bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract A189: Influence of smoking on the pharmacology of taxane therapy.
Authors: de Graan Anne-Joy M. , Loos Walter J. , Friberg Lena E. , Baker Sharyn D. , van der Bol Jessica M. , Wiemer Erik AC , van der Holt Bronno B. , Verweij Jaap , Mathijssen Ron HJ
Published: June 2012

Background: Smoking interacts with the metabolism of several anti-cancer drugs such as erlotinib and irinotecan. It may also affect the incidence and severity of side effects and the efficacy of chemotherapy. The main objective of this study was to examine the effects of smoking on the bone marrow toxicities and pharmacokinetics (PK) of the taxanes docetaxel and paclitaxel. Both taxanes are metabolized through a CYP3A-based conversion.

Methods: 566 patients (429 non-smokers and 137 smokers) were treated with docetaxel or paclitaxel. We determined their toxicity profiles and PK parameters. PK samples were measured by HPLC or LC-MS/MS, and individual PK parameters were estimated from previously developed population PK models by non-linear mixed effects modeling in the software NONMEM. P-values were calculated by the Mann-Whitney U or 2 tests, while multivariate logistic regression analysis was used to adjust for covariates.

Results: Smokers treated with docetaxel (43% vs 57% p = 0.03) or paclitaxel (11% vs 25% p = 0.02) showed less grade 3–4 leucopenia (white blood cell count (WBC) < 2.0×109/L) than non-smokers. These effects remained apparent in a multivariate analysis correcting for dose and co-medication (docetaxel: odds ratio (OR) = 0.56, 95% confidence interval 0.32–0.97, p = 0.04; and paclitaxel: OR = 0.3, 95% CI 0.13–0.83, p = 0.02). There was also significantly less grade 4 neutropenia (absolute neutrophil count (ANC) < 0.5×109/L) in smokers than in non-smokers (OR = 0.46, 95% CI = 0.26–0.81, p = 0.007) in docetaxel treated patients. However, the incidence of neutropenic fever did not differ between smoking groups. Furthermore, the percentage decrease in WBC and ANC from baseline to nadir did not differ between smoking groups. The protective effect of smoking on bone marrow counts is probably attributable to smokers having higher baseline WBC (9.2 vs. 7.5 ×109/L; p < 0.0001) and ANC (6.7 vs. 5.1 ×109/L; p = 0.002) than non-smokers. Docetaxel and paclitaxel clearance did not differ between smokers and non-smokers (docetaxel: 39.1 vs. 39.4 L/h; p = 0.99; paclitaxel: 463 vs. 450 L/h; p = 0.77).

Conclusion: This is the first large study on the effects of smoking on the treatment of docetaxel and paclitaxel. Smokers had lower incidence of leucopenia and neutropenia, possibly because smoking induces bone marrow growth. However, this did not affect the incidence of neutropenic fever. As no effect on PK was seen, the inductive effect of smoking on CYP3A suggested by previous studies might be substrate dependent or less apparent.

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 A189.
Abstract A194: A QT/QTc and multi-dose pharmacokinetic (PK) study of abiraterone acetate (AA) plus prednisone (P) in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC).
Authors: Pili Roberto , Chi Kim , Shore Neal , Papadopoulos Kyriakos , Smith Lon , Beeram Muralidhar , Molina Arturo , Acharya Milin , Kheoh Thian , Jiao James , Gonzalez Martha , Pankras Catherine , Trinh Angela , Tran NamPhuong , Tolcher Anthony
Published: June 2012

Background: AA is the prodrug of abiraterone (A), an androgen biosynthesis inhibitor that selectively inhibits CYP17, thereby blocking testicular, adrenal, and prostatic intratumoral androgen biosynthesis. In a phase 3 study, AA+P demonstrated survival improvements in post-docetaxel mCRPC pts (De Bono ESMO 2010). ADT with an LHRH analog (LHRHa) has been associated with median QTc interval prolongation of 9–21 msec (Garnick ASCO 2004). Primary objective: effects of AA+P on QT/QTc interval duration in mCRPC pts receiving LHRHa. Secondary objectives: pharmacokinetics (PK) of AA and abiraterone (A) after single/multiple doses of AA.

Methods: In this open-label, single-arm phase 1b study (COU-AA-006/NCT00910754), 33 mCRPC pts with disease progression after failure of GnRH hormone therapy, a PSA ≥2 ng/mL and ≤1 course of prior chemotherapy, received AA 1000mg orally QD + P 5mg orally BID. ECGs were collected in triplicate using 12-lead Holter monitoring. Baseline ECGs were obtained on Cycle (C)1 Day (D)-1. Serial ECG recordings and time-matched PK blood samples were collected over 24 hrs on C1D1 and C2D1. Serial PK blood samples were also collected over 24 hrs on C1D8.

Results: After AA administration, the upper bound of the 2-sided 90% CI for the mean baseline-adjusted QTcF change was <10 msec; no subjects discontinued due to QTc prolongation or AEs. Most AA plasma concentrations were below the quantification limit; thus AA PK analysis was not performed. A linear mixed-effects model showed no apparent relationship between change in QTcF and A plasma concentrations (estimated slope [90%CI): 0.0031 [−0.0040, 0.0102]). Exposure to A after multiple AA dosing on C1D8 and C2D1 increased versus exposure after single dose on C1D1; accumulation ratios for C1D8 (1.8–2.0) and C2D1 (2.0–2.2) were similar. The most commonly reported treatment-emergent AE (TEAE) was dizziness (12%); all TEAEs were grade 1; except 1 grade 3 AE (increased ALP) with no grade 4 TEAEs.

