Optimization of Lipophilic Metalloporphyrins Modifies Disease Outcomes in a Rat Model of Parkinsonism.

Oxidative stress plays a crucial role in the pathogenesis of Parkinson disease (PD), and one strategy for neuroprotective therapy for PD is to scavenge reactive species using a catalytic antioxidant. Previous studies in our laboratory revealed that pretreatment of lipophilic metalloporphyrins showed protective effects in a mouse PD model. In this study, we optimized the formulations of these metalloporphyrins to deliver them orally and tested their efficacy on disease outcomes in a second species after initiation of an insult (i.e., disease modification). In this study, a pharmaceutical formulation of two metalloporphyrin catalytic antioxidants, AEOL11207 and AEOL11114, was tested for oral drug delivery. Both compounds showed gastrointestinal absorption, achieved high plasma concentrations, and readily penetrated the blood-brain barrier after intravenous or oral delivery. AEOL11207 and AEOL11114 bioavailabilities were calculated to be 24% and 25%, respectively, at a dose of 10 mg/kg via the oral route. In addition, both compounds significantly attenuated 6-hydroxydopamine (6-OHDA)-induced neurotoxic damage, including dopamine depletion, cytokine production, and microglial activation in the striata; dopaminergic neuronal loss in the substantia nigra; oxidative/nitrative stress indices (glutathione disulfide and 3-nitrotyrosine) in the ventral midbrain; and rotation behavioral abnormality in rats. These results indicate that AEOL11207 and AEOL11114 are orally active metalloporphyrins and protect against 6-OHDA neurotoxicity 1-3 days postlesioning, suggesting disease-modifying properties and translational potential for PD. SIGNIFICANCE STATEMENT: Two catalytic antioxidants showed gastrointestinal absorption, achieved high plasma concentrations, and readily penetrated the blood-brain barrier. Both compounds significantly attenuated dopamine depletion, cytokine production, microglial activation, dopaminergic neuronal loss, oxidative/nitrative stress indices, and behavioral abnormality in a Parkinson disease rat model. The results suggest that both metalloporphyrins possess disease-modifying properties that may be useful in treating Parkinson disease.

Antitumor activity of the polo-like kinase inhibitor, TAK-960, against preclinical models of colorectal cancer.

BACKGROUND: Polo-like kinase 1 (Plk1) is a serine/threonine kinase that is a key regulator of multiple stages of mitotic progression. Plk1 is upregulated in many tumor types including colorectal cancer (CRC) and portends a poor prognosis. TAK-960 is an ATP-competitive Plk1 inhibitor that has demonstrated efficacy across a broad range of cancer cell lines, including CRC. In this study, we investigated the activity of TAK-960 against a large collection of CRC models including 55 cell lines and 18 patient-derived xenografts. METHODS: Fifty-five CRC cell lines and 18 PDX models were exposed to TAK-960 and evaluated for proliferation (IC50) and Tumor Growth Inhibition Index, respectively. Additionally, 2 KRAS wild type and 2 KRAS mutant PDX models were treated with TAK-960 as single agent or in combination with cetuximab or irinotecan. TAK-960 mechanism of action was elucidated through immunoblotting and cell cycle analysis. RESULTS: CRC cell lines demonstrated a variable anti-proliferative response to TAK-960 with IC50 values ranging from 0.001 to > 0.75 µmol/L. Anti-proliferative effects were sustained after removal of drug. Following TAK-960 treatment a highly variable accumulation of mitotic (indicating cell cycle arrest) and apoptotic markers was observed. Cell cycle analysis demonstrated that TAK-960 treatment induced G2/M arrest and polyploidy. Six out of the eighteen PDX models responded to single agent TAK-960 therapy (TGII< 20). The addition of TAK-960 to standard of care chemotherapy resulted in largely additive antitumor effects. CONCLUSION: TAK-960 is an active anti-proliferative agent against CRC cell lines and PDX models. Collectively, these data suggest that TAK-960 may be of therapeutic benefit alone or in combination with other agents, although future work should focus on the development of predictive biomarkers and hypothesis-driven rational combinations.

