Transient CHO expression platform for robust antibody production and its enhanced N-glycan sialylation on therapeutic glycoproteins.

Large-scale transient expression in mammalian cells is a rapid protein production technology often used to shorten overall timelines for biotherapeutics drug discovery. In this study we demonstrate transient expression in a Chinese hamster ovary (CHO) host (ExpiCHO-S™) cell line capable of achieving high recombinant antibody expression titers, comparable to levels obtained using human embryonic kidney (HEK) 293 cells. For some antibodies, ExpiCHO-S™ cells generated protein materials with better titers and improved protein quality characteristics (i.e., less aggregation) than those from HEK293. Green fluorescent protein imaging data indicated that ExpiCHO-S™ displayed a delayed but prolonged transient protein expression process compared to HEK293. When therapeutic glycoproteins containing non-Fc N-linked glycans were expressed in transient ExpiCHO-S™, the glycan pattern was unexpectedly found to have few sialylated N-glycans, in contrast to glycans produced within a stable CHO expression system. To improve N-glycan sialylation in transient ExpiCHO-S™, we co-transfected galactosyltransferase and sialyltransferase genes along with the target genes, as well as supplemented the culture medium with glycan precursors. The authors have demonstrated that co-transfection of glycosyltransferases combined with medium addition of galactose and uridine led to increased sialylation content of N-glycans during transient ExpiCHO-S™ expression. These results have provided a scientific basis for developing a future transient CHO system with N-glycan compositions that are similar to those profiles obtained from stable CHO protein production systems. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2724, 2019.

Parallel loading and complete automation of a 3-step mAb purification process for multiple samples using a customized preparative chromatography instrument with networked pumps.

Advancement in high-throughput screening methods of novel therapeutic proteins for early stage research and development, specifically mAbs, have given mid-scale (milligram to gram scale) purification groups access to more of these molecules. The available purification technologies built to support mid-scale production was not efficient or versatile enough to keep up with this surge. To remedy this problem, we have designed and built a custom instrument using an ÄKTA Pure. This system enables parallel processing up to 5 samples and has the versatility to perform 1- to 3-step purification processes in a single queue. Furthermore, a unique purification scheme can be selected for each of the five samples in the queue. Overall processing time has reduced by 83% compared to manual, non-parallel load methods. Here, we describe our novel approach and demonstrate the flexibility, speed and efficiency of the instrument.