Overcoming HCP Co-Elution Issues Using Cell Line Engineering

During cell line development (CLD) for a customer’s therapeutic protein, product quality assessments revealed that the product was binding to and co-eluting with a range of hydrophobic host cell proteins (HCPs). However, the standard solution of adjusting downstream purification conditions was ineffective in this case as a specific HCP was directly binding to the product.

Review a solution that took an alternative approach by utilizing cell line engineering. By utilizing proteomics analysis to identify the problem HCP and CRISPR-based gene editing to make indel edits in the HCP gene, a frameshift mutation was produced that degraded the HCP and prevented its binding to the product. Through transfection and clone selection processes, AGC Biologics identified clones with successful HCP gene edits and high product titers.

The selected clones not only solved the problem of HCP binding but also showed increased product titers compared to the original cell line. This allowed for more resources to be allocated to the intended product. Stability studies confirmed the stable expression of the product protein in the selected clones.

The upstream optimization project had a significantly shorter timeline and was more cost-effective than a downstream development project would have been. Additionally, the removal of the specific HCP resulted in cost savings for the customer in subsequent manufacturing lots.

This innovative approach proved to be a superior choice for removing this type of HCP impurity. By using cell line engineering and CRISPR-based gene editing, the customer not only solved the problem but also improved the product titer, resulting in cost savings and increased efficiency for both parties.