Generation of an industrially ideal host cell line for producing completely-defucosylated antibody with enhanced antibody-dependent cellular cytotoxicity (ADCC)

To generate industrially applicable new host cell lines for antibody production with optimizing antibody-dependent cellular cytotoxicity (ADCC) we focused on the most important carbohydrate structure “fucose residues attached to the innermost GlcNAc residue of N-linked oligosaccharides via -1,6 linkage” (Shields, 2002; Shinkawa, 2003), and succeeded in disrupting both FUT8 ( -1,6-fucosyltransferase gene) alleles in Chinese hamster ovary (CHO) cell line by sequential homologous recombination. FUT8-/cell lines have morphology and growth kinetics similar to those of the parent. Antibodies produced by the engineered CHO cell lines strongly bound to human Fc receptor IIIa (Fc RIIIa) and showed approximately two orders of magnitude higher ADCC than antiCD20 antibodies (Rituxan) produced by parental cell lines without changing antigen-binding and complement-dependent cytotoxicity (CDC). Moreover, the engineered cell line remains stable, producing completelydefucosylated antibody with fixed quality and efficacy even in serum-free fed-batch culture. Thus, our approaches provide a new strategy for controlling the glycosylation profile of therapeutic recombinant proteins and could be a considerable advantage for the manufacture of glycoprotein therapeutics, especially antibodies.