A transposon-based transient transfection system in CHO-K1 cells enables quality prediction of stable cell line proteins.

In biologics drug discovery, transient protein expression is widely used to rapidly produce biologics, thereby accelerating the identification of lead candidates. However, the accuracy and consistency of predicting further product quality in large-scale production needs to be considered, especially with respect to physicochemical properties and posttranslational modifications. With this in mind, a transient expression system utilizing Chinese hamster ovary K1 (CHO-K1) has been established, which integrates high expression capability with quality profiles similar to those of the protein produced by stable cell lines. A well-designed vector containing transposon elements overcomes the blindness of random integration and ensures the sustained viability of cells and production capability, thus addressing the critical bottlenecks in classical transiently transfected workflows. Combined with the optimization of various transfection parameters, the customized platform achieved a titer over 1.5 g/L in the production of a bispecific antibody while maintaining a proportion of fragments, aggregates and glycosylation patterns that are comparable to those of the stable cell line protein. More importantly, this platform also demonstrated reliability in terms of quality across diverse antibody formats. This innovative protein expression platform bridges the gap between transient and stable expression on the basis of CHO-K1, ensuring the consistency of host cell types throughout the antibody discovery and development process.