A Closer Look into Freeze-Thaw Processes for Therapeutic Protein Formulations

Freezing and thawing are essential processes of the life cycle for a therapeutic protein. They enable stability during transport or storage as well as decoupling of DS and DP shelf-life for most Biologics Bulk Drug Substances (BDS).

Reports and publications about the impact of freezing and thawing on the stability of therapeutic proteins are contradictory. Some link a fast freezing process with an increase in protein degradation, others report the reverse.

Protein stress factors during freezing include an increase in interfaces (such as ice to liquid or to air), but also cold denaturation or cryoconcentration could lead to degradation. Furthermore, it has been reported that cryo-protectants, which should stabilize the protein in frozen state, can crystalize during frozen storage and can cause aggregate formation.

The importance of the thawing process is often being underestimated, as a 300% increase in protein concentration is not uncommon due to stratification effects and can cause degradation. Additionally, various studies show that slow and apparent mild thawing conditions at low temperatures can lead to gelation or precipitation due to protein-protein interactions.