Figure 4.

PK-modifying anchors allow efficient modulation of blood circulating times and biodistribution of chemically distinct siRNA conjugates

(A) (Top) Schematic of fully modified asymmetric siRNAs conjugated to sugar (N-Acetylgalactosamine [GalNAc]) or lipid moieties (docosahexaenoic acid [DHA], docosanoic acid [DCA], Chol) at the 3′ end of the sense strand. (Bottom) Schematic of an 8-mer oligonucleotide anchor conjugated to a 40-kDa PEG moiety binding to a parent asymmetric siRNA containing a ligand. (B) Wild-type FVB/N female mice treated intravenously (28.5 nmol, ∼13 mg/kg) with parent asymmetric siRNA duplex (21–13) containing a ligand (sugar or lipid) or a PEGylated variant (21-13-8 PEG40k) of the parent compound. Concentrations of the guide strand in the blood and tissues were assessed by PNA-based hybridization assay, and values were normalized to the MW of an unconjugated 21–13 asymmetric siRNA duplex for comparison. (B) (Left) Concentration-time profiles for each parent asymmetric siRNA and corresponding PEGylated version using PK-modifying anchors. Serial blood samples were collected from the saphenous vein. (Right) Tissue biodistribution profile for each parent asymmetric siRNA and corresponding PEGylated version at 48 h post-injection. n = 4–5/group. Mean ± Standard deviation (SD).