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Lanabecestat (AZD3293; LY3314814) is an orally active potent inhibitor of human β-secretase 1 in clinical development for the treatment of Alzheimer disease. In this first Japanese clinical study for an Alzheimer disease intervention to include cerebrospinal fluid (CSF) sampling in Japanese elderly healthy subjects, we report the pharmacokinetics and effects on plasma and CSF amyloid-β (Aβ) peptides of lanabecestat in a phase 1 study involving 40 healthy Japanese subjects (NCT02005211). No safety and tolerability concerns were identified in healthy Japanese subjects exposed to lanabecestat up to the highest doses given, which is consistent with observations in a US phase 1 study of lanabecestat. Exposure to lanabecestat was similar for young and elderly subjects and increased in a dose-dependent manner. For elderly subjects, plasma lanabecestat half-life after multiple dosing was 12 to 17 hours (on days 10 and 14). Robust plasma and CSF Aβ peptide reductions were also seen at all doses, with CSF Aβ 42 concentrations reduced by 63% and 79% in the 15- and 50-mg lanabecestat groups, respectively. CSF soluble amyloid-β precursor protein β also decreased following lanabecestat treatment. Suppression of CSF Aβ peptides was similar in elderly healthy Japanese subjects and US patients with mild to moderate Alzheimer disease. Lanabecestat is a promising potentially disease-modifying treatment in phase 3 development for patients with early Alzheimer disease., (© 2017, The American College of Clinical Pharmacology.)

A growing body of pathological, biomarker, genetic, and mechanistic data suggests that amyloid accumulation, as a result of changes in production, processing, and/or clearance of brain amyloid-β peptide (Aβ) concentrations, plays a key role in the pathogenesis of Alzheimer's disease (AD). Beta-secretase 1 (BACE1) mediates the first step in the processing of amyloid-β protein precursor (AβPP) to Aβ peptides, with the soluble N terminal fragment of AβPP (sAβPPβ) as a direct product, and BACE1 inhibition is an attractive target for therapeutic intervention to reduce the production of Aβ. Here, we report the in vitro and in vivo pharmacological profile of AZD3293, a potent, highly permeable, orally active, blood-brain barrier (BBB) penetrating, BACE1 inhibitor with unique slow off-rate kinetics. The in vitro potency of AZD3293 was demonstrated in several cellular models, including primary cortical neurons. In vivo in mice, guinea pigs, and dogs, AZD3293 displayed significant dose- and time-dependent reductions in plasma, cerebrospinal fluid, and brain concentrations of Aβ40, Aβ42, and sAβPPβ. The in vitro potency of AZD3293 in mouse and guinea pig primary cortical neuronal cells was correlated to the in vivo potency expressed as free AZD3293 concentrations in mouse and guinea pig brains. In mice and dogs, the slow off-rate from BACE1 may have translated into a prolongation of the observed effect beyond the turnover rate of Aβ. The preclinical data strongly support the clinical development of AZD3293, and patients with AD are currently being recruited into a combined Phase 2/3 study to test the disease-modifying properties of AZD3293.