A new drug, Caba-780, was synthesized by chemical coupling of the heptamethyl phthalocyanine near-infrared fluorescent (NIRF) dye IR-780 and the paclitaxel-based chemotherapeutic drug cabazitaxel. Then, the potential value of Caba-780 in the diagnosis and treatment of castration-resistant prostate cancer (CRPC) was evaluated. The CRPC cell lines DU145 and PC-3, as well as the normal human prostate stromal cell line WPMY-1, were used to evaluate the uptake of Caba-780 and its antitumor effect in vitro. The distribution, antitumor effect, and safety of Caba-780 were also evaluated in tumor-bearing mouse xenograft models. Our results showed that Caba-780 was efficiently absorbed by DU145 and PC-3 cells and that the cytotoxicity of Caba-780 was significantly stronger than that of IR-780 and cabazitaxel. In addition, Caba-780 inhibited the migration and invasion of DU145 and PC-3 cells and promoted apoptosis by prolonging the G2 phase of the cell cycle. Further analysis indicated that Caba-780 could be used to effectively image tumor xenografts. At the same time, this drug inhibited the growth of tumors in vivo. Therefore, the new synthetic drug Caba-780 has potential applications in the diagnosis and treatment of CRPC.
