Cell experiment:

Cell proliferation in case of different treatment conditions, relative to untreated control cells (treated as 100% viable, or a live control), is quantified using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), a yellow colored reagent which is converted to formazan (a purple dye) by living cells. For screening experiments, transfections are carried out in 96-well cell culture plates, that are seeded with 50,000 cells per well. Following 48 h of transfection, 10 μL of MTT reagent is added to the cells and incubated at 37℃ for 2-4 h, and the cells are then lysed by adding 20 μL of MTT detergent and incubated for an additional 2 h at room temperature. Inhibitor dose-optimization transfections are carried out in 24-well plates that are seeded with 50,000 cells per well. After 48 h, 20 μL MTT reagent is added, followed by 100 μL of MTT detergent for lysis for 2 h[4].

Animal experiment:

The ground HMN-214 is suspended with an agate pestle by gradually adding 0.5% methylcellulose 4000 solution to make a 3 mg/mL suspension. This is additionally diluted with methylcellulose 4000 solution to obtain suspensions of the appropriate concentