rHuPH20 Enhances Extravascular Delivery of mRNA Lipid Nanoparticles in Mice and Minipigs.

Extravascular administration of mRNA lipid nanoparticles (mRNA-LNPs) offers practical and clinical advantages but is limited by tissue barriers that restrict dispersion, lymphatic access, systemic exposure, and ultimately, target tissue expression. Recombinant human hyaluronidase PH20 (rHuPH20) transiently modifies the hyaluronan-rich extracellular matrix in the subcutaneous (SC) space, enhancing SC delivery of protein therapeutics; however, its effect on mRNA-LNP delivery has not been systematically evaluated. Here, the impact of rHuPH20 on extravascular mRNA-LNP delivery was assessed across routes of administration and formulations. In a coordinated series of mouse and minipig studies, mRNA-LNP expression, biodistribution, lymphatic trafficking, systemic exposure, tissue deposition, and inflammatory responses were evaluated following SC, intramuscular (IM), and intravenous (IV) administration. In mice, co-administration with rHuPH20 increased local expression after IM dosing of luciferase mRNA-LNPs up to 7-fold and whole-body expression after SC dosing up to 38-fold, relative to the corresponding route without rHuPH20. In minipigs, rHuPH20-enabled SC administration of huEPO mRNA-LNPs produced serum huEPO exposure that approached IV benchmarks. rHuPH20 also increased hepatic expression following extravascular delivery, demonstrated consistent effects across ionizable lipid chemistries, and was associated with reduced pro-inflammatory cytokine responses following repeat-dosing. Collectively, these findings support rHuPH20 as an effective enabler of extravascular mRNA-LNP delivery.