Background

Monoclonal antibody drug formulations have to be stable at high concentrations (≥ 100 mg/mL) to achieve the low volumes required for subcutaneous delivery. Therefore, the development process to achieve such a preparation of antibody must include a regimen of thorough biophysical characterization while altering common formulation variables (e.g., pH, ionic strength, buffering agent, etc.). Since many biophysical techniques require sample dilution prior to measurement, the characterization may not accurately predict antibody behavior at high concentrations. Small angle X-ray scattering is well-suited to measuring antibodies, and macromolecules in general, at both low and high concentrations, and in the exact conditions of the formulation. Here, we analyzed two recombinant immunoglobulin G (IgG) variants at a range of concentrations with the BioSAXS-2000 to quickly characterize their solution behavior.