bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract A93: Topical ISC-4 for the prevention of melanoma
Authors: Sharma Arati , Nguyen Natalie , Nguyen Nhung , Sharma Arun , Desai Dhimant , Huh Sung Jin , Amin Shantu , Robertson Gavin P.
Published: June 2012

New strategies are urgently needed to prevent development of melanoma. Currently, surgical excision is the mainstay for eliminating early melanocytic lesions or preventing development of more aggressive cancer. However, use of sunscreen or body lotions containing topical agents with chemopreventive efficacy could be potentially useful for preventing cancer development. Therefore, novel topical chemopreventive agents with negligible systemic toxicity to prevent melanocytic lesion development would be a highly significant. In order to meet this unmet medical need, potent anti-melanoma agents called isoselenocyanates (ISC) have been developed from naturally occurring isothiocyanates (ITC), which are derived from plants. In these agents, sulfur has been replaced with selenium and the alkyl side chain has been lengthened from 1 or 2 to 4 or 6. The chemopreventive efficacy of ISC-4 for preventing melanoma development was evaluated in a human skin melanoma model containing early or advanced stage melanocytic lesion cell lines. Cumulative topical application of ISC-4 resulted in a >75% reduction in melanoma nodule developed in 3-D human skin reconstructs. Histological examination of drug treated skin reconstructs confirmed the chemopreventive efficacy without any obvious damage to skin cells. Furthermore, topical application of ISC-4 also effectively prevented melanoma tumor development in animals by ∼70% at 3. 83 mM with negligible toxicity compared to vehicle control. Mechanistically, ISC-4 decreased melanoma tumorigenesis causing an 3-fold increase in apoptosis by reducing pAkt3 and pPRAS40 levels and triggered caspase-3/7 activity. Furthermore, ISC-4 treatment reduced G0–G1 phase cells (30–40% decrease), and increased G2-M population by 50–60%. A 15-fold increase in the sub-G0–G1 cell population was also observed upon ISC-4 treatment compared to vehicle control treated cells. Thus, ISC-4 is a potent selenium-containing topical chemopreventive agent with significant potential to prevent melanocytic lesion development.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A93.
Abstract B100: The expression of thioredoxin-interacting protein (Txnip): Modulators, mechanisms and functions
Authors: Yu Faxing , Luo Yan
Published: June 2012

Thioredoxin interacting protein (Txnip) is a multifunctional protein involved in regulation of cell cycle events and cellular metabolism; the expression of the Txnip gene is down-regulated in a large range of cancer cells and up-regulated in diabetic and pre-diabetic patients. Therefore, Txnip might be a link between metabolism and cancer development, and the study of regulatory mechanism(s) that governs Txnip expression has important clinical relevance.

The expression of Txnip is induced by glucose, which is mediated by an earlier defined carbohydrate response element (ChoRE) on Txnip promoter and its associated transcription factors, MondoA (or its homolog, ChREBP) and Max-like protein X (MLX). Here, we show that the transcription of the Txnip gene is induced by an array of adenosine-containing molecules, of which an intact adenosine moiety is necessary and sufficient. When cells are treated with adenosine-containing molecules, the glucose uptake is inhibited and cell cycle progression is retarded, probably attributed to enhanced Txnip expression. The induction of Txnip expression by adenosine-containing molecules is in a glucose-dependent manner, and MondoA and MLX are known to convey stimulatory signals from extracellular molecules to the Txnip promoter. Therefore, the regulatory role of adenosine-containing molecules is exerted via amplifying glucose signaling, hence suggesting that these molecules may modulate the kinetics of glucose homeostasis. To gain more knowledge about the regulation of Txnip expression, we have also studied the underlying regulatory mechanisms of glucose and adenosine-containing molecules on Txnip expression in details. An additional ChoRE on the promoter of Txnip gene has been identified, and this ChoRE is able to recruit MondoA and MLX in a similar fashion as the previously identified ChoRE in vitro and in vivo. Both ChoREs function cooperatively to mediate optimal Txnip expression under glucose or adenosine-containing molecules treatment. However, these two ChoREs are not sufficient to mediate the induction of Txnip expression by glucose or adenosine-containing molecules, and two CCAAT boxes, both can recruit nuclear factor Y (NF-Y) to the Txnip promoter, are also required for the induction. We also found that the function of ChoREs and associated factors is contingent on tandem CCAAT boxes, in that the occupancy of the Txnip promoter by the CCAAT box-associated NF-Y is a prerequisite for efficacious recruitment of MondoA/MLX to ChoREs under glucose stimulation. Such a strategy suggests a synergy between NF-Y and MondoA/MLX in enhancing Txnip expression, which leads us to propose a model for the glucose-dependent Txnip expression mediated by dynamic chromatin changes in response to diverse physiological inducers.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B100.
Abstract B105: Axl is an essential epithelial-to-mesenchymal transition-induced regulator of breast cancer metastasis and patient survival
Authors: Gjerdrum Christine , Tiron Crina , Høiby Torill , Stefansson Ingunn , Haugen Hallvard , Sandal Tone , Collet Karin , Li Shan , McCormack Emmet , Gjertsen Bjørn Tore , Micklem David , Akslen Lars , Glackin Carlotta , Lorens James
Published: June 2012

