NAP Peptide (Davunetide): A Nose-to-Brain Approach to Alzheimer's Tau Tangles

NAP (NAPVSIPQ), an 8-amino-acid neuroprotective peptide delivered intranasally as AL-108, showed positive results on memory function in a Phase IIa clinical trial for patients with amnestic mild cognitive impairment (aMCI), a precursor to Alzheimer's disease. NAP works by stabilizing microtubules — the internal structural scaffolding of neurons — against tau-related damage that causes neurofibrillary tangles, one of the hallmarks of Alzheimer's. This was one of the first tau-targeted peptide approaches to reach clinical testing.

Review of NAP's discovery, preclinical pharmacology (in vitro and in vivo neuroprotection studies), mechanism of action (microtubule stabilization), and Phase IIa clinical trial results in amnestic mild cognitive impairment.

While most Alzheimer's drug development has focused on amyloid plaques, this peptide targets the other hallmark of the disease: tau tangles. NAP/AL-108 represented a novel approach — a small peptide that could be delivered through the nose to bypass the blood-brain barrier and protect neurons by stabilizing their internal architecture. The positive Phase IIa results suggested this tau-directed peptide strategy had clinical potential.

NAP/davunetide was one of the pioneering peptide-based approaches to Alzheimer's that targeted tau pathology rather than amyloid. While later clinical development of davunetide did not succeed (a Phase II/III trial in progressive supranuclear palsy failed in 2012), the concept of tau-targeted neuroprotective peptides remains relevant. The approach also demonstrated the feasibility of intranasal peptide delivery to the brain, a route now being explored for many other neuropeptide therapeutics.

Phase IIa is a small, early clinical trial — positive signals need confirmation in larger Phase II/III trials. The review is authored by the drug's developers, which introduces potential bias. Intranasal delivery of peptides to the brain remains technically challenging with variable absorption.