Conclusions: There is no significant effect of AA+P on the cardiac QT/QTc interval in mCRPC pts. No relationship between change in QTcF and A plasma concentration was observed.

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 A194.
Abstract A198: Identification and preclinical testing of novel targeted therapies for human triple-negative breast cancer.
Authors: Mittereder Lara R. , Tomlinson Christine C. , Bennett Christina N. , Michalowski Aleksandra , Caplen Natasha , Green Jeffrey E.
Published: June 2012

Basal-like triple negative breast cancer (BTNBC) is characterized by the absence of estrogen receptor, progesterone receptor, and Her2 expression, and represents an estimated 15% of all human breast cancers. This subtype is highly prevalent in African American women (35%) and is associated with distant metastasis and poor prognosis. As there are currently no targeted therapies for this subtype of breast cancer, our research focuses on the development of improved therapies to increase patient survival. We have previously shown that primary mammary tumors from the C3(1)/SV40-TAg genetically engineered mouse (GEM) model express a critical proliferation/ DNA repair/ cell cycle gene signature (TAg signature) that is shared with human BTNBC. SV40-TAg functionally inactivates p53 and pRb, two critical tumor suppressor genes whose functions are lost in most human BTNBC. We hypothesize that targeting dysregulated genes and biological networks present in the TAg signature will lead to the identification of novel targets and potential combination therapies.

To test this idea we developed a custom siRNA library screen to inhibit the expression of individual genes represented in the TAg signature using human MDA-MB-231 BTNBC cells. Additionally, we performed a synthetic lethal screen in which TAg signature genes were knocked down in MDA-MB-231 cells using pooled siRNAs in combination with either UCN-01 or gemcitabine, small molecule inhibitors of CHK1 and RRM1/2 respectively. It was found that the knockdown of BMI-1, EZH2, GeneA, GeneB, or GeneC significantly decreased cell proliferation with the addition of UCN-01 or gemcitabine. A second synthetic lethal screen was performed in which the above genes were knocked down using four deconvoluted siRNAs per gene with the addition of gemcitabine, UCN-01, or AZD7762 (a more specific CHK1 inhibitor). Synergistic activity was shown between the siRNA knockdown of these genes and UCN-01 and AZD7762 compared to siRNA alone. To determine whether the knockdown of these genes alters sensitivity to gemcitabine or CHK1 inhibitors, the EC50 values of these drugs are currently being evaluated in stable knockdown MDA-MB-231 cell lines expressing shRNA to the selected genes. Our results suggest that using GEM models to help identify new targets may be useful in the development of novel therapeutics for BTNBC in combination with available CHK1 inhibitors and/or gemcitabine. These studies will enhance our understanding of BTNBC and allow us to identify innovative combination therapies to treat this challenging form of breast 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 A198.
Abstract A210: Mechanism of action of MM-151, a potent mixture of three human antibody antagonists targeting EGFR.
Authors: Tan Gege , Kearns Jeffrey D. , Gerami-Moayed Nastaran , Kohli Neeraj , Werner Shannon L. , King Anne M. , Sloss Callum M. , Bukhalid Raghida , Nielsen Ulrik B.
Published: June 2012

Epidermal growth factor receptor (EGFR) is a key regulator of cancer cell proliferation, apoptosis, invasion, and metastasis. However, the clinical benefits of EGFR targeted agents such as erlotinib and cetuximab have been modest. Using Merrimack's Network Biology platform, a computational systems analysis was performed to identify how best to inhibit signaling through the EGFR-ERK network. These simulations predicted that enhanced inhibition is required to overcome the robust signal amplification inherent to this network and is best achieved through treatment with a combination of at least two noncompetitive ligand antagonists. The MM-151 therapeutic was developed to achieve the simulated design criteria and consists of a mixture of three fully human monoclonal antibodies directed against distinct non-overlapping epitopes in EGFR. Detailed in vitro and on-cell binding experiments, supported by computational simulations, with single component antibodies and their monovalent Fab variants, display a rich complexity of antibody affinity and avidity. All three antibodies are shown to have subnanomolar monovalent affinity to EGFR but to vary in the degree to which they functionally crosslink receptor (two antibodies display high avidity while the third has weak avidity). Ligand competition experiments with saturating antibody concentrations (EC90 of on-cell binding) demonstrate that two of the antibodies are each complete ligand antagonists while the third antibody is a partial (approx. 25%) antagonist. When combined into the MM-151 mixture, these antibodies simultaneously engage and robustly crosslink receptor to form a highly antagonistic therapeutic. Treatment of human tumor-derived cell lines with MM-151 elicits complete inhibition of ligand-mediated ERK signaling over a wide range of both EGF receptor density (as high as 2×10∘6 receptors per cell in the A431 cell line) and ligand burden (8 and 80nM EGF). In contrast, monoclonal EGFR targeted therapeutics, such as cetuximab and panitumumab, as well as oligoclonal inhibitors similar to MM-151, show weaker or even no effect on ERK signaling under similar conditions. Furthermore, the potency of monovalent MM-151 (Fab variants) is diminished in EGF mediated EGFR and ERK signaling, highlighting the importance of receptor crosslinking through antibody avidity as a determinant of efficacy. Together, these data demonstrate that MM-151 is a potent inhibitor of the EGFR-ERK signaling axis with the potential of improved efficacy over current EGFR targeted 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 A210.
Abstract A219: Efficacy of a spectrum-selective cathepsin inhibitor in a mouse model of bone cancer.
Authors: Holsinger Leslie J. , Ondoua-Lozano Alysia , Rodriguez Jade , Hanlon Katherine , Bilsky Edward J. , Havelin Joshua , Dener Jeffrey M. , Booth Robert , Vanderah Todd W.
Published: June 2012

