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


METHODS
Posiphen 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.


METHODS
Pharmacodynamic: sAPPα, sAPPβ, Aβ(42), 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.


RESULTS
Posiphen 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 Aβ(42).


CONCLUSIONS
These 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.
QR Pharma, Inc., Berwyn, PA, USA.
Maria L
ML
Maccecchini
Mee Young
MY
Chang
Catherine
C
Pan
Varghese
V
John
Henrik
H
Zetterberg
Nigel H
NH
Greig
D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid*; D016564:Amyloid beta-Protein Precursor / Q000134:cerebrospinal fluid*; D000818:Animals; D060825:Cognitive Dysfunction / Q000097:blood / Q000134:cerebrospinal fluid / Q000188:drug therapy*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D018836:Inflammation Mediators / Q000134:cerebrospinal fluid; D008297:Male; D010446:Peptide Fragments / Q000134:cerebrospinal fluid*; D010830:Physostigmine / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344; D016875:tau Proteins / Q000134:cerebrospinal fluid*
D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D018836:Inflammation Mediators; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42); D016875:tau Proteins; D010830:Physostigmine; C092280:phenserine