The researchers reported in a study of osteosarcoma that HER2-CAR T cells, proliferated, produced immunostimulatory T helper 1 (Th1) cytokines, and killed HER2+ osteosarcoma cells in vitro, and HER2-CAR T cells caused regression of established osteosarcoma xenografts in locoregional as well as metastatic mouse models (44). The gene discussed is ERBB2; the disease is osteosarcoma.