DTS-108 is a prodrug of SN38 (a topoisomerase I inhibitor). It is a conjugate formed by linking SN38 to a human oligopeptide through an esterase-sensitive crosslinker. DTS-108 exhibits anticancer activity against colorectal cancer, lung cancer, and breast cancer.

DTS-108 exhibits cytotoxicity against colon cancer cell lines (HCT 116, HT-29, and LS 174T), lung cancer cell line (NCI-H460), and breast cancer cell line (MDA-MB-231) with IC 50 values of 24, 94, 2, 40, and 834 nM, respectively. The compound has a half-life of 400 minutes in human plasma and 290 minutes in dog plasma (2.55 μM, 0-48 h), which is significantly better compared to less than 3 minutes in mouse plasma.

At doses of 5 or 10 mg/kg, DTS-108 does not exhibit significant toxicity in dogs, although there is a moderate, non-dose-dependent decrease in white blood cell counts. DTS-108, when administered intravenously at doses ranging from 32 to 95 mg/kg on days 3, 7, and 11, shows dose-dependent antitumor activity in a human tumor xenograft model (HCT116) with a minimum T/C ratio of 10% at 95 mg/kg. Additionally, DTS-108 demonstrates antitumor effects in nude mice implanted with colorectal, lung, and breast cancer cells at 80 mg/kg on days 3, 5, 7, 10, 12, 14, 17, 19, and 21, as well as in rats implanted with colorectal cancer cells at 63 mg/kg on days 14, 18, 21, 25, and 29. In colon cancer mice carrying human HT-29 cells, DTS-108 at 40 mg/kg intravenously shows antitumor activity, which is enhanced when combined with 5-FU (40 mg/kg) or bevacizumab (2 mg/kg).