Comparative study on incorporation of three recombinant human α-galactosidase A drugs (agalsidases) into cultured fibroblasts and organs/tissues of Fabry mice.

Enzyme replacement therapy (ERT) with recombinant human α-galactosidase A (α-Gal A) drugs (agalsidases) has been successfully used for treatment of Fabry disease, and three kinds of agalsidases are now available in Japan. To compare the biochemical characteristics of these drugs, especially focusing on their incorporation into cultured fibroblasts and organs/tissues of Fabry mice, we performed in vitro, cell, and animal experiments. The results revealed that there were no differences in the kinetic parameters and enzyme activity between these agalsidases. But their affinity for domain 9 of cation-independent mannose 6-phosphate receptor (CI-M6PR), which exists in various cells, was higher in the order: agalsidase beta biosimilar 1 (agalsidase beta BS) > agalsidase beta > agalsidase alfa, which almost coincided with the experimental results regarding the efficiency of their incorporation into cultured fibroblasts derived from a Fabry mouse. The results of animal experiments using Fabry mice revealed that the incorporation of the agalsidases into the kidneys and heart, where CI-M6PRs are widely distributed, was efficient in the order: agalsidase beta/agalsidase beta BS > agalsidase alfa, which reflected the degree of reduction of glycosphingolipids accumulated in the organs/tissues. On the other hand, no differences in the efficiency of their uptake or reduction of the accumulated substances were observed in the liver, probably due to asialoglycoprotein receptors expressed on the surface of hepatocytes. This information will be useful for making a suitable ERT plan for individual Fabry patients with various backgrounds and for developing new ERT drugs in the future.