A cell line change was instituted for the production of Eculizumab, a recombinant IgG (rIgG). Eculizumab is produced using NS0 cell line and its production using CHO cells is being investigated. The goal of this study is to observe the type and extent of glycosylation changes.
Oligosaccharide mapping using normal phase HPLC with fluorescent detection showed several changes in glycosylation. The amount of high Mannose glycans increased 28 fold. Two percent of the total glycans in the rIgG from NS0 contained αGal-containing glycans, while none from CHO contained such glycans. Proportions of G0F increased, while G1F decreased. Hence, a net decrease in Galactose-containing glycans was observed. Monosaccharide composition corroborated this finding. Surprisingly, no G2F was detected by MALDI mass spectrometry. Instead a substantial amount of Man5 was detected. The regular oligosaccharide mapping technique was modified to confirm this.
A change in the retention times of mono- and bisialyl glycans implied a change in the sialic acid type. In addition, there was a reduction in the heterogeneity and a 15 fold reduction in the amount of sialyl glycans. Again, this was corroborated by sialic acid assay using reverse phase HPLC with fluorescent detection. The control NS0 cell line produced rIgG with N-glycolyl neuraminic acid whereas the CHO cell line produced predominantly N-acetyl neuraminic acid rIgG.
Some of the changes were predicted since they are well documented in published literature. The acceptance criteria were met for most but not all the observed changes. The change control needed going forward will be discussed.
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