CXCL13 and neoplasm: The limited efficacy of CAR T therapy in solid tumors is primarily due to T cell exhaustion, insufficient persistence, and inadequate tumor infiltration.[7] In the TME, CAR T cells are subjected to prolonged antigen stimulation, leading to terminal differentiation and exhaustion, which compromises their cytotoxic capacity.[47] While the role of CXCL13 in T cell recruitment is well‐documented,[35] its effects on T cell phenotypes are less understood.