Phase 4, single-arm trial testing a secondary infusion of relmacabtagene autoleucel (CARTEYVA), an autologous, gene‑modified CD19-directed CAR‑T cell therapy, in adults with relapsed/refractory B‑cell lymphoma who failed to achieve complete remission after the first infusion. Mechanism: patient T cells are engineered to express an anti‑CD19 CAR with 4‑1BB costimulatory and CD3ζ signaling domains, upon binding CD19, CAR‑T cells expand and kill malignant B cells via perforin/granzyme-mediated cytotoxicity, leading to B‑cell depletion. Targets/pathways: CD19 on B‑cell lymphomas, T‑cell activation and persistence via 4‑1BB/CD3ζ signaling, aiming to overcome inadequate expansion/persistence or functional exhaustion.