GPC2 and neuroblastoma: To identify optimum CARs against two antigens in neuroblastoma, GPC2 and CD276, that together are expressed in 95% of neuroblastoma samples, they designed a competition assay pooling eight clones of anti-GPC2 CAR-T cells and six anti-CD276 CAR-T cells and cultured them with and without target tumor cells for 24 h.