results: The combination of tipifarnib with simvastatin was shown to induce a synergistic cytotoxic effect in all cell lines tested. Notably, our results showed that coadministarion of simvastatin and tipifarnib resulted in the induction of apoptosis through the activation of several apoptotic markers including Caspase 3, 7 and 9 as well as the upregulation of cleaved PARP. These effects were accompanied by disruption of Ras membrane localization and its sequestration into the cytosol.

Conclusions: These findings demonstrate that combining simvastatin with tipifarnib effectively disrupts Ras prenylation and induces apoptosis in human leukemia cell lines. These effects were observed with simvastatin and tipifarnib concentrations that can be achieved in the clinic. Thus, the effectiveness of this combination should be explored further in future clinical studies.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A78.
Abstract A79: Evidence that the antitumor effects of AMPK activation and crosstalk with the Akt pathway are dependent on the genetic profiles of human breast cancer cell types.
Authors: El-Masry Omar S.
Published: June 2012

The prevalence of breast cancer and drawbacks of many current therapeutic modalities underline the need for novel therapies. Those based on signal transduction have the potential for fewer side effects due to inherent redundancy of pathways. The fuel sensing enzyme, AMP-activated protein kinase (AMPK), is activated by low energy levels. We (El-Masry et al, Oncology Letters, in press), and others, have identified that AMPK is involved in cell proliferation and growth and could be a potential therapeutic target in cancer. Pharmacological activation of AMPK in MCF-7 (p53wt, ER+), MDA-MB-231 (p53−, ER−) and T47D (p53−, ER+) human breast cancer cell lines using 5-Aminoimidazole-4-carboxamide ribotide (AICA-ribonucleotide) resulted in anti-proliferative effects, with T47D cells being the most sensitive. These effects correlated with changes in apoptosis, including mitochondrial membrane potential (assayed by fluorescence activated cell sorting (FACS)) and Bax translocation to the outer mitochondrial membrane (assayed by immunofluorescence) suggesting that the apoptotic signal was p53 independent. Caspase inhibition showed that the anti-proliferative effect of AMPK activation was mediated by caspase 9 in all cell types. Execution was by caspase 6 in MCF-7 cells and caspase 3 and 6 in MDA-MB-231 cells. T47D cells were less responsive to both caspase inhibition and PARP cleavage than MCF-7 and MDA-MB-231. AMPK activation also resulted in trans-activation of p21, although this was dependent on the basal level of p21 in the different cell types. Previously we reported differential effects on the same cell lines in terms of PI3K/Akt signaling. Our current studies on possible crosstalk between the AMPK and PI3K/Akt pathways show that, whilst AMPK activation led to inhibition of Akt phosphorylation, the effect of Akt inhibition on AMPK phophorylation was cell type dependent. Akt inhibition increased phosphorylation of AMPK in T47D cells, but not in MCF-7 or MDA-MB-231 cells. Inhibition of Akt also decreased proliferation of T47D and MCF-7 cells, without effect on MDA-MB-231 cells. The adipokine leptin inhibited AMPK phosphorylation in all cell lines. Blockade of either Akt or mTOR inhibited this effect of leptin in T47D cells, suggesting that was mediated, at least in part, by activation of Akt, but did not affect MCF-7 or MDA-MB-231 cells. These data demonstrate crosstalk between metabolic and survival signaling. This interactive signaling was cell type dependent. In conclusion, the potential therapeutic effects of AMPK and its interaction with survival pathways were found to be different depending on genetics of the breast cancers investigated.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A79.
Abstract A82: Bardoxolone (5MeCDDO), which induces the antioxidant response element (ARE), is ineffective in inhibiting cancer progression but inhibits cancer initiation in rodent models of cancer. What does it mean for the ARE as a primary prevention target?
Authors: Lubet Ronald A. , Townsend Reid , Clapper Margie L. , Steele Vernon E. , Grubbs Clinton J.
Published: June 2012

