Trifluridine/tipiracil (TFTD) is a
combination drug that is used for the treatment of metastatic
colorectal cancer and was formerly known as
TAS-102. It is a combination of two active pharmaceutical compounds,
trifluridine, an
antineoplastic thymidine-based
nucleoside analog, and
tipiracil, which enhances the bioavailability of
trifluridine in vivo. TFTD is used for the treatment of patients with unresectable advanced or recurrent
colorectal cancer that is resistant to standard
therapies. In the present study, the anticancer effects of
trifluridine in combination with
nintedanib, an oral triple angiokinase inhibitor, on human
colorectal cancer cell lines were investigated. The cytotoxicity against DLD-1, HT-29, and HCT116 cell lines was determined by the
crystal violet staining method. The combination of
trifluridine and
nintedanib exerted an additive effect on the growth inhibition of DLD-1 and HT-29 cells and a sub-additive effect on HCT116 cells, as determined by isobologram analyses. Subsequently, the human
colorectal cancer cell lines were implanted subcutaneously into nude mice to allow the evaluation of the in vivo
tumor growth inhibitory effects of TFTD and
nintedanib combination
therapy. TFTD (150 mg/kg/day) and/or
nintedanib (40 mg/kg/day) were orally administered to the mice twice daily from day 1 to day 14. The
tumor growth inhibition with combination
therapy was 61.5, 72.8, 67.6 and 67.5% for the DLD-1, DLD-1/5-FU, HT-29, and HCT116 xenografts, respectively. This was significantly (P<0.05) higher than the effects of monotherapy with either TFTD or
nintedanib. These results demonstrated the effectiveness of the combination of TFTD and
nintedanib in the treatment of
colorectal cancer xenografts. The concentration of
trifluridine incorporated into
DNA in the HT-29 and HCT116
tumors was determined by liquid chromatography-tandem mass spectrometry. The incorporation levels following treatment with TFTD and
nintedanib for 14 consecutive days were higher than those associated with TFTD treatment alone. The preclinical findings indicate that the combination
therapy with TFTD and
nintedanib is a promising treatment option for
colorectal cancer.