The article "Multivalent N-Acetylglucosamine-Conjugated siRNA Localizes in Hepatocytes and Elicits Robust RNAi-Mediated Gene Silencing" by Jayaprakash K. Nair et al. describes the development and evaluation of siRNA conjugated to N-acetylgalactosamine (GalNAc) for targeted delivery to hepatocytes. The study demonstrates that these conjugates, when administered subcutaneously (SC), exhibit robust RNAi-mediated gene silencing in the liver. Key findings include: 1. **Synthesis and Stability**: The GalNAc-conjugated siRNAs were synthesized using solid-phase oligonucleotide synthesis and showed comparable yields to standard oligonucleotides. The conjugates were stable against nucleases and had improved pharmacokinetics compared to unconjugated siRNAs. 2. **Uptake and Binding**: In vitro studies showed that the conjugates were efficiently taken up by primary mouse hepatocytes, mediated by specific binding to the asialoglycoprotein receptor (ASGPR). The binding affinity and receptor-ligand interaction were crucial for uptake efficiency. 3. **In Vivo Efficacy**: In vivo studies in mice revealed that SC administration of the GalNAc-conjugated siRNAs resulted in significant gene silencing of the target mRNA in the liver. The conjugates showed higher efficacy and sustained pharmacological effects compared to intravenous (IV) administration, with a median effective dose (ED50) of 1 mg/kg. 4. **Chronic Treatment**: Chronic weekly dosing of the conjugates over 9 months resulted in dose-dependent gene silencing without adverse effects, indicating the potential for long-term treatment. 5. **Optimization**: Further optimization of the siRNA chemistry and conjugation design led to a 5-fold improvement in efficacy, making the approach suitable for treating a wide range of diseases involving liver-expressed genes. The study highlights the potential of GalNAc-conjugated siRNAs as a novel class of RNAi therapeutics with promising preclinical efficacy and therapeutic potential.The article "Multivalent N-Acetylglucosamine-Conjugated siRNA Localizes in Hepatocytes and Elicits Robust RNAi-Mediated Gene Silencing" by Jayaprakash K. Nair et al. describes the development and evaluation of siRNA conjugated to N-acetylgalactosamine (GalNAc) for targeted delivery to hepatocytes. The study demonstrates that these conjugates, when administered subcutaneously (SC), exhibit robust RNAi-mediated gene silencing in the liver. Key findings include: 1. **Synthesis and Stability**: The GalNAc-conjugated siRNAs were synthesized using solid-phase oligonucleotide synthesis and showed comparable yields to standard oligonucleotides. The conjugates were stable against nucleases and had improved pharmacokinetics compared to unconjugated siRNAs. 2. **Uptake and Binding**: In vitro studies showed that the conjugates were efficiently taken up by primary mouse hepatocytes, mediated by specific binding to the asialoglycoprotein receptor (ASGPR). The binding affinity and receptor-ligand interaction were crucial for uptake efficiency. 3. **In Vivo Efficacy**: In vivo studies in mice revealed that SC administration of the GalNAc-conjugated siRNAs resulted in significant gene silencing of the target mRNA in the liver. The conjugates showed higher efficacy and sustained pharmacological effects compared to intravenous (IV) administration, with a median effective dose (ED50) of 1 mg/kg. 4. **Chronic Treatment**: Chronic weekly dosing of the conjugates over 9 months resulted in dose-dependent gene silencing without adverse effects, indicating the potential for long-term treatment. 5. **Optimization**: Further optimization of the siRNA chemistry and conjugation design led to a 5-fold improvement in efficacy, making the approach suitable for treating a wide range of diseases involving liver-expressed genes. The study highlights the potential of GalNAc-conjugated siRNAs as a novel class of RNAi therapeutics with promising preclinical efficacy and therapeutic potential.