Liso-cel is the first CAR T-cell to be approved by the FDA in March 2024 for the management of patients with R/R CLL who failed at least two previous lines of treatment, including a BTK inhibitor and a BCL-2 inhibitor, based on the results of the TRANSCEND CLL 004 phase I/II trial. The gene discussed is BTK; the disease is B-cell chronic lymphocytic leukemia.