NQO1-selective activated prodrugs of combretastatin A-4: Synthesis and biological evaluation.

Tumor-specific prodrug treatment renders the exclusive delivery of antitumor agents with the lowest untoward effects. In this work, we reported the synthesis and biological assessment of four NQO1-activatable combretastatin A-4 prodrugs constituted by active drug CA-4, different self-immolating linkers, and NQO1-responsive trigger groups. The in vitro antiproliferative activities showed that prodrug 4 displayed greater selective toxicity toward the tumor cells that overexpressed NQO1, taxol-resistant A549 cells, hypoxia-exposed A549 and HepG2 cells, and incurred lower damage to normal cells in comparison with combretastatin A-4, prodrugs 1, 2, and 3. Moreover, based on a mechanistic study, NQO1 triggered prodrug 4 to effectively liberate the parent drug combretastatin A-4 and kill tumor cells. Furthermore, we also demonstrated that prodrug 4 exerted a stronger anticancer effect and greater safety than combretastatin A-4 under in vivo conditions. Hence, from the above results, NQO1 can be used as a specific delivery system for releasing anticancer agents; besides, prodrug 4 can serve as a candidate lead for developing specific anticancer agents.