Peptide-mediated delivery of an α-synuclein-targeting antisense oligonucleotide: Pharmacokinetics, safety, and central nervous system efficacy in a synucleinopathy model.

Effective blood-brain barrier penetration is a major challenge for antisense oligonucleotide (ASO) therapies targeting neurodegenerative diseases. We utilized an 11-amino acid peptide derived from apolipoprotein B (ApoB11) that binds the low-density lipoprotein receptor to cross the blood-brain barrier, to deliver an ASO systemically to the central nervous system (CNS) and suppress targeted transcripts in neurodegenerative disease models. This study evaluates the pharmacokinetics, CNS penetration, and therapeutic efficacy of ApoB11:2'-O-methyl ASO-α-Syn, an ASO for α-synuclein (α-Syn) suppression in synucleinopathies. After a single intraperitoneal injection (2 mg/kg) in C57BL/6 mice, ApoB11:ASO-α-Syn showed robust brain penetration, reaching peak concentrations (maximum concentration [Cmax] = 0.14 nmol/mg) at 1.5 hours and persisting at high levels over the 96-hour observation period, indicating prolonged CNS retention. Immunofluorescence confirmed widespread uptake in neurons and endothelial cells. The ASO also accumulated in the liver (Cmax = 419.5 nmol/mg, t1/2 = 104.9 hours), consistent with receptor-mediated uptake. Acute and subacute toxicity studies revealed no systemic toxicity at the highest nonlethal dose (32 mg/kg). In a mouse model of dementia with Lewy bodies overexpressing human α-Syn, ApoB11:ASO-α-Syn reduced α-Syn mRNA and protein levels in the hippocampus and cortex by ∼50% at 16 mg/kg, a reduction that is biologically meaningful based on human genetic evidence (SNCA duplications/triplications) and preclinical studies. These results demonstrate that ApoB11 is an effective ASO carrier for CNS delivery, and that partial α-Syn reduction is expected to have disease-relevant effects, supporting its potential as a therapeutic strategy for synucleinopathies. SIGNIFICANCE STATEMENT: This study demonstrates that systemically delivered ApoB11-conjugated antisense oligonucleotides effectively cross the blood-brain barrier, achieve sustained central nervous system retention, and produce a biologically meaningful reduction (∼50%) in α-synuclein expression in a transgenic mouse model of synucleinopathy. These findings highlight a minimally invasive, peptide-mediated strategy for targeting neurodegenerative diseases and overcoming major delivery limitations of antisense oligonucleotide therapies.