Metastasis underlies the majority of cancer-related deaths. Hence, furthering our understanding of the molecular mechanisms that enable tumor cell dissemination is a vital health issue. Epithelial-to-mesenchymal transitions (EMT) endow carcinoma cells with enhanced migratory and survival attributes that facilitate malignant progression. Characterization of EMT effectors is likely to yield new insights into metastasis and novel avenues for treatment. We show that the presence of the receptor tyrosine kinase Axl in mammography-detected primary breast cancers independently predicts strongly reduced overall patient survival, and matched patient metastatic lesions show enhanced Axl expression. We demonstrate that Axl is strongly induced by epithelial-to-mesenchymal transition in pre-malignant mammary epithelial cells that establishes an autocrine signaling loop with its ligand, Gas6. Using epi-allelic RNA interference analysis in metastatic breast cancer cells we delineated a distinct threshold of Axl expression for mesenchymal-like in vitro cell invasiveness, and to form tumors in foreign and tissue engineered microenvironments in vivo. Importantly, Axl knockdown completely prevented the spread of highly metastatic breast carcinoma cells from the mammary gland to lymph nodes and several major organs, and increased overall survival, in two different optical imaging-based experimental breast cancer models. Thus, Axl represents a novel downstream effector of tumor cell EMT that is required for breast cancer metastasis. The detection and targeted treatment of Axl-expressing tumors represents an important new therapeutic strategy for breast cancer.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B105.
Abstract B117: Expression of c-MET and related oncogenic signals in formalin-fixed paraffin-embedded human tumors
Authors: Cousens Laura , Waghorne Carol , Rodig Scott J. , Gu Xiubin , Zhao Xiaolan , Yu Yi , Chang Edward , Chan Thomas C.K.
Published: June 2012

Background: Hepatocyte growth factor (HGF) and its receptor tyrosine kinase c-MET are often dysregulated in cancer. Stimulation of the HGF/MET signaling pathway can lead to increased cell migration, proliferation, and angiogenesis and is associated with highly invasive malignant cancers. Oncogenic activation of the c-MET pathway occurs by gene amplification, mutation, or autocrine/paracrine stimulation.

Methods: We have examined the expression of total c-MET and the active, phosphorylated forms of MET and associated cellular signals in a panel of solid human tumors by immunohistochemistry (IHC).

Results: Total c-MET is expressed in a wide variety of human tumors including breast, lung, colorectal, pancreatic, liver, glial and testicular cancers. Phospho-MET (p-c-MET) and phospho-focal adhesion kinase (pFAK, a downstream signal of MET) are expressed in a subset of c-MET expressing tumors. Table 1 includes preliminary results.

Conclusions: Detection of p-c-MET and p-FAK in archival formalin fixed paraffin embedded tumors by IHC staining is possible, and we have identified a subset of tumors where HGF/MET activation is evident. These tumors would be an important indication for c-MET targeted antitumor therapies.

Table 1 Percentage of human tumors that express c-MET biomarkers Positive IHC Staining Tumors Total Tumor Type c-MET (N) p-c-MET (N) p-FAK (N) breast 96% (23) 61% (23) 65% (23) lung (NSCLC) 75% (36) 50% (36) 61% (36) colorectal 85% (20) 50% (20) ND pancreas 85% (55) 64% (53) 58% (55) Liver 91% (22) 14% (22) 18% (22) glioma 83% (18) 39% (18) 39% (18) Testis 65% (30) 23% (30) 45% (28) ND = not done

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B117.
Abstract B130: Monoclonal antibody (mAb)-induced down-regulation of the RON receptor tyrosine kinase impairs malignant phenotypes of colon cancer cells
Authors: Li Zhuzhu , Guin Sunny , Padhyep Snehal , Yao Hangping , Wang Monghai
Published: June 2012

Targeting receptor tyrosine kinases (RTK) with specific mAbs disrupts oncogenic signals and diminishes tumorigenic activities. The RON receptor tyrosine kinase is a member of the MET proto-oncogene family and contributes to motile/invasive phenotypes of colon cancer cells. Here, we studied mAb-induced down-regulation of RON in modulating tumorigenic phenotypes of colon cancer cells. Three mAbs (Zt/g4, Zt/c9 and Zt/f2), recognizing different epitopes in the RON extracellular sequences, were used in various in vitro experiments. Colon cancer SW620 and other cells were used as the model. Treatment of SW620 cells individual mAbs results in transient RON phosphorylation within minutes. However, persistent treatment of cells with Zt/g4 or other mAb causes the down-regulation RON expression as evident by Western blot and cell surface fluorescent analyses. The effect of mAb was in both concentration and time-dependent manners. These activities were not related to antigenic epitopes recognized by individual mAb but highly specific to RON because MET or EGFR expression was not affected. Down regulation of RON impairs intracellular signaling events. Phosphorylation of Erk1/2 and AKT was dramatically reduced after Zt/g4 and other mAb treatment, indicating that the anti-RON mAb has the ability to disrupt downstream signal cascades. Functional studies showed that treatment of SW620 cells with anti-RON mAb affects tumor cell growth in soft agar. It also increases the sensitivity of colon cancer SW620 cells towards chemoagent gemcitabine. In this case, the cytotoxicity of SW620 cells treated with mAbs was significantly increased with reduced IC50 of gemcitabine. In conclusion, our results demonstrated that the persistent treatment of cancer cells with antibodies specific to the RON extracellular domains results in down-regulation of RON expression in colon cancer cells. The reduced RON expression is accompanied with the impaired signaling events and diminished tumorigenic activities. Thus, anti-RON mAb directed targeting could have therapeutic implication for controlling malignant phenotypes of cancer cells (*supported in part by NIH R01 grant Ca91980 and Amarillo Area Foundation of Texas)

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B130.
Abstract B131: Enhanced therapeutic effect of combined treatments with h7C10, a humanized antibody against insulin-like growth factor-1 receptor, and chemotherapeutic agents: In vitro results on MCF-7 cell line
Authors: Klinguer-Hamour Christine , Lokteff Maryline , Lepecquet Anne-Marie , Goetsch Liliane , Corvaia Nathalie
Published: June 2012

IGF-1 receptor (IGF-1R) plays a key role in the development of numerous tumors. Blockade of IGF-1R axis using monoclonal antibodies constitutes an interesting approach to inhibit tumor growth. We have previously described h7C10 (also named MK-0646), a humanized anti-IGF-1R Mab, that exhibits a potent anti-tumor activity both in vitro and in vivo. It blocks IGF-1 and IGF-2 induced signaling and blocks in vivo tumor growth of IGF-IR expressing tumors. In this report, we examined the in vitro effects of this selective IGF-1R Mab in combination with a panel of chemotherapeutic agents. The effect of drugs and h7C10 on the growth of human breast cancer cell line MCF-7 was determined by 3H-thymidine incorporation in DNA. The combined effect of drugs and h7C10 on MCF-7 cell line was evaluated by the combination index (CI) analysis method described by Chou and Talalay. We showed that the combination of h7C10 with a panel of drugs namely, paclitaxel, docetaxel, doxorubicin and gemcitabine induced synergistic inhibitory effects on MCF-7 breast cancer cell proliferation in vitro.