Introduction: Increased cathepsin levels and activity have been shown to play a role in a variety of tumors, including lung and breast malignancies, and are correlated to poor patient prognosis. Proteolytic activity of cathepsins S, L, B and K may play a role in degradation of the basement membrane and extracellular matrix allowing a loss of cell adhesion and facilitating tumor metastasis. Cathepsin K inhibition has been reported to suppress bone resorption in women with breast cancer by inhibiting osteoclast function. Studies with cathepsin S inhibitors have demonstrated a reduction in nociception in animals, suggesting a role for cathepsin S in tumor-associated neuropathy. We report the efficacy of the spectrum-selective cathepsin inhibitor VBY-825 in a mouse model of metastatic breast cancer.

Results and Discussion: VBY-825 is a potent ketoamide-based inhibitor of cathepsins S, B, K, V, and L with pM or single digit nM affinity on this spectrum of cysteine proteases. VBY-825 has been shown to have potent anti-tumor activity in a spontaneous mouse model of pancreatic cancer (Elie et al, 2010, Biochimie). VBY-825 potently inhibited angiogenesis in tumor cell lines, endothelial cell co-cultures and tumor matrix invasion when assayed in an in vitro 3D tumor cell growth assay. Pharmacokinetic behavior of VBY-825 supported once daily dosing resulting in plasma levels sufficient for sustained inhibition of the target cathepsins. Efficacy of VBY-825 was assessed in a murine bone cancer model in which murine 66.1 breast cancer cells are injected and confined to the intramedullary space of the femur of non-immunocompromised mice. Beginning on post surgical day 7 animals received either VBY-825, zoledronic acid, or 5% dextrose vehicle once daily for 14 days. Similarly to the bisphosphonate, VBY-825 in this model significantly reduced bone matrix degradation. VBY-825 also reduced behaviors associated with spontaneous pain including flinching and guarding with significantly greater efficacy than zoledronic acid suggesting that VBY-825 may also induce analgesia against bone cancer pain.

Conclusions: These studies demonstrate that the cathepsin inhibitor VBY-825 is effective in a model of bone cancer and associated chronic pain, demonstrating both analgesic activity as well as protection from bone matrix loss and remodeling. These studies support the role of multiple cathepsins as therapeutic targets in metastatic and primary bone 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 A219.
Abstract A226: Mechanism of action of iniparib: Stimulation of reactive oxygen species (ROS) production in an iniparib-sensitive breast cancer cell line.
Authors: Licht Stuart , Cao Hui , Li Zhifang , Zhang Jingxin , Liu Feng , Brittain Scott , Shen Junqing , Zhang Bailin , Hopke Joern , Newcombe Rick , Reiling Stephan , Pollard Jack , Watters James , Cheng Hong , Reddy Venkateshwar , Bergstrom Donald A.
Published: June 2012

Iniparib (BSI-201) holds substantial promise as an anti-cancer agent, and knowledge about its mechanism of bioactivity is evolving. While PARP inhibition has been proposed as iniparib's primary mechanism of action, the low potency of iniparib against PARP observed in a number of assays and models suggests that other mechanisms account for its bioactivity. These mechanisms are likely to include metabolic conversion of iniparib to a bioactive species. Here, we present an integrated analysis of profiling experiments (transcriptional and proteomic) and synergy screens (bioactive compound and shRNA) designed to identify the pathways associated with iniparib bioactivity. Proteomic and transcriptional profiling in MDA-MB-453 cells indicate that, at concentrations close to its in vitro potency as a cytotoxic agent, iniparib induces activation of the Nrf2 transcription factor, a known mediator of cellular anti-oxidant/anti-xenobiotic defense. Furthermore, Gene Set Enrichment Analysis (GSEA) comparing iniparib's transcriptional profile to drugs with known mechanism of action reveals similarity between iniparib and inhibitors of the mitochondrial electron transport chain. Bioactive compound and shRNA synergy screens also identify both Nrf2 and the components of the mitochondrial electron transport chain as genes required for maximum iniparib bioactivity. Cell-based imaging studies indicate that iniparib stimulates the production of reactive oxygen species (ROS). Taken together, these results are consistent with a mechanism in which a component of the Nrf2-mediated antioxidant response and/or the mitochondrial electron transport chain converts iniparib to its putative active metabolite, and this metabolite uncouples electron transport from oxidative phosphorylation, leading to the production of ROS at cytotoxic levels. The results of the integrated analysis may assist in the discovery of biomarkers for iniparib sensitivity.

