CXCL13 and neoplasm: To assess whether CXCL13 might recruit B cells into the tumor—given their essential role in tertiary lymphoid structure (TLS) formation[35]—we generated a new CXCL13‐overexpressing CAR T cell targeting Claudin 18.2 (CLDN18.2), thereby preserving endogenous B cells (Figure S6e,Supporting Information).