These findings demonstrated that h7C10 combined with established cancer therapeutics is highly effective against cancer cells that expressed IGF-1R and support clinical evaluation of h7C10 in combination with these drugs in the treatment of human cancers.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B131.
Abstract B132: Enhanced therapeutic effect of combined treatments with h7C10, a humanized antibody against insulin-like growth factor-1 receptor, and chemotherapeutic agents in xenograft models
Authors: Beau-Larvor Charlotte , Akla Barbara , Lepecquet Anne-Marie , Corvaia Nathalie , Goetsch Liliane
Published: June 2012

IGF-1 receptor (IGF-1R) plays a key role in the development of numerous tumors. Blockade of IGF-1R axis using monoclonal antibodies constitutes an interesting approach to inhibit tumor growth. We have previously described h7C10, a humanized anti-IGF-1R Mab, that exhibits a potent anti-tumor activity both in vitro and in vivo. It blocks IGF-1 and IGF-2 induced signaling, inhibits cell proliferation and colony formation, induces cell cycle arrest and promotes IGF-1R degradation. In this report, a panel of combinations of h7C10 with chemotherapeutic drugs were tested in vivo in xenograft models based on preliminary studies performed in vitro using the method described by Chou and Talalay.

Our results confirmed a significant benefit of in vivo combinations of h7C10 with doxorubicin, docetaxel and paclitaxel. Data were less clear when h7C10 was combined to gemcitabine. An interesting combined effect was also noticed in mice treated by both h7C10 and 5-FU.

These findings demonstrate that h7C10 combined with established cancer therapeutics is highly effective in vivo against tumors expressing IGF-1R and support clinical evaluation of h7C10 in combination with these drugs for the treatment of human cancers.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B132.
Abstract B14: The broad spectrum antitumor efficacy and tolerability of the RTK inhibitor, linifanib (ABT-869) alone and in combination with various cytotoxic therapies
Authors: Donawho Cherrie K. , Bukofzer Gail , Ellis Paul A. , Montgomery Debra A. , Rodriguez Luis E. , Wang Yi-Chun , Dai Yujia , Davidsen Steven K. , Frost David J. , Palma Joann P.
Published: June 2012

The RTKI, linifanib (ABT-869), is a potent inhibitor of vascular endothelial growth factor (VEGF) as well as platelet-derived growth factor (PDGF) receptors and is currently in Phase 1 – 2 clinical trials. It exhibits potent inhibition of mutant kinases, such as fms-like tyrosine kinase 3 (FLT3), c-kit (CD117) and colony stimulating factor-1 receptor (CSF1R). Hepatocellular carcinoma (HCC), renal cell carcinoma (RCC) and prostate carcinoma (PC) are known hypervascular/angiogenic tumor types. The role of the vascular process in HCC tumor progression, HIF-mediated induction of VEGF in many VHL-deleted RCCs, as well as PDGF expression in PC, highlight the potential of anti angiogenic therapy as an attractive therapeutic strategy. Previous studies have shown potent anti-tumor and anti-angiogenic activity against a spectrum of xenografts (HCC, RCC, PC, fibrosarcoma and NSCLC). Thus, the ability of linifanib to inhibit tumor growth in known hypervascular/angiogenic tumors suggests on-mechanism activity. Linifanib was well tolerated in the clinic and activity was observed in HCC, NSCLC, and renal carcinoma. The ability to be used as combination treatment regimen without excessive impact on tolerability is of great interest to increase clinical efficacy and positively impact patient outcomes. In this study, we sought to evaluate the activity of linifanib in a broad spectrum of xenograft models (breast, colon, HNSCC, liver, NSCLC, SCLC, ovarian and pancreatic), alone or in combination with various cytotoxic therapies (carbotaxol, irinotecan, radiation, 5-FU/leucovorin, gemcitabine and oxaliplatin). The doses used for ABT-869 were clinically relevant. For the cytotoxic therapies, doses were determined both by clinical schedules and tolerability as single agents in mice. In all studies, linifanib (25, 12.6, 6.25, p.o., b.i.d.x21) was well tolerated alone or in combination with cytotoxic therapy and demonstrated no exacerbation of cytotoxic agent toxicity as assessed by animal health observations. Significant anti-tumor efficacy (measured by percent tumor growth inhibition, % TGI) was observed with linifanib monotherapy and the combination with cytotoxic therapies showed significant efficacy over linifanib or cytotoxic therapies alone. Further, lower doses of linifanib in combination with cytotoxic agents achieved similar efficacy as higher doses of linifanib alone. These studies demonstrate the significant activity of linifanib or linifanib in combination with multiple cytotoxic therapies in a spectrum of models representing multiple histological types and provide a rationale for future clinical investigations.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B14.
Abstract B145: Highly selective pyrazolopyrimidine mTOR inhibitors with profound in vivo antitumor activity
Authors: Zask Arie , Kaplan Joshua , Curran Kevin , Verheijen Jeroen C. , Richard David J. , Brooijmans Natasja , Bennett Eric , Lucas Judy , Toral-Barza Lourdes , Hollander Irwin , Gibbons James J. , Abraham Robert T. , Ayral-Kaloustian Semiramis , Mansour Tarek S. , Yu Ker
Published: June 2012

