Strategic feeding of NS0 and CHO cell cultures to control glycan profiles and immunogenic epitopes of monoclonal antibodies

The control of glycosylation profiles is essential to the consistent manufacture of therapeutic monoclonal antibodies that may be produced from a variety of cell lines including CHO and NS0. Of particular concern is the potential for generating non-human epitopes such as N-glycolylneuraminic acid (Neu5Gc) and Galα1−3 Gal that may be immunogenic. We have looked at the effects of a commonly used media supplements of manganese, galactose and uridine (MGU) on Mab production from CHO and NS0 cells in enhancing galactosylation and sialylation as well as the generation of these non-human glycan epitopes. In the absence of the MGU supplement, the humanized IgG1 antibody (Hu1D10) produced from NS0 cells showed a low level of mono- and di-sialylated structures (SI:0.09) of which 75 % of sialic acid was Neu5Gc. The chimeric human-llama Mab (EG2-hFc) produced from CHO cells showed an equally low level of sialylation (SI: 0.12) but the Neu5Gc content of sialic acid was negligible (<3%). Combinations of the MGU supplements added to the production cultures resulted in a substantial increase in the galactosylation of both Mabs (up to GI:0.78 in Hu1D10 and 0.81 in EG2-hFc). However, the effects on sialylation differed between the two Mabs. We observed a slight increase in sialylation of the EG2-hFc Mab by a combination of MG but it appeared that one of the components (uridine) was inhibitory to sialylation. On the other hand, MG or MGU increased sialylation of Hu1D10 substantially (SI:0.72) with an increase that could be attributed predominantly to the formation of Neu5Ac rather than Neu5Gc. The increased level of galactosylation observed with MG or MGU was attributed to an activation of the galactosyl transferase enzymes through enhanced intracellular levels of UDP-Gal and the availability of Mn2+ as an enzymic co-factor. However, this effect not only increased the desirable beta 1−4 Gal linkage to GlcNAc but unfortunately in NS0 cells increased the formation of Galα1−3 Gal which was shown to increase x3 in the presence of combinations of the MGU supplements. Supplementation of media with fetal bovine serum (FBS) increased the availability of free Neu5Ac which resulted in a significant increase in the sialylation of Hu1D10 from NS0 cells. This also resulted in a significant decrease in the proportion of Neu5Gc in the measured sialic acid from the Mab.