The preventive efficacies of the triterprenoid 5MeCDDO were examined in three preclinical models of breast cancer. We initially evaluated 5MeCDDO in an ER+ mammary model in which female Sprague-Dawley rats were administered MNU, i.v., at 50 days of age. 5MeCDDO (27 ppm) was administered in the diet beginning 5 days after MNU, and continuing for the duration of the study. Doses >50 ppm were toxic. 5MeCDDO failed to decrease tumor latency or multiplicity and, in fact, increased the size of the cancers which did develop. This concentration of 5MeCDDO greatly increased liver to body weight ratios. We also examined the preventive efficacy of 5MeCDDO (54 and 27 mg/kg diet) in a bitransgenic model (MMTV-Neu/p53KO) of ER− mammary cancer. In this model, animals develop cancers which overexpress Neu and fail to have a mutation in the transmembrane domain of Neu. Similarly to results in the MNU model, 5 MeCDDO did not alter either tumor latency or multiplicity. The effect of 5MeCDDO was further evaluated in a third model in which ER+ tumors were induced by the procarcinogen dimethylbenzanthracene (DMBA). DMBA was administered by gavage to female Sprague-Dawley rats at 50 days of age. In this model (which examines the ability of an agent to alter the activation of the carcinogen) the preventive agent was administered beginning 7 days prior to DMBA and was continued until 7 days post DMBA. 5,6 Benzoflavone (500 ppm), a positive control, decreased tumor multiplicity >90%, while 5MeCDDO (27 or 2.7 ppm) decreased multiplicity 65 and 35%, respectively. The efficacy observed in this model is in agreement with the ability of the agent to stimulate the ARE, and to induce a variety of ARE related proteins in the liver of treated rats including GST Pi, AKF 1A8, epoxide hydrolase. Thus, as expected, high induction of the ARE was associated with a decrease in DMBA-induced cancer initiation, but not a decrease in the progression stage of mammary cancer development in three cancer models. 5MeCDDO was ineffective in blocking the formation of adenomas in Min mice which have a germline mutation in the APC gene. This latter finding brings into question whether merely measuring induction of the ARE (e.g., quinone reductase) is sufficient to imply the general preventive efficacy of a given agent or mixture.

Supported by NCI contract number HHSN261200433001C.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A82.
Abstract A83: 4-Ketopinoresinol, a novel naturally occurring ARE activator, induces the Nrf2/HO-1 axis and protects against oxidative stress-induced cell injury via activation of PI3K/AKT signaling.
Authors: Kuo Ching-Chuan , Chen Huang-Hui , Chen Yu-Tsen , Huang Yen-Wen , Tsai Hui-Ju
Published: June 2012

The Nrf2/ARE pathway plays an important role in inducing phase II detoxifying enzymes and antioxidant proteins, and has been considered as a potential target for cancer chemoprevention by eliminating harmful reactive oxygen species (ROS) or reactive intermediates generated from carcinogens. The objectives of this study were to identify a novel Nrf2/ARE activator and to investigate the mechanistic signaling pathway involved in the activation of Nrf2-mediated cytoprotective effects against oxidative-induced cell injury. A stable ARE-driven luciferase reporter cell line was established to screen the potentially cytoprotective compound. 4-Ketopinoresinol (4-KPR), the (−) double cyclized type of lignan obtained from adlay (Coix lachrymal-jobi L. var. ma-yuen Stapf), more effectively activates ARE-driven luciferase activity than the classical ARE activator, tert-butylhydroquinone. 4-KPR treatment resulted in a transient increase in AKT phosphorylation and subsequent phosphorylation and nuclear translocation of Nrf2, along with increased expression of ARE-dependent cytoprotective genes, such as heme oxygenase-1 (HO-1), aldo-keto reductases, and glutathione synthetic enzyme, and their protein products. 4-KPR suppresses oxidative stress-induced DNA damage and cell death via up-regulation of HO-1. Inhibition of PI3K/AKT signal by chemical inhibitors or RNA interference suppressed Nrf2 activation and HO-1 up-regulation. These observations in an ARE-regulated gene system suggest that 4-KPR is a novel Nrf2/ARE-mediated transcription activator, activates the Nrf2/HO-1 axis, and protects against oxidative stress-induced cell injury via activation of PI3K/AKT signaling. These results may have relevance to the clinical application of 4-KPR and its significance in cancer chemoprevention.

