Researchers at the University of Toronto's Leslie Dan Faculty of Pharmacy have revealed a groundbreaking ionizable lipid nanoparticle named iso-A11B5C1. This nanoparticle stands out for its ability to deliver mRNA specifically to muscle tissues, minimizing the risk of off-target delivery to other organs. In a significant application, the researchers demonstrated that mRNA delivered by iso-A11B5C1 could initiate robust cellular-level immune responses, serving as a proof-of-concept for a melanoma cancer vaccine.
Iso-A11B5C1 efficiently delivers mRNA to muscle tissues while minimizing unintended translation in organs such as the liver and spleen. Notably, intramuscular administration of mRNA formulated with this nanoparticle induced potent cellular immune responses, even with limited expression observed in lymph nodes. This study represents a breakthrough, as it is the first instance of mRNA lipid nanoparticles effectively stimulating a cellular immune response and generating robust anti-tumor effects without directly targeting or transfecting lymph nodes.
Lipid nanoparticles (LNPs), crucial for delivering mRNA-based therapies such as the widely used COVID-19 mRNA vaccines, have encountered challenges due to some designs resulting in significant mRNA expression in off-target tissues, leading to treatable but undesirable side effects. The imperative to enhance the safety of mRNA therapies and minimize off-target effects calls for the development of LNPs like iso-A11B5C1.
In comparison to the benchmark LNP developed by Moderna, the Massachusetts-based biotechnology company, iso-A11B5C1 demonstrated superior muscle-specific mRNA delivery efficiency. It also triggered a distinct immune response compared to vaccines targeting infectious diseases, eliciting a lower humoral immune response while maintaining a comparable cellular immune response. The insights gained from iso-A11B5C1's unique platform offer valuable guidance for future lipid design and evaluation processes, providing the field with enhanced speed, precision, and insight in addressing challenges related to RNA delivery.