RNAi-mediated gene silencing in non-human primates

Area of Science:

• Biotechnology
• Molecular Biology
• Pharmacology

Background:

• RNA interference (RNAi) offers a promising therapeutic strategy for silencing disease-causing genes.
• Systemic delivery of small interfering RNAs (siRNAs) for RNAi has faced challenges, with limited success reported in non-rodent models.

Purpose of the Study:

• To investigate the efficacy of systemically delivered siRNAs in silencing the apolipoprotein B (ApoB) gene in non-human primates.
• To evaluate the potential of RNAi therapeutics for treating diseases with currently untreatable targets.

Main Methods:

• APOB-specific siRNAs were encapsulated in stable nucleic acid lipid particles (SNALP).
• SNALP-siRNAs were administered intravenously to cynomolgus monkeys at doses of 1 or 2.5 mg/kg.
• Gene and protein expression, along with serum lipid levels, were analyzed post-administration.

Main Results:

• A single intravenous siRNA injection resulted in dose-dependent silencing of APOB messenger RNA in the liver (>90% maximal silencing).
• Silencing was confirmed to occur via APOB mRNA cleavage, consistent with the RNAi mechanism.
• Significant reductions in ApoB protein, serum cholesterol, and LDL levels were observed within 24 hours and lasted up to 11 days.

Conclusions:

• Systemic delivery of siRNAs in a liposomal formulation (SNALP) achieves clinically relevant gene silencing in non-human primates.
• RNAi-mediated gene silencing demonstrates immediate, potent, and lasting biological effects, supporting its potential as a new class of drugs.
• These findings advance the development of RNAi therapeutics for a broader range of diseases.