The mammalian target of rapamycin (mTOR) is an important target for cancer chemotherapy due to the deregulation of its signaling pathway in a wide spectrum of human tumors. mTOR exists in at least two functional protein complexes: mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). While rapamycin and its analogs (rapalogs) inhibit only mTORC1, ATP-competitive inhibitors of mTOR target both mTORC1 and mTORC2 and therefore have the potential for improved anticancer efficacy. We have previously reported on the pyrazolopyrimidine series of ATP-competitive mTOR inhibitors (J. Med. Chem. 2009, 52, 5013 – 5016). We now report that derivatization of the morpholine ring in these inhibitors leads to greatly enhanced mTOR selectivity versus PI3K. Selective mTOR inhibitors have the potential to achieve a higher therapeutic index in the clinic due to better tolerability. Testing these inhibitors in tumor cells and evaluating the most potent analogs in human tumor xenograft models in the nude mouse led to the identification of WYE-125132, a candidate for clinical development. WYE-125132 is also selective versus a wide range of other kinases including the closely-related PIKKs. Detailed structure activity relationships in the pyrazolopyrimidine series will be presented. In conclusion, modification of the morpholine ring of a series of pyrazolopyrimidines leads to analogs with enhanced mTOR selectivity over PI3K and potent efficacy in human tumor xenograft models in the nude mouse.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B145.
Abstract B146: XL388: A novel, selective, orally bioavailable mTORC1 and mTORC2 inhibitor that demonstrates pharmacodynamic and antitumor activity in multiple human cancer xenograft models
Authors: Miller Nicole
Published: June 2012

Background: The mTOR kinase exists in at least two distinct kinase complexes, mTORC1 and mTORC2 which collectively regulate cell growth, proliferation, survival, autophagy, and angiogenesis. Derivatives of the macrolide antibiotic rapamycin have shown encouraging clinical activity as cancer therapeutics; however, these molecules only partially inhibit mTORC1 and mTORC2 activity. Here we provide the first pre-clinical description of XL388, a selective and orally bioavailable small-molecule ATP-competitive inhibitor of mTORC1 and mTORC2 that demonstrates pharmacodynamic and anti-tumor activity in multiple human cancer xenograft models.

Methods: The in vitro inhibition of mTORC1 and mTORC2 by XL388 was assayed using purified, recombinant mTOR/G L/raptor kinase and mTORC2 immunoprecipitated from cells, respectively. mTORC1 and mTORC2 substrate phosphorylation and pharmacodynamic activity were measured by phosphospecific immunoblot of lysates prepared from XL388-treated cancer cells or from xenograft tumor lysates prepared from XL388-treated animals. Cancer cell viability was determined by measuring cellular ATP concentrations or the disruption of cell membrane integrity. Synergy of XL388 with chemotherapeutics was measured by the combination index (CI) method as established by Chou and Talalay (1984). XL388 in vivo efficacy and pharmacodynamic studies were performed in nude mice bearing human tumor xenografts and dosed orally with XL388.

Results and Conclusions: XL388 inhibits mTORC1 and mTORC2 in vitro with IC50 values of 8 nM and 166 nM, respectively. In MCF-7 cells, XL388 blocks mTORC1 phosphorylation of p70S6K (T389) with an IC50 value of 94 nM and blocks mTORC2 phosphorylation of AKT (S473) with an IC50 value of 350 nM. In vitro, XL388 inhibits the viability of solid and hematopoietic tumor cell lines when assayed as a single agent. XL388 also synergizes with chemotherapeutics in cell-based assays to block cell viability. When dosed orally once daily in mice, XL388 shows robust anti-tumor activity in multiple xenograft models including > 100% tumor growth inhibition in the MCF-7 xenograft model. Taken together, these data indicate that XL388 may have broad utility in cancer therapy both as a single agent and in combination with chemotherapeutics.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B146.
Abstract B149: Phase I, open-label, dose-escalating clinical and pharmacokinetic study of PM00104 administered weekly resting every fourth week, intravenously, over 1 hour to patients with advanced malignant solid tumors or lymphoma
Authors: Plummer Ruth , Coronado C. , Massard Christophe , Calvert AH , Margetts J. , Bahleda Rastilav , Prados R. , Kahatt C. , Soria Jean-Charles
Published: June 2012

Background: PM00104 (Zalypsis®) is a new synthetic alkaloid related to jorumycin. Preliminary data on mechanism of action suggested DNA-binding properties acting at minor groove and effects on the cell cycle (phase S). PM00104 shows a broad spectrum of activity against solid tumors both in vitro (bladder, gastric, kidney, melanoma, pancreas, prostate, sarcoma, thyroid, leukemia and lymphoma cell lines) and in vivo (xenografts of breast, gastric, prostate, and renal tumor).

Methods: Patients (n=49) with metastatic or advanced solid tumors were enrolled in a phase I, open-label, dose-escalating clinical and pharmacokinetic study of PM00104 administered weekly resting every fourth week, intravenously, over 1 hour. The starting dose was 0.75 mg/m2 and the study followed an accelerated escalation design from 0.75 to 3.037 mg/m2 distributed in 9 dose levels

