Upstream Mitigation Part 1: Cell Bank and Bulk Harvest Testing

Abstract

Monoclonal antibodies (mAbs) are typically produced using mammalian cell lines, which are known to express endogenous retrovirus-like particles (RVLP) and also have the potential to be infected by viruses. This session focused on the detection and measurement of these viruses and RVLP. In the first talk it was demonstrated that Next Generation Sequencing (NGS) can detect, with a similar sensitivity as PCR, viruses in cells without a-priori knowledge of the specific virus and importantly, that a specific NGS approach can decipher whether the signal corresponds to a replicating virus or not. The second talk provided data showing that the PCR assay for detection of ERV genome is an alternative to qTEM for quantification of RVLP. In addition, the potential use of a harvest filter for RVLP retention in a perfusion process was discussed. In the third talk RVLP data from 67 different Pfizer programs spanning different conditions were presented. No single factor that had a significant impact on the level of RVLPs. It was suggested that a "generic" or "worst-case" RVLP value, derived from a well-characterized platform cell culture process, could be used with confidence to determine a conservative retroviral safety margin for platform processes. In the fourth talk, the sensitivity of several cell culture- and PCR-based assays for detection of different MMV strains using several production cells was discussed. It was found that molecular assays were generally superior in breadth of detection with equivalent sensitivity.