Glycosylation can significantly influence the safety and efficacy profiles of biopharmaceuticals. Changes in product glycosylation
during scale-up can lead to serious regulatory and commercial problems because of the risk of altered clinical performance.
This article presents an approach to biopharmaceutical development and manufacturing that reduces these scale-up risks. It
combines a Quality by Design (QbD) framework and a suite of visual informatics tools designed to aid the implementation of
QbD for therapeutics with complex glycosylation.
Biopharmaceutical glycosylation is highly complex and a major source of within-batch heterogeneity and between-batch variability.
Designers and manufacturers of biologics, therefore, must effectively measure and control glycosylation throughout the drug
lifecycle, particularly during scale-up and after significant manufacturing changes.1
TRADITIONAL APPROACH TO GLYCOSYLATION AND SCALE-UP
The possibility of nonuniform glycosylation during scale-up is inherent in the traditional approach to biopharmaceutical development,
which typically is:
- produce a drug product for early-stage development in a small-scale bioreactor (this becomes the reference material for subsequent
- characterize the glycosylation of the reference material, invoking ICH Q6B and other relevant guidelines to direct the analyses
- scale up in stages, optimizing cell -culture conditions and downstream processing to keep the scaled-up material similar to
the reference material.
- invoke ICH Q5E to compare the glycosylation material from large- and small-scale bioreactors. During this exercise, focus
on the overall shape of oligosaccharide patterns by comparing the relative amounts of major glycan species.
There are three main risks of this approach. First, the cells of the expression system could behave differently in the scaled-up
process, thus resulting in altered glycosylation—so the comparability exercise fails. The risk is the possible modification
of safety or efficacy profiles. Second, the overall f pattern might look the same after scale-up but the safety or efficacy profiles do change significantly because of alterations
in relative quantities of minor glycoforms with high bioactivity that were not considered significant in the glycan structure
analyses (glycoforms are forms of the drug that share the same protein backbone but have different oligosaccharides). Third,
the glycosylation could alter after scale-up, leading to modified clinical performance of the drug, but the structural changes
may not have been picked up during glycoprofiling.
This article outlines a five-step approach to the realization of glycoprotein therapeutics that reduces scale-up risks. It
combines a Quality by Design (QbD) framework for the development and manufacture of the drug and a suite of visual informatics
tools designed to aid the implementation of QbD for drugs with complex glycosylation.