Apolipoprotein C-III (APOC3) plays a crucial role in triglyceride metabolism, and its high expression leads to hypertriglyceridemia, which can contribute to an increased risk of cardiovascular disease Show more
Apolipoprotein C-III (APOC3) plays a crucial role in triglyceride metabolism, and its high expression leads to hypertriglyceridemia, which can contribute to an increased risk of cardiovascular disease and, when severely increased, can lead to acute pancreatitis. Loss-of-function variants in APOC3 are linked to lower triglyceride levels and reduced incidence of coronary artery disease. APOC3 mRNA, primarily synthesized by hepatocytes, is an ideal target for GalNAc-conjugated RNA-targeted therapies such as the antisense oligonucleotide (ASO) oleszarsen and small-interference RNA (siRNA) plozasiran. Herein, we systematically evaluate siRNA chemical modifications or multiple siRNAs to identify a long-acting APOC3 siRNA with a minimal number of 2'-F nucleotides. Using a series of structure-activity relationship (SAR) studies, we explored the effects of various oligonucleotide chemical modification scaffolds on siRNA potency, efficacy, and durability. These efforts led to the identification of an APOC3 targeting siRNA containing a novel chemical scaffold with robust activity and an extended duration of action in preclinical models. Additionally, selectivity and tolerability assessments in human cells, rodents, and nonhuman primates showed excellent safety and tolerability. A comparative analysis of the lead APOC3 siRNA with a surrogate of a clinical-stage APOC3 siRNA drug suggests the potential for similar or better potency and efficacy combined with less frequent dosing, potentially reducing the treatment burden on patients with hypertriglyceridemia. Show less
Hepatitis C virus (HCV) is a leading cause of chronic liver diseases and the most common indication for liver transplantation in the United States. HCV particles in the blood of infected patients are Show more
Hepatitis C virus (HCV) is a leading cause of chronic liver diseases and the most common indication for liver transplantation in the United States. HCV particles in the blood of infected patients are characterized by heterogeneous buoyant densities, likely owing to HCV association with lipoproteins. However, clinical isolates are not infectious in vitro and the relative infectivity of the particles with respect to their buoyant density therefore cannot be determined, pointing to the need for better in vivo model systems. To analyze the evolution of the buoyant density of in vivo-derived infectious HCV particles over time, we infected immunodeficient human liver chimeric fumaryl acetoacetate hydrolase Similar to the severe combined immunodeficiency disease/Albumin-urokinase plasminogen activator human liver chimeric mouse model, density fractionation of infectious mouse serum showed higher infectivity in the low-density fractions early after infection. However, over the course of the infection, viral particle heterogeneity increased and the overall in vitro infectivity diminished without loss of the human liver graft over time. In mice provided with a sucrose-rich diet we observed a minor shift in HCV infectivity toward lower density that correlated with a redistribution of triglycerides and cholesterol among lipoproteins. Our work indicates that the heterogeneity in buoyant density of infectious HCV particles evolves over the course of infection and can be influenced by diet. Show less