Recommendations for the evaluation of specimen stability for flow cytometric testing during drug development.

The objective of this manuscript is to present an approach for evaluating specimen stability for flow cytometric methods used during drug development. While this approach specifically addresses stability assessment for assays to be used in clinical trials with centralized testing facilities, the concepts can be applied to any stability assessment for flow cytometric methods. The proposed approach is implemented during assay development and optimization, and includes suggestions for designing a stability assessment plan, data evaluation and acceptance criteria. Given that no single solution will be applicable in all scenarios, this manuscript offers the reader a roadmap for stability assessment and is intended to guide the investigator during both the method development phase and in the experimental design of the validation plan.

Development and validation of flow cytometry methods for pharmacodynamic clinical biomarkers.

Flow cytometry is a powerful analytical tool for the analysis of multiple biological parameters of individual cells or particles within heterogeneous cell populations. It has been widely used in biomedical research to perform immunophenotyping, cell counting and numerous cell function assessments, such as intracellular cytokine production, protein phosphorylation, cell proliferation and apoptosis. The implementation of standardized flow cytometry-based biomarker assays in clinical trials remains a challenge due to the limited stability of clinical specimens and the technical variations between instruments. To ensure data quality, it is crucial to develop robust assays for clinical applications. In this review, we summarize current practice in developing, validating and implementing flow cytometry assays to evaluate biomarkers in clinical research.