SAR exploration at the C-3 position of tetrahydro-ß-carboline sstr3 antagonists.

MK-4256, a tetrahydro-ß-carboline sstr3 antagonist, was discontinued due to a cardiovascular (CV) adverse effect observed in dogs. Additional investigations revealed that the CV liability (QTc prolongation) was caused by the hERG off-target activity of MK-4256 and was not due to sstr3 antagonism. In this Letter, we describe our extensive SAR effort at the C3 position of the tetrahydro-ß-carboline structure. This effort resulted in identification of 5-fluoro-pyridin-2-yl as the optimal substituent on the imidazole ring to balance sstr3 activity and the hERG off-target liability.

Reversal of methylprednisolone effects in allergen-exposed female BALB/c mice.

A high percentage of asthma is associated with aeroallergen exposures. Glucocorticoids such as methylprednisolone represent a major method for managing chronic asthma. However, studies suggested that corticosteroid therapy might have the potential to stimulate rather than inhibit adaptive immune inflammatory reactions, raising concerns about possible adverse reactions due to excessive repeated methylprednisolone treatment. Therefore, a murine model of allergen-induced inflammation was characterized and used to investigate the effects of repeated intraperitoneal (ip) and transnasal treatments with methylprednisolone (0-20 mg/kg body weight) and cyclosporin A (20 mg/kg body weight). Sensitized BALB/c female mice were exposed daily to ovalbumin (OVA) aerosols for up to 5 d with 24-h postexposure analyses for airway responses to methacholine aerosols and inflammatory cell recoveries by bronchoalveolar lavage (BAL) and tissue collagenase dispersion. Although increased tissue neutrophils, lymphocytes, monocytes, and macrophages reached maximal levels after 2 daily OVA exposures, recoverable eosinophil numbers continued to rise over the 5-d period. Daily ip treatments with a 5-mg/kg body weight dose of methylprednisolone diminished both OVA-induced airway responses to methacholine and inflammatory-cell accumulations to levels comparable to those observed with cyclosporin A. However, treatments with higher doses of methylprednisolone reversed this anti-inflammatory effect, indicated by a return to untreated levels of OVA-induced eosinophil recovery. A similar biphasic response in eosinophil recoveries was observed using daily transnasal methylprednisolone treatments that correlated with a concomitant fall and rise in BAL interleukin-13. These results supported the hypothesis that repeated high-steroid treatments might activate rather than suppress allergen-induced immune responses.

Nonclinical safety assessment of the histone deacetylase inhibitor vorinostat.

Vorinostat (SAHA, Zolinza), a histone deacetylase inhibitor, is assessed in nonclinical studies to support its approval for cutaneous T-cell lymphoma. Vorinostat is weakly mutagenic in the Ames assay; is clastogenic in rodent (ie, CHO) cells but not in normal human lymphocytes; and is weakly positive in an in vivo mouse micronucleus assay. No effects are observed on potassium ion currents in the hERG assay up to 300 microM (safety margin approximately 300-fold the approximately 1 microM serum concentration associated with the 400 mg/d maximum recommended human dose. No rat respiratory or central nervous system effects are found at 150 mg/kg (>2-fold maximum recommended human dose). No cardiovascular effects, including effects on QTc interval, are observed after a single oral dose (150 mg/kg) in dogs. Vorinostat is orally dosed daily in rats (controls, 20, 50, or 150 mg/kg/d) and dogs (controls, 60, 80, or 100/125/160 mg/kg/d) for 26 weeks with a 4-week recovery. Rat vorinostat-related adverse findings are decreased food consumption, weight loss, and hematologic changes; a no observed adverse effects level is not established. In dogs, adverse effects are primarily gastrointestinal; the no observed adverse effects level is 60 mg/kg/d (approximately 6-fold maximum recommended human dose). Toxicities are reversible and can be monitored in the clinic.

Assessment of female and male fertility in Sprague-Dawley rats administered vorinostat, a histone deacetylase inhibitor.

