In recent years, the numbers of cell therapies in development and that have been approved has rapidly increased. This has thrown up a number of challenges which the industry has risen to meet, namely challenges in manufacturing, such as scalable processes, the innate variability of the biological starting material and variability of critical quality assays (CQAs) for characterization.
However, despite work from various organizations, such as the International Stem Cell Banking Initiative, on consensus around steps such as cell expansion and storage, harmonization of characterization assays for product release remains low.
In the Perspective, a team from Likarda, LLC (MO, USA) has investigated the most common CQAs for sterility, identity, impurity and potency, and discussed discrepancies and inconsistencies in how they are described and applied. For example, FDA lists an assay for endotoxins under purity whereas bacterial testing falls under sterility.
Despite the structure and nomenclature of CQAs being seemingly straightforward, the authors suggest that “a lack of clarity and common definitions still creates confusion”. They believe that better understanding of these terms, definitions and their application will lead to “more efficient delineation of critical quality attributes needed for product release and licensure, providing a clearer approach to the design and implementation of characterization assays”.