Analytical & Quality
Advances and Challenges in the Analytical Characterization of Biosimilar Products
Biosimilar development is based on demonstrating analytical similarity to the reference product, with abbreviated clinical studies utilized to remove residual uncertainty. Pfenex Inc., a leader in biosimilar development, has significant experience in deploying our extensive analytical capabilities in support of product development and regulatory reviews. Significant challenges can arise in the process of demonstrating analytical similarity. For example, reference products may contain protein excipients, such as Human Serum Albumin (HSA), that are present in excess amounts relative to the active protein drug, thereby interfering with analytical similarity assessment. To enable a thorough comparison of Pfenex’s interferon beta-1b biosimilar candidate and the marketed HSA-formulated reference product, we developed an HSA-depletion method. By minimizing interferences from the excipient, we successfully conducted additional characterization at all levels of protein structure, including hydrogen/deuterium exchange (H/DX) to elucidate higher order structural (HOS) forms. Additionally, exploration and characterization of possible protein complexes, protein form distribution, and activity for both formulations was performed by 2-dimensional analysis across the product profile. The data from these experiments demonstrate high similarity between Pfenex’s biosimilar candidate and the reference product, based on the analytical methods developed and employed.