Method for the production of a glycosylated immunoglobulin

What is this patent about?

’769 is related to the field of large-scale immunoglobulin production using eukaryotic cell cultures. Specifically, it addresses the technical challenge of controlling post-translational modifications, such as the glycosylation pattern, during the fermentation process. In the production of therapeutic antibodies, the specific arrangement of sugars attached to the protein is critical because it directly influences the drug’s efficacy, stability, and biological safety profile.

The underlying idea behind ’769 is that the amount of a specific, often undesirable sugar structure known as mannose-5 (M5) can be precisely regulated by manipulating the glucose supply. Rather than providing an excess of nutrients, the inventor discovered that keeping the cells in a state of controlled glucose starvation—where the available sugar is strictly limited to a fraction of what the cells could actually consume—prevents the accumulation of high-mannose structures without compromising the overall protein yield.

The claims of ’769 focus on a fed-batch cultivation method for Chinese Hamster Ovary (CHO) cells that utilizes a highly specific restricted glucose feeding strategy. The method requires maintaining a constant Degree of Glucose Limitation (DGL) at a single value between 0.1 and 0.5. This means the glucose available in each time unit is kept at a fixed, limited level, and this restricted feeding protocol is triggered only after the initial glucose in the medium has dropped to a predefined threshold, typically starting around day two or three of the culture.

In practice, the invention works by calculating the maximum possible glucose consumption rate of the cell line and then intentionally underfeeding the culture. By maintaining a constant DGL, the system ensures that the metabolic state of the cells remains uniform throughout the production phase. This is achieved by adjusting the absolute amount of glucose fed into the bioreactor in real-time based on the current viable cell density, ensuring the relative limitation remains steady even as the population grows.

This approach differs from prior methods that either provided glucose in excess or used simple constant-rate feeding, which often led to fluctuating metabolic states and inconsistent glycan profiles. By locking the cells into a specific metabolic bottleneck, the process suppresses the formation of the M5 glycostructure to 10% or less of the total isoforms. This provides a reliable engineering lever to ensure batch-to-batch consistency and high product quality in the manufacturing of complex biologics like Tocilizumab.