Translating the therapeutic promise of cell and gene therapies into clinical reality relies on robust potency assays. However, designing assays that accurately reflect the complex mechanisms of these therapies can feel like chasing a moving target. Here, Charlotte Barker, Editor, Cell & Gene Therapy Insights, speaks with Giorgio Zenere, CMC technical project lead in the Global QC Technology Innovation Team, Kite Pharma, and Dirk Windgassen, Director of Analytical Development, Miltenyi Biotec, to discuss best practices and future trends in developing potency assays for cell and gene therapies.