Correction to "Structure-Based Design of ASK1 Inhibitors as Potential Agents for Heart Failure".

[This corrects the article DOI: 10.1021/acsmedchemlett.6b00481.].

Structure-Based Design of ASK1 Inhibitors as Potential Agents for Heart Failure.

Apoptosis signal-regulating kinase 1 (ASK1/MAP3K) is a mitogen-activated protein kinase family member shown to contribute to acute ischemia/reperfusion injury. Using structure-based drug design, deconstruction, and reoptimization of a known ASK1 inhibitor, a lead compound was identified. This compound displayed robust MAP3K pathway inhibition and reduction of infarct size in an isolated perfused heart model of cardiac injury.

Found in Translation: Maximizing the Clinical Relevance of Nonclinical Oncology Studies.

Purpose: The translation of nonclinical oncology studies is a subject of continuous debate. We propose that translational oncology studies need to optimize both pharmacokinetic (drug exposure) and pharmacodynamic (xenograft model) aspects. While improvements in pharmacodynamic translatability can be obtained by choosing cell lines or patient-derived xenograft models closer to the clinical indication, significant ambiguity and variability exists when optimizing the pharmacokinetic translation of small molecule and biotherapeutic agents.Experimental Design and Results: In this work, we propose a pharmacokinetic-based strategy to select nonclinical doses for approved drug molecules. We define a clinically relevant dose (CRD) as the dosing regimen in mice that most closely approximates the relevant pharmacokinetic metric in humans. Such metrics include area under the time-concentration curve and maximal or minimal concentrations within the dosing interval. The methodology is applied to six drugs, including targeted agents and chemotherapeutics, small and large molecules (erlotinib, dasatinib, vismodegib, trastuzumab, irinotecan, and capecitabine). The resulting efficacy response at the CRD is compared with clinical responses.Conclusions: We conclude that nonclinical studies designed with the appropriate CRDs of approved drug molecules will maximize the translatability of efficacy results, which is critical when testing approved and investigational agents in combination. Clin Cancer Res; 23(4); 1080-90. ©2016 AACR.

Antitumor activity of the aurora a selective kinase inhibitor, alisertib, against preclinical models of colorectal cancer.

BACKGROUND: The Aurora kinases are a family of serine/threonine kinases comprised of Aurora A, B, and C which execute critical steps in mitotic and meiotic progression. Alisertib (MLN8237) is an investigational Aurora A selective inhibitor that has demonstrated activity against a wide variety of tumor types in vitro and in vivo, including CRC. RESULTS: CRC cell lines demonstrated varying sensitivity to alisertib with IC50 values ranging from 0.06 to > 5 umol/L. Following exposure to alisertib we observed a decrease in pAurora A, B and C in four CRC cell lines. We also observed an increase in p53 and p21 in a sensitive p53 wildtype cell line in contrast to the p53 mutant cell line or the resistant cell lines. The addition of alisertib to standard CRC treatments demonstrated improvement over single agent arms; however, the benefit was largely less than additive, but not antagonistic. METHODS: Forty-seven CRC cell lines were exposed to alisertib and IC50s were calculated. Twenty-one PDX models were treated with alisertib and the Tumor Growth Inhibition Index was assessed. Additionally, 5 KRAS wildtype and mutant PDX models were treated with alisertib as single agent or in combination with cetuximab or irinotecan, respectively. CONCLUSION: Alisertib demonstrated anti-proliferative effects against CRC cell lines and PDX models. Our data suggest that the addition of alisertib to standard therapies in colorectal cancer if pursued clinically, will require further investigation of patient selection strategies and these combinations may facilitate future clinical studies.

Phase I trial of vandetanib in combination with gemcitabine and capecitabine in patients with advanced solid tumors with an expanded cohort in pancreatic and biliary cancers.

