Furthermore, UA pretreatment increased the expression of activation markers (CD25, CD27, CD28, CD44, CD69, and ICOS) while reducing the expression of inhibitory receptors (PD‐1, Tim‐3, and CTLA4) on adoptively transferred CTLs in the tumor and spleen (Figure 1R,S; Figure S2K,L, Supporting Information), suggesting that UA treatment directly inhibits T cell exhaustion after adoptive transfer. Here, ICOS is linked to neoplasm.