Differences in Proportion of N-acetyllactosamine and O-acetylated Sialic Acid Have No Significant Effect on the Pharmacokinetics and Biological Activity of Darbepoetin Alfa

Darbepoetin alfa is used to treat anemia in patients with chronic renal failure and is a therapeutic glycoprotein with five N-glycosylation sites and one O-glycosylation site. Since the glycosylation of therapeutic proteins is known to affect pharmacokinetics and biological activity, it was wondered how the certain glycosylation structure of darbepoetin alfa affects pharmacokinetics and biological activity. To investigate the effects of glycosylation structures, several darbepoetin alfa samples were generated through the processes slightly modified from HK-DPO production process. Analysis of N-linked glycosylation profiles showed that darbepoetin alfa samples have different proportions of N-acetyllactosamine and O-acetylated sialic acids. Since these structures were known to affect the stability and efficacy of glycoproteins, we evaluated the pharmacokinetics and biological activities of darbepoetin alfa samples. As a result of pharmacokinetics, the time course of the concentration in plasma was similar to that of NESP®, commercially available darbepoetin alfa. Also, the relative AUC last ratio (sample/reference) was ranged from 84% to 114%, which indicated they did not have meaningful differences. For in vitro biological activity, a cell proliferation test was conducted in the EPO-dependent F36E cell-line. An in vivo biological activity test was performed with EP-based assay using B6D2F1 female mice. As a result, the biological activities of each samples were similar to those of reference drug, NESP®. In conclusion, different proportions of N-acetyllactosamine and O-acetylation of sialic acid in darbepoetin alfa did not show any meaningful effects on pharmacokinetics and biological activities.