Conjugates are defined single chemical entities with fully modified siRNA conjugated to targeting ligand to help them find their way to a specific cell or tissue within the body. Conjugates are a “lock and key” system, where the lock is the receptor found on the target cell and the key is the ligand attached to the siRNA.
We leverage two conjugate approaches to enable targeted delivery to the liver and the central nervous system (CNS)—GalNAc conjugates and CNS-targeted siRNA conjugates.
GalNAc conjugates – GalNAc, or N-acetylgalactosamine, is a sugar molecule that can recognize and bind to a cell surface protein, the asialoglycoprotein receptor (ASGPR), which is abundantly expressed on liver cells (hepatocytes). The binding affinity to the receptor increases exponentially if several GalNAc units are combined into a multivalent ligand. Our GalNAc-conjugated siRNAs are trivalent, meaning that three GalNAc molecules are clustered and conjugated to one siRNA molecule. This setup guarantees high affinity (strength) of the interaction between ASGPR and the GalNAc ligand, thus promoting optimal efficiency of siRNA delivery to the liver.
RNAi therapeutics utilizing GalNAc conjugate technology are administered subcutaneously. Our medicines GIVLAARI® (givosiran), OXLUMO® (lumasiran), and Leqvio® (inclisiran)* utilize GalNAc conjugate delivery.
CNS/Ocular-targeted siRNA conjugates – Our preclinical pipeline features several intrathecally administered siRNA conjugates engineered for delivery to the central nervous system (CNS) and the eye.
*Licensed to Novartis