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 A226.
Abstract A234: Identification and characterization of inhibitor-resistant mutants of the protein-tyrosine kinase c-Fes.
Authors: Hellwig Sabine , Gray Nathanael S. , Smithgall Thomas E.
Published: June 2012

Lack of target selectivity is a well-known limitation to the use of chemical inhibitors to pinpoint individual kinase functions in the intricate network of cellular signaling pathways that often involve closely related kinases or unrelated off-target effects. A possible solution to this problem involves the use of inhibitor-resistant mutants of the targeted kinase. Such mutants can be employed in rescue experiments, in which introduction of the mutant kinase reverses the phenotype resulting from chemical inhibition of the endogenous kinase. This chemical genetics approach has been successfully used by our group to dissect roles for individual members of the Src kinase family in embryonic stem cell differentiation and chronic myelogenous leukemia, despite close structural homology within this kinase family. In the present study, we used this approach to validate the specificity of a series of potent inhibitors of the c-Fes kinase that we recently identified in a kinase-biased chemical library screen. The c-Fes protein-tyrosine kinase is involved in multiple cellular signaling pathways that modulate differentiation, the innate immune response, vasculogenesis and tumorigenesis. Using site-directed mutagenesis, we systematically altered residues around the inhibitor-binding pocket defined in a recent crystal structure of the c-Fes SH2-kinase region bound to the diaminopyrimidine inhibitor, TAE684. We first mutated the gatekeeper methionine (Met636) of Fes, which helps mediate TAE684 binding in the crystal, but found that substitutions at this position inactivated kinase function. Additional point mutations that retained kinase activity were then tested against TAE684 and other potent small molecule inhibitors of c-Fes. This screen identified a leucine residue near the gatekeeper position (Leu638) to be critical in conferring sensitivity to both TAE864 and the more Fes-selective pyrazolopyrimidine, WZ-4-49-8. Replacement of this Leu638 with a bulkier tyrosine or phenylalanine rendered c-Fes very resistant to WZ-4-49-8, with IC50 values increasing from the low nanomolar range for wild-type Fes to the micromolar range for the mutants in an in vitro kinase assay. These data implicate Leu638 as an important specificity determinant for future design of more potent and selective inhibitors of c-Fes. Ongoing studies are using this resistant mutant to validate novel roles for Fes in biological systems impacted by TAE684 and WZ-4-49-8 treatment, including differentiation of macrophages (a major site of c-Fes expression) to osteoclasts.

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 A234.
Abstract A246: Blockade of CSF-1R/CSF-1 signaling by PLX3397 attenuates prostate cancer cell growth in bone, prostate cancer-induced skeletal pain, and pathological bone remodeling.
Authors: Jimenez-Andrade Juan Miguel , Bloom Aaron P. , Kaczmarska Magdalena J. , Burton Elizabeth A. , Zhang Jiazhong , Lin Paul S. , West Brian L. , Mantyh Patrick W.
Published: June 2012

Prostate tumors that have metastasized to bone frequently proliferate in bone and induce significant bone pain and pathological remodeling, all of which are difficult to control fully using currently available therapies. Colony stimulating factor-1 (CSF-1) regulates the survival, proliferation, differentiation and function of cells in the monocyte lineage including macrophages and osteoclasts. Human studies have reported a greater expression of CSF-1 and its receptor, CSF-1R (also known as c-Fms), in tumor and stromal cells of metastatic prostate cancers versus non-metastatic prostate cancers. To assess the role of CSF-1R in pain and disease progression in bone from prostate cancer, a novel small molecule inhibitor of CSF-1R, PLX3397, was administered to mice that were injected in the femur marrow space with ACE-1 canine prostate cancer cells. Intrafemoral injection of prostate cancer cells resulted in significant growth of tumor, which in turn induced significant skeletal pain and massive formation of pathological, disordered, woven bone. Sustained administration of PLX3397 started on day 12 after the tumors were well established and pathological bone remodeling was evident. Six weeks treatment with PLX3397 significantly attenuated (∼50%) prostate tumor cell growth (p=0.018), bone cancer pain behaviors (p<0.001) and the prostate cancer cell induced pathological remodeling of the bone (p<0.001). These results suggest that blockade of CSF-1R/CSF-1 signaling by PLX3397 is highly effective in not only reducing prostate cancer growth in the bone, but also prostate cancer induced bone pain and pathological remodeling. PLX3397 is currently undergoing Phase 2 clinical testing in patients with a variety of tumors, and these data further support its evaluation in patients with prostate 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 A246.
Abstract A26: Autophagy acts as a safeguard mechanism against G-quadruplex ligand-mediated telomere damage.
Authors: Folini Marco , Orlotti Nicola I. , Cimino-Reale Graziella , Borghini Erika , Daidone Maria Grazia , Palumbo Manlio , Sissi Claudia , Zaffaroni Nadia
Published: June 2012

