Process scale considerations in evaluation studies and scale-up.

This paper focuses on the scale of validation studies that are performed in order to demonstrate viral clearance in downstream processing of biopharmaceutical products. A serious concern for rDNA-derived proteins from recombinant mammalian cell cultures and monoclonal antibodies (MAbs) derived from hybridoma cultures is the potential risk from contaminating retroviral particles or adventitious viruses. Accordingly the downstream process has to be designed to reduce a potential virus load significantly: by virus removal and by virus inactivation methods. Such viral clearance is essential for drug safety- and has to be validated. This means that the design of downstream processing has to take into consideration both the capability for viral clearance and the capability for validation respectively.