Davunetide vs FGL

Stabilizes microtubules by interacting with tubulin and microtubule-associated proteins. Activates SIRT1, reduces amyloid-β toxicity, and enhances synaptic plasticity. Protects against tau hyperphosphorylation.

Davunetide (AL-108; NAP; NAPVSIPQ) is a synthetic octapeptide derived from activity-dependent neuroprotective protein (ADNP), initially identified as a neuroprotective sequence from ADNP and investigated in clinical trials as a candidate treatment for cognitive impairment associated with schizophrenia and tauopathies including progressive supranuclear palsy. Davunetide is proposed to stabilize microtubule dynamics by interacting with tubulin and preventing tau hyperphosphorylation-related cytoskeletal disruption, and preclinical models demonstrated neuroprotective and procognitive effects at nanomolar concentrations. Clinical investigation included Phase 2 trials examining cognitive outcomes and MRS neuroimaging biomarkers in schizophrenia patients, and a Phase 2/3 trial in progressive supranuclear palsy; results showed some neurochemical effects but no consistent meaningful cognitive improvement across clinical endpoints, and the PSP program did not meet its primary outcomes. Davunetide has no FDA approval and no approved indication in any jurisdiction; clinical development has been discontinued following negative trial outcomes, and while its preclinical neuroprotective profile remains scientifically interesting, the clinical evidence does not establish efficacy for cognitive enhancement or neuroprotection in any condition.

Mimics NCAM-mediated signaling via FGFR (fibroblast growth factor receptor) activation. Stimulates downstream Erk1/2 and PLCγ pathways. Promotes long-term potentiation (LTP) and synaptogenesis.

FGL (EVYVVAENQQGKSKA) is a synthetic 15-amino-acid peptide derived from the fibronectin type III homology domain 2 of the neural cell adhesion molecule (NCAM), designed as a pharmacomimetic agonist of NCAM to activate FGFR-mediated neurotrophic signaling and mimic the synaptogenic and neuroprotective effects of NCAM receptor engagement in the central nervous system. FGL activates downstream FGFR signaling to promote synaptic plasticity, neuronal survival, and spatial learning in preclinical models; rodent studies have demonstrated cognitive-enhancing and anxiolytic effects in aged animals and in models of neurodegeneration, establishing a preclinical rationale for further investigation. No published human clinical trials, pharmacokinetic studies, or safety evaluations of FGL have been indexed in PubMed; the entirety of the evidence base consists of animal and in vitro studies, and no regulatory body has approved or evaluated FGL for any human indication. FGL has no FDA approval or regulatory approval in any jurisdiction; it is a research compound with a defined neurotrophic mechanism and an exclusively preclinical evidence base, and no clinical data exists to inform its pharmacokinetics, safety, or therapeutic utility in humans.