BACKGROUND: Histone deacetylase (HDAC) inhibitors have been shown to mediate the regulation of gene expression, induce cell growth, cell differentiation, and apoptosis of tumor cells. These compounds are now marketed or are in clinical development. One such HDAC inhibitor, vorinostat (suberoylanilide hydroxamic acid [SAHA], Zolinza), was assessed for its potential effects on fertility in Sprague-Dawley rats. METHODS: Female rats were administered oral dose levels of 0 (vehicle only), 15, 50, or 150 mg/kg/day of vorinostat for 14 days before cohabitation, during cohabitation, and through Gestation Day (GD) 7. In a separate study, male rats were administered oral dose levels of 0 (vehicle only), 20, 50, or 150 mg/kg/day for 10 weeks before cohabitation, during cohabitation, and until the day before scheduled sacrifice (approximately 14 weeks total). In both studies, % peri-implantation loss and % postimplantation loss were evaluated on GD 15-17. Testicular weight and histomorphology, cauda epididymal sperm count, and sperm motility were evaluated in the male rat study at termination. RESULTS: There were treatment-related decreases in body weight gain at 150 mg/kg/day in both studies. There were no effects on mating or fertility indices in either study. In the female study there were increased numbers of corpora lutea in all drug-treated groups (only 1 or 2 affected dams in low and mid-dose groups), and a marked increase in percent postimplantation loss only in the high-dose group. No treatment-related effects were observed on litter or sperm parameters of the male study. CONCLUSIONS: Vorinostat had no effects on mating or fertility in rats up to 150 mg/kg/day. There were no indications of reproductive toxicity in drug-treated male rats. Increases in corpora lutea or resorptions were observed in treated female rats.

Radiation-induced angiosarcoma of the breast shows major response to docetaxel after failure of anthracycline-based chemotherapy.

We report on the case of a patient with a diagnosis of an uncommon breast tumour, namely a radiation-induced angiosarcoma, which was primarily refractory to anthracycline-based chemotherapy, but highly sensitive to docetaxel. Although the sarcomas in general tend to be relatively refractory to taxanes, there is some evidence that the angiosarcomas may be sensitive to these agents. This is particularly well documented with paclitaxel, but may also be the case with docetaxel.

Adjuvant anthracycline-based chemotherapy for early breast cancer: do the dose and schedule matter?

The rationale to justify the use of anthracyclines as adjuvant therapy for breast cancer is their proven superiority over CMF. Indeed, this has been demonstrated by a number of randomised clinical trials and recently confirmed by the Oxford meta-analysis. Nevertheless, the absolute benefit is modest (on average 4%), and with the cost of increased toxicity. Interestingly, many individual trials were unable to confirm the role of anthracyclines in early breast cancer, though most of these were either underpowered to show such small differences, or had inappropriate experimental arms. On the other hand, several trials included in the meta-analysis also had inadequate control arms. So far, probably only three trials were able to individually confirm this benefit: the American INT 0102, the Canadian MA5 and more recently, the British NEAT/NCTBG. Numerous different anthracycline schedules have been used as adjuvant therapy, many of these having never been compared to CMF. Unfortunately, as research is moving towards other more important questions, many of these uncertainties may never be clarified. In this paper, we review the current evidence behind some of the most commonly used anthracycline schedules.

Management of breast cancer in patients prenatally exposed to diethylstilbestrol: are we prepared?

The use of diethylstilbestrol (DES) for high risk pregnancy has exposed millions of mothers to an increased risk of breast cancer, and also resulted in a generation of women with genital tract abnormalities, such as vaginal adenosis. It is still too early to say that exposure to DES will also result in an increased risk of breast cancer in the offspring, though there is some preliminary evidence to support this. The employment of optimal hormonal therapy (for breast cancer) in this special population may be hampered by the fact that agents with oestrogen agonistic activity (such as tamoxifen) may be contraindicated. Though some of the newer hormonal agents, such as the pure anti-oestrogen Fulvestrant and the aromatase inhibitors, could be considered interesting alternatives for postmenopausal patients, their safety in this population has never been evaluated. Finally, the prevalence prenatal exposure to DES may have been underestimated patients diagnosed with breast cancer, though this information might have major implications in their management. We report on the interesting example of a young woman with a history of vaginal adenosis, who was also diagnosed with early breast cancer.

