Bruce Levine, PhD, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, discusses the key remaining challenges associated with the manufacture of chimeric antigen receptor (CAR) T-cell therapies. The in vivo measurement of potency remains a challenge and the correlation between ex vivo measurements and in vivo potency is still unclear. Once CAR-T cell therapies for solid tumors start to gain regulatory approval in the future, the scaling up of manufacturing is also going to be a significant challenge, which highlights the importance of improving automation and manufacturing processes in order to meet the increased demand. This interview took place during the International Society for Cell & Gene Therapy (ISCT) Annual Meeting 2021.