TNFRSF9 and neoplasm: While LDH release and cytokine secretion were donor‐dependently induced (Figure 5A,B), CD8+ T cells were activated in tumor‐border slices of most donors as denoted by a significant upregulation of CD137 (mean: 2.7% to 3.7%), CD107a (mean: 9.8% to 12.9%) and intracellular IFNγ (mean: 33.1% to 38.4%) expression (Figure 5C,D).