Phospholipase B-like protein (PLBL2) is identified as a lysosomal protein that can be secreted as a by-product of the primary metabolic pathway within suspended recombinant CHO cell cultures. PLBL2 derived from recombinant murine cultures has approximately 80% amino acid sequence identity with it human counterpart (PLBD2), and many of the differences are related to surface exposed peptide sequences. Due these differences, it is reasonable to assume that the PLBL2 content within the recombinant biologic product dosage may provoke an immune response in a future patient population. PLBL2 is known to bind to the hinge portion of the constant domain within recombinant IgG thus providing a vehicle for co-elution and carryover in the bulk drug substance. Further increasing the risk of patient introduction, commercially available HCP ELISA kits for CHO cultures frequently under-report PLBL2 levels within purified biologic intermediates due to antigen excess which causes sample dilution non-linearity. A series of studies utilizing a recombinant CHO cell bank producing a non-commercialized monoclonal antibody were commissioned with distinct formulations of a chemically defined media recipe. Results of the studies indicate that variance in media components impact the level of excreted PLBL2 across the duration of the culture. Variance in input metabolites produced differences in both absolute concentration (ng/ml) as well as specific yield (ng/cell). Further studies are focused on selected media components to understand the mechanism of impact on secreted PLBL2 specific yield. A dynamic flux balance modelling approach is being used to provide insight into the mechanisms for this variance as well as to determine optimal metabolite concentration to minimize secretion.

Characterization of chemically defined media variation on the level of secreted phospholipase-B like protein by recombinant CHO cell cultures

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.