Michael Reilly

The Novel γ Secretase Inhibitor N-[cis-4-[(4-Chlorophenyl)sulfonyl]-4-(2,5-difluorophenyl)cyclohexyl]-1,1,1-trifluoromethanesulfonamide (MRK-560) Reduces Amyloid Plaque Deposition without Evidence of Notch-Related Pathology in the Tg2576 Mouse

There is a substantial body of evidence indicating that β-amyloid peptides (Aβ) are critical factors in the onset and development of Alzheimers disease (AD). One strategy for combating AD is to reduce or eliminate the production of Aβ through inhibition of the γ-secretase enzyme, which cleaves Aβ from the amyloid precursor protein (APP). We demonstrate here that chronic treatment for 3 months with 3 mg/kg of the potent, orally bioavailable and brain-penetrant γ-secretase inhibitor N-[cis-4-[(4-chlorophenyl)-sulfonyl]-4-(2,5-difluorophenyl)cyclohexyl]-1,1,1-trifluoromethanesulfonamide (MRK-560) attenuates the appearance of amyloid plaques in the Tg2576 mouse. These reductions in plaques were also accompanied by a decrease in the level of reactive gliosis. The morphometric and histological measures agreed with biochemical analysis of Aβ(40) and Aβ(42) in the cortex. Interestingly, the volume of the plaques across treatment groups did not change, indicating that reducing Aβ levels does not significantly alter deposit growth once initiated. Furthermore, we demonstrate that these beneficial effects can be achieved without causing histopathological changes in the ileum, spleen, or thymus as a consequence of blockade of the processing of alternative substrates, such as the Notch family of receptors. This indicates that in vivo a therapeutic window between these substrates seems possible—a key concern in the development of this approach to AD. An understanding of the mechanisms whereby MRK-560 shows differentiation between the APP and Notch proteolytic pathway of γ-secretase should provide the basis for the next generation of γ-secretase inhibitors.

Standardizing evaluation of on-line continuing medical education: physician knowledge, attitudes, and reflection on practice.

Introduction: Physicians increasingly earn continuing medical education (CME) credits through on‐line courses, but there have been few rigorous evaluations to determine their effects. The present study explores the feasibility of implementing standardized evaluation templates and tests them to evaluate 30 on‐line CME courses. Methods: A time series design was used to compare the knowledge, attitudes, and reported changes in practice of physician participants who completed any of 30 on‐line CME courses that were hosted on an academic CME Web site and a CME Web portal during the period from August 1, 2002, through March 31, 2003. Data were collected at baseline, at course completion, and 4 weeks later. Paired t tests were used to compare the means of responses across time. Results: U.S. physicians completed 720 post‐tests. Quality of content was the characteristic of most importance to participants; too little interaction was the largest source of dissatis‐faction. Overall mean knowledge scores increased from 58.1% to 75.6% at post‐test and then decreased to 68.2% at 4 weeks following the course. Effect sizes of increased knowledge immediately following the course were larger for case‐based than for text‐based courses. Nearly all physicians reported making changes in practice following course completion, although reported changes differed from expected changes. Conclusions: Increases in physician knowledge and knowledge retention were demonstrated following participation in on‐line CME courses. The implementation of standardized evaluation tests proved to be feasible and allowed longitudinal evaluation analyses across CME providers and content areas.

In Vivo Characterization of Aβ(40) Changes in Brain and Cerebrospinal Fluid Using the Novel γ-Secretase Inhibitor N-[cis-4-[(4-Chlorophenyl)sulfonyl]-4-(2,5-difluorophenyl)cyclohexyl]-1,1,1-trifluoromethanesulfonamide (MRK-560) in the Rat

Plaques in the parenchyma of the brain containing Aβ peptides are one of the hallmarks of Alzheimers disease. These Aβ peptides are produced by the final proteolytic cleavage of the amyloid precursor protein by the intramembraneous aspartyl protease γ-secretase. Thus, one approach to lowering levels of Aβ has been via the inhibition of the γ-secretase enzyme. Here, we report a novel, bioavailable γ-secretase inhibitor, N-[cis-4-[(4-chlorophenyl)sulfonyl]-4-(2,5-difluorophenyl)cyclohexyl]-1,1,1-trifluoromethanesulfonamide (MRK-560) that displayed oral pharmacokinetics suitable for once-a-day dosing. It was able to markedly reduce Aβ in the brain and cerebrospinal fluid (CSF) in the rat, with ED50 values of 6 and 10 mg/kg, respectively. Time-course experiments using MRK-560 demonstrated these reductions in Aβ could be maintained for 24 h, and comparable temporal reductions in rat brain and CSF Aβ(40) further suggested that these two pools of Aβ are related. This relationship between the brain and CSF Aβ was maintained when MRK-560 was dosed once a day for 2 weeks, and accordingly, when all the data for the dose-response curve and time courses were correlated, a strong association was observed between the brain and CSF Aβ levels. These results demonstrate that MRK-560 is an orally bioavailable γ-secretase inhibitor with the ability to markedly reduce Aβ peptide in the brain and CSF of the rat and confirm the utility of the rat for assessing the effects of γ-secretase inhibitors on central nervous system Aβ(40) levels in vivo.

