The US Patent (No 6,852,510) covers Cardinal's GPEx gene product expression technology platform, which allows rapid genetic engineering of stable mammalian cell lines.
Conventional methods of introducing gene sequences into host mammalian cells include calcium phosphate precipitation, microinjection, lipofection, and electroporation. Alternatively, cells are grown and selected for those that amplify the introduced gene. In these methods, the cells are transfected with a gene encoding an amplifiable selection marker alongside the gene encoding the target protein.
However, these techniques have drawbacks, including low expression levels and instability that leads to the loss of protein expression over time. Through insertion of multiple copies of required genetic sequences, GPEx can generate, in as little as half the time required using traditional methods, stable cell lines that exhibit significantly higher levels of expression than those cell lines generated by other methods.
For example, Cardinal can take the gene for a protein that is believed to treat a particular cancer, and generate a cell line that expresses that protein. This protein is then isolated from the cell culture media after the cell line is grown and has expressed and secreted the protein.
And in addition to enabling rapid cell line development and availability of candidate gene products, the GPEx technology is also suited for pilot and large-scale production of antibodies and other therapeutic recombinant proteins, according to Cardinal.
Cardinal is already using the GPEx cell line engineering technology within its clinical scale mammalian cell culture manufacturing to provide "a faster way for its clients to get biopharmaceutical products, such as monoclonal antibodies, into clinical development," according to Paul Weiss, head of Cardinal's Biopharmaceutical Development Services centre.
Cardinal acquired the GPEx technology from Gala Biotech in 2003 as part of a drive to increase its services to the biotech sector. The company now offers drug development and bio-manufacturing services, including formulation development, fill-finish, bioassay development, biosafety testing, and cGMP manufacturing.