rAlbumin's Stabilization Effect
Aggregation can cause numerous issues during the therapeutic protein manufacturing process. This association of mis-folded proteins can result in significant product losses, potentially increasing the immunogenicity of the drug product. Aggregation can occur as a consequence of process operations like refolding, purification, mixing, freeze-thawing, freeze drying, and reconstitution as well as during transportation and storage.
In a study conducted at Novozymes Biopharma, recombinant albumin was evaluated for its ability to suppress amyloid-fibril formation by the merozoite surface protein, MSP-2 protein, after a single freeze–thaw cycle.
A range of rAlbumin concentrations was evaluated for their ability to suppress aggregation, where fibril formation was measured by the effect on light scattering at 320 nm.
rAlbumin at various concentrations was dissolved in a solution of PBS buffer; the MSP-2 protein (3.5 mg/mL) was then added to all samples followed by a single freeze-thaw cycle. Samples were then aliquoted into 96-well plates and stored at 2–8ºC. Absorbance readings were taken at multiple time intervals over a five-day period.
Excipients, which are widely applied across the industry to enhance protein stability, were also assessed against rAlbumin for their ability to reduce protein aggregation. rAlbumin (15 mg/mL), glycine (20 mg/mL), PEG 400 (1 mg/mL), polysorbate 80 (0.82 mg/mL), or polysorbate 80 (8.2 mg/mL) were tested in the same model as described above.
Aggregation was suppressed by 50% at a 1:1 molar ratio of the antigen to rAlbumin and reduced by 80% in the presence of the highest concentration of rAlbumin. rAlbumin also suppressed aggregation of the MSP-2 antigen to a greater extent compared to other commercially available excipients (Figure 1).