Since the major anti-cancer effector T cells are known to be CD8+ T cells [31, 32], and in the present study we found CD8+ T cells to account for a major portion (∼60%) of the post-REP TILs, we speculate that CD8+ T cells would have played a major role in mediating the anti-tumor reactivity we observed in vitro and in vivo after ACT in the PDX model. Here, CD8A is linked to cancer.