A Study of Atlacabtagene Autoleucel CAR T-cells for Adults With Relapsed Large B-cell Lymphoma

The goal of this clinical trial is to learn if a new type of chimeric antigen receptor (CAR) T-cell therapy called atlacabtagene autoleucel is effective and safe for the treatment large B-cell lymphomas (LBCL) that have not responded to or have come back after standard chemotherapy. The main questions this trial aims to answer are: * What is the likelihood of complete response of the lymphoma after atlacabtagene autoleucel treatment? * What is the risk of altered brain function (neurotoxicity) after atlacabtagene autoleucel? All eligible participants will receive atlacabtagene autoleucel; the researchers will compare the complete response rate and neurotoxicity rate with historical groups of patients who were treated with similar therapies. Participants will: * Have a procedure to gather white blood cells * Receive chemotherapy to prepare for the CAR T-cells * Receive atlacabtagene autoleucel CAR T-cells through a vein * Be monitored closely for the first 14 days for certain side effects * Have scans 28 days and 3, 6, 12 and 24 months after atlacabtagene autoleucel CAR T-cells to check if the treatment has worked