Inhibition of angiogenesis is a promising and clinically validated approach for limiting tumor growth and survival. The receptor tyrosine kinase Tie-2 is expressed almost exclusively in the vascular ...endothelium and is required for developmental angiogenesis and vessel maturation. However, the significance of Tie-2 signaling in tumor angiogenesis is not well understood. In order to evaluate the therapeutic utility of inhibiting Tie-2 signaling, we developed a series of potent and orally bioavailable small molecule Tie-2 kinase inhibitors with selectivity over other kinases, especially those that are believed to be important for tumor angiogenesis. Our earlier work provided pyridinyl pyrimidine 6 as a potent, nonselective Tie-2 inhibitor that was designed on the basis of X-ray cocrystal structures of KDR inhibitors 34 (triazine) and 35 (nicotinamide). Lead optimization resulted in pyridinyl triazine 63, which exhibited >30-fold selectivity over a panel of kinases, good oral exposure, and in vivo inhibition of Tie-2 phosphorylation.
The novel solution-phase synthesis of an array of biologically relevant quinoxalinones in a simple two-step procedure is revealed. Transformations are carried out in excellent yield by condensation ...of mono-Boc protected
ortho-phenylene di-amine, glyoxylic acids and supporting Ugi reagents. Subsequent acid treatment and evaporation affords quinoxalinones in good to excellent yields.
This letter reveals a novel two-step synthesis of arrays of biologically relevant quinoxalinones, containing four points of potential diversity. The approach utilizes the so-called UDC (Ugi/de-Boc/cyclize) strategy.
Background
Parkinson's disease (PD) is a progressive neurodegenerative disorder with a hallmark feature of intraneuronal inclusions termed Lewy bodies (LBs), which is defined by aggregated, b‐sheet ...rich a‐synuclein (a‐syn) fibrils. The misfolded a‐syn aggregates are widely accepted to play a key role in PD pathogenesis and regarded as potential therapeutic target.
Method
Herein, we describe the development of a family of degrader compounds, which recruit E3 ubiquitin ligase to specifically eliminate a‐syn aggregates.
Result
Our degraders have been demonstrated to selectively recognize pathological a‐syn aggregates derived form a patient with dementia with Lewy bodies (DLB) over tau aggregates from an Alzheimer patient. More importantly, these degraders trigger proteasome‐dependent eliminations of a‐syn aggregates in ReNcell VM neuronal model. The half‐maximal concentrations (DC50) are within nanomolar range. Furthermore, the degraders are capable of crossing blood‐brain barrier (BBB) when systemically administrations a dose at 25 mg/kg to C57BL/6 mice via intravenous (IV) injection. The brain AUCs have achieved > 1000 (hr*ng/mL).
Conclusion
The results suggest that development of a‐syn degraders represents a potential therapeutic strategy for treatment of PD.
Tau and Aβ assemblies of Alzheimer’s disease (AD) can be visualized in living subjects using positron emission tomography (PET). Tau assemblies comprise paired helical and straight filaments (PHFs ...and SFs). APN-1607 (PM-PBB3) is a recently described PET ligand for AD and other tau proteinopathies. Since it is not known where in the tau folds PET ligands bind, we used electron cryo-microscopy (cryo-EM) to determine the binding sites of APN-1607 in the Alzheimer fold. We identified two major sites in the β-helix of PHFs and SFs and a third major site in the C-shaped cavity of SFs. In addition, we report that tau filaments from posterior cortical atrophy (PCA) and primary age-related tauopathy (PART) are identical to those from AD. In support, fluorescence labelling showed binding of APN-1607 to intraneuronal inclusions in AD, PART and PCA. Knowledge of the binding modes of APN-1607 to tau filaments may lead to the development of new ligands with increased specificity and binding activity. We show that cryo-EM can be used to identify the binding sites of small molecules in amyloid filaments.
The brain plaques associated with Alzheimer's disease (AD) are composed primarily of the amyloid beta peptides (A beta 40,42) which are produced from the proteolytic processing of the beta -amyloid ...precursor protein (APP). The production of A beta from APP proceeds via two cleavages which are catalyzed by distinct protease activities known as the secretases. The cleavage of APP at the A beta N-terminal residue is catalyzed by the recently cloned and characterized aspartic acid protease named beta -secretase. The A beta C-terminal cleavage which occurs at the transmembrane region of APP is attributed to the action of the yet unknown protease(s) designated gamma -secretase(s). In the brain of the AD patient, aggregates of A beta peptides are deposited resulting in formation of the insoluble plaques and vascular deposits characteristic of AD pathology. The overproduction of the relatively hydrophobic A beta 42 component has been particularly associated with plaque formation. Genetic evidence suggests elevated brain levels of A beta 42 to be the cause of early-onset familial AD. Inhibition of the beta - and gamma -secretase proteolytic pathways would be expected to decrease the production of A beta and potentially to slow the progression of AD. Cellular assays to measure inhibition of the overproduction of A beta 42 have recently been developed. These assays have allowed the initiation of investigations toward the discovery of small-molecule inhibitors of A beta production in cell culture. Among the reports of A beta production inhibitors in the patent literature, the cyclohexylalanine-based statine 1 and the lipophilic dimethylaminoethyl tetralin 2 serve as examples of chemically stable small-molecule inhibitors of A beta production in cell culture.