Antiangiogenesis and anticancer efficacy of TA138, a novel alphavbeta3 antagonist.

BACKGROUND: Angiogenesis is a complex process involving endothelial cell migration, proliferation, invasion, and tube formation. Inhibition of these processes might have implications in various angiogenesis-mediated disorders. MATERIALS AND METHODS: The antiangiogenic efficacy of the novel alphavbeta3 antagonist TA138 was examined using in vivo and in vitro model systems. RESULTS: The in vitro studies demonstrated the ability of TA138 and RP747 (conjugated TA138) to inhibit endothelial cell migration toward vitronectin, with an IC50=0.04 and 0.045 microM, respectively. Furthermore, utilizing the chick chorioallantoic membrane models, TA138 inhibited basic fibroblast growth factor-induced neovascularization. CONCLUSION: TA138 might be a useful tool for the inhibition of angiogenesis associated with human tumor growth, or other pathological neovascularization processes. RP747 demonstrated antitumor efficacy in 1 spontaneous tumor model (c-neu oncomouse model, alphavbeta3 positive cells) and in 1 xenograft model (HCT116 human tumor colon carcinoma, alphavbeta3 negative cells) injected subcutaneously into nude mice.

Discovery of MK-1421, a Potent, Selective sstr3 Antagonist, as a Development Candidate for Type 2 Diabetes.

The imidazolyl-tetrahydro-ß-carboline class of sstr3 antagonists have demonstrated efficacy in a murine model of glucose excursion and may have potential as a treatment for type 2 diabetes. The first candidate in this class caused unacceptable QTc interval prolongation in oral, telemetrized cardiovascular (CV) dogs. Herein, we describe our efforts to identify an acceptable candidate without CV effects. These efforts resulted in the identification of (1R,3R)-3-(4-(5-fluoropyridin-2-yl)-1H-imidazol-2-yl)-1-(1-ethyl-pyrazol-4-yl)-1-(3-methyl-1,3,4-oxadiazol-3H-2-one-5-yl)-2,3,4,9-tetrahydro-1H-ß-carboline (17e, MK-1421).

The alpha v integrin antagonists as novel anticancer agents: an update.

Integrins are involved in many cellular processes, including some pathological ones associated with various cancers, both solid tumours and metastases. Since integrins are involved in such critical processes as gene expression, which lead to cellular proliferation, migration, survival and angiogenesis, they represent potential targets for therapeutic intervention. The alpha(v)beta(3) integrin is one of the most widely studied integrins because it is one of the most promiscuous. Published studies provide compelling evidence that small molecule antagonists have the potential to treat both solid tumours and metastases, serve as diagnostic imaging agents and be used for site-directed delivery of drugs to solid tumours. The alpha(v)beta(3) integrin antagonists also inhibit blood vessel formation associated with tumour growth. Therapeutic candidates have included antibodies, cyclic peptides, peptidomimetics and small molecules. A number of potent small-molecule antagonists of the alpha(v)beta(3) integrin have now been identified and are progressing in the clinic. This review focuses on the role of alpha(v)beta(3) in cancer. The rationale for the development of the therapeutic and diagnostic candidates based on the key role of alpha(v)beta(3) is discussed.

An objective procedure for ischemic area evaluation of the stroke intraluminal thread model in the mouse and rat.

