Lipid Nanoparticle Delivery of TALEN mRNA Targeting LPA Causes Gene Disruption and Plasma Lipoprotein(a) Reduction in Transgenic Mice.

Lipoprotein(a), or Lp(a), is encoded by the LPA gene and is a causal genetic risk factor for cardiovascular disease. Individuals with high Lp(a) are at risk for cardiovascular morbidity and are refractory to standard lipid-lowering agents. Lp(a)-lowering therapies currently in clinical development require repetitive dosing, while a gene editing approach presents an opportunity for a single-dose treatment. In this study, mRNAs encoding Transcription Activator-Like Effector Nucleases (TALENs) were designed to target human LPA for gene disruption and permanent Lp(a) reduction. TALEN mRNAs were screened in vitro and found to cause on-target gene editing and target protein reduction with minimal off-target editing. TALEN mRNAs were then encapsulated with LUNAR®, a proprietary lipid nanoparticle (LNP), and administered to transgenic mice that expressed a human LPA transgene. A single dose of TALEN mRNA-LNPs reduced plasma Lp(a) levels in mice by over 80%, which was sustained for at least 5 weeks. Moreover, both standard and long-read next generation sequencing confirmed the presence of gene-inactivating deletions at LPA transgene loci. Overall, this study serves as a proof-of-concept for using TALEN-mediated gene editing to disrupt LPA in vivo, paving the way for the development of a feasible gene editing therapy for patients with high Lp(a).