In previous studies, CD19-directed chimeric antigen receptor (CAR) T-cell therapies showed promise as a potential treatment modality for relapsed/refractory CLL [45,46,47,48,49]; however, T cells from patients with CLL are known to be dysfunctional and producing functional CAR T cells capable of both in vivo expansion and persistence can be challenging [50]. The gene discussed is CD19; the disease is B-cell chronic lymphocytic leukemia.