TNFRSF9 and cancer: Based on preclinical findings showing the therapeutic efficacy of a combinatorial approach including PD-1 blockade and CD137 activation in murine cancer models [82], a Phase I clinical trial (NCT02652455) evaluated the safety and feasibility of combining nivolumab with TIL adoptive cell therapy (ACT) cultured in the presence of CD137 agonism to improve culture success rates, growth kinetics, and CD8+ T-cell composition.