BACKGROUND: Vandetanib is a multitargeted tyrosine kinase inhibitor that affects vascular endothelial growth factor receptor (VEGF), epidermal growth factor (EGF), and rearranged during transfection (RET) mediated receptors which are important for growth and invasion of biliary and pancreatic cancers. This phase I study evaluated the safety profile of vandetanib in combination with standard doses of gemcitabine and capecitabine in order to determine the maximum tolerated dose (MTD). METHODS: In this single center phase I trial, patients received gemcitabine intravenously (i.v.) at 1000 mg/m2 days 1, 8, 15 in a 28 day cycle, capecitabine orally at 850 mg/m2 twice daily on days 1-21, and escalating doses of vandetanib (200 or 300 mg orally daily). Once the MTD was defined, an expansion cohort of patients with advanced biliary cancers and locally advanced or metastatic pancreatic cancer was enrolled. Blood samples were also collected at predetermined time points for biomarker analysis. RESULTS: Twenty-three patients were enrolled: 9 in the dose escalation and 14 in the dose expansion cohort. One dose limiting toxicity (DLT), of grade 4 neutropenia, occurred in the 200 mg vandetanib cohort. The most common adverse effects were diarrhea (39 %), nausea and vomiting (34%), and rash (33%). There were 3 partial responses and stable disease of >2 months (range 2-45, median 5) was observed in 15/23 patients. There was no association between changes in biomarker analytes and disease response. CONCLUSION: The combination of gemcitabine, capecitabine and vandetanib is well tolerated at the recommended phase II dose of gemcitabine 1000 mg/m2 weekly for three consecutive weeks, capecitabine 850 mg/m2 BID days 1-21, and vandetanib 300 mg daily, every 28 days. This combination demonstrated promising activity in pancreaticobiliary cancers and further evaluation is warranted in these diseases. NCT00551096.

Combined inhibition of MEK and Aurora A kinase in KRAS/PIK3CA double-mutant colorectal cancer models.

Aurora A kinase and MEK inhibitors induce different, and potentially complementary, effects on the cell cycle of malignant cells, suggesting a rational basis for utilizing these agents in combination. In this work, the combination of an Aurora A kinase and MEK inhibitor was evaluated in pre-clinical colorectal cancer models, with a focus on identifying a subpopulation in which it might be most effective. Increased synergistic activity of the drug combination was identified in colorectal cancer cell lines with concomitant KRAS and PIK3CA mutations. Anti-proliferative effects were observed upon treatment of these double-mutant cell lines with the drug combination, and tumor growth inhibition was observed in double-mutant human tumor xenografts, though effects were variable within this subset. Additional evaluation suggests that degree of G2/M delay and p53 mutation status affect apoptotic activity induced by combination therapy with an Aurora A kinase and MEK inhibitor in KRAS and PIK3CA mutant colorectal cancer. Overall, in vitro and in vivo testing was unable to identify a subset of colorectal cancer that was consistently responsive to the combination of a MEK and Aurora A kinase inhibitor.

Dual pharmacological targeting of the MAP kinase and PI3K/mTOR pathway in preclinical models of colorectal cancer.

BACKGROUND: The activation of the MAPK and PI3K/AKT/mTOR pathways is implicated in the majority of cancers. Activating mutations in both of these pathways has been described in colorectal cancer (CRC), thus indicating their potential as therapeutic targets. This study evaluated the combination of a PI3K/mTOR inhibitor (PF-04691502/PF-502) in combination with a MEK inhibitor (PD-0325901/PD-901) in CRC cell lines and patient-derived CRC tumor xenograft models (PDTX). MATERIALS AND METHODS: The anti-proliferative effects of PF-502 and PD-901 were assessed as single agents and in combination against a panel of CRC cell lines with various molecular backgrounds. Synergy was evaluated using the Bliss Additivity method. In selected cell lines, we investigated the combination effects on downstream effectors by immunoblotting. The combination was then evaluated in several fully genetically annotated CRC PDTX models. RESULTS: The in vitro experiments demonstrated a wide range of IC50 values for both agents against a cell line panel. The combination of PF-502 and PD-901 demonstrated synergistic anti-proliferative activity with Bliss values in the additive range. As expected, p-AKT and p-ERK were downregulated by PF-502 and PD-901, respectively. In PDTX models, following a 30-day exposure to PF-502, PD-901 or the combination, the combination demonstrated enhanced reduction in tumor growth as compared to either single agent regardless of KRAS or PI3K mutational status. CONCLUSIONS: The combination of a PI3K/mTOR and a MEK inhibitor demonstrated enhanced anti-proliferative effects against CRC cell lines and PDTX models.

