CD274 and colorectal cancer: Thus, by employing copper ionophores (a kind of compounds capable of selectively binding to copper ions and transporting them into cells or specific organelles, such as DSF, ES), it becomes feasible to upregulate PD-L1 expression in tumor cells, thereby transforming colorectal cancer from a “cold tumor” into an immunologically responsive “hot tumor” and enhancing the efficacy of immunotherapy.