Molecule

Description

LY-411575 is a potent γ-secretase inhibitor with IC50 of 0.078 nM and 0.082 nM for membrane- and cell-based γ-secretase.

Targets

IC₅₀

In Vitro

LY-411575 inhibits γ-secretase which can be assessed by the substrates like amyloid precursor protein (APP) and Notch S3 cleavage. ^[1] LY-411575, which blocks Notch activation, results in apoptosis in primary and immortalized KS cells. ^[2]

In Vivo

10 mg/kg oral dose of LY-411575 decreases brain and plasma Aβ40 and -42 dose-dependently. ^[1] LY-411575 reduces cortical Aβ40 in young (preplaque) transgenic CRND8 mice (ED50 ≈ 0.6 mg/kg) and produces significant thymus atrophy and intestinal goblet cell hyperplasia at higher doses (>3 mg/kg). The therapeutic window is similar after oral and subcutaneous administration and in young and aged CRND8 mice. Both the thymus and intestinal side effects are reversible after a 2-week washout period. Three-week treatment with 1 mg/kg LY411575 reduces cortical Aβ40 by 69% without inducing intestinal effects, although a previously unreported change in coat color is observed. ^[3]

Clinical Trials

Features

Assays for Aβ and NICD

Procedures for measuring γ-secretase activity in membranes prepared from HEK293 cells expressing APP have been described previously (Zhang L et al Biochemistry 40, 5049-5055). Intact HEK293 cells expressing either APP or NΔE are treated with various concentrations of LY- 411,575 for 4 hours at 37 °C. In the case of cells expressing NΔE, cells are lysed, the cell lysates are separated on a 4–12% NuPAGE gel, and the processed NICD fragment is detected via Western blot with a cleavage site-specific antibody. The inhibition of NICD production is quantified by spot densitometric analysis using FluorChem. In the case of cells expressing APP, the conditioned medium is collected, centrifuged at 10,000 × g for 5 minutes to remove cell debris, and stored at -20 °C prior to the determination of Aβ levels. Aβ40 and -42 produced in HEK293 membrane- and cell-based assays, as well as plasma Aβ40 and cortex Aβ40 from TgCRND8 mice, are analyzed without pretreatment using an electrochemiluminescence detection-based immunoassay. Plasma Aβ42 is measured by enzyme-linked immunosorbent assay. A commercially available enzyme-linked immunosorbent assay kit is used to measure cortex Aβ42 according to the manufacturer’s instructions.

Cell Lines

primary and immortalized KS cells

Concentrations

500 μM

Incubation Time

24 hours

Methods

Animal Models

TgCRND8 mice model

Formulation

LY-411575 is formulated as 10 mg/mL solutions in 50% polyethylene glycol, 30% propylene glycol, 10% ethanol and diluted in 0.4% methylcellulose for dosing.

Doses

1–10 mg/kg

Administration

Orally