Luteal phase dynamics of follicle-stimulating and luteinizing hormones in obese and normal weight women.

OBJECTIVES: Female obesity is a state of relative hypogonadotrophic hypogonadism. The aim of this study is to examine gonadotrophin secretion and response to gonadotrophin-releasing hormone (GnRH) in the luteal phase of the menstrual cycle and to investigate the pharmacodynamics and pharmacokinetics of endogenous and exogenous luteinizing hormone (LH) in obese women. DESIGN: Participants underwent a luteal phase frequent blood sampling study. Endogenous LH pulsatility was observed, gonadotrophin-releasing hormone (GnRH) was given in two weight-based doses, and GnRH antagonist was administered followed by recombinant LH. PATIENTS: Regularly menstruating obese (n = 10) and normal weight (n = 10) women. MEASUREMENTS: Endogenous hypothalamic-pituitary function (as measured by LH pulsatility), pituitary sensitivity (GnRH-induced LH secretion), pharmacodynamics of endogenous LH and pharmacokinetics of exogenous LH were compared between the obese and normal weight groups. RESULTS: There were no statistically significant differences in endogenous LH pulsatility or pituitary responses to two weight-based doses of GnRH between the obese and normal weight women. There were no differences in the pharmacodynamics of endogenous LH or the pharmacokinetics of exogenous LH between the groups. FSH dynamics did not differ between the groups throughout the study. CONCLUSIONS: The relative hypogonadotrophic hypogonadism of obesity cannot be explained by differences in LH and FSH luteal phase dynamics or differences in endogenous LH pharmacodynamics or exogenous LH pharmacokinetics.

Evidence of GnRH antagonist escape in obese women.

CONTEXT: Assisted reproductive technology (ART) cycle cancelation rates are increased among overweight and obese women; however, the reasons for this are not completely clear. Premature luteinization due to inadequate endogenous gonadotropin suppression is a possibility for this higher risk of cancellation. OBJECTIVE: The objective of the study was to investigate the impact of female obesity on the pharmacokinetics of cetrorelix (GnRH antagonist). DESIGN: This was an interventional study. SETTING: The study was conducted at a university clinical and translational research center. PARTICIPANTS: Regularly menstruating obese (n = 10) and normal-weight (n = 10) women participated in the study. INTERVENTIONS: A frequent blood sampling study was performed after a GnRH antagonist was administered, followed by recombinant LH. MAIN OUTCOMES MEASURED: Pharmacokinetics of cetrorelix in obese vs normal weight women were measured. RESULTS: Five of the obese women (50%) and none of the normal-weight women had a rebound of LH (defined as >50% increase in LH level from nadir) over the 14-hour postdose observation period. The obese group had a significantly decreased distributional half-life of cetrorelix compared with the normal-weight group (8.1 ± 1.6 vs 12.7 ± 6.2 hours, P = .02). The obese group exhibited increased clearance of cetrorelix compared with the normal-weight group (25.8 ± 6.8 vs 20.1 ± 8.3 L/h, P = .058). CONCLUSIONS: The altered pharmacokinetics of cetrorelix in obese women may lead to premature ovulation during ART, and this could be one of the mechanisms that results in increased cycle cancelation in this group of women. In accordance with the higher gonadotropin requirements for obese women undergoing ART, weight-based dosing of GnRH antagonists may be required.

Targeting nuclear kinases in cancer: development of cell cycle kinase inhibitors.

