Evaluation of an FcRn affinity chromatographic method for IgG1-type antibodies and evaluation of IgG variants

The neonatal Fc-receptor (FcRn) mediates long serum half-life of therapeutic IgG-type antibodies. This interaction represents a critical quality attribute in terms of pharmacokinetics and should be covered by respective quality control strategies. Antibodies are taken up by cells unspecifically and can bind to FcRn in early endosomes preventing lysosomal degradation and allowing release back into circulation. Reflecting this complex cycle in an in vitro assay strategy represents a challenging task.

We report the qualification of an FcRn affinity chromatographic method and, for the first time, establish a noncriticality window. We analyzed different IgG-type antibodies, subtypes, glycoforms as well as mutants.

The FcRn affinity chromatographic method allows the assessment of mAb samples with respect to their pH-dependent FcRn interaction. Furthermore, the method's capabilities and current limitations are discussed.