Mammalian cell line stability is an important consideration when establishing a biologics manufacturing process in the biopharmaceutical and in vitro diagnostics (IVD) industries. Traditional CHO cell line development methods use a random integration approach that requires transfection, selection, optional amplification, screenings, and single-cell cloning to select clones with acceptable productivity, product quality, and genetic stability. Site-specific integration reduces these disadvantages, and new technologies have been developed to mitigate risks associated with genetic instability. In this study, we applied the Leap-In® transposase-mediated expression system from ATUM to generate stable CHOK1 pools for the production of four recombinant antibody reagents for IVD immunoassays. CHO cell line stability is defined by consistent antibody production over time. Three of the CHOK1 pools maintained productivity suitable for manufacturing, with high antibody yields. The productivity of the remaining CHOK1 pool decreased over time; however, derivative clones showed acceptable stability. L-glutamine had variable effects on CHOK1 cell line or stable pool stability and significantly affected antibody product titer. Compared with traditional random integration methods, the ATUM Leap-In system can reduce the time needed to develop new immunoassays by using semi-site specific integration to generate high yield stable pools that meet manufacturing stability requirements.

The development of highly productive, genetically stable manufacturing cell lines is on the critical path to IND filing for protein based biologic drugs. Here we describe Leap-In Transpoasase® platform, a novel transposon-based mammalian (e.g. CHO) cell line development system that produces high titer stable pools with productivity and product quality attributes that are highly comparable to clones that are subsequently derived therefrom. The productivity distributions of clones are strongly biased towards high producers and both genetic and expression stability is consistently high. By avoiding the poor integration rates, concatemer formation, detrimental transgene recombination, low average expression level, unpredictable product quality and inconsistent genetic stability characteristic of non-homologous recombination methods, Leap-In provides several opportunities to de-risk programs early and reduce timelines and resources.