ABSTRACT
BACKGROUND: A hallmark of Alzheimer's disease is the presence of senile plaques in human brain primarily containing the amyloid peptides Aß42 and Aß40. Many drug discovery efforts have focused on decreasing the production of Aß42 through γ-secretase inhibition. However, identification of γ-secretase inhibitors has also uncovered mechanism-based side effects. One approach to circumvent these side effects has been modulation of γ-secretase to shift Aß production to favor shorter, less amyloidogenic peptides than Aß42, without affecting the overall cleavage efficiency of the enzyme. This approach, frequently called γ-secretase modulation, appears more promising and has lead to the development of new therapeutic candidates for disease modification in Alzheimer's disease. RESULTS: Here we describe EVP-0015962, a novel small molecule γ-secretase modulator. EVP-0015962 decreased Aß42 in H4 cells (IC50 = 67 nM) and increased the shorter Aß38 by 1.7 fold at the IC50 for lowering of Aß42. AßTotal, as well as other carboxyl-terminal fragments of amyloid precursor protein, were not changed. EVP-0015962 did not cause the accumulation of other γ-secretase substrates, such as the Notch and ephrin A4 receptors, whereas a γ-secretase inhibitor reduced processing of both. A single oral dose of EVP-0015962 (30 mg/kg) decreased Aß42 and did not alter AßTotal peptide levels in a dose-dependent manner in Tg2576 mouse brain at an age when overt Aß deposition was not present. In Tg2576 mice, chronic treatment with EVP-0015962 (20 or 60 mg/kg/day in a food formulation) reduced Aß aggregates, amyloid plaques, inflammatory markers, and cognitive deficits. CONCLUSIONS: EVP-0015962 is orally bioavailable, detected in brain, and a potent, selective γ-secretase modulator in vitro and in vivo. Chronic treatment with EVP-0015962 was well tolerated in mice and lowered the production of Aß42, attenuated memory deficits, and reduced Aß plaque formation and inflammation in Tg2576 transgenic animals. In summary, these data suggest that γ-secretase modulation with EVP-0015962 represents a viable therapeutic alternative for disease modification in Alzheimer's disease.
Subject(s)
Alzheimer Disease/enzymology , Amyloid Precursor Protein Secretases/drug effects , Amyloid beta-Peptides/drug effects , Behavior, Animal/drug effects , Biphenyl Compounds/pharmacology , Phenylpropionates/pharmacology , Propionates/pharmacology , Amyloid Precursor Protein Secretases/metabolism , Amyloid beta-Peptides/metabolism , Animals , Cell Line, Tumor , Humans , Mice , Mice, Transgenic , TransfectionABSTRACT
Female F344 rats were fed diets containing 0.02%, 0.2%, or 2.0% white mineral oil for 90 days. There were no gross or microscopic differences in target organs at the 0.02% level. In the higher-dose groups, relative liver and mesenteric lymph node (MLN) weights were increased, and MLN inflammation was observed. At the 2% level, there was very limited evidence of microgranuloma formation in the liver but at a lower incidence and at lesser severity than has been reported in studies of C22-C25 oils. Analysis of liver extracts from treated rats revealed that C15-C20 constituents were underrepresented by comparison to their corresponding concentrations in the test oil. These results provide evidence that although hydrocarbons with carbon numbers < C20 are absorbed, they are not preferentially retained and do not contribute to inflammatory processes in liver.
Subject(s)
Mineral Oil/toxicity , Animals , Female , Granuloma/chemically induced , Hydrocarbons/metabolism , Kidney/drug effects , Kidney/metabolism , Kidney/pathology , Liver/drug effects , Liver/metabolism , Liver/pathology , Lymph Nodes/drug effects , Lymph Nodes/metabolism , Lymph Nodes/pathology , Mineral Oil/pharmacokinetics , Molecular Weight , Organ Size/drug effects , Rats , Rats, Inbred F344ABSTRACT
Oral repeated-dose studies with low-viscosity mineral oils showed distinct species and strain differences, which are hypothesized to be due to differences in bioavailability, with Fischer 344 rats being more susceptible than Sprague-Dawley rats or dogs. Sensitive analytical methodology was developed for accurate measurement of low levels of mineral hydrocarbons and applied in single-dose toxicokinetics studies in rats and humans. Fischer 344 rats showed a 4-fold higher AUC(0-∞) and consistently higher blood and liver concentrations were found than Sprague-Dawley rats. Hepatic mineral hydrocarbon concentration tracked the blood concentration in both strains, indicating that blood concentrations can serve as functional surrogate measure for hepatic concentrations. In human volunteers receiving 1mg/kg body weight of low-viscosity white oil, all blood concentrations of mineral hydrocarbons were below the detection limit. Comparison with threshold blood concentrations associated with NOAELs in both rat strains, indicate that the margin-of-exposure is at least 37-fold. Using an internal dose metric rather than applied dose reduces the uncertainty around the temporary ADI considerably since it intrinsically accounts for intra- and inter-species differences. The current data support replacement of the temporary ADI of 0.01 mg/kg/day by a (permanent) ADI of at least 1.0mg/kg/day for low- and medium-viscosity mineral oils.