Results: Median age of patients (pts) was 58 (range, 22–76 y), 29 pts were males. The median ECOG was 1 (0–2). The most frequent cancer types were colorectal, gastric, esophageal and melanoma tumors (n=15/5/4/4). Most patients were heavily pretreated with a median of 3 (1–9) prior lines. A median of 2 cycles of Zalypsis (1–8) were given to each pt. Common mild (G1–2) toxicities were asthenia, anorexia, nausea/emesis, stomatitis, weight decreased, headache and hypotension. The highest dose achieved was 3.035 mg/m2, where 2 pts had DLTs: one had G4 asthenia and G3 nausea, and the other had G4 neutropenia and thrombopenia. At the next lowest level (2.5 mg/m2) 3 pts had DLTs (G3 asthenia and nausea in one pt; febrile neutropenia, G4 thrombopenia and G3 anemia in one pt, and G1 neutropenia and thrombopenia that resulted in two skipped doses in the third pt). Thus, this dose level was declared the MTD. The RD was 2 mg/m2, at which 24 pts were treated and only one pt had DLT (G4 asymptomatic lipase increase). Preliminary PK data showed a relatively prolonged half-life (up to 60 h, with a median value at the RD of 21 h), a wide distribution and high inter-patient variability. Efficacy data showed prolonged stabilization > 3 months in 12 pts, mostly with gastrointestinal tumors (colon, pancreas, esophageal and gastroesophageal junction, n=1 each)

Conclusions: PM00104 shows acceptable safety and tolerability profile and prolonged stabilization (SD ≥3 months) in different tumor types. DLTs were manageable hematological and gastrointestinal toxicities. The RD for phase II studies is 2 mg/m2 weekly.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B149.
Abstract B165: Abl kinase myristate-site inhibitor, mechanism and application
Authors: Zhang Jianming , Gray Nathanael S. , Sim Taebo , Choi Yongmun , Deng Xianming , Adrián Francisco , Li Allen , Sun Frank , Liu Yi , Okram Barun , Warmuth Markus , Iacob Roxana , Engen John , Powers John , Azam Mohammad , Daley George , Jahnke Wolfgang , Cowan-Jacob Sandra , Manley Paul
Published: June 2012

We recently reported a new class of allosteric inhibitors, exemplified by GNF-2, that selectively inhibit the proliferation of Bcr-Abl dependent cells. Here we demonstrate, using selection for resistant Bcr-Abl clones, site-directed mutagenesis, affinity chromatography, and steady-state kinetics, that GNF-2 inhibits Bcr-Abl kinase activity by binding to the Abl myristate binding pocket and stabilizes the auto-inhibited conformation. We demonstrate that the 2-hydroxyethyl amide analog of GNF-2, GNF-5, in combination with ATP-competitive inhibitors such as nilotinib and dasatinib can overcome the T315I “gatekeeper” mutant of Bcr-Abl which is resistant to all clinically approved Bcr-Abl inhibitors. These studies demonstrate that targeting of the Abl myristate binding site can provide an important pharmacological means to overcome mutations that cause resistance to ATP-competitive inhibitors.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B165.
Abstract B17: Fsn0503: A novel cathepsin S-specific antibody that blocks tumor invasion and angiogenesis
Authors: Ward Claire , Burden Roberta E. , Gormley Julie , Small Donna , Jacquin Thomas , Gazdoiu Mihaela , Bicknell Roy , Johnston James A. , Scott Christopher J. , Olwill Shane A.
Published: June 2012

Cathepsin S is a member of the papain family of cysteine proteases, which is normally localised in the lysosomes of antigen presenting cells. However cathepsin S has also been shown to be overexpressed and secreted in the tumor microenvironment of astrocytoma, breast, colorectal and prostate carcinomas. Upon secretion into the tumor microenvironment, it facilitates extracellular matrix remodelling, a process important for cancer cell invasion and angiogenesis. We have developed Fsn0503, a novel monoclonal antibody that targets and inhibits cathepsin S. We have demonstrated that Fsn0503 attenuates invasion of a range of invasive tumor cell lines, through inhibition of the hydrolysis of extracellular matrix components mediated by cathepsin S. Cathepsin S has also been implicated in promotion of endothelial cell movement during angiogenesis and in agreement with this we have shown that Fsn0503 significantly blocks HUVEC tube formation and rat aorta vessel outgrowth. Furthermore, these findings were replicated in vivo where administration of Fsn0503 impaired tumor growth and neovascularisaton in HCT116 xenografts. Our data indicates that Fsn0503 may yield significant clinical utility in the treatment of invasive and angiogenic tumors.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B17.
Abstract B173: Synergistic interaction between CENP-E inhibitor GSK923295 and MEK inhibitor GSK1120212
Authors: Degenhardt Yan Y. , Zhang Xiping , Moy Christopher , Conway Theresa , Mcneil Liz , Jing Junping , Greshock Joel , Wegrzyn Ronald , Yin Holy , Mousses Spyro , Wooster Richard , Bachman Kurtis
Published: June 2012

Centromere protein-E (CENP-E) is a mitotic kinesin that is required during mitosis for metaphase chromosome alignment. GSK923295 (′295) is a potent and specific inhibitor of human CENP-E currently being developed as a next generation antimitotic drug for the treatment of cancer. It has shown a broad spectrum of anti-cancer activity in vitro and in vivo. A siRNA library screen targeting the ‘druggable genome’ identified multiple MAPK pathway genes as sensitizers to ′295, including BRAF and ERK1. Since the MEK protein plays an important role in the MAPK pathway, combination studies between GSK MEK inhibitor GSK1120212 (′212) and ′295 were performed in cancer cell lines from different tissue origins, and the combination effect was evaluated based on three different criteria: Excess over Single Highest Agent (EOHSA), Bliss, and Combination Index (CI).. Synergistic response was observed in 5/6 colon cancer cell lines, 5/15 lung cancer cell lines, and 6/8 pancreas cancer cell lines. Additionally, the combination of ′212 and ′295 treatment induced a much stronger apoptotic response than either drug alone in two colon cancer cell lines. These data suggest that combining MEK and CENP-E inhibitors might improve clinical efficacy over either as a single agent in selected tumors.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B173.
Abstract B187: Role of aminopeptidase N in the activation of the alkylating prodrug J1
Authors: Wickström Malin , Viktorsson Kristina , Lundholm Lovisa , Aesoy Reidun , Nygren Helen , Sooman Linda , Fryknäs Mårten , Lewensohn Rolf , Larsson Rolf , Gullbo Joachim
Published: June 2012

Aminopeptidase N is a zinc-dependent metalloprotease which is involved in cancer invasion, metastasis and angiogenesis, and considered as a suitable target for anti-cancer drug design.

