Proceedings of the 2017 Viral Clearance Symposium, Session 4: Submission Strategies.

Appropriate performance of virus validation studies and testing of unprocessed bulk harvests for retrovirus particle count are procedures in the demonstration of an acceptable level of viral safety for cell-derived biotechnology products. Product-specific validation studies on virus reduction with two model viruses [usually murine leukemia virus (MuLV) and a parvovirus] performed in duplicate runs are standard for clinical trial applications. For the retroviral safety margin, a 6 log reduction is normally expected. Retroviral particle counts are measured traditionally by transmission electron microscopy (TEM) and are commonly performed at contract laboratories. These procedures are quite time-consuming and can be associated with significant costs. In particular, the time factor is a hurdle for companies that want to quickly bring their new products to the clinic. In this session, several strategies on how to lower time, cost, and workload in the evaluation of viral safety for early clinical trial applications, while still ensuring sufficient level of viral safety of the product, were presented. In addition, virus reduction strategies for molecules that do not have the standard antibody structure are presented. Also presented in this session is the feasibility of the use of retrovirus-like particle (RVLP) in the prevalidation of virus removal and the use of quantitative polymerase chain reaction (qPCR) as an alternative to infectivity assays in virus validation studies as well as its use as an alternative to quantitative TEM analysis for determining RVLP count in the bulk harvest of a perfusion bioreactor. LAY ABSTRACT: In this session, several strategies on how to lower time, cost, and workload in the evaluation of viral safety for early clinical trial applications of cell-derived biotechnology products, while still ensuring sufficient level of viral safety of the product, were presented. In addition, virus reduction strategies for molecules that do not have the standard antibody structure are presented. Also presented in this session is the feasibility of the use of retrovirus-like particle (RVLP) in the prevalidation of virus removal and the use of quantitative polymerase chain reaction (qPCR) as an alternative to infectivity assays in virus validation studies as well as its use as an alternative to quantitative TEM analysis for determining RVLP count in the bulk harvest of a perfusion bioreactor.