Purpose: P. pastoris has previously been genetically engineered to generate strains that are capable of producing mammalian-like glycoforms. Our objective was to investigate the correlation between sialic acid content and pharmacokinetic properties of recombinant TNFR2:Fc fusion proteins generated in glycoengineered P. pastoris strains.
Methods: TNFR2:Fc fusion proteins were generated with varying degrees of sialic acid content. The pharmacokinetic properties of these proteins were assessed by intravenous and subcutaneous routes of administration in rats. The binding of these variants to FcRn were also evaluated for possible correlations between in vitro binding and in vivo PK.
Results: The pharmacokinetic profiles of recombinant TNFR2:Fc produced in P. pastoris demonstrated a direct positive correlation between the extent of glycoprotein sialylation and in vivo pharmacokinetic properties. Furthermore, recombinant TNFR2:Fc produced in glycoengineered Pichia, with a similar sialic acid content to CHO-produced etanercept, demonstrated similar in vivo pharmacokinetic properties to the commercial material. In vitro surface plasmon resonance FcRn binding at pH6.0 showed an inverse relationship between sialic acid content and receptor binding affinity, with the higher affinity binders having poorer in vivo PK profiles.
Conclusions: Sialic acid content is a critical attribute for modulating the pharmacokinetics of recombinant TNFR2:Fc produced in glycoengineered P. pastoris.