Many of the industry and regulatory guidelines, highlight the importance of robust development practices for analytical methods. One such guidance is the ICHQ14 Analytical Procedure Development. For first in class, novel biotech products, also known as Advanced Therapeutic Medicine Product (ATMP), this can mean developing radically new and unique assay systems/platforms, utilizing rare and not commercially available biological reagents. Firms working on novel ATMPs are usually staffed with subject matter experts who are well-educated and skilled in the biology of their product. This results in wonderful assays with the critical link to the Mechanism of Action (MoA) of the product. However, they are typically not honed to become Quality Control assays designed to provide reportable values to support product release by assessing whether a particular batch meets potency specifications. 

All of us in our career have been in this situation, after 5 to 15 years of scientific education we suddenly find ourselves not understanding basic potency assay principles, such as:

• Relative potency assay which compares entire dose-response curves rather than reading a single point off a reference curve.
• The critical role of dose-response curve similarity, what it is and how is it determined.
• System suitability, assay acceptance and the difference between invalidating an entire run vs. a single test sample result.
• Use of Design of Experiments to improve assay precision
• The two approaches for bioassay method validation, that delineated in ICHQ2 and the approach outlined in USP 1034.