G-quadruplex structures have attracted considerable interest as targets for the development of novel anticancer therapies due to their capability to interfere with telomere structure and function. Elucidation of the structures of telomeric G-quadruplexes has led, in the past few years, to the rational development of effective G-quadruplex-stabilizing small molecules. In the present study we show that short-term exposure of melanoma cells to Ant1,5 (an anthracene-based telomeric G-quadruplex stabilizer) impaired cell growth without inducing cell senescence or apoptosis. Conversely, drug-treated cells were characterized by the occurrence of typical biochemical and morphological features usually associated to autophagy, such as an increase in the lipidated form of the autophagic marker LC3b and its co-localization with the lysosome marker LAMP2A. Such drug-induced autophagy occurred as a consequence of telomere uncapping and associated DNA damage response, through a pathway converging on the cyclin-dependent kinase inhibitor p21waf1. The inhibition of autophagy by the pharmacologic inhibitor Bafilomycin A1 or through RNAi-mediated depletion of ATG5 gene enhanced the cytotoxic activity of Ant1,5, as revealed by the marked increase in drug-induced apoptosis. Our data outline a molecular scenario in which G-quadruplex ligand-induced telomeric dysfunctions are translated into an autophagic response and provide the first evidence of autophagy as a safeguard mechanism activated by melanoma cells to counteract drug-mediated telomeric stress. As a consequence, interference with the autophagy pathway in melanoma could be a suitable approach to extend the therapeutic options for this malignancy.

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 A26.
Abstract A29: Bcl-2 overexpression provides short-term resistance to doxorubicin-DNA adducts but does not protect against longer-term treatments in HL-60 cells.
Authors: Ugarenko Michal , Rephaeli Ada , Nudelman Abraham , Koch Tad H. , Phillips Don R. , Cutts Suzanne M.
Published: June 2012

The anthracycline anticancer agent doxorubicin functions primarily as a topoisomerase II inhibitor but forms more cytotoxic DNA adducts in the presence of formaldehyde. For this reason, the efficacy of doxorubicin can be greatly enhanced with the co-administration of formaldehyde-releasing prodrugs such as AN-9. The combination of doxorubicin with AN-9 results in DNA adduct formation and synergistic apoptosis in HL-60 leukemic cells after 6 hr. Under the same conditions HL-60 cells overexpressing the anti-apoptotic protein Bcl-2 (HL-60/Bcl-2 cells) are completely resistant to doxorubicin/AN-9 treatments. This resistance can be overcome with the use of the small molecule Bcl-2/Bcl-xL/BCL-W inhibitor ABT-737.

While it appears that Bcl-2 overexpression confers resistance and thus may limit the therapeutic potential of doxorubicin-DNA adduct forming treatments, this is shown to be only a short-term effect. The use of a DNA adduct forming doxorubicin-formaldehyde conjugate, doxazolidine, produced similar results to the doxorubicin/AN-9 combination with HL-60/Bcl-2 cells being resistant to the drug after 4 hr treatment. This resistance was maintained up to 12 hr treatment, however, after 18 hr the HL-60/Bcl-2 cells started to display classical hallmarks of apoptosis including DNA fragmentation, and chromatin condensation which increased over time (18–36 hr). These results suggest that the Bcl-2 protection is only short-lived and that over time the resistance is overcome and the cells die via classical apoptosis. The exact mechanisms involved in overcoming this resistance in HL-60/Bcl-2 cells are currently being investigated and may involve changes in expression of Bcl-2 family proteins, or Bcl-2 interactions with pro-apoptotic proteins which tip the balance in favour of apoptosis. These findings imply that the damage caused by these DNA adduct forming compounds may be sufficient to overcome Bcl-2 mediated resistance observed in tumors in vivo.

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 A29.
Abstract A3: Axitinib combined with paclitaxel and carboplatin in melanoma: Response in genetically selected subsets.
Authors: Daud Adil , Cha Edward , Ziani Leslie , Cortez Brandon , Algazi Alain P.
Published: June 2012

Background: Axitinib is a potent VEGFR inhibitor. We tested the hypothesis that axitinib could increase the effectiveness of carboplatin/paclitaxel in specific subtypes of advanced melanoma.

Methods: A prospective single arm phase I/II trial of this combination was initiated August 2010 in metastatic melanoma (NCT01174238) at UCSF. Twenty seven patients have been enrolled, 16 are evaluable for response to date. Patients had an ECOG PS 0–1, and normal organ function. Axitinib 5 mg PO bid was taken days 1 − 14 of each 21-day cycle, and carboplatin/paclitaxel was administered on day 21. Biopsy specimens were sequenced for mutations in BRAF, NRAS, c-KIT, GNAQ and G11 and FLT-PET scans were done in selected patients to on days 1, 14, 17, and 20 of cycle 1.

Results: This regimen was well tolerated with adverse events including GI toxicity, musculoskeletal pain, fatigue, hypertension, and mild sensory neuropathy. Grade 3 adverse events have been uncommon, and grade 4 adverse events have not been observed. Four of 13 WT/NRAS patients have had a PR by RECIST, 7/13 have had some shrinkage of tumor while only 2/13 have had PD. Of the 3 patients with BRAF V600 E/K mutations, all have had PD. In the overall study population, median OS and PFS have not been reached.

