TNFRSF9 and osteosarcoma: In light of the unavailability of the anti-CD137 agonist antibody used to expand autologous TILs, the aims of this study were to establish methods for the expansion of tumor-reactive TILs from freshly resected soft tissue sarcoma in a clinically relevant, GMP-adherent manner and to test the method for other types of sarcomas, such as osteosarcoma.