Cellular proliferation is a tightly controlled set of events that is regulated by numerous nuclear protein kinases. The proteins involved include checkpoint kinases (CHK), cyclin-dependent kinases (CDK), which regulate the cell cycle and aurora kinases (AURK) and polo-like kinases (PLK), which regulate mitosis. In cancer, these nuclear kinases are often dysregulated and cause uncontrolled cell proliferation and growth. Much work has gone into developing novel therapeutics that target each of these protein kinases in cancer but none have been approved in patients. In this review we provide an overview of the current compounds being developed clinically to target these nuclear kinases involved in regulating the cell cycle and mitosis.

The development of a fully-integrated immune response model (FIRM) simulator of the immune response through integration of multiple subset models.

BACKGROUND: The complexity and multiscale nature of the mammalian immune response provides an excellent test bed for the potential of mathematical modeling and simulation to facilitate mechanistic understanding. Historically, mathematical models of the immune response focused on subsets of the immune system and/or specific aspects of the response. Mathematical models have been developed for the humoral side of the immune response, or for the cellular side, or for cytokine kinetics, but rarely have they been proposed to encompass the overall system complexity. We propose here a framework for integration of subset models, based on a system biology approach. RESULTS: A dynamic simulator, the Fully-integrated Immune Response Model (FIRM), was built in a stepwise fashion by integrating published subset models and adding novel features. The approach used to build the model includes the formulation of the network of interacting species and the subsequent introduction of rate laws to describe each biological process. The resulting model represents a multi-organ structure, comprised of the target organ where the immune response takes place, circulating blood, lymphoid T, and lymphoid B tissue. The cell types accounted for include macrophages, a few T-cell lineages (cytotoxic, regulatory, helper 1, and helper 2), and B-cell activation to plasma cells. Four different cytokines were accounted for: IFN-γ, IL-4, IL-10 and IL-12. In addition, generic inflammatory signals are used to represent the kinetics of IL-1, IL-2, and TGF-ß. Cell recruitment, differentiation, replication, apoptosis and migration are described as appropriate for the different cell types. The model is a hybrid structure containing information from several mammalian species. The structure of the network was built to be physiologically and biochemically consistent. Rate laws for all the cellular fate processes, growth factor production rates and half-lives, together with antibody production rates and half-lives, are provided. The results demonstrate how this framework can be used to integrate mathematical models of the immune response from several published sources and describe qualitative predictions of global immune system response arising from the integrated, hybrid model. In addition, we show how the model can be expanded to include novel biological findings. Case studies were carried out to simulate TB infection, tumor rejection, response to a blood borne pathogen and the consequences of accounting for regulatory T-cells. CONCLUSIONS: The final result of this work is a postulated and increasingly comprehensive representation of the mammalian immune system, based on physiological knowledge and susceptible to further experimental testing and validation. We believe that the integrated nature of FIRM has the potential to simulate a range of responses under a variety of conditions, from modeling of immune responses after tuberculosis (TB) infection to tumor formation in tissues. FIRM also has the flexibility to be expanded to include both complex and novel immunological response features as our knowledge of the immune system advances.

Association of the epithelial-to-mesenchymal transition phenotype with responsiveness to the p21-activated kinase inhibitor, PF-3758309, in colon cancer models.

The p21-activated kinase (PAK) family of serine/threonine kinases, which are overexpressed in several cancer types, are critical mediators of cell survival, motility, mitosis, transcription, and translation. In the study presented here, we utilized a panel of colorectal cancer (CRC) cell lines to identify potential biomarkers of sensitivity or resistance that may be used to individualize therapy to the PAK inhibitor PF-03758309. We observed a wide range of proliferative responses in the CRC cell lines exposed to PF-03758309, this response was recapitulated in other phenotypic assays such as anchorage-independent growth, three-dimensional (3D) tumor spheroid formation, and migration. Interestingly, we observed that cells most sensitive to PF-03758309 exhibited up-regulation of genes associated with a mesenchymal phenotype (CALD1, VIM, ZEB1) and cells more resistant had an up-regulation of genes associated with an epithelial phenotype (CLDN2, CDH1, CLDN3, CDH17) allowing us to derive an epithelial-to-mesenchymal transition (EMT) gene signature for this agent. We assessed the functional role of EMT-associated genes in mediating responsiveness to PF-3758309, by targeting known genes and transcriptional regulators of EMT. We observed that suppression of genes associated with the mesenchymal phenotype conferred resistance to PF-3758309, in vitro and in vivo. These results indicate that PAK inhibition is associated with a unique response phenotype in CRC and that further studies should be conducted to facilitate both patient selection and rational combination strategies with these agents.

