Design, synthesis, and anti-cancer evaluation of NQO1-responsive prodrug of gemcitabine

Enhancing the efficacy of gemcitabine (dFdC), a widely used nucleoside analogue in cancer therapy, through prodrug strategies to address clinical issues such as drug resistance and safety is a highly appealing and promising approach. This study focused on NQO1, a redox enzyme highly expressed in tumor cells, and designed a novel class of NQO1-responsive dFdC prodrugs. Among these prodrugs, prodrug 2 remained stable in plasma and liver/intestinal S9 fractions, releasing dFdC in an NQO1-dependent manner. Prodrug 2 demonstrated significant antitumor activity against both A549 and MCF-7 cell lines, primarily inducing S-phase arrest and apoptosis. It also inhibited tumor cell colony formation and migration. Additionally, prodrug 2 had the potential to overcome dFdC resistance and can efficiently generate dFdC within cells while producing fewer inactive metabolites (dFdU) than dFdC. Furthermore, in an A549 xenograft tumor model in mice, prodrug 2 significantly reduced tumor volume without affecting survival or body weight. Overall, our study demonstrates that an NQO1-responsive prodrug strategy can effectively enhance the antitumor properties of dFdC. The optimized prodrug 2 warrants further development as a preclinical candidate drug.