(356g) Ionizable Lipids for Effective Translation of mRNA at Reduced Total Lnp Dosages

Delivery systems for mRNA-based therapeutics have gained enormous attention since the FDA approval of lipid nanoparticle (LNP)-based vaccines for SARS-CoV-2. LNPs are the most clinically advanced platform for nucleic acid delivery and can be formulated for various applications such as gene editing, protein replacement, and vaccine applications. Despite the enormous potential of these delivery systems, questions remain about the repeated dosage of LNPs and their potential side effects.

To address these concerns, we developed a library of thirteen lipids with a two-nitrogen lipid design aimed at mRNA delivery for various applications. In vitro screening of lipid nanoparticles (LNPs) revealed that incorporating branched tails significantly increased the translation efficiency. The structure-activity relationship showed that branched tails exhibited superior mRNA delivery, as a result of endosomal escape compared to tails with cis bonds. The head group, in comparison, did not play a significant role.

LNPs incorporating the most effective lipids from in vitro screening were subsequently evaluated in vivo for translation efficiency using FLuc mRNA. Among the various LNPs tested, the whole-body luminescence of the LNP containing one ionizable lipid was remarkable. In vivo screening showed that branched tails show superior translation efficiency compared to tails containing cis bonds. The most efficient lipid underwent further testing with different formulations to determine if the translation efficiency could be further improved.

Importantly, the LNP formulation with DSPC did not show any adverse effects based on whole blood analysis, and liver enzyme markers such as AST, and ALT. Furthermore, histological analysis did not reveal any abnormal effects. Overall, this library of lipids utilized a lower amount of total lipids compared to Spikevax® containing SM-102.