Gram-Scale Isolation of MAb Charge Variants by Displacement Chromatography for Subcutaneous Animal PK Studies

The pharmacokinetic profiles of monoclonal antibody charge variants are poorly understood because they differ only slightly from the “main” antibody species, are low in abundance, and extremely difficult to isolate in pure pools for intensive in vitro and in vivo studies. Because of this, the acceptance criterion for charge variants has historically been based on manufacturing capability, rather than pharmacokinetic data. Isolation and characterization of these charge variants supports a scientifically based product specification, inline with the Quality by Design initiative.

Traditional HPLC separation techniques are not well-suited for isolating significant amounts of charge variants; larger columns do not provide the necessary resolution and analytical columns require multiple cycles and significant sample handling, which can subject the material to microbial contamination.

Displacement Chromatography is a powerful tool that is well-suited for resolving closely-related species from one another. This mode forces the components to compete with each other for binding sites, exploiting small differences between components and forcing them to self-segregate as they move down the column.

This presentation describes a displacement method for isolating sufficient amounts of charge variants to study their PK effects in animal models. It demonstrates a method capable of producing charge variant pools at >90% purity. In addition, this method is ~50x faster than the current HPLC method and reduces sample handling more than 50-fold.