Conclusions: Striking activity was seen in patients whose tumors are WT for BRAF including those with NRAS mutation. Given the urgent need for effective therapies in this population, this combination warrants further study.

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 A3.
Abstract A32: Novel ceramide analogs induce apoptosis in chemoresistant breast cancer.
Authors: Ponnapakkam Adharsh , Beckman Barbara , Foroozesh Maryam
Published: June 2012

Ceramide, a central molecule in sphingolipid metabolism, has been shown to mediate cell death by both apoptotic and non-apoptotic pathways. However, the use of endogenous ceramides as a pharmacological intervention is limited by the naturally hydrophobic nature of the ceramide molecule, which prevents efficient penetration of the cellular membrane. One novel approach is to synthesize ceramide analogs with a greater efficacy and specificity than endogenous ceramides. Our laboratory has previously shown that ceramide analogs have therapeutic potential in the treatment of chemo-sensitive and -resistant breast cancer. In this study, the effect of 5 novel ceramide analogs (designated 401–406) on cellular viability and clonogenic survival was examined in the chemosensitive MCF-7, endocrine-resistant MDA-MB-231, and chemoresistant MCF-7TN-R breast cancer cell lines, as well as the Human Embryonic Kidney (HEK) cell line. In the viability assay, analogs 401 and 406 showed the greatest efficacy in the MCF7-TNR cell line, with IC50 values of 4.0 μM and 4.2 μM in metastatic MCF-7TN-R cells. In the clonogenic survival assay, analogs 401 and 406 were again the most effective in the MCF7-TNR cell line with IC50 values of 1.9 and 1.8 respectively. Additionally, Analog 406 showed a 3.8 fold increase over control in the induction of apoptosis (p<0.05), and demonstrated a 3.4-fold increase in caspase-9 activity (p<0.05). Because ceramide has been shown to be involved in tumor sensitivity to apoptosis and chemoresistance, we suggest that development of ceramide analogs with increased antitumor activity represents a potential new class of chemotherapeutic agents.

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 A32.
Abstract A40: A novel cMET pharmacodynamic assay using human hair follicles.
Authors: Mo Jan-Rung , Egge Bryan , Sykes Kara , Li Lixia , Ware Chris , Laskey Jason , Wexler Roseanne , Reilly John , Young Jonathan , Marshall Gary , Strack Peter
Published: June 2012

The Receptor Tyrosine Kinase cMET is an oncogenic driver of gastric and lung cancer. Clinical development of cMET inhibitors to treat these cancers would be aided by a robust Pharmacodynamic (PD) marker, as we have observed heterogenous expression of phosphor-cMET (pMET) in these tumor types with limited clinical access. Here we describe the development of a novel cMET PD marker in plucked human hair follicles to address these issues. To evaluate the presence of activated cMET this surrogate tissue, 50 ug of protein extract derived from 25 plucked human hair follicles was analyzed by Receptor Tyrosine Kinase arrays. Active EGFR, HER2, HER3 IGF1R, Insulin receptor, EphA1, EphB2, and ROR1 were observed; however, no active MET was detected. Ex vivo treatment of human hair follicles with the cMET ligand HGF did however induce activation of MET as measured by pMET. A quantitative METpY1349 mesoscale assay demonstrated that HGF activated MET could be detected in a little as 2 human hair follicles or 1 ug of protein. HGF (EC50 22 ng/ml) induced a 22–38 fold time-dependent increase in pMETpY1349 and could be inhibited by the selective cMET inhibitor MK-2461 (IC50 63 nM). Current efforts to translate this assay to preclinical species will be described. These data provide additional evidence for the expression of functional cMET in human hair follicles and assays described may provide alternative means for measuring cMET inhibitor effect in a clinically relevant surrogate tissue.

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 A40.
Abstract A46: A novel immunoassay (ELISA) for quantitative gamma-H2AX detection and pharmacodynamic monitoring of DNA damage induced by chemotherapeutic agents and PARP inhibitors.
Authors: Ji Jay , Zhang Yiping , Kinders Robert , Redon Christophe , Solier Stephanie , Agama Keli , Pommier Yves , Bonner William , Hollingshead Melinda , Rubinstein Larry , Chen Alice , Kummar Shivaani , Parchment Ralph E. , Tomaszewski Joseph E. , Doroshow James H.
Published: June 2012

A 96-well plate-based enzyme-linked immunosorbent assay (ELISA) for quantifying gamma-H2AX as a biomarker to monitor DNA damage was developed and compared with gamma-H2AX detection by both Western blot (WB) and quantitative immunofluorescence assay (IFA). Using a pair of high-affinity gamma-H2AX antibodies for protein capture and detection and a synthetic peptide calibrator, this chemiluminescence ELISA can quantify gamma-H2AX concentrations as low as 16 pg/mL in crude extracts from cancer cells and solid tumors. The assay has a lower limit of detection of less than 4 pg/mL, upper limit of quantitation of 2000 pg/mL, and coefficient of variation of 20%. Treatments under evaluation using the gamma-H2AX ELISA include the topoisomerase 1 inhibitors topotecan and irinotecan, the apoptosis-inducing biomolecule TRAIL (TNF-related apoptosis-inducing ligand), and ionizing irradiation. The gamma-H2AX ELISA showed utility for drug discovery screening, molecular pharmacology studies, and pharmacodynamic monitoring. In a mouse xenograft model (A375 melanoma), the assay detected dose- and time-dependent changes in gamma-H2AX in response to treatment with irinotecan administrated alone or in combination with the poly(ADP-ribose) polymerase inhibitors ABT-888 (veliparib), AZD-2281 (olaparib), or MK-4827. Overall quantitative correlation was 0.96 between the ELISA and IFA, and 0.66 between ELISA and WB. This assay format should prove useful in situations when higher throughput and accurate quantitation are needed and gamma-H2AX analysis does not need to be restricted to nuclear foci.

