Clinical and Biological Correlates of Resistance and Relapse After CD19-Directed CAR T-Cell Therapy in Large B-Cell Lymphoma: A Structured Narrative Review

Background/Objectives: CD19-directed chimeric antigen receptor (CAR) T-cell therapy has transformed the treatment of relapsed/refractory large B-cell lymphoma (r/r LBCL), yet primary resistance and relapse remain common. We evaluated how recent clinical and translational evidence refines established resistance frameworks and which knowledge gaps prevent the relative contribution of individual mechanisms from being determined.