TNFRSF9 and neuroblastoma: The effect was heightened against neuroblastoma cells expressing low L1CAM levels (SH-SY5Y), with a 12.6-fold increase in the L1CAM-4-1BB CAR T cell-directed cytotoxicity and a 3.4-fold increase in L1CAM-CD28 CAR T cell-directed cytotoxicity.