Utilization of quantitative in vivo pharmacology approaches to assess combination effects of everolimus and irinotecan in mouse xenograft models of colorectal cancer.

PURPOSE: The PI3K/AKT/mTOR pathway is frequently dysregulated in cancers and inhibition of mTOR has demonstrated the ability to modulate pro-survival pathways. As such, we sought to determine the ability of the mTOR inhibitor everolimus to potentiate the antitumor effects of irinotecan in colorectal cancer (CRC). EXPERIMENTAL DESIGN: The combinatorial effects of everolimus and irinotecan were evaluated in vitro and in vivo in CRC cell lines harboring commonly found mutations in PIK3CA, KRAS and/or BRAF. Pharmacokinetically-directed dosing protocols of everolimus and irinotecan were established and used to assess the in vivo antitumor effects of the agents. At the end of treatment, 3-6 tumors per treatment arm were harvested for biomarker analysis by NMR metabolomics. RESULTS: Everolimus and irinotecan/SN38 demonstrated synergistic anti-proliferative effects in multiple CRC cell lines in vitro. Combination effects of everolimus and irinotecan were determined in CRC xenograft models using clinically-relevant dosing protocols. Everolimus demonstrated significant tumor growth inhibition alone and when combined with irinotecan in HT29 and HCT116 tumor xenografts. Metabolomic analysis showed that HT29 tumors were more metabolically responsive than HCT116 tumors. Everolimus caused a decrease in glycolysis in both tumor types whilst irinotecan treatment resulted in a profound accumulation of lipids in HT29 tumors indicating a cytotoxic effect. CONCLUSIONS: Quantitative analysis of tumor growth and metabolomic data showed that the combination of everolimus and irinotecan was more beneficial in the BRAF/PIK3CA mutant HT29 tumor xenografts, which had an additive effect, than the KRAS/PIK3CA mutant HCT116 tumor xenografts, which had a less than additive effect.

Preclinical activity of the rational combination of selumetinib (AZD6244) in combination with vorinostat in KRAS-mutant colorectal cancer models.

PURPOSE: Despite the availability of several active combination regimens for advanced colorectal cancer (CRC), the 5-year survival rate remains poor at less than 10%, supporting the development of novel therapeutic approaches. In this study, we focused on the preclinical assessment of a rationally based combination against KRAS-mutated CRC by testing the combination of the MEK inhibitor, selumetinib, and vorinostat, a histone deacetylase (HDAC) inhibitor. EXPERIMENTAL DESIGN: Transcriptional profiling and gene set enrichment analysis (baseline and posttreatment) of CRC cell lines provided the rationale for the combination. The activity of selumetinib and vorinostat against the KRAS-mutant SW620 and SW480 CRC cell lines was studied in vitro and in vivo. The effects of this combination on tumor phenotype were assessed using monolayer and 3-dimensional cultures, flow cytometry, apoptosis, and cell migration. In vivo, tumor growth inhibition, (18)F-fluoro-deoxy-glucose positron emission tomography (FDG-PET), and proton nuclear magnetic resonance were carried out to evaluate the growth inhibitory and metabolic responses, respectively, in CRC xenografts. RESULTS: In vitro, treatment with selumetinib and vorinostat resulted in a synergistic inhibition of proliferation and spheroid formation in both CRC cell lines. This inhibition was associated with an increase in apoptosis, cell-cycle arrest in G(1), and reduced cellular migration and VEGF-A secretion. In vivo, the combination resulted in additive tumor growth inhibition. The metabolic response to selumetinib and vorinostat consisted of significant inhibition of membrane phospholipids; no significant changes in glucose uptake or metabolism were observed in any of the treatment groups. CONCLUSION: These data indicate that the rationally based combination of the mitogen-activated protein kinase/extracellular signal-regulated kinase inhibitor, selumetinib, with the HDAC inhibitor vorinostat results in synergistic antiproliferative activity against KRAS-mutant CRC cell lines in vitro. In vivo, the combination showed additive effects that were associated with metabolic changes in phospholipid turnover, but not on FDG-PET, indicating that the former is a more sensitive endpoint of the combination effects.

