Design, synthesis, and anti-cancer evaluation of the novel conjugate of gemcitabine's ProTide prodrug based on CD13

NUC1031 is a gemcitabine ProTide prodrug which is currently undergoing phase III. CD13 inhibitor bestatin is utilized as an adjunct therapy in conjunction with chemotherapy for cancer treatment, which has limitations in cytotoxic efficacy. In this study, we designed and synthesized a novel series of bestatin-gemcitabine's ProTide prodrug conjugates aimed at enhancing the antitumor efficacy of NUC1031. The representative compound 5f demonstrates a 10-fold increase in anti-proliferative activity compared to NUC-1031, with an IC₅₀ of 8.5 nM against the prostate cancer cell line 22Rv1. In vitro and in vivo pharmacokinetic studies revealed that compound 5f gradually degrades into the metabolic product 17, potentially extending its anti-tumor activity. 5f demonstrates significant in vivo anti-tumor activity in 22Rv1 xenograft tumor models. Our findings indicate that 5f shows strong potential for further development as a candidate for the treatment of prostate cancer.