Computer-assisted procedures are used to measure infarct areas in animal stroke models, but this approach usually follows the less objective manual tracing of the boundaries of the infarct. Building on previously reported methodology using scanned images of triphenyltetrazolium chloride (TTC)-stained rat brains in the intraluminal thread model, we developed an objective method to assess ischemic damage in both the mouse and rat brains. The unique addition to our approach is the use of sham-treated animals, which thereby permits the removal of normal brain white matter from the ipsilateral injured brain. All brain sections per animal were scanned simultaneously using a Microtek Scanmaker 4 flatbed scanner. Color segmentation on full color images of 2 mm coronal brain sections was performed. Using Image Pro Plus (4.0) and color segmentation, ischemic and normal white matter areas were measured in the green channel and the entire brain area in the red channel. The percent of unstained tissue was calculated for sham-treated animals and for those with cerebral ischemia. By subtracting the average unstained area of the sham-treated group from the average unstained area from the ischemic group, the ischemic area was calculated. This methodology was validated using mouse and rat permanent and transient, focal ischemia models and MK-801 in the permanent ischemia models. MK-801, dosed at 3 mg/kg i.p. prior to the injury, reduced the injury by 75% in the mouse and 44% in the rat permanent occlusion models. The benefits of this methodology include: objectivity of the analysis of the ischemic injury, use of readily available software so that costs can be contained and removal of normal subcortical white matter from the calculation. This method should allow more consistent evaluation of changes in the infarct size, therefore, resulting in reduced variability and higher productivity.

The notion of evidence in evidence-based practice by the Nursing Philosophy Working Group.

Questions concerning the nature of evidence in evidence-based practice have kindled debate within nursing and other health care disciplines. Such questions include the ends for which evidence is sought, the form(s) of evidence, and the values underlying evidence-based practice. In this article, some of the issues, contradictions, and tensions implicit in these questions are highlighted. It is imperative that the nursing profession continue to explore the philosophic perspectives that underscore evidence-based practice and their implications for decision making in nursing practice.

Investigation of Cardiovascular Effects of Tetrahydro-ß-carboline sstr3 antagonists.

Antagonism of somatostatin subtype receptor 3 (sstr3) has emerged as a potential treatment of Type 2 diabetes. Unfortunately, the development of our first preclinical candidate, MK-4256, was discontinued due to a dose-dependent QTc (QT interval corrected for heart rate) prolongation observed in a conscious cardiovascular (CV) dog model. As the fate of the entire program rested on resolving this issue, it was imperative to determine whether the observed QTc prolongation was associated with hERG channel (the protein encoded by the human Ether-à-go-go-Related Gene) binding or was mechanism-based as a result of antagonizing sstr3. We investigated a structural series containing carboxylic acids to reduce the putative hERG off-target activity. A key tool compound, 3A, was identified from this SAR effort. As a potent sstr3 antagonist, 3A was shown to reduce glucose excursion in a mouse oGTT assay. Consistent with its minimal hERG activity from in vitro assays, 3A elicited little to no effect in an anesthetized, vagus-intact CV dog model at high plasma drug levels. These results afforded the critical conclusion that sstr3 antagonism is not responsible for the QTc effects and therefore cleared a path for the program to progress.

Assessment of developmental toxicity of vorinostat, a histone deacetylase inhibitor, in Sprague-Dawley rats and Dutch Belted rabbits.

BACKGROUND: The developmental toxicity potential of vorinostat (suberoylanilide hydroxamic acid [SAHA], ZOLINZA), a potent inhibitor of histone deacetylase (HDAC), was assessed in Sprague-Dawley rats and Dutch Belted rabbits. HDAC inhibitors have been shown to mediate the regulation of gene expression, induce cell growth, cell differentiation, and apoptosis of tumor cells. Range-finding studies established oral dose levels of 5, 15, or 50 mg/kg/day and 20, 50, or 150 mg/kg/day in rats and rabbits, respectively. METHODS: Animals were dosed on Gestation Days 6-20 or 7-20, respectively, with litter/fetal parameters evaluated on GD 21 and 28, respectively. Separate studies evaluated toxicokinetic parameters at the mid- and high-dose levels. RESULTS: There was no maternal toxicity observed at the highest dose levels; however, hematology and serum biochemistry changes were characterized in the range-finding studies. Vorinostat did not induce morphological malformations in either rat or rabbit fetuses. In rats, drug-related developmental toxicity was observed only in the high-dose group and consisted of markedly decreased fetal weight and increases in fetuses with a limited number of skeletal variations. In rabbits, drug-related developmental toxicity was also observed only in the high-dose group and consisted of slightly decreased fetal weight and increases in fetuses with a short 13th rib and incomplete ossification of metacarpals. Maternal exposures to vorinostat based on AUC and Cmax values were comparable at the high-dose levels of both species. Rabbits tolerated higher dosages probably due to more extensive metabolism. Maternal concentrations of vorinostat were approximately 1,000-fold above the known in vitro HDAC inhibitory concentration. CONCLUSIONS: Review of previous work with valproic acid, another HDAC inhibitor, suggest that the developmental toxicity profiles of these 2 compounds are not the result of HDAC inhibition but involve other mechanisms.