Assessment of the in vivo antitumor effects of ENMD-2076, a novel multitargeted kinase inhibitor, against primary and cell line-derived human colorectal cancer xenograft models.

PURPOSE: This in vivo study was designed to investigate the efficacy of ENMD-2076, a small-molecule kinase inhibitor with activity against the Aurora kinases A and B, and several other tyrosine kinases linked to cancer, including vascular endothelial growth factor receptor 2, cKit, and fibroblast growth factor receptor 1, against murine xenograft models of human colorectal cancer (CRC). EXPERIMENTAL DESIGN: HT-29 CRC cell line xenografts were treated with either vehicle or ENMD-2076 (100 or 200 mg/kg) orally daily for 28 days. Tumor growth inhibition, dynamic contrast-enhanced magnetic resonance imaging, and (18)FDG-positron emission tomography were conducted to assess the antiproliferative, antiangiogenic, and antimetabolic responses, respectively. Effects on proliferation were also analyzed by immunohistochemical methods. Additionally, three patient-derived xenografts from primary and metastatic sites were treated with ENMD-2076 (100 mg/kg) and assessed for tumor growth inhibition. RESULTS: In the HT-29 xenograft model, ENMD-2076 induced initial tumor growth inhibition followed by regression. Treatment was associated with significant tumor blanching, indicating a loss of vascularity and substantial reductions in tumor vascular permeability and perfusion as measured by dynamic contrast-enhanced magnetic resonance imaging. Positron emission tomography scanning showed significant decreases in (18)FDG uptake at days 3 and 21 of treatment, which was associated with a marked reduction in proliferation as assessed by Ki-67. All three of the patient-derived xenografts tested were sensitive to treatment with ENMD 2076 as measured by tumor growth inhibition. CONCLUSIONS: ENMD-2076 showed robust antitumor activity against cell line and patient-derived xenograft models of CRC that is detectable by functional imaging, supporting clinical investigation of this agent in CRC.

Renal inflammation: targeted iron oxide nanoparticles for molecular MR imaging in mice.

PURPOSE: To determine the feasibility of T2-weighted magnetic resonance (MR) imaging in the noninvasive quantification of renal inflammation by using superparamagnetic iron oxide (SPIO) nanoparticles targeted to tissue-bound C3 activation fragments in a mouse model of lupus nephritis. MATERIALS AND METHODS: All animal procedures were approved by the University of Colorado-Denver animal care and use committee. SPIO nanoparticles were encapsulated by using amine-functionalized phospholipids. A recombinant protein containing the C3d-binding region of complement receptor type 2 (CR2) was then conjugated to the surface of the SPIO nanoparticle. Five MRL/lpr mice (a model of lupus nephritis) and six C57BL/6 wild-type mice were assessed with T2-weighted MR imaging at baseline and after SPIO injection. The same five MRL/lpr mice and three C57BL/6 mice also underwent MR imaging after injection of CR2-targeted SPIO. A series of T2-weighted pulses with 16 echo times was used to enable precise T2 mapping and calculation of T2 relaxation times in the cortex and outer and inner medulla of the kidneys, as well as in the spleen, muscle, and fat. The effects of treatment and animal genotype on T2 relaxation times were analyzed with repeated-measures analysis of variance. RESULTS: At baseline, the T2-weighted signal intensity in the kidneys of MRL/lpr mice was higher than that in the kidneys of wild-type mice. Injection of untargeted SPIO did not alter the T2-weighted signal in the kidneys in either strain of mice. Injection of CR2-targeted SPIO in MRL/lpr mice, however, caused a significant accumulation of targeted iron oxide with a subsequent decrease in T2 relaxation times in the cortex and outer and inner medulla of the kidneys. No changes in T2 relaxation time were observed in the wild-type mice after injection of targeted SPIO. CONCLUSION: Injection of CR2-conjugated SPIO caused a significant reduction in T2-weighted MR imaging signal and T2 relaxation time in nephritic kidneys.