The study was supported by grants of DOH100-TD-C-111-004, NSC98-2320-B-400-003-MY3, and NSC99-2323-B-400-006.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A83.
Abstract A98: Dual regulation of heme oxygenase-1 (HO-1) expression by retinoic acid in HL-60 cells.
Authors: Kim Jong-Suk , Noh Eun-Mi , Lee Young-Rae , Park Jinny
Published: June 2012

Heme oxygenase (HO)-1 has anti-oxidative, anti-inflammatory, and anti-apoptotic activities. However, little is known about the regulation of HO-1 in acute promyeolocytic leukemia (APML) cells. HL-60 cells are well differentiated by all-trans-retinoic acid (ATRA) and dimethylsulfoxide (DMSO). Here, we found that ATRA and DMSO initially stimulated HO-1 expression in HL-60 cells. However, HO-1 was clearly down-regulated at later times. Interestingly, zinc protoporphyrin (ZnPP), a strong inhibitor of HO-1, induced down-regulation of HO-1 and differentiation of HL-60 cells, as evidenced by a marked increase in the expression of the differentiation marker CD11b following ZnPP treatment. In contrast, treatment with cobalt protoporphyrin (CoPP), a strong activator of HO-1, induced HO-1 up-regulation and decreased CD11b expression. In conclusion, these data indicate that ATRA and DMSO negatively regulate HO-1 expression for inducing the differentiation of HL-60 cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A98.
Abstract B119: AF4 mimetic peptide SPK111 prolongs survival of MLL xenografted leukemias.
Authors: Barretto Nisha , Hemenway Charles
Published: June 2012

Acute leukemias with balanced translocations of the MLL gene are aggressive blood cancers with generally poor prognosis. Importantly, MLL leukemias are the most common type of leukemia in babies and account for 70% of the secondary leukemias that arise following treatment with topoisomerase II inhibitors. Only 40% of infants treated for acute lymphoblastic leukemia (ALL) with MLL gene rearrangements survive to the age of five while the survival rate is 90% for patients in the same age group whose disease lacks a translocated MLL gene. Hence, better treatment options for MLL-rearranged leukemias need to be explored.

As results of reciprocal translocations, the 5' coding region of MLL is fused to the 3' coding region of one of many different genes. This results in transcripts that encode chimeric proteins. AF4 and AF9 proteins are the two most frequent fusion partners of MLL. They are components of the protein complex P-TEFb that promotes transcriptional elongation. Misdirection of the transcriptional elongation complex is one proposed mechanism by which oncogenic transformation occurs in MLL leukemias. Our laboratory previously identified the amino acids required for direct physical interaction between AF4 and AF9 and designed an AF4 mimetic peptide that disrupts the AF4 - AF9 interaction. Treatment of cell lines with MLL-AF4 and MLL-AF9 translocations with the mimetic peptide leads to necrotic cell death without affecting normal hematopoietic cells.

