Intervention: GLPG CAR T-cell therapies—gene-modified autologous T-cell immunotherapies made with integrating lentiviral vectors to express chimeric antigen receptors, this study provides follow-up only (no new product administered). Mechanism of action: CARs bind a tumor-associated surface antigen (not specified) on hematologic cancer cells and trigger TCR-independent signaling via CD3ζ and costimulatory domains, inducing T-cell activation, clonal expansion, cytokine release, and targeted cytotoxic killing, persistence of CAR T cells is evaluated. Targets/pathways: malignant hematologic cells expressing the CAR antigen, CAR signaling pathways, T-cell effector/memory persistence, safety monitoring for replication-competent lentivirus and insertional events.