Horizon's GS Null CHO K1 cells are in the process of being independently evaluated in over 15 organisations globally. Some of these evaluations have given us permission to share their cell line development data relating to the expression of recombinant proteins, including monoclonal antibodies and bispecifics. Although at this stage considerable optimisation is still being performed on the culture process, we are consistently receiving reports of expression exceeding expectations. While some of the data provided below utilises MSX to improve the stringency of selection with individual vectors, the CHO SOURCE platform combining Horizon's GS null CHO K1 cell line with an expression vector from ProteoNic does not require MSX during selection, nor does it require any amplification steps commonly associated with alternative metabolic selection systems such as the Methotrexate / DHFR selection approaches.
After being transfected with a GS selection vector containing a monoclonal antibody and placed under metabolic selection in glutamine free media, the cells expressed significantly higher titres of recombinant protein than the reference system comprising MSX treated wild type CHO K1 cells. Data shown is generated in a 5L Bioreactor and represents titre from stable pools of cells.
As part of an evaluation of different vector technologies, the cells were transfected with a construct expressing a monoclonal antibody in a vector containing UnicTM elements from ProteoNic.
Titres in excess of 2g/L of a biosimilar IgG were achieved at stable pool stage.
Four hundred clones from the stable pool above were screened and assessed for productivity. Three clones expressed at >5g/L.
This is currently an un-optimised process, with further advances expected.
As part of an evaluation of HD-BIOP3, a Biopharmaceutical company in China developed stable pools using a vector provided by DNA 2.0. They assessed the impact of using bulk selection compared with generating minipools through applying selection to 500 cells. Together with this, they evaluated the impact of using MSX with this vector.
Data shown is after 5 days of shake culture.
As part of an evaluation of HD-BIOP3, a Biopharmaceutical company in the USA developed stable pools using a vector provided by DNA 2.0, together with increasing concentrations of MSX.
Data shown is after Protein A purification.