Method for the production of a glycosylated immunoglobulin

What is this patent about?

’678 is related to the field of immunoglobulin production in eukaryotic cells, specifically focusing on how cultivation parameters influence the post-translational modification of proteins. In the manufacture of therapeutic antibodies, the specific arrangement of sugar molecules, or glycosylation pattern, is critical because it dictates the drug’s stability, half-life, and biological efficacy. A common challenge in large-scale fermentation is the unintended increase of certain glycostructures, such as mannose-5, which can occur when cells are stressed or nutrient-deprived.

The underlying idea behind ’678 is that the amount of the mannose-5 glycostructure can be precisely controlled and limited by maintaining a specific, constant level of glucose restriction throughout the cultivation process. Rather than providing an excess of nutrients, the invention relies on the insight that keeping the degree of glucose limitation (DGL) within a defined window—specifically between 10% and 80% of the cell's maximum metabolic capacity—prevents the erratic glycosylation shifts typically seen in standard fed-batch cultures. This creates a metabolic steady state that favors a predictable and desirable distribution of antibody isoforms.

The claims of ’678 focus on a method for producing a composition of Tocilizumab (an anti-IL-6R antibody) where the mannose-5 fraction is strictly maintained between 2.8% and 10% of the total glycostructure area. The process requires cultivating recombinant CHO cells at an initial density of at least 10^5 cells/ml while tightly regulating the environment at a pH between 7.0 and 7.2. The independent claims specifically protect the use of a controlled glucose supply, defined either as a percentage of maximum utilization or as a DGL value between 0.2 and 0.8, to achieve this specific molecular profile.

In practice, the invention works by monitoring the viable cell density and the current glucose consumption rate to adjust the feeding rate dynamically. Instead of a fixed-volume feed, the system calculates the exact amount of glucose needed to maintain the target glucose limitation ratio. By keeping the cells in a state of partial but constant hunger, the internal cellular machinery processes the antibody's sugar chains more consistently. The results demonstrate that even with variations in initial cell seeding, this feedback-loop approach ensures the final product meets strict quality specifications for its carbohydrate components.

This approach differs from prior methods that often resulted in high mannose-5 levels due to uncontrolled glucose starvation at the end of a batch or excessive lactate buildup from overfeeding. By coupling pH regulation with a constant DGL, the invention avoids the fluctuations in glycosylation that typically occur as cell density increases. The method effectively decouples protein yield from glycan heterogeneity, allowing for high-titer antibody production while ensuring the resulting therapeutic remains within a narrow, safe, and effective structural range.