RO6807936 as a novel positron emission tomography (PET) radiotracer for in vitro and in vivo visualization and quantification of beta-site amyloid precursor protein cleaving enzyme (BACE1) in the rodent and baboon brain.

The beta-site amyloid precursor protein cleaving enzyme (BACE1) is responsible for initiating the generation of beta-amyloid, the major constituent of amyloid plaques in Alzheimer's disease (AD). The purpose of this study was to develop a specific BACE1 radioligand for visualization of the distribution pattern and quantification of the BACE1 protein in the rodent and monkey brain both in vitro by autoradiography and in vivo by positron emission tomography (PET). The BACE1 inhibitor RO6807936 originating from an in-house chemical drug optimization program was selected based on its PET tracer-like physicochemical properties and a favorable pharmacokinetic profile.

A subcutaneous cellular implant for passive immunization against amyloid-β reduces brain amyloid and tau pathologies.

Passive immunization against misfolded toxic proteins is a promising approach to treat neurodegenerative disorders. For effective immunotherapy against Alzheimer's disease, recent clinical data indicate that monoclonal antibodies directed against the amyloid-β peptide should be administered before the onset of symptoms associated with irreversible brain damage. It is therefore critical to develop technologies for continuous antibody delivery applicable to disease prevention.

Cargo Delivery into the Brain by in vivo identified Transport Peptides.

The blood-brain barrier and the blood-cerebrospinal fluid barrier prevent access of biotherapeutics to their targets in the central nervous system and therefore prohibit the effective treatment of neurological disorders. In an attempt to discover novel brain transport vectors in vivo, we injected a T7 phage peptide library and continuously collected blood and cerebrospinal fluid (CSF) using a cisterna magna cannulated conscious rat model. Specific phage clones were highly enriched in the CSF after four rounds of selection.

Combined treatment with a BACE inhibitor and anti-Aβ antibody gantenerumab enhances amyloid reduction in APPLondon mice.

Therapeutic approaches for prevention or reduction of amyloidosis are currently a main objective in basic and clinical research on Alzheimer's disease. Among the agents explored in clinical trials are anti-Aβ peptide antibodies and secretase inhibitors. Most anti-Aβ antibodies are considered to act via inhibition of amyloidosis and enhanced clearance of existing amyloid, although secretase inhibitors reduce the de novo production of Aβ.

Genetic engineering of cell lines using lentiviral vectors to achieve antibody secretion following encapsulated implantation.

The controlled delivery of antibodies by immunoisolated bioimplants containing genetically engineered cells is an attractive and safe approach for chronic treatments. To reach therapeutic antibody levels there is a need to generate renewable cell lines, which can long-term survive in macroencapsulation devices while maintaining high antibody specific productivity. Here we have developed a dual lentiviral vector strategy for the genetic engineering of cell lines compatible with macroencapsulation, using separate vectors encoding IgG light and heavy chains.

BACE1 inhibitors: a head group scan on a series of amides.

A series of amides bearing a variety of amidine head groups was investigated as BACE1 inhibitors with respect to inhibitory activity in a BACE1 enzyme as well as a cell-based assay. Determination of their basicity as well as their properties as substrates of P-glycoprotein revealed that a 2-amino-1,3-oxazine head group would be a suitable starting point for further development of brain penetrating compounds for potential Alzheimer's disease treatment.

β-Secretase (BACE1) inhibitors with high in vivo efficacy suitable for clinical evaluation in Alzheimer's disease.

An extensive fluorine scan of 1,3-oxazines revealed the power of fluorine(s) to lower the pKa and thereby dramatically change the pharmacological profile of this class of BACE1 inhibitors. The CF3 substituted oxazine 89, a potent and highly brain penetrant BACE1 inhibitor, was able to reduce significantly CSF Aβ40 and 42 in rats at oral doses as low as 1 mg/kg. The effect was long lasting, showing a significant reduction of Aβ40 and 42 even after 24 h.

Morphologic and functional effects of gamma secretase inhibition on splenic marginal zone B cells.

