4-5 Schenerman CMCpt2.indd

LEVEL: INTERMEDIATE T he objective of the WellCharacterized Biotechnology Pharmaceutical (WCBP) CMC Strategy Forum is to provide an environment for the development of technical and regulatory consensus positions regarding topics of interest to WCBP. The January 2005 forum was devoted to a discussion of live virus vaccines and viral vectors used for gene therapy. The purpose of that meeting was to determine whether consensus positions could be reached among the delegates regarding lot release, stability, characterization, and comparability testing. The overarching questions posed were • What is the required testing for lot release and stability of vaccines? • What is the required testing for lot release and stability of viral vectors for genetic therapy? • What are the acceptable attributes of a “potency” test? • What is the best means of quantifying total and infectious viral particles? • What analytical parameters (obviously including those above) would be considered essential to support “comparability” of a viral product made by a modified process to that of the original process? In Part 1 (BioProcess International, April 2006) we described factors influencing the choices of lot-release and stability assays for vaccines and gene-therapy products. Part 2 presents case studies to illustrate potency testing (for a multivalent vaccine), characterization (for influenza), and comparability studies (for an adenovirus). The article concludes here by summarizing the panel discussion.