In vivo characterisation of Aβ(40) changes in brain and CSF using the novel γ-secretase inhibitor MRK-560 (N-[cis-4-[(4-chlorophenyl)sulfonyl]-4- (2,5-difluorophenyl)cyclohexyl]-1,1,1- trifluoromethanesulfonamide) in the rat

Plaques in the parenchyma of the brain containing Aβ peptides are one of the hallmarks of Alzheimers disease. These Aβ peptides are produced by the final proteolytic cleavage of the amyloid precursor protein by the intramembraneous aspartyl protease γ-secretase. Thus, one approach to lowering levels of Aβ has been via the inhibition of the γ-secretase enzyme. Here, we report a novel, bioavailable γ-secretase inhibitor, N-[cis-4-[(4-chlorophenyl)sulfonyl]-4-(2,5-difluorophenyl)cyclohexyl]-1,1,1-trifluoromethanesulfonamide (MRK-560) that displayed oral pharmacokinetics suitable for once-a-day dosing. It was able to markedly reduce Aβ in the brain and cerebrospinal fluid (CSF) in the rat, with ED50 values of 6 and 10 mg/kg, respectively. Time-course experiments using MRK-560 demonstrated these reductions in Aβ could be maintained for 24 h, and comparable temporal reductions in rat brain and CSF Aβ(40) further suggested that these two pools of Aβ are related. This relationship between the brain and CSF Aβ was maintained when MRK-560 was dosed once a day for 2 weeks, and accordingly, when all the data for the dose-response curve and time courses were correlated, a strong association was observed between the brain and CSF Aβ levels. These results demonstrate that MRK-560 is an orally bioavailable γ-secretase inhibitor with the ability to markedly reduce Aβ peptide in the brain and CSF of the rat and confirm the utility of the rat for assessing the effects of γ-secretase inhibitors on central nervous system Aβ(40) levels in vivo.

Discovery of a First-in-Class Receptor Interacting Protein 1 (RIP1) Kinase Specific Clinical Candidate (GSK2982772) for the Treatment of Inflammatory Diseases

RIP1 regulates necroptosis and inflammation and may play an important role in contributing to a variety of human pathologies, including immune-mediated inflammatory diseases. Small-molecule inhibitors of RIP1 kinase that are suitable for advancement into the clinic have yet to be described. Herein, we report our lead optimization of a benzoxazepinone hit from a DNA-encoded library and the discovery and profile of clinical candidate GSK2982772 (compound 5), currently in phase 2a clinical studies for psoriasis, rheumatoid arthritis, and ulcerative colitis. Compound 5 potently binds to RIP1 with exquisite kinase specificity and has excellent activity in blocking many TNF-dependent cellular responses. Highlighting its potential as a novel anti-inflammatory agent, the inhibitor was also able to reduce spontaneous production of cytokines from human ulcerative colitis explants. The highly favorable physicochemical and ADMET properties of 5, combined with high potency, led to a predicted low oral dose in humans.

Design, synthesis, and evaluation of novel 3,6-diaryl-4-aminoalkoxyquinolines as selective agonists of somatostatin receptor subtype 2.

Agonists of somatostatin receptor subtype 2 (sst(2)) have been proposed as therapeutics for the treatment of proliferative diabetic retinopathy and exudative age-related macular degeneration. An HTS screen identified 2-quinolones as weak agonists of sst(2), and these were optimized to provide small molecules with sst(2) binding and functional potency comparable to peptide agonists. Agonist 21 was shown to inhibit rat growth hormone secretion following systemic administration and to inhibit ocular neovascular lesion formation after local administration.

The Identification and Pharmacological Characterization of 6-(tert-Butylsulfonyl)-N-(5-fluoro-1H-indazol-3-yl)quinolin-4-amine (GSK583), a Highly Potent and Selective Inhibitor of RIP2 Kinase

RIP2 kinase is a central component of the innate immune system and enables downstream signaling following activation of the pattern recognition receptors NOD1 and NOD2, leading to the production of inflammatory cytokines. Recently, several inhibitors of RIP2 kinase have been disclosed that have contributed to the fundamental understanding of the role of RIP2 in this pathway. However, because they lack either broad kinase selectivity or strong affinity for RIP2, these tools have only limited utility to assess the role of RIP2 in complex environments. We present, herein, the discovery and pharmacological characterization of GSK583, a next-generation RIP2 inhibitor possessing exquisite selectivity and potency. Having demonstrated the pharmacological precision of this tool compound, we report its use in elucidating the role of RIP2 kinase in a variety of in vitro, in vivo, and ex vivo experiments, further clarifying our understanding of the role of RIP2 in NOD1 and NOD2 mediated disease pathogenesis.