TNFRSF9 and sarcoma: This is probably because (1) TIL treatments for immunologically nonresponsive “cold” tumors have not been explored extensively (2); the heterogeneity of sarcoma makes it a challenged target for which to design and produce TILs; and (3) the discontinued supply of the anti-CD137 agonist antibody halted the process of generating selective antitumor TILs and could be detrimental to the clinical efficacy of TIL-based ACT.