This in vitro study demonstrates a role of APN in the activation of J1, a prodrug of the alkylating agent melphalan, and subsequently, its cytotoxic activity. J1 (melphalanyl-L-p-fluorophenylalanyl ethyl ester) is currently in a phase I/II clinical trial. Previous studies have shown that J1-mediated cytotoxicity is dependent on hydrolytic activity of tumor cells. In this report we have analyzed potential peptidases and esterases of importance for release of free melphalan from J1. Exposure of tumor cell lines to J1 resulted in a significant increased level of free intracellular melphalan, at least ten-fold at Cmax, compared to exposure to melphalan at the same molar concentration. This efficient intracellular delivery could be inhibited in both magnitude and in time by bestatin, a broad spectrum inhibitor of the aminopeptidases, including the metalloproteinase aminopeptidase N (APN) and ebelactone A, an esterase inhibitor. These effects resulted, as expected, in decreased cytotoxic effects of J1. A specific role of APN in hydrolyzing J1 releasing free melphalan was demonstrated in vitro with pure APN enzyme. By using plasmid-based overexpression of APN or down regulation of endogenous APN with siRNA in different tumor cell lines we confirmed the involvement of APN in J1-mediated cytotoxic and apoptotic signaling. Given that APN is shown to be overexpressed in several solid tumors our data suggest that J1 may be activated in a tumor selective manner.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B187.
Abstract B198: The pattern of in vivo biological activity of Zalypsis® is different from that of trabectedin
Authors: Frapolli Roberta , Bello E. , Galmarini Carlos , Cuevas Carmen , Aviles Pablo M. , Guillen Maria José , D'Incalci Maurizio
Published: June 2012

Trabectedin is a tetrahydroisoquinoline molecule that was originally derived from the Caribbean marine tunicate Ectenaiscidia turbinata and is now produced by chemical synthesis. The compound is approved in the European Union and a number of other countries for use in patients with advanced soft tissue sarcomas. Zalypsis® (PM00104) is a novel synthetic tetrahydroisoquinoline structurally related to jorumycin. Both compounds have a similar A and B ring structures that bind DNA but differ in their C ring which protrudes out of DNA and is possibly relevant for the interaction with DNA binding proteins, including DNA repair proteins and transcription factors. In the present study, we characterized the in vivo antitumor activity compared to trabectedin. The antitumor activity of Zalypsis® was investigated in two murine models, M5076 reticulosarcoma and MNMCA1 fibrosarcoma, respectively metastasizing liver and lung. Zalypsis® (0.9 mg/kg) and trabectedin (0.15 mg/kg) were administered intravenously every week for three times (q7dx3). In both models Zalypsis® was very effective in inhibiting the primary tumors (T/C 18% and 20% respectively). In the case of MNMCA1, it was also effective against metastasis whereas it was inactive against liver metastasis of M5076 sarcoma. In the two experiments, trabectedin was very effective against metastasis although against M5076 sarcoma it was only marginally able to inhibit primary tumor growth (T/C 52%). In Cen3 tel sarcoma, of human origin, Zalypsis® was very effective with a T/C of 19% whereas trabectedin was essentially inactive (T/C 78%). In contrast Zalypsis® was less effective than trabectedin against HOC22 ovarian carcinoma. In summary it appears that Zalypsis® is biologically different from trabectedin when tested on in vivo tumor models, therefore its clinical development should not necessarily addressed to the same tumors that have shown sensitivity to trabectedin.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B198.
Abstract B2: Results of a phase 1b study of PTC299, a novel oral inhibitor of tumor VEGF expression, in patients with advanced cancer
Authors: Schwartz Gary , Miao Harry , Dickson Mark , Rodrigues Leslie , Llorente Mary , Cao Yen , Dials Heather , Darby Charles H. , Elfring Gary , Miller Langdon L.
Published: June 2012

Background: PTC299 is a novel, orally bioavailable, small molecule designed to inhibit the expression of tumor-derived VEGF and other angiogenic cytokines. In multiple xenograft models of human cancers, single-agent PTC299 decreases tumor and plasma VEGF levels and induces significant tumor regression or growth delay.

Methods: A Phase 1b study has been initiated with 3 stages, each using a classic 3+3 design. In Stages 1 and 2, patients received PTC299 monotherapy in repeated 6-week cycles (Stage 1: 4 weeks on and 2 weeks off therapy with body-weight-adjusted BID dosing; Stage 2: continuous therapy with unit BID or TID dosing). In Stage 3, unit dosing PTC299 is administered with docetaxel. In all stages, treatment was given until disease progression or unacceptable toxicity. Safety, PK, PD activity, and antitumor activity have been assessed.