The γ-secretase complex is a promising target in Alzheimer's disease because of its role in the amyloidogenic processing of β-amyloid precursor protein. This enzyme also catalyzes the cleavage of Notch receptor, resulting in the nuclear translocation of intracellular Notch where it modulates gene transcription. Notch signaling is essential in cell fate decisions during embryogenesis, neuronal differentiation, hematopoiesis, and development of T and B cells, including splenic marginal zone (MZ) B cells.

The dynamics of Aβ distribution after γ-secretase inhibitor treatment, as determined by experimental and modelling approaches in a wild type rat.

Inhibition of the enzyme(s) that produce the Amyloid beta (Aβ) peptide, namely BACE and γ-secretase, is considered an attractive target for Alzheimer's disease therapy. However, the optimal pharmacokinetic-pharmacodynamic modelling method to describe the changes in Aβ levels after drug treatment is unclear. In this study, turnover models were employed to describe Aβ levels following treatment with the γ-secretase inhibitor RO5036450, in the wild type rat.

Aminothiazoles as γ-secretase modulators.

We herein report the discovery of a new γ-secretase modulator class with an aminothiazole core starting from a HTS hit (3). Synthesis and SAR of this series are discussed. These novel compounds demonstrate moderate to good in vitro potency in inhibiting amyloid beta (Aβ) peptide production.

In vitro pharmacological selectivity profile of oseltamivir prodrug (Tamiflu) and active metabolite.

Neuropsychiatric adverse events have been reported in influenza patients with and without exposure to oseltamivir (Tamiflu), triggering speculation as to whether oseltamivir may be interacting with any human receptors and contributing to such neuropsychiatric events. In this study, the in vitro selectivity profile of oseltamivir prodrug and active metabolite was investigated. Both compounds lacked clinically relevant pharmacological activities on human, rodent and primate neuraminidases and on a panel of 155 other molecular targets, including those relevant for mood, cognition and behavior.

Preclinical profile of a potent gamma-secretase inhibitor targeting notch signaling with in vivo efficacy and pharmacodynamic properties.

Notch signaling is an area of great interest in oncology. RO4929097 is a potent and selective inhibitor of gamma-secretase, producing inhibitory activity of Notch signaling in tumor cells. The RO4929097 IC50 in cell-free and cellular assays is in the low nanomolar range with >100-fold selectivity with respect to 75 other proteins of various types (receptors, ion channels, and enzymes).

Alzheimer's disease: from pathology to therapeutic approaches.

Mind how you go: The current strategies for the development of therapies for Alzheimer's disease are very diverse. Particular attention is given to the search for inhibitors (see picture for two examples) of the proteolytic enzyme beta- and gamma-secretase, which inhibits the cleavage of the amyloid precursor proteins into amyloid beta peptides, from which the disease-defining deposits of plaque in the brains of Alzheimer's patients originates.Research on senile dementia and Alzheimer's disease covers an extremely broad range of scientific activities.

Expression of transgenic APP mRNA is the key determinant for beta-amyloid deposition in PS2APP transgenic mice.

Background: Alzheimer's disease is the most common cause of dementia occurring in the elderly. The identification of the genetic factors in the familial forms of the disease enabled the generation of transgenic animals which reproduce an essential part of its pathology. Various lines of transgenic mice expressing human wild-type or mutated APP have been reported.

ProNGF inhibits NGF-mediated TrkA activation in PC12 cells.

Degeneration of cholinergic basal forebrain neurons (CBFN) is a hallmark in the pathology of Alzheimer's disease (AD). Critically depending upon the neurotrophic support through nerve growth factor (NGF), CBFN in the AD brain face elevated concentrations of the pro-form of NGF (proNGF) and suffer from an imbalance between TrkA and p75(NTR) expression. Research for the underlying mechanisms of CBFN death suggested a pro-apoptotic activity of proNGF.

Substituted 2-oxo-azepane derivatives are potent, orally active gamma-secretase inhibitors.

