Voyager Therapeutics (Nasdaq: VYGR) has registered a Phase I trial of VY1706 in early Alzheimer's disease, setting up the first clinical test of an AAV gene therapy designed to reduce tau production. The Lexington, Massachusetts-based company registered the study on August 11, 2026, with an estimated start date of August 24. The trial is not yet recruiting.
The open-label, dose-escalation study (NCT07764146) will enroll up to 18 adults with mild cognitive impairment due to Alzheimer's disease or mild Alzheimer's disease, with amyloid and tau pathology confirmed by positron emission tomography (PET). Participants will receive a single intravenous infusion of VY1706 across three sequential dose cohorts. The primary endpoint will assess safety and tolerability over 52 weeks, while secondary endpoints include changes in cerebrospinal fluid (CSF) tau biomarkers and tau pathology measured by PET. Primary completion is projected for April 2029.
VY1706 combines an AAV vector with a small interfering RNA (siRNA) targeting microtubule-associated protein tau (MAPT) mRNA, with the aim of reducing production of both intracellular and extracellular tau after a single dose. The vector uses a capsid generated through Voyager's TRACER (Tropism Redirection of AAV by Cell-type-specific Expression of RNA) platform that leverages the ALPL receptor on brain vascular endothelial cells to cross the blood-brain barrier. Voyager said the receptor is well conserved across species, potentially supporting translation of its non-human primate (NHP) findings to humans. The capsid is also designed to reduce liver uptake, a potential safety advantage for systemic AAV delivery.
In a six-month GLP toxicology study presented at the Alzheimer's Association International Conference (AAIC) in July 2026, a single IV dose of VY1706 produced reductions of up to 75% in MAPT mRNA and tau protein in Alzheimer's disease-relevant brain regions in NHPs, with the effect sustained through six months. Voyager reported no adverse clinical pathology or histopathological findings in the central nervous system, dorsal root ganglia, or peripheral organs at doses up to 5E13 vg/kg. Earlier three-month data presented at the American Society of Gene & Cell Therapy (ASGCT) 2026 annual meeting showed tau protein reductions of 48–64%. The US FDA cleared VY1706's investigational new drug (IND) application in June, which Voyager described as the first IND clearance for a tau-targeted gene therapy.
VY1706 enters a developing clinical field of therapies designed to reduce tau production. Arrowhead Pharmaceuticals (Nasdaq: ARWR) began a Phase I/IIa study of ARO-MAPT, an RNA interference therapeutic targeting MAPT mRNA, in December 2025. Unlike the one-time IV administration planned for VY1706, ARO-MAPT is delivered subcutaneously on a repeat-dose schedule. Biogen's antisense oligonucleotide diranersen (BIIB080), which targets MAPT mRNA through intrathecal administration, reported Phase II CELIA results in May. The study missed its primary dose-response endpoint on the Clinical Dementia Rating–Sum of Boxes, but produced substantial reductions in CSF tau and tau PET pathology alongside signals of slower cognitive decline, prompting Biogen to advance the program toward Phase III development.