Short‐hairpin‐RNA‐mediated silencing of fucosyltransferase 8 in Chinese‐hamster ovary cells for the production of antibodies with enhanced antibody immune effector function

Antibody-producing Chinese-hamster ovary cells (CHO-DG44) were converted into cells producing antibodies with strongly enhanced ADCC (antibody-dependent cellular cytotoxicity) by knocking down FuT8 (α-1,6-fucosyltransferase or fucosyltransferase 8) via constitutive expression of shRNA (short-hairpin RNA) against FuT8. After the introduction of a FuT8 shRNA expression plasmid under the control of a U6 promoter, CHO-DG44 clones with less than 5% residual FuT8 mRNA expression were isolated by selection for neomycin resistance, followed by low affinity nerve growth factor receptor enrichment and selection for LCA [Lens culinaris (culinary lentil) agglutinin] resistance. The CHO-DG44 clones identified produced highly afucosylated anti-[IGF-1R (insulin-like-growth-factor-1 receptor)] antibodies (up to 88%) that exhibited considerably enhanced ADCC compared with anti-IGF-1R wild-type antibodies produced by parental CHO cells. At the same time, antibody productivity was not significantly decreased. Analysis of stability showed that the clones obtained may be suitable for up-scaling, since low residual levels of FuT8 mRNA and production of afucosylated antibodies were maintained for at least 4 weeks.