Stability of production of recombinant antibodies from glutamine synthetase amplified CHO and NS0 cell lines

An expression system based on amplification of the glutamine synthetase (gs) gene leads to high level expression of heterologous proteins in CHO and NS0 cells. Two high copy number gs-CHO producer cell lines maintained high specific productivity in the presence of drug selection, but one was unstable in the absence of drug selection. A gs-CHO cell line with a single heterologous gene copy was found to be stable in the absence of drug selection. The gs-NS0 system was found to be highly stable for two high-yielding cell lines producing recombinant antibodies in the presence or absence of drug selection. Fed-batch serum-free suspension fermentation yielded a harvest titre of 895mg/l of recombinant antibody from one gs-NS0 cell line. Authors: Hassell, T.E., Brand, H.N., Renner, G.L., Westlake, A.J., et al.