Background
The hallmark of neurodegenerative diseases, such as Parkinson’s disease (PD) and Alzheimer’s disease (AD), is an accumulation of protein aggregates, which lead to neurotoxicity and ...dysfunction. Small molecule therapeutics that can remove pathological aggregates are highly desired for both diseases.
Method
Our small molecule discovery platform consists of our proprietary small molecule collection, unique PET imaging biomarkers and cryoEM structures. Our proprietary collection of CNS‐focused aggregated protein binding agents, previously developed by APRINOIA to map the structure‐activity relationship of its tau PET tracer programs, is selectively coupled with agents designed to hijack cellular quality‐control systems which facilitate aggregation clearance. We have developed a screening funnel to interrogate the ability of our small molecules to affect clearance of protein aggregates.
Result
Therapeutic compounds developed have been shown to bind to intracellular tau aggregates in fluorescence assays. Furthermore, we have identified compounds that show proteosome dependent elimination of aSyn aggregates in the ReNcell VM neuronal model. PK studies show that these compounds can cross the BBB. In vivo studies with rTg4510 mice show that a single dose of our degraders can affect reduction of tau protein.
Conclusion
APRINOIA’s small molecule discovery platform has produced lead compounds capable of degrading protein aggregates in cellular assays and in vivo models. Further development is ongoing.
Background
The high value for Alzheimer’s Disease and other taupathies of a small molecule treatment that can alter disease course is widely acknowledged. We aim to investigate such a therapeutic by ...leveraging our small molecule CNS aggregated protein discovery platform.
Method
Our small molecule discovery platform consists of our proprietary small molecule collection, unique PET imaging biomarkers and cryoEM structures. Our proprietary collection of CNS‐focused aggregated protein binding agents, previously developed by APRINOIA to map the structure‐activity relationship of its tau PET tracer programs, was screened for tau binding and further interrogated for other desirable properties such as selectivity and oral availability. Further efforts derived guidance from the cryoEM structure of our lead compound bound to Tau aggregates. These efforts resulted in our small molecule lead compound APN‐1808.
Using rTg4510 mice, which over express 4R tau, we first investigated dose‐response by using in‐vivo PET imaging to measure percent occupancy of APN‐1808. Upon selecting an appropriate dose range, we engaged in 90 day, twice a day dosing of APN‐1808 in rTg4510 mice.
Result
Mice dosed with APN‐1808 showed improvements both biochemically and phenotypically over vehicle controls. Improvements included increase in synaptic protein level, reduction in overall tau burden, reduction in weight loss and other behavioral observations.
Conclusion
Several readouts showed improvement in the dosed groups compared to controls, including increase of synapse level, reduction of weight loss and reduction of total tau. Further investigations are ongoing.
Background
Alzheimer’s disease (AD) is characterized by progressive decline of memory and cognitive functions. Accumulation of hyperphosphorylated tau is a pathological hallmark of AD and also plays ...a pathogenic role in disease progression. Proteolysis Targeting Chimera (PROTAC) technology enables the selective removal of a target protein by cellular ubiquitin‐proteasome system. Here we describe the characterization of tau PROTAC degrader developed at APRINOIA as a novel disease modifying treatment.
Methods
Tau degrader was synthesized by linking a proprietary tau binder from Aprinoia tau PET tracer program with a ligand of E3 ligase. The PROTAC mediated tau degradation was first evaluated in HEK293 cells expressing P301L tau, which develops tau oligomer and aggregates upon incubation with “tau seeds” from brain lysates of rTg4510 mice. The reduction of tau aggregates was measured using a HTRF based immunoassay. A similar seeding induced tau aggregation assay was established in primary neurons to confirm the degrader activity. Efficacy was further evaluated in rTg4510 mice following treatment with IV injection.
Results
PROTAC tau degrader reduced tau oligomer/aggregates in cellular models as well as in therTg4510 mice. Preliminary data suggests degrader is more effective in degradation of soluble tau oligomers in early stage of pathological tau development.
Conclusion
Tau PROTAC degrader generated from proprietary tau warhead can selectively decrease the oligomer/aggregated tau in both in vitro and in vivo models. Current effort is focused on optimization of ADME properties of tau degrader as a promising therapy for AD primary tauopathies.
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