5-Fluorouracil-methotrexate conjugate enhances the efficacy of 5-fluorouracil in colorectal cancer therapy

To extend the short half-life of fluorouracil (Fu), enhance its tumor targeting, improve efficacy, and reduce side effects, providing a new approach for colorectal cancer treatment. Fluorouracil was hydroxylated and conjugated with methotrexate to form a 5-fluorouracil-methotrexate conjugate (MF). This was complexed with sulfobutyl ether-beta-cyclodextrin (MF-SEBCD) using a stirring method to create an injectable formulation. In vitro studies assessed the conversion of MF-SEBCD in plasma and its antitumor activity. In vivo studies examined antitumor activity, preliminary safety, pharmacokinetics, and tissue distribution. MF was synthesized with a 25% yield and purity above 95%. The water solubility of MF increased by 92-fold with MF-SEBCD preparation. In vitro, MF-SEBCD effectively converted into Fu in plasma and showed strong antitumor activity, with IC50 values of 0.51, 1.29, and 1.26 mu M for MC38, HT29, and 4T1 cells, respectively. In vivo, MF-SEBCD achieved a tumor inhibition rate of 57.08%. Pharmacokinetic studies showed that MF-SEBCD extended Fu's half-life to 47 min, nearly double that of Fu injection. Tissue distribution analysis confirmed improved tumor targeting. MF-SEBCD effectively prolongs Fu's half-life, enhances tumor targeting, increases antitumor efficacy, and reduces side effects, offering a promising approach for colorectal cancer treatment.