Oral Presentation Asia-Pacific Vaccine and Immunotherapy Congress 2026

Oligo(ethylene glycol)-functionalized polycarbonate lipid nanoparticles for mRNA delivery with attenuated PEG immunogenicity (#44)

Dao TH Le 1 2 , Chuan Yang 1 , Yue Zhang 1 , Gui Zhao 1 , Brandon Seow 1 , Xinxin Zhao 1 , Ki Hyun Bae 1 , James Hui 2 , Yi Yan Yang 1 2
  1. A*STAR - Agency for Science, Technology and Research, Singapore, SINGAPORE
  2. National University of Singapore, Singapore

Introduction: Certain risks associated with mRNA-lipid nanoparticle (mRNA-LNP) vaccines during our global immunization efforts against the COVID-19 pandemic have raised concerns about PEG immunogenicity and reduced efficacy upon repeated dosing1–3. Based on recent studies on PEGylated lipid replacements using primarily non-degradable polymer backbones4,5, we synthesized a series of oligo(ethylene glycol)-functionalized biodegradable polycarbonate lipids (OPL-1 to OPL-8) as alternatives to ALC-0159 used in the Comirnaty mRNA vaccine to ameliorate the PEG immunogenicity of LNPs.

Methods: OPLs were synthesized by ring-opening polymerization of cyclic carbonate monomers with an OEG pending group (MTC-OEG) using DTD-OH as an initiator in the presence of TU and DBU as co-catalysts. Then an ethanol phase composed of ALC-0315, DSPC, cholesterol, and OPL was mixed with an aqueous mRNA solution to make OPL LNPs, while ALC-0159 was used instead of OPL to formulate ALC-0159 LNPs. Physicochemical characterizations of mRNA-LNPs were determined by Z-average size, polydispersity index, zeta potential, and mRNA encapsulation efficiency. In vitro FLuc mRNA transfection and cellular uptake study in RAW264.7 and DC2.4 cells, as well as in vivo and ex vivo bioluminescence imaging in BALB/c mice were evaluated. A prime-boost vaccination study on BALB/c mice investigated the neutralizing antibody activity, spike-specific IgG titers, B cell subpopulations, and anti-PEG IgM titers. Moreover, in vitro anti-PEG antibody recognition against LNPs was examined by ELISA.

Results: The length of OEG (m) played a key role in formulating LNPs with desirable physicochemical properties: OPL-7 and OPL-8 with EG9 produced nanosized LNPs and their high encapsulation efficiency, comparable to ALC-0159 LNPs. A more efficient cellular uptake might explain their significantly higher in vitro mRNA translation efficiency than ALC-0159 LNPs. Furthermore, OPL-7 and OPL-8 LNPs showed a significantly reduced liver biodistribution and relatively higher accumulation in lymph nodes while achieving significantly greater lymph node to liver uptake ratios.

The vaccination study of OPL-7 and OPL-8 LNPs induced robust humoral immune responses against spike glycoproteins of SARS-CoV-2 Delta variant B.1.617.2 encoded in the encapsulated mRNA without significant toxicities. Repeated dosing of the OPL-7 or OPL-8 LNP vaccination generated significantly lower anti-PEG antibody titers compared to ALC-0159 LNPs, as well as reduced the pre-existing anti-PEG antibody recognition.

Conclusions: Our results showed impacts of OEG length on the physicochemical attributes of OPL LNPs. Additionally, OPL-7 and OPL-8 LNPs shared similar biodistribution tendencies and could be used for mRNA delivery to mitigate PEG immunogenicity.

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