Practical Use of Analytical Tools for Glycan Structures Related to Functionality and Safety of Biopharmaceuticals

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It is known that glycosylation of biopharmaceuticals relates to drug potency and half-life in blood. Since glycan modification is essential for the effector effect in antibody drugs, biopharmaceuticals are produced by using biosynthesis of mammalian cells but not microorganisms like as Escherichia coli. In particular, a biantennary N-glycan attached on Fc region of antibody is an important factor for interaction with its receptor FcRIIIa, and lack of a core-fucose residue attached to innermost GlcNAc at reducing end of N-glycan dramatically enhances interaction between FcRIIIa and IgG. Recently, it is reported that a particular galactose residue at non-reducing end of biantennary N-glycan also promotes the interaction with FcRIIIa receptor. On the other hand, glycan structure of post-translational modification by the use of mammalian-derived cells for production of biopharmaceuticals is different from that of human in some cases, and non-human type glycans is observed sometimes. For instance, high-mannose N-glycan is observed in unpreferable process step of manufacturing production and non-human type glycans are found depend on host cell type. Antigenicity of α1,3galactose (α1,3Gal) antigen and N-glycolylneuraminic acid (NeuGc) are observed at non-human type glycans well-known as xenoantigen. Because human lacks the enzyme activities of α1,3Gal and NeuGc synthesis for during the process of evolution with acquired gene mutations, immune response may act as a exogeneous antigen when they are injected to human patients. Therefore, contamination of antigenic glycosylation is considered to affect the safety of biopharmaceuticals. Currently, general standards have not been established regarding methods for glycan analysis from the viewpoint of the functionality and safety of biopharmaceuticals. Furthermore, it seems that the comprehensive supply system of glycan standards and recognition probes is still partial. We will report our developed tools regarding glycan standards and recognition probes. The glycan standards are available for quantitative analysis of reducing terminal core fucose and non-reducing terminal galactose (G2 and 6-G1 glycans) to evaluate the effector function of antibody drugs. The recognition probes derived from chicken are expected to be applied for qualitative analysis of an allergy risk factor caused by xenoantigen (α1,3Gal and NeuGc epitopes). The tools developed in this study would contribute to the analysis of glycan structures that affect the quality of biopharmaceuticals.