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Over the past decade, several drug development companies have opted to work with CROs in the early phase of discovery and drug development. This shift in the drug development landscape is helpful as CROs help reduce budgets and modulate drug candidate failure, with balancing regulatory guidelines and expectations. According to FDA requirements, assay validation services must perform human clinical studies or GLP toxicology studies with completely validated bioanalytical assays.
Instead of a fully validated method, assay validation services and drug developers prefer the fit-for-purpose assay during early clinical development as an innovative and often cost-effective approach to analytical method development and validation. The fit-for-purpose assay has now become a standard approach in method validation and assay method development.
The need for a flexible strategy
Analytical assay development and validation is never a rigid and straightforward process. Throughout the drug development phase, assay validation services face challenges with varying degrees of difficulties requiring a more flexible strategy like fit-for-purpose assays. Resource availability and diverse study objectives limit the development of a full assay method validation. If assay validation services do not perform a fully validated method development, they must provide appropriate scientific justification and accept some degrees of risk. If drug developers cannot avoid the uncertainty, they should perform full assay method validation following regulatory guidelines that may lead to increased production costs and delays.
Fit-for-purpose method validation
Ideally, method validation comprises two core components, experimental and operational. The experimental element deals with the establishment of method purpose and its relative outcome and values, whereas the operational part characterizes assay performance through experimentation. The most important aspect is the assessment of assay performance compared to the predefined purpose. If the assay performs according to the predefined purpose, it is deemed as fit for the purpose, and if not, then it is not fit for the predefined goal. Therefore, it is critical to compare the performance against the predefined intention without taking the purpose out of the picture.
Generally, the method validation process can be broken down into five vital phases. The first phase and perhaps most crucial step is defining the purpose and selecting the assay candidate accordingly. In the second phase, scientists assemble all required components and reagents and decide the method validation plan and final assay classification. The third phase is the experimental stage, where scientists test the assay performance to attest fitness-for-purpose label for the specific bioanalytical method.
During the fourth phase, the assay is further tested in the study to assess its clinical robustness and determine some crucial components such as storage, stability, and collection issues. In the last phase, the assay is used routinely, where proficiency testing, quality control, and batch-to-batch issues are fully explored. A successful fit-for-purpose assay is the one where it is subjected to continual development, and various alternatives are explored to make the final product a reliable and accurate process.
Conclusion
Clinical research must be carried out with appropriate experimental design and validated assay protocols. Fit-for-purpose assay maintains the balance between stringency and burden of assay method validation, along with taking into account both the context and nature of the technology applied. In conclusion, a fit-for-purpose validation provides an efficient and resource-effective solution for analytical method development and validation and facilitates data-based decision-making.