Oncologic imaging end-points for the assessment of therapy response.

Sophisticated clinical and diagnostic imaging modalities are critical for the detection, staging, treatment, and follow-up surveillance of cancer. Previously, uni- and bi-dimensional measurements of a tumor lesion were considered the "holy grail" of the assessment of tumor growth and provided imaging end-points for cytotoxic chemotherapeutic agents. With increasing understanding of cancer-related pathways and emerging discoveries of targeted signal transduction inhibitors for cancer treatment, novel pharmacodynamic endpoints of treatment efficacy are required. The innovations in medical imaging include computed tomography (CT), magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), positron emission tomography (PET), single photon emission tomography (SPECT), ultrasonography (US) and, mostly in the pre-clinical arena, optical imaging. While CT and MRI provide superb anatomic resolution, physiological changes in tumor microenvironment can be assessed by dynamic contrast enhanced MRI (DCE-MRI), metabolic endpoints can be established with PET and MRS protocol, and molecular biomarkers can be non-invasively followed up using PET and MRI-based molecular probes (and optical imaging mostly in pre-clinical setting). Novel protocols for improved spatial resolution, automated quantitative methods for anatomic assessment, and development of physiological, metabolic and molecular imaging probes are currently under investigation. The imaging future promises new avenues for exploration of physiological, metabolic, molecular and genetic events in the human body, performed non-invasively and in real time, using multi-modality imaging platforms. The aim of this article is to represent the available patents on imaging response assessment in oncology.

Pharmacokinetic-directed dosing of vandetanib and docetaxel in a mouse model of human squamous cell carcinoma.

Docetaxel, usually administered according to maximum tolerated dose (MTD), can inhibit endothelial cell proliferation at low nanomolar concentrations. Docetaxel may exert antiangiogenic effects if dosed so plasma levels are maintained at low nanomolar concentrations over a prolonged time. We evaluated metronomic and MTD-based dosing of docetaxel with and without vandetanib, a vascular endothelial growth factor receptor-2 and epidermal growth factor receptor tyrosine kinase inhibitor with antiangiogenic and antitumor activity, in a head and neck xenograft model. A murine physiologically based pharmacokinetic model was modified to predict docetaxel distribution following i.p. administration to design dosing regimens that target prespecified plasma concentrations, for antiendothelial effects (metronomic), or exposure, to mimic 30 mg/m2 (weekly/MTD) docetaxel in humans. Animals were treated for 28 days with 1 mg/kg/d (DTX1) or 6 mg/kg q4d (DTX6) docetaxel with or without vandetanib (15 mg/kg/d p.o.) in mice bearing UMSCC2 tumor xenografts. The DTX1 dosing scheme was adjusted to treatment for 10 days followed by 9 days off due to severe gastrointestinal toxicity. All treatment groups significantly reduced tumor volume, tumor proliferation (Ki-67), and tumor endothelial cell proliferation (Ki-67/von Willebrand factor) compared with control. Addition of vandetanib to docetaxel treatment significantly enhanced tumor growth inhibition over single-agent therapy. A positive correlation of tumor endothelial cell proliferation with tumor growth rates demonstrates vandetanib and docetaxel antiangiogenic effects. Due to the morbidity observed with DTX1 treatment, it is difficult to clearly ascertain if metronomic schedules will be effective for treatment. Docetaxel with vandetanib is effective in treating UMSCC2 xenografts at concentrations relevant to exposures in humans.