Non-fucose level as a function of glycoenzyme transcription in a glycoengineered CHO cell line

Background and novelty Antibody-dependent cellular cytotoxicity (ADCC) is one important mode of action for therapeutic mAbs in the field of oncology. It is strongly dependent on the glycan pattern of the Fc N-glycan: low core-fucose levels (= high non-fucose levels) typically result in an increased ADCC. There are several options to reach high non-fucose levels like the selection of the right host that expresses the desired pattern, in vitro glycosylation, use of glycosylation inhibitors, alteration of process parameters and generating glycosylation mutants with modified glycan synthesis activities by cell line engineering. Within Roche Pharma we are working with CHO cell lines designed to produce therapeutic antibodies based on the GlycArt system. These cell lines contain in addition to the recombinant gene for the therapeutic monoclonal antibody (mAb), also recombinant genes for two glycosyltransferases, N-acetylglucosaminyltransferase-III (GntIII) and mannosidase-II (ManII). As a result the CHO cells produce antibodies with a modified glycosylation structure characterized by a low-fucose Fc part. The selection system for the two glycosylation enzymes is based on the use of puromycin whereas for the mAB MSX is used.