In order to further establish the AF4 - AF9 interaction as an effective target for MLL leukemias, we tested effect of a modified peptide designed to enhance its stability in xenografted mice. The peptide, designated SPK-111 exherts effective antitumor activity without causing overt toxicity. It significantly improves the survival of NOD/SCID mice engrafted with human cell lines carrying MLL gene rearrangements when used as a single agent. Here, we describe the in vivo activity of the peptide and propose that it, or other derivatives, may represent a clinically important agent for the treatment of MLL leukemias.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B119.
Abstract B129: RAF inhibition promotes tumorigenesis in a mouse model of HPV-driven squamous cell carcinoma.
Authors: Holderfield Matthew , Lorenzana Edward , Chan John , Ghoddusi Majid , Daniel Dylan , Pryer Nancy , McCormick Frank , Stuart Darrin
Published: June 2012

Recent approval to market the RAF kinase inhibitor vemurafenib for treatment of metastatic melanomas positive for the BRAFV600E mutation highlights the clinical importance of MEK/ERK signaling in human cancers. Vemurafenib treatment resulted in objective responses in 52% of BRAFV600E mutation melanoma patients, although a subset of patients (20–30%) were reported to develop cutaneous squamous-cell carcinomas (cSCCs) and/or keratoacanthomas, which are independent of the melanoma and thought to be related to exposure to the RAF inhibitor. While vemurafenib effectively inhibits proliferation of BRAFV600E mutant melanomas, vemurafenib and other selective RAF kinase inhibitors can paradoxically activate the MAPK pathway and stimulate growth of BRAF wild-type cells. One hypothesis to explain the appearance cSCCs is that paradoxical activation of the MAPK pathway by RAF inhibitor treatment, in the presence of pre-existing genetic lesions, such as the loss of a tumor suppressor(s), is sufficient to promote cSCC growth. To investigate this hypothesis, we used a genetic murine model (K14-HPV16) for cSCC, which is driven by basal keratinocyte-specific expression (Keratin 14 promoter) of human papiloma virus (HPV) type 16 genes E6 and E7, inactivating the p53 and pRB tumor suppressor proteins respectively. The frequency of cSCC in K14-HPV16 mice is ∼10–20% by 8 months of age. Consistent with our hypothesis, 60 day exposure to vemurafenib at a clinically relevant dose increased the cSCC incidence to ∼65%. In addition, the incidence and severity of skin lesions was proportional to the dose of vemurafenib. Mice treated with vemurafenib also exhibited RAF activation as measured by increased levels of MAPK pathway transcriptional targets in dermal tissues where lesions most often arise. Together, these results suggest that hyperactivation of the MAPK pathway caused by vemurafenib promotes tumorigenesis of HPV-driven cSCC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B129.
Abstract B133: Antitumor effects of novel high-hydrophilic and non-ATP-competitive MEK1/2 inhibitor SMK-17.
Authors: Kiga Masaki , Tanzawa Fumie , Iwasaki Shiho , Inaba Fumi , Fujiwara Kosaku , Iwadare Hayato , Echigo Tomoki , Nakamura Yuji , Shibata Tomoyuki , Suzuki Kanae , Yasumatsu Isao , Nakayama Ayako , Sasazawa Yukiko , Tashiro Etsu , Imoto Masaya , Kurakata Shinichi
Published: June 2012

The mitogen-activated protein kinase (MAPK) signal pathway plays a central role in regulating tumor cell proliferation, survival, and differentiation. The components of this pathway, Ras/Raf/MEK/ERK, are frequently activated in human cancers. Targeting this pathway is considered to be a promising anticancer strategy. In particular, MEK is an attractive drug target due to its high selectivity to ERK. We can expect potent growth inhibitory and proapoptotic effects by inhibiting MEK.

We synthesized derivatives of N-[2-(2-Chloro-4-iodo-phenylamino)-3,4-difluorophenyl] -methanesulfonamide as novel MEK1/2 inhibitors. Among these compounds, we found SMK-17 to be a potent MEK1/2 inhibitor with high aqueous solubility. The in silico docking study suggested that SMK-17 be bound to an allosteric pocket of MEK1. The kinetics study and kinase profiler analysis confirmed the allosteric character of SMK-17. SMK-17 inhibited MEK1 kinase activity by a non-ATP-competitive manner and it was highly selective to MEK1 and 2. SMK-17 inhibited the growth of tumor cell lines in vitro. Especially, it seemed that cell lines harboring highly phosphorylated MEK1/2 and ERK1/2 were highly sensitive to SMK-17. Moreover, unlike previously reported MEK inhibitors, PD184352 or U0126, SMK-17 did not inhibit phosphorylation of ERK5. In vivo, SMK-17 exhibited potent antitumor activity in animal models by oral administration. SMK-17 selectively blocked the MAPK pathway signaling without affecting other signal pathways, which resulted in significant antitumor efficacy without notable side effects.

