Posiphen as a candidate drug to lower CSF amyloid precursor protein, amyloid-β peptide and τ levels: target engagement, tolerability and pharmacokinetics in humans

• Published in: Journal of neurology, neurosurgery and psychiatry Vol. 83; no. 9; pp. 894 - 902
• Main Authors: Maccecchini, Maria L, Chang, Mee Young, Pan, Catherine, John, Varghese, Zetterberg, Henrik, Greig, Nigel H
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd 01.09.2012; BMJ Publishing Group; BMJ Group
• Series: Research paper
• Subjects: Alzheimer's disease; amyloid; Amyloid beta-Peptides - cerebrospinal fluid; Amyloid beta-Protein Precursor - cerebrospinal fluid; amyloid precursor protein; amyloid-β peptide; Animals; B12 deficiency; Biological and medical sciences; Cognitive Dysfunction - blood; Cognitive Dysfunction - cerebrospinal fluid; Cognitive Dysfunction - drug therapy; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Dose-Response Relationship, Drug; Double-Blind Method; Female; genetics; head injury; Humans; Inflammation Mediators - cerebrospinal fluid; inflammatory markers; Male; Medical sciences; mild cognitive impairment; neurochemistry; Neurodegeneration; Neurology; Parkinson's disease; Peptide Fragments - cerebrospinal fluid; Physostigmine - adverse effects; Physostigmine - analogs & derivatives; Physostigmine - pharmacokinetics; Physostigmine - pharmacology; Posiphen; Rats; Rats, Inbred F344; tau Proteins - cerebrospinal fluid; Human; Nervous system diseases; Peptides; β Amyloid protein; Cerebrospinal fluid; Pharmacokinetics; Amyloid precursor protein
• ISSN: 0022-3050; 1468-330X; 1468-330X
• DOI: 10.1136/jnnp-2012-302589

AimA first in human study to evaluate tolerability and pharmacokinetics followed by an early proof of mechanism (POM) study to determine whether the small orally, available molecule, Posiphen tartrate (Posiphen), lowers secreted (s) amyloid-β precursor protein (APP) α and -β, amyloid-β peptide (Aβ), tau (τ) and inflammatory markers in CSF of patients with mild cognitive impairment (MCI).Study designPosiphen single and multiple ascending dose phase 1 randomised, double blind, placebo-controlled safety, tolerance, pharmacokinetic studies were undertaken in a total of 120 healthy volunteers to define a dose that was then used in a small non-randomised study of five MCI subjects, used as their own controls, to define target engagement.Main outcome measuresPharmacodynamic: sAPPα, sAPPβ, Aβ42, τ (total (t) and phosphorylated (p)) and inflammatory marker levels were time-dependently measured over 12 h and compared prior to and following 10 days of oral Posiphen treatment in four MCI subjects who completed the study. Pharmacokinetic: plasma and CSF drug and primary metabolite concentrations with estimated brain levels extrapolated from steady-state drug administration in rats.ResultsPosiphen proved well tolerated and significantly lowered CSF levels of sAPPα, sAPPβ, t-τ, p-τ and specific inflammatory markers, and demonstrated a trend to lower CSF Aβ42.ConclusionsThese results confirm preclinical POM studies, demonstrate that pharmacologically relevant drug/metabolite levels reach brain and support the continued clinical optimisation and evaluation of Posiphen for MCI and Alzheimer's disease.