Funded, in part, by NCI Contract No. HHSN261201100001E and by the Center for Cancer Research, Intramural Program of the National Cancer Institute.

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 A46.
Abstract A53: Prostate cancer cell capture using immobilized inhibitors of prostate-specific membrane antigen.
Authors: Wu Lisa Y. , Liu TianCheng , Hopkins Mark R. , Davis Willian C. , Berkman Clifford E.
Published: June 2012

Prostate circulating tumor cells (PCTCs) in the peripheral blood are shed from either a primary tumor or its metastases. These disseminated PCTCs are directly responsible for the most cancer deaths and the major cause of prostate cancer-related mortality. Therefore, elucidating the quantity of the exfoliated PCTCs in blood circulation can serve as an indicator for the clinical management in prostate cancer diseases by providing information on the success/failure of therapy. And the isolation and removal of PCTCs from circulation could potentially reduce prostate cancer metastasis. Furthermore, culturing and characterizing captured PCTCs from a patient is an attractive strategy for developing personalized treatment options. It has been established that prostate-specific membrane antigen (PSMA) is up-regulated and strongly expressed on prostate cancer cells associated with high grade primary, androgen independent, and metastatic tumors. While it is known that PSMA expression is heterogeneous in primary prostate tumors and metastases, completely PSMA negative prostate carcinomas are rare. The present study has outfitted streptavidin coated magnetic beads with a unique irreversible small-molecule PSMA inhibitor, Biotin-PEG12-CTT-54, and demonstrated that they can selectively capture PSMA + cells. The results demonstrated prostate cancer cells capturing is very specific and highly efficient, and high recovery and high viability were obtained. Subsequent in vitro propagation of these viable captured lymph node-based metastatic prostate LnCaP cells is possible without removal of magnetic beads on the cell surface. The results suggested that PCTCs enrichment by streptavidin coated magnetic beads with biotinated PSMA inhibitor has a high PCTC detection rate with an easy manual protocol, and can serve as an additional research tool and clinical assay in PCTC.

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 A53.
Abstract A59: Wnt, Notch, and Hedgehog pathways as potential therapeutic targets in OCT4A expressing cancer stem cells of malignant melanoma.
Authors: Welte Yvonne , Kohlhof Hella , Leban Johann , Regenbrecht Christian RA
Published: June 2012

Recent findings have demonstrated that within tumors a small subpopulation of so called cancer stem cells (CSCs) exists, which exhibits a self-renewing capacity and seems responsible for tumor maintenance and metastasis. But today's methods of isolating CSCs from the bulk of cells are highly inefficient. The most important step in the field of CSC research is to identify markers that represent stem cell criteria like self-renewal and asymmetric cell division. We identified small subpopulations of OCT4A+ cells within patient-derived malignant melanoma cells providing such criteria. To enrich for putative CSCs we sorted these low-passage melanoma cells into CD133+ and CD133− fractions and found the TGF-β signaling cascade only active in CD133+ cells. Furthermore, the self-renewal factor OCT4 is predominantly present in CD133+ but not in CD133− tumor cells. Sequencing and restriction digest confirmed specific expression of OCT4A. OCT4A+ and OCT4A− cells were then transfected with a phOCT4-EGFP reporter construct and FACS sorted into the respective subpopulations. Immunocytological staining with an anti-OCT4A-specific antibody confirmed that OCT4-EGFP+ melanoma cells express nuclear OCT4A. Results showed a strong nuclear staining pattern for OCT4A in OCT4-EGFP+ melanoma cells whereas OCT4-EGFP− melanoma cells were only weakly and unspecifically stained all over the cell body. To further characterize OCT4-EGFP+ and OCT4-EGFP− cells we performed genome-wide expression profiling. KEGG pathway analysis revealed that key developmental pathways such as Wnt, Notch and Hedgehog signaling were amongst the most up-regulated pathways in OCT4-EGFP+ compared to OCT4-EGFP− melanoma cells, thus suggesting that OCT4 expression plays a crucial role in maintaining cancer stem-like properties in melanoma-derived cells. In embryonic stem cells processes that govern development, self-renewal and cell fate are mainly regulated by the Wnt, Notch and Hedgehog pathways. These pathways are also known to be frequently deregulated in many types of cancers. Our data provide evidence that only a small subpopulation of melanoma cells is characterized by aberrant developmental pathways. These OCT4+ cells comprise both, the characteristics of stem-like cells and malignant tumors, thus defining CSCs in melanoma. In conclusion, Notch, Wnt and Hedgehog pathways might be ideal targets to eradicate CSCs from the tumor, thus preventing regrowth and metastasis. In combination with classical chemotherapeutic agents this might be an effective therapeutic strategy to circumvent the failure of conventional 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 A59.
Abstract A63: Targeting cancer stem cells with small molecule inhibitors.
Authors: Kohlhof Hella , Regenbrecht Christian , Welte Yvonne , Zybarth Gabriele , Leban Johann , Zaja Mirko , Kronthaler Kerstin , Schrepfer Sabine , Baumgartner Roland , Vitt Daniel
Published: June 2012

