TNFRSF9 and head and neck squamous cell carcinoma: Another interesting dose-escalation/dose-expansion phase I clinical trial (NCT02315066) is investigating the effect of administration of ivuxolimab (PF-04518600), an OX40 agonist, alone/or in combination with utomilumab (PF-05082566), a 4-1BB agonist in patients with advanced or metastatic cancers, including HNSCC.