Results: The study has enrolled 18 subjects (6 males, 12 females) with median [range] age 61 [31–81] years, ECOG performance status of 0 (n=10) or 1 (n=8), 9 different tumor types, and median [range] of prior therapies of 3 [0–8] to receive PTC299 in Stage 1 (n=12) and Stage 2 (n=6). Median [range] of time on treatment has been 2 [1–7] cycles. No maximum tolerated dose (MTD) has been established through the highest dose levels tested: Stage 1, 1.2 mg/kg/dose BID and Stage 2, 100 mg/dose TID. Adverse events have been infrequent, usually Grade 1, and have not generally been considered PTC299-related. No hypertension has been observed. PTC299 pharmacokinetics is generally dose proportional, with rapid appearance of drug in plasma, Tmax of ∼4 hours, and an effective t1/2 of ∼12 hours. From Day 1 to Day 28 in Stage 1 (Day 42 in Stage 2), there has been an increase in plasma concentrations at all dose levels, indicating accumulation (∼2 fold) when PTC299 is dosed continuously. PTC299 trough plasma concentrations have exceeded values of 0.5–1.0 g/mL associated with maximal activity in mouse xenograft models. PTC299 treatment has been associated with reductions in circulating angiogenic/inflammatory cytokines. Five of eighteen (28%) patients with thyroid cancer, melanoma, basal cell carcinoma, and chondrosarcoma (2) have remained on study with stable disease for 11+, 4.5, 5, 6+, and 4.5+ months respectively. A patient with papillary thyroid cancer has had a sustained tumor marker decrease of >50% lasting for >7 months.

Discussion: Single-agent PTC299 has been well tolerated, has achieved target plasma concentrations, and has shown evidence of pharmacodynamic and clinical activity. Accrual to Stage 3 with docetaxel has been initiated.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B2.
Abstract B201: Selective peptides for targeting EphA2 in cancer cells
Authors: Mitra Sayantan , Duggineni Srinivas , Koolpe Mitchell , Dail Monique , Zhu Xuejun , Huang Ziwei , Pasquale Elena B.
Published: June 2012

EphA2 receptor tyrosine kinase is highly overexpressed in tumors and is rapidly emerging as a promising new therapeutic target in cancer. Agents that target EphA2 have been shown to deliver cytotoxins/drugs selectively to cells expressing EphA2 and to decrease tumor growth and metastasis in animal models. We have recently isolated two peptides (YSA and SWL) by phage display that selectively target EphA2, and show the ability to deliver quantum dots and phage particles to cancer cells overexpressing EphA2. Furthermore, we elucidated the structure-activity relationship of one of the EphA2 agonistic peptides (YSA) by alanine scanning mutagenesis, characterized the SWL peptide and a series of related peptides, all of which retain their selectivity for EphA2. The selectivity of the peptides was determined by measuring the ability of the Eph receptors to bind immobilized peptide, and their potency was measured using an ELISA assay that monitors the inhibition of ephrin-A1 binding to EphA2. Our analysis revealed that only 4 of the 12 amino acids are critical for binding of YSA, and a 5-mer peptide derived from YSA retains selectivity for EphA2. All these peptides are reasonably stable in conditioned cell culture medium and rat liver microsomal preparations. In addition, at least some of these peptides show the ability to activate the EphA2 receptor inducing its phosphorylation and inhibit serum-induced phosphorylation of Akt and Erk1/Erk2 MAP kinases, which are key mediators in major oncogenic pathways. Therefore, our results indicate that in addition to selectively targeting cancer cells, these peptides can also lead to inhibition of oncogenic pathways.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B201.
Abstract B209: A self-emulsifying lipid suspension formulation enhances oral bioavailability of MP-470 in a randomized two-way crossover study in healthy male subjects
Authors: Joshi-Hangal Rajashree , Tang Chunlin , Roger Inloes , Shi Chongtie , Geddes Denice , Collier J. , Rodriguez Sara , Angelique Mittan , McLaughlin Heather , Fine Gil , Sanjeev Redkar , Choy Gavin
Published: June 2012

Background: MP-470 is an orally bioavailable multi-targeted tyrosine kinase inhibitor specifically designed to be a potent inhibitor of mutant c-Kit and PDGFR. MP-470 is also active as an inhibitor of DNA repair following chemotherapy. MP-470 has shown significant synergistic activity with DNA damaging chemotherapy in several xenograft models and in a phase I combination study. Oral bioavailability of this agent is limited by its solubility but not permeability. An in vitro/in vivo iterative approach was utilized preclinically for formulation selection. In the Beagle dog model, the oral bioavailability of MP-470 is enhanced to a maximum of 4–5-fold by formulating it in tocopherols and lipidic surfactants with self-emulsification ability (5%, dry powder vs. 20%, lipid suspension). Results presented herein are from a randomized two-way crossover pharmacokinetic (PK) study evaluating two formulations in healthy human subjects.

Methods: Twelve healthy male subjects 18–45 years with a body mass index of 18–35 kg/m2 were randomized in a 1:1 ratio to receive either a 100 mg dry powder capsule or 90 mg (3 × 30 mg) lipid suspension capsules in a fasted condition with 240 mL of water. Subjects receiving MP-470 90 mg lipid suspension capsules ingested all three capsules within one minute. The alternate formulation was administered after a 14 day washout. Plasma for PK assessments was collected and evaluated at pre-dose through hour 48 post MP-470 administration.

Results: Comparative PK results from twelve subjects are summarized below. Additional information will be summarized in the final presentation.

Conclusions: Solubility of the drug in the formulation vehicle alone plays a limited role in bioavailability enhancement; rather the ability of the formulation to keep the drug in solution after dilution in the GI tract seems critical. It is also possible that physiological mechanisms such as active transport or metabolism contribute to the enhanced absorption of MP-470 in the tocopherol-based vehicles. Consistent with preclinical Beagle dog data, the lipid suspension formulation offers an enhanced oral bioavailability over the dry powder formulation in healthy human subjects. The lipid suspension formulation will be utilized in future MP-470 clinical studies.