4SC AG develops a mini portfolio of small molecule inhibitors to target cancer stem cells. The portfolio includes a Wnt inhibitor, a class I specific HDAC inhibitor and a specific metabolism inhibiting agent. The Wnt inhibitor targets the self-renewal capacity of cancer stem cells and has been shown to prevent anchorage independent growth of CD133+ and unsorted patient derived melanoma cells and other cell lines. Additionally, it inhibits spheroid formation of colon cancer cells and embryonic carcinoma cells in a low μM range. From gene expression profiling experiments it seems as if the HDAC inhibitor and the metabolism inhibiting agent induce differentiation in cancer stem cells and their inhibitory potency has been shown in CD133+ and unsorted patient derived melanoma cells, respectively. The metabolism inhibiting agent has been shown to reduce the expression of NANOG on the mRNA level. Nanog is one of the core transcription factors that regulate and maintain stemness. Currently a comprehensive characterization of the therapeutic potential especially on cancer stem cells is ongoing. A specific focus of our research is on the mechanisms involved in inhibiting self-renewal or inducing differentiation of cancer stem cells, in vitro and in vivo.

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 A63.
Abstract A65: Targeting the defective decatenation checkpoint in melanoma.
Authors: Brooks Kelly M. , Ranall Max , Pavey Sandra , Mukhopadhyay Pamela , Wigan Matthew , Giles Nicole , Gabrielli Brian
Published: June 2012

In Australia melanomas account for 10% of all reported cancers and 3% of cancer mortalities. Current treatments offer <25% response rate and <8 months improved survival. Cancers frequently demonstrate defects in the cell cycle, particularly the checkpoint mechanisms. Loss of these protective mechanisms may provide opportunities for selectively targeting cancer cells. One G2 phase checkpoint, the decatenation checkpoint, ensures that entangled sister chromatids can be segregated with high fidelity during cellular replication. Topoisomerase II is responsible for resolving these tangles.

Using ICRF-193, an inhibitor of Topoisomerase II, a panel of melanoma cell lines were investigated for decatenation checkpoint function. This analysis revealed that 17/25 melanoma cell lines possessed a defective decatenation checkpoint, suggesting it to be a common defect. Treatment with ICRF-193 caused checkpoint defective cells to undergo an aberrant mitosis, resulting in accumulation of cells exhibiting abnormal nuclear morphologies, while checkpoint functional cells remained relatively unaffected. Comparative gene expression analysis revealed differential expression of cell-division and cell-death associated genes, suggesting adaptive changes compensating for checkpoint failure. A strong gene-expression signature for the checkpoint defect was also observed in this analysis and potential bio-markers are being investigated for use identifying this defect in tumors. A synthetic lethality siRNA screen of the kinome (∼700 genes) was carried out to identify genes/pathways crucial to the viability of cell lines with a defective decatentation checkpoint. This screen identified 10 potential hits, many involved in PI3Kinase signaling. We have validated this pathway as a selective target.

This research has shown that the defective decatenation checkpoint is a viable target in melanoma. Using targets identified by the synthetic lethality screens and bio-markers to the defect in tumors, it should be possible to identify tumors most likely to be sensitive to drugs targeting the checkpoint defect, providing effective and selective therapeutics for the treatment of metastatic melanoma.

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 A65.
Abstract A68: MCT-1 oncoprotein induces chromosomal aberrations through impairing centrosomal and mitotic-spindle checkpoints.
Authors: Chen Yen-An , Shih Hung-Ju , Chu Kang-Lin , Choy Chik-On , Wu Pei-Hsuan , Wu Meng-Hsun , Hsu Hsin-Ling
Published: June 2012

Centrosome amplification and chromosome abnormalities are frequently detected in neoplasia and during tumorigenesis; however, the mechanism underlying these defects is still unclear. We here identify that the translational regulator, MCT-1, is a novel proto-oncoprotein located at the spindle-organizing apparatus. Decrease of cellular MCT-1 level results in intercellular bridging, chromosome mis-congregation, cytokinesis delay, and post-mitotic apoptosis. MCT-1 induction alongside p53 deficiency (MCT-1-p53) synergistically deregulates mitotic checkpoint kinases and induces Cyclin E protein degradation. These are implicated with increased frequency of cytokinesis failure, multi-nucleation, and centrosome amplification in the subsequent cell cycle. Consistent with the incidences of polyploidy and aneuploidy are progressively induced by the continued cell cultivation and further promoted by the disruption of microtubule structure, array CGH analysis confirms that the pronounced chromosome amplifications and deletions occur on MCT-1-p53 cellular background. This is the first demonstration that MCT-1 plays an important role in the regulation of centrosome integrity and mitotic progression.

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 A68.