Developing a Multitargeted Anticancer Bi-Copper(II)-Centered Thiocarbohydrazone Agent Based on Lys-199 and His-242 Residues in the IIA Subdomain of Human Serum Albumin

To develop the next generation of more efficient anticancer metal therapeutics and simultaneously achieve targeted therapy, we proposed to develop a bimetallic-centered agent that utilizes the properties of human serum albumin (HSA). To this end, a series of bi-copper (Cu)-centered thiocarbohydrazone compounds were optimized to obtain a bi-Cu(II)-centered compound (C3) with remarkable cytotoxicity. Subsequently, we not only constructed a novel HSA-C3 complex delivery system but also determined the structure of the HSA-C3 complex. Importantly, the HSA-C3 complex inhibits tumor growth more effectively (inhibition rate = 74.20%) than C3 alone (inhibition rate = 48.71%) while enhancing the tumor-targeting ability and reducing the <i>in vivo</i> side effects of C3. Furthermore, we confirmed that the C3 and HSA-C3 complex inhibits tumor growth by not only inducing tumor cell apoptosis but also dual activating the immune system by blocking the PD-1/PD-L1 interaction and resetting tumor-associated macrophages toward the M1 phenotype.