[Show abstract][Hide abstract] ABSTRACT: The first disclosure of the synthesis, pre-clinical profile and in vivo efficacy in rat xenograft models of the novel and selective anaplastic lymphoma kinase inhibitor LDK378 (14b) is described. In this initial report, preliminary structure activity relationships (SAR) are described as well as the rational design strategy employed to overcome the de-velopment deficiencies of the first generation clinical candidate 4 (TAE684). Compound 14b is currently in Phase 1 and 2 clinical trials with substantial antitumor activity being observed in ALK-positive cancer patients.
Journal of Medicinal Chemistry 06/2013; · 5.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Accumulation of β-amyloid (Aβ) in the brain is believed to contribute to the pathology of Alzheimer's Disease (AD). Aβ levels are controlled by the production of Aβ from amyloid precursor protein, degradation by proteases, and peripheral clearance. In this study we sought to determine whether enhancing clearance of plasma Aβ with a peripherally administered Aβ-degrading protease would reduce brain Aβ levels through a peripheral sink. Neprilysin (NEP) is a zinc-dependent metalloprotease that is one of the key Aβ-degrading enzymes in the brain. We developed a NEP fusion protein with in vitro degradation of Aβ and a 10 day plasma half-life in mouse. Intravenous administration of NEP to wild-type and APP23 transgenic mice resulted in dose-dependent clearance of plasma Aβ. However, this did not correspond to reduced levels of soluble brain Aβ with treatment up to 5 weeks in WT mice or formic acid-extractable brain Aβ with 3 month treatment in aged APP23. In contrast, intracranial injection of NEP resulted in an acute decrease in soluble brain Aβ. We found no change in amyloid precursor protein gene expression in mice treated with intravenous NEP, suggesting that the lack of effects in the brain following this route of administration was not caused by compensatory upregulation of Aβ production. Taken together, these results suggest a lack of a robust peripheral Aβ efflux sink through which brain amyloid burdens can be therapeutically reduced.
Journal of Neuroscience 02/2013; 33(6):2457-64. · 6.91 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Successful drug discovery relies on the selection of drug candidates with good in vivo pharmacokinetic (PK) properties as well as appropriate preclinical efficacy and safety profiles. In vivo PK profiling is often a bottleneck in the discovery process. In this review, we focus on the tiered in vivo PK approaches implemented at the Genomics Institute of the Novartis Research Foundation (GNF), which includes snapshot PK, rapid PK and full PK studies. These in vivo PK approaches are well integrated within discovery research, allow tremendous flexibility and are highly efficient in supporting the diverse needs and increasing demand for in vivo profiling. The tiered in vivo PK studies expedite compound profiling and help guide the selection of more desirable compounds into efficacy models and for progression into development.
Drug discovery today 09/2012; · 6.63 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: On the basis of the initial success of optimization of a novel series of imidazolopiperazines, a second generation of compounds involving changes in the core piperazine ring was synthesized to improve antimalarial properties. These changes were carried out to further improve the potency and metabolic stability of the compounds by leveraging the outcome of a set of in vitro metabolic identification studies. The optimized 8,8-dimethyl imidazolopiperazine analogues exhibited improved potency, in vitro metabolic stability profile and, as a result, enhanced oral exposure in vivo in mice. The optimized compounds were found to be more efficacious than the current antimalarials in a malaria mouse model. They exhibit moderate oral exposure in rat pharmacokinetic studies to achieve sufficient multiples of the oral exposure at the efficacious dose in toxicology studies.
Journal of Medicinal Chemistry 04/2012; 55(9):4244-73. · 5.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Transient transfection of mammalian cells in suspension culture has recently emerged as a very useful method for production of research-scale quantities of recombinant proteins. The most commonly used cell lines for this purpose are suspension-adapted HEK and CHO cells. We report here that the plasma exposure in mice of an IL-23R extracellular domain Fc fusion protein (IL23R-Fc) differed dramatically depending on whether the protein was prepared by transient transfection of HEK or CHO cells. Specifically, IL23R-Fc expressed using CHO cells had about 30-fold higher in vivo plasma exposure compared to the HEK-expressed protein. In contrast to their differing plasma exposures, the HEK- and CHO-expressed proteins had equivalent in vitro biological activity. Characterization of the CHO- and HEK-expressed IL23R-Fc proteins indicated that the differences in in vivo plasma exposure between them are due to differential glycosylation.
Protein Expression and Purification 05/2010; 71(1):96-102. · 1.43 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A novel series of benzo[a]carbazole-based small molecule agonists of the thrombopoietin (Tpo) receptor is reported. Starting from a 3.4 microM high throughput screen hit, members of this series have been identified which are full agonists with functional potency <50 nM and oral bioavailability in mice.
[Show abstract][Hide abstract] ABSTRACT: Described in this article are strategies implemented to increase the throughput of in vivo rodent pharmacokinetic (PK) studies using the snapshot PK study design and automated methods for compound submission, sample processing, data analysis and reporting. Applying snapshot PK studies to categorize the oral exposure of >1300 discovery compounds as low, moderate or high resulted in an attrition rate of 86%. The follow up full PK studies on the remaining compounds found that 98% of the compounds were predicted in the correct (69%) or adjacent (29%) oral exposure category by the snapshot PK studies. These results demonstrate that the snapshot PK screen in rodents can serve as an effective and efficient in vivo tool in the compound selection process in drug discovery.
Drug Discovery Today 05/2008; 13(7-8):360-7. · 6.55 Impact Factor