The comparative analysis of two Phase I studies (one evaluating GPC3 CAR-T cell therapy (NCT02932956, NCT02905188) and the other evaluating the same CAR combined with IL-15 expression (NCT04377932, NCT05103631) revealed higher peak expansion, a higher response rate and similarly effective tumor trafficking for the IL-15 GPC3 CAR-T cells (Steffin et al. The gene discussed is GPC3; the disease is neoplasm.