Predicting responses following CAR T-cell therapy is of major importance. In this interview, Arnon Nagler, MD, of Chaim Sheba Medical Center, Tel-Aviv, Israel, evaluates the use of serum interleukin-8 (IL8) as a surrogate marker of true immediate tumor progression following CAR-T therapy in patients with non-Hodgkin lymphoma (NHL). This interview took place during the Transplantation & Cellular Therapy (TCT) 2021 Meetings.