In conclusion, we found very potent MEK inhibitor SMK-17 from our structure-activity correlation study of new derivative series of diphenyl amine sulfonamide. Kinase profiler and kinetics study revealed that SMK-17 is a non-ATP-competitive and highly selective MEK1/2 inhibitor. Moreover, SMK-17 exhibited potent antitumor activity in animal models by oral administration. SMK-17 selectively blocked the MAPK pathway signaling without affecting other signal pathways both in vitro and in vivo. These findings suggest that SMK-17 is a useful chemical biology tool for characterizing the function of MEK/MAPK signaling.

Furthermore, we are now investigating the combination effects of SMK-17 with several drugs, and studying about prediction marker of this compound.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B133.
Abstract B152: Modulating the activity of nerve growth factor (NGF) and its receptors tropomyosin-related kinase A (TRKA) and p75 neurotrophin receptor (p75NTR) in perineural invasion (PNI) in pancreatic cancer.
Authors: Bapat Aditi A. , Munoz Ruben M. , Maredia Saaiqa , Von Hoff Daniel D. , Han Haiyong
Published: June 2012

Pancreatic cancer is the fourth leading cause of cancer-related death in the US with a 5-year survival rate of less than 5%. Even after surgery and chemotherapy, prognosis is dismal due to tumor re-occurrence. Perineural Invasion (PNI) is a process where surrounding pancreatic nerves are invaded by pancreatic cancer cells. This invasive and proliferative ability of pancreatic cancer cells is indicative of their aggressiveness and is shown to be associated with poor prognosis and pain in pancreatic cancer patients. The nerve growth factor (NGF) signaling pathway is implicated in PNI and NGF binds to a high-affinity receptor, tropomyosin kinase A (TRKA), which is differentially expressed in pancreatic tumor tissues and a low-affinity receptor, p75 neurotrophin receptor (p75NTR), whose role in PNI in pancreatic cancer is unclear. In this study, we seek to understand the molecular mechanisms of NGF regulation of PNI in pancreatic cancer. Whether NGF regulates PNI via an autocrine or paracrine manner is not well understood. Signaling via NGF-TRKA pathway induces neurites in the PC-12 neurite extension assay and conditioned media (CM) from several pancreatic cancer cell lines including BxPC3 induced neurites in this assay. Addition of an antibody to neutralize NGF in the CM or an azaoxindole inhibitor (GW441756) of TRKA resulted approximately in a 50% and 40% decrease in neurites respectively in the PC-12 assay. These results could indicate a paracrine action of NGF in promoting neurite extension in the PC-12 assay and perhaps nerve growth as related to PNI. Furthermore, knocking down the expression of NGF, p75NTR, TRKA using siRNA or inhibitor GW441756 of TRKA decreased migration of BxPC3 pancreatic cancer cells in the Boyden chamber assay by 45 − 60%. A similar inhibitory effect was observed in the movement of pancreatic cancer cells towards dorsal root ganglia (DRG) in a DRG-pancreatic cancer cell co-culture assay. Thus, NGF may function in an autocrine manner to increase proliferation and invasiveness of pancreatic cancer cells in PNI. Currently, we are working to further optimize our assays to delineate the interplay between NGF and TrkA (autocrine or paracrine) in PNI and understand the involvement of p75NTR (low-affinity NGF receptor) in NGF signaling and consequently in PNI. Understanding the molecular mechanisms involved in PNI will aid in designing novel therapeutics that prevent PNI and alleviate pain associated with PNI in patients with pancreatic cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B152.