Advances in CAR T-cell therapy for the treatment of chronic lymphocytic leukemia (CLL) are promising. However, it has become apparent that CLL cells have a hindering effect on the mitochondrial function of CD8+ T-cells and therefore can have a negative effect on the efficacy of CAR T-cell therapy. Arnon Kater, MD, PhD, of the University of Amsterdam, Amsterdam, Netherlands, discusses this phenomenon and describes in vitro and in vivo studies that have shown how immune metabolism and mitochondrial function in T-cells positively correlates to how well patients respond to CAR T-cell therapy. This interview was filmed at the American Society of Hematology (ASH) 2018 Annual Meeting and Exposition in San Diego, CA.