Prevention of disulfide bond reduction during recombinant production of polypeptides

What is this patent about?

’037 is related to the field of recombinant protein production and biopharmaceutical manufacturing. Specifically, it addresses the technical challenges associated with maintaining the structural integrity of disulfide-containing polypeptides, such as monoclonal antibodies, during the transition from cell culture fermentation to the harvesting and purification stages.

The underlying idea behind ’037 is that the unintended reduction of disulfide bonds during harvest is driven by an active thioredoxin enzyme system released upon cell lysis. The inventor’s key insight was identifying that cellular enzymes—specifically thioredoxin, thioredoxin reductase, and the NADPH-generating pathways of glycolysis and the pentose phosphate pathway—remain functional in the harvested fluid and actively break the inter-chain bonds of the target protein.

The claims of ’037 focus on a method for producing a therapeutic monoclonal antibody that binds to HER2 using Chinese Hamster Ovary (CHO) cells. The claimed process specifically requires air sparging the pre-harvest cell culture fluid following the production phase to inhibit disulfide bond reduction, maintaining a dissolved oxygen level of at least 10% to counteract the reducing environment.

In practice, this implementation works by utilizing oxygen as a non-specific oxidizing agent to deplete the necessary cofactors, such as NADPH and glucose-6-phosphate, that the thioredoxin system requires to function. By maintaining a minimum dissolved oxygen threshold, the method ensures that the redox potential of the fluid remains oxidative, effectively neutralizing the enzymatic machinery that would otherwise fragment the antibody into separate heavy and light chains.

This approach differs from prior solutions by targeting the biochemical root cause of bond instability rather than merely adjusting generic storage temperatures or speeds. While traditional methods often struggle with protein degradation once cell lysis reaches a certain threshold, this invention provides a robust mechanical control—aeration—to stabilize the antibody’s tertiary structure throughout the critical harvesting window before formal purification begins.