Written by expert: Wilfried, Director of Science and Innovation
For protein-based biopharmaceuticals, product yield from mammalian cell lines is a critical economic driver. Naturally, increased specific productivity – microgram product per cell per day – decreases the cost of goods. This allows lower prices while retaining expected profit margins. That is why expression technologies allowing generation of high protein producer mammalian cell lines are highly sought after. However, we sometimes see that a process yielding the highest achievable product concentrations compromises quality. The process with the highest product concentration does not always deliver a product that adheres to the set product quality requirements. For some difficult to express proteins, even extensive process development does not result in a substantial improvement in product concentration, forcing us to accept somewhat lower product concentrations.
In this article, I would like to show you an example of stable cell line development for a difficult to express protein. In this example, we developed and selected a CHO cell line stably expressing high levels of  laronidase . Eventually, however, we accepted a somewhat lower product concentration to guarantee product quality. Laronidase is an enzyme. This enzyme breaks down glycosaminoglycans. Laronidase is a marketed product used for treatment of lysomal disorders, such as Hurler forms of MPS1 and Scheie syndrome. Treatment costs are around $400,000 per patient per year. The costs are high, because the enzyme is highly glycosylated and very complex to manufacture.
Yield versus product quality
Using our  STEP® technology , we selected a cell clone showing a high and stable specific productivity, expressing laronidase at 100 mg/L in a generic fed-batch process. Next, we performed a limited basal media screening study and fed-batch studies. These studies resulted in a fed-batch process providing 750 mg/L enzyme at day-11.
However, careful analysis demonstrated that at day-11, the glycosylation profile of substantially deviated from the reference product and the product produced in our hands up to day-8. We then embarked on extensive small scale R&D studies testing a wide range of basal media and feed strategies. Additionally, we optimized the harvest time. Unfortunately, none of these activities allowed us to push the culture beyond day-8 without compromising the product quality. Therefore, the results forced us to lock-in the process using day-8 harvest as starting point for the purification. Fortunately, up to 500 mg/L laronidase was obtained, in a shortened overall process time, with virtually identical glycosylation profile as the reference product.
Laronidase cell line project status
Small scale process development resulted in a process able to reach a sufficient product concentration for laronidase. The purified product has very similar biological activity and glycan profile as the reference product. We are proud to have successfully developed a promising stable cell line and process for this difficult to express protein. The cell line and process are expected to lower the ultimate production costs when compared with the currently marketed reference product.
Batavia Biosciences offers a broad range of  process development  and  manufacturing  services for all major classes of biopharmaceuticals. We are dedicated to help bring biopharmaceuticals to the market at higher speed, with reduced costs, and with a higher success rate. Batavia Biosciences has vast experience in developing cell lines and processes for protein-based biopharmaceuticals. Our experienced scientists and technicians are well equipped to take on any challenge associated with biopharmaceutical development.