Factors contributing to frailty: literature review.

AIM: This paper presents a review of theoretical and research literature in order to identify the factors contributing to frailty. BACKGROUND: Frailty is a multifaceted gerontological concept that lacks a clear definition, but may result from an identifiable homogeneous cluster of bio-psycho-social-spiritual factors. METHOD: A total of 134 articles were identified through a search of the MEDLINE (1966 to July 2004), CINAHL (1982 to July 2004), PsychInfo (1985 to July 2004) and Ageline (1995 to July 2004) databases. Each article was reviewed to determine its fit with inclusion/exclusion criteria. Seven research and 11 theoretical articles were retained and further reviewed for methodological quality using a validity tool. FINDINGS: Seventeen different definitions of frailty were identified. Regardless of the differing definitions, common contributing factors could be identified. Physical, cognitive/psychological, nutritional and social factors, as well as ageing and disease, were evident in both the theoretical and research literature. CONCLUSIONS: Although there is strong agreement that a relationship exists between a cluster of factors and frailty, designation of the factors as contributors or outcomes of frailty differs. Without a clear explanatory theory of the path from contributors to frailty to outcomes, research will continue to produce confusing results. A theoretical framework that includes bio-psycho-social-spiritual factors as contributors to frailty is recommended as the most useful framework for gerontological nursing.

The impact of adult day programs on family caregivers of elderly relatives.

Adult day programs for elderly people have been implemented throughout North America but not widely evaluated for their impact on family caregivers. This study examined caregiver outcomes at 14 programs in Alberta, Canada. Caregivers were measured on burden, quality of life, perceived health, opinion on institutionalization at 4 time points (just prior to client admission, 2 weeks, 2 months, and 6 months after admission), and satisfaction with the program at 3 points after client admission. Caregiver status on burden, quality of life, and perceived health status remained stable over time. In addition, caregivers' opinion on institutionalization remained negative and satisfaction with the programs high. Caregivers reported that client socializing and improved health were what they liked best about the programs, followed by respite for themselves. Time conflicts-limits and transportation were identified as problems. The results suggest that adult day programs may help caregivers to continue in their caregiving role and to keep clients in the community longer.

Antisense oligonucleotides selectively regulate aspartyl beta-hydroxylase and its truncated protein isoform in vitro but distribute poorly into A549 tumors in vivo.

Alternative splicing of the human beta-aspartyl (asparaginyl) hydroxylase (BAH) gene results in the expression of humbug, a truncated form of BAH that lacks the catalytic domain of the enzyme. Overexpression of BAH and humbug has been associated with a variety of human cancers, and although humbug lacks enzymatic activity, it is expressed at levels comparable with that of BAH in various cancer cell lines. Phosphorothioate antisense oligonucleotides (ONs) were designed to dissect out the function of these hydroxylase protein isoforms. In A549 cells, these ONs differentially down-regulated BAH and humbug at the mRNA and protein level. Phosphorothioate ON uptake and antisense studies were conducted in parallel in nude mice bearing A549 tumor xenografts. Microscopic examination of the tumor after administration of a fluorescein-labeled ON showed strong labeling of the outer layers of the tumor connective tissue but cells within the interior of the tumor were sparsely labeled. A modest but significant effect on tumor growth was observed in animals treated with an antisense ON directed against both BAH and humbug transcripts. However, Northern analysis of tumor RNA did not indicate a down-regulation of the targeted mRNA species. These results demonstrate the successful development of antisense ONs that selectively differentiate between the closely related beta-hydroxylase protein isoforms. However, determination of the biological function of these proteins in vivo was limited by the poor uptake properties of phosphorothioate ONs in A549 tumors.