Lumasiran is a hydroxyacid oxidase 1 (HAO1)-directed double-stranded small interfering ribonucleic acid (siRNA), covalently linked to a ligand containing N-acetylgalactosamine (GalNAc). It reduces levels of glycolate oxidase (GO) enzyme by targeting the HAO1 gene messenger ribonucleic acid (mRNA) in hepatocytes through RNA interference. Decreased GO enzyme levels reduce the amount of available glyoxylate, a substrate for oxalate production. As the GO enzyme is upstream of the deficient alanine:glyoxylate aminotransferase (AGT) enzyme that causes PH1, the mechanism of action of lumasiran is independent of the underlying AGXT gene mutation.