Pharmacokinetic summary - Dry Powder vs. Lipid Suspension Capsules Parameters 100 mg MP-470 Dry Powder Average (CV, n=12) 90 mg MP-470 Lipid Suspension Average (CV, n=12) Average % Increase* (95% CI) Cmax (ng/mL) 23.2 (71%) 132.6 (55%) 635% (420%, 851%) Tmax (h) 4.1 (44%) 1.7 (54%) - AUClast (ng·h/mL) 253 (54%) 488 (40%) 131% (85%, 177%)

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B209.
Abstract B210: Shed MET (sMET), VEGFA, and sVEGFR2 are markers of foretinib treatment in metastatic gastric cancer patients
Authors: Cecchi Fabiola , Liu Yuan , Gagnon Robert C. , Kallender Howard , Rabe Daniel C. , Shah Manish A. , Martin Anne-Marie , Bottaro Donald P.
Published: June 2012

Foretinib (formerly GSK1363089) is a small molecule multikinase inhibitor which includes inhibition of MET and VEGFR2. The ongoing phase II study, MET111643, is evaluating the safety and efficacy of 2 dosing schedules (continuous daily dosing and intermittent 5 days on/9 days off dosing) of foretinib as a single agent in pts with metastatic GC. An additional component of the study is to collect patient plasma samples before and during treatment with foretinib, to explore the potential pharmacodynamic effect and/or the modulation by foretinib of MET and VEGFR2.

Plasma samples were collected from 42 pts on the intermittent 5 days on/9 off foretinib schedule at baseline and prior to dosing on days 5, 15, 29, and 47. The plasma levels of sMET, HGF, sVEGFR2, and VEGFA were measured using the Meso Scale Discovery platform (MSD). These marker changes from baseline were analyzed at each time point using analysis of variance and their relationships with plasma concentrations of foretinib (PK) and clinical outcome (progression free survival [PFS] and RECIST response) were also examined.

Statistically significant increases from baseline of sMET at days 5, 15, 29, and 47 (p<.0001, p =.0344, p=.0353, p<.0001 respectively), VEGFA at days 5 (p<.0001) and 47 (p<.0001), and HGF at day 47 (p<.0001) were observed. Statistically significant decreases of sVEGFR2 at days 5, 15, 29, and 47 (all p<.0001) were also observed. Plasma VEGFA levels at day 5, 15, 29 are weakly correlated with PK (p=.033, p=.0138, p=.0165, respectively). Plasma sMET levels and changes from baseline at day 47 showed significant correlation with baseline tumor SLD (sum of longest diameter, R=0.54, p=0.0042; R=0.40, p=0.0443 respectively). Plasma VEGFA levels and changes from baseline at day 47 showed significant correlation with baseline tumor SLD (R=0.55, 0.44, respectively, p<0.01) and SLD at 8 weeks (R=0.64, 0.61, respectively, p<0.01). No correlation was observed between these four markers and PFS/RECIST response.

Changes in sMET, VEGFA, and sVEGFR2 levels were observed for both intermittent and daily dosing schedules in the gastric cancer study. Although SLD at 8 weeks did not change significantly from baseline in the GC study, plasma levels of sMET and VEGFA correlated positively with the week 8 magnitude of SLD. Hence plasma levels of sMET and VEGFA may reflect biological changes following foretinib treatment.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B210.
Abstract B211: Pralatrexate pharmacokinetics with intravenous administration to oncology patients
Authors: Venitz J. , Brar S.S. , Pronk G. J. , Huntington M. , Wilroy S. , O'Connor O.A. , Azzoli C.G.
Published: June 2012

Pralatrexate is a rationally designed antifolate with high affinity for reduced folate carrier-1 (RFC-1) and folyl poly-glutamyl synthetase (FPGS), resulting in efficient uptake and retention in cancer cells. Pralatrexate is being developed for various indications, including peripheral T-cell lymphoma (PTCL), cutaneous T-cell lymphoma, non-small cell lung cancer (NSCLC), and bladder cancer. Pralatrexate is a 1:1 racemic mixture of R- and S- diastereomers. Here we summarize the pharmacokinetics (PK) of pralatrexate from 3 Phase 1–2 studies. Pralatrexate was administered weekly or bi-weekly by IV push over 3–5 minutes (n=44) or as a 60-minute infusion (n=10) at doses ranging from 30–325 mg/m2. Serial plasma and urine samples, collected for up to 72 hours after dosing, were analyzed using a validated chiral LC-MS/MS method (lower limit of quantitation: 0.5 ng/ml). PK parameters were estimated by noncompartmental PK analysis. Clinical covariates were captured at screening to explore relationships with pralatrexate PK. The final PK results were based on 54 patients; 10 with relapsed/refractory PTCL (PDX-008), 38 with advanced NSCLC (PDX-007), and 6 with advanced solid tumors and concurrent docetaxel administration (PDX-99-083). The PK population was predominantlyWhite (81%) and balanced by gender (52% female). Age ranged from 24 to 77 (mean 60) years, body weight from 43–127 (77) kg, and estimated creatinine clearance from 53 to 130 (89) mL/min. Patients had adequate hepatic and hematologic function. Both pralatrexate diastereomers showed a similar multiphasic decline in plasma concentrations with a slow terminal phase (t½term = 12∓18h, PDX-008), likely reflecting the return from deep intracellular compartments. There was no evidence of PK nonlinearities in the dose range of 30–325 mg/m2. On a weekly or biweekly administration schedule, there was no significant drug accumulation in plasma over the first 2–6 doses. Other than expected changes in Cmax and Tmax, there were no apparent differences in PK between IV administration over 3–5 minutes and 60-minute infusion. Mean (COV) values (n=41−54) for total body clearance, renal clearance and volume of distribution at steady-state were 495 mL/min (57%), 125 mL/min (71%) and 106 L (121%) for the S-diastereomer and 218 mL/min (44%), 74 mL/min (60%) and 36 L (78%) for the R-diastereomer, respectively. These results suggest net renal tubular secretion, low hepatic extraction, and limited tissue distribution for both diastereomers. Consistent with approximately 30% contribution of renal excretion to overall drug elimination, creatinine clearance and age accounted for only 10% of the observed variability in total body clearance. In conclusion, this analysis suggests that pralatrexate PK is linear and dose-proportional across the dose range tested, with no accumulation with repeated dosing.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B211.