Tubulin colchicine site binding agent LL01 displays potent antitumor efficiency both in vitro and in vivo with suitable drug-like properties

Through rational drug design, we previously identified an indenoprazole derivative, 2-(6-ethoxy-3-(3-ethoxyphenylamino)-1-methyl-1,4-dihydroindeno[1,2-c]pyrazol-7-yloxy)acetamide (LL01), as a potent tubulin polymerization inhibitor targeting the tubulin colchicine binding site. In this study, we further demonstrated that LL01 was not a P-gp substrate. It potently inhibited the growth of a variety of tumor cells, including those with multidrug resistance, with GI50 values in the low nanomole ranges. In vitro liver microsome stability assay, LL01 was modest stable in the liver microsomes of human, mouse and rat, but was fast metabolized in dog. After single oral administration of LL01 at a dose of 10 mg/kg in SD male rats, LL01 showed acceptable PK properties with a mean bioavailability of 41%. In human HepG2 hepatoma xenograft, at the oral doses of 25 mg/kg/day and 12.5 mg/kg/day, LL01 inhibited the tumor growth by 61.27%, and 43.74%, respectively, which is much better than the positive drug sorafenib (29.45%; 30 mg/kg/day). Therefore, LL01 might be a potential drug candidate for further investigation for hepatocellular carcinoma therapy.