A hydroxamic acid screening hit 1 was elaborated to 5,5-dimethyl-2-oxoazepane derivatives exhibiting low nanomolar inhibition of gamma-secretase, a key proteolytic enzyme involved in Alzheimer's disease. Early ADME data showed a high metabolic clearance for the geminal dimethyl analogs which could be overcome by replacement with the bioisosteric geminal difluoro group. Synthesis and structure-activity relationship are discussed and in vivo active compounds are presented.

Generation of Abeta38 and Abeta42 is independently and differentially affected by familial Alzheimer disease-associated presenilin mutations and gamma-secretase modulation.

Alzheimer disease amyloid beta-peptide (Abeta) is generated via proteolytic processing of the beta-amyloid precursor protein by beta- and gamma-secretase. Gamma-secretase can be blocked by selective inhibitors but can also be modulated by a subset of non-steroidal anti-inflammatory drugs, including sulindac sulfide. These drugs selectively reduce the generation of the aggregation-prone 42-amino acid Abeta(42) and concomitantly increase the levels of the rather benign Abeta(38).

Novel orally active, dibenzazepinone-based gamma-secretase inhibitors.

Structural modifications of the gamma-secretase inhibitor, LY411575, led to a malonamide analogue (S),(S)-1 with potent inhibitory activity in vitro, but disappointing activity in a mouse model of Alzheimer's disease. Identification and replacement of a metabolically labile position provided an improved compound (R/S),(S)-13 with high in vitro activity (IC(50)=1.7 nM), and in vivo activity after oral administration (MED=3 mg/kg).

Cholesterol independent effect of LXR agonist TO-901317 on gamma-secretase.

The balance of intracellular cholesterol has proven to be critical to the production of beta-amyloid (A beta). Reducing cholesterol in vitro leads to decreased production of A beta, whereas an increase in cellular cholesterol induces A beta production. Liver X Receptor (LXR) agonists are known to increase cholesterol efflux from cells, but there are conflicting reports as to the effects of these agonists on A beta production.

BACE/APPV717F double-transgenic mice develop cerebral amyloidosis and inflammation.

Most of the transgenic mice generated to model Alzheimer's disease express human amyloid precursor protein (APP) mutants alone or in conjunction with presenilin mutants. We have generated a mouse model by overexpressing human BACE and human APP with the V717F mutation. The combination of a mutation at the gamma-secretase cleavage site of APP and of increased beta-secretase activity should favour the production of amyloid peptides.

Altered metabolic profile in the frontal cortex of PS2APP transgenic mice, monitored throughout their life span.

The transgenic mouse line PS2APP (PS2N141I x APP(swe)) develops an age-related cognitive decline associated with severe amyloidosis, mimicking the pathophysiologic processes in Alzheimer disease (AD). In the quest for biomarkers to monitor, noninvasively, the progression of the disease, we used magnetic resonance imaging and 1H-spectroscopy to characterize PS2APP mice throughout their life span. Morphometric measurements revealed only small size differences to controls.

PS2APP transgenic mice, coexpressing hPS2mut and hAPPswe, show age-related cognitive deficits associated with discrete brain amyloid deposition and inflammation.

Transgenic mice, expressing mutant beta-amyloid precursor proteins (betaAPPs), have lead to a better understanding of the pathophysiological processes in Alzheimer's disease (AD). In many of these models, however, the temporal development of cognitive decline and the relationship to Abeta deposition and inflammation are unclear. We now report a novel transgenic mouse line, PS2APP (PS2N141I x APPswe), which develops a severe cerebral amyloidosis in discrete brain regions, and present a cross-sectional analysis of these mice at 4, 8, 12, and 16 months of age.

Hyperphosphorylation and insolubility of alpha-synuclein in transgenic mouse oligodendrocytes.

(Oligodendro)glial cytoplasmic inclusions composed of alpha-synuclein (alpha SYN) characterize multiple system atrophy (MSA). Mature oligodendrocytes (OLs) do not normally express alpha SYN, so MSA pathology may arise from aberrant expression of alpha SYN in OLs. To study pathological deposition of alpha SYN in OLs, transgenic mice were generated in which human wild-type alpha SYN was driven by a proteolipid protein promoter.