Proceedings of the 2023 Viral Clearance Symposium, Session 2: Viral Clearance Strategy and Case Studies.

This session deals with the rational design of viral clearance studies for biopharmaceuticals including recombinant proteins such as monoclonal antibodies and, as new in scope of the symposium, also viral clearance for adeno-associated viral (AAV) vectors. For recombinant proteins, large datasets were accumulated over the last decades and are intended to be used for accelerated product process development and streamlining of viral clearance studies. How to utilize prior knowledge in viral clearance validation and how it can be used in a risk assessment tool to decide whether additional virus clearance studies are necessary during product development is being addressed by three of the presentations of this session. This also includes an a priori intended design and generation of validation data for a new kind of detergent such as CG-110, to build up a platform dataset to be used as prior knowledge in future marketing application. Another presentation investigates the virus removal mechanism of a newly developed hydrophobic interaction chromatography (HIC) resin and demonstrates for highly hydrophobic antibodies appropriate reduction for a retrovirus and impurities in a defined process range in contrast to the moderate to poor virus reduction of recent HIC resins. The last two presentations deal with virus clearance approaches for AAV, which will become mandatory with approval of the ICH Q5A revision. Appropriate virus removal and virus inactivation procedures can be implemented into the manufacturing processes of AAV vectors including viral filtration, viral inactivation (e.g., heat inactivation), affinity chromatography, and anion-exchange chromatography with which it seems possible to achieve a good clearance for helper and also adventitious viruses. The heat treatment step can be even a robust step for adenovirus helper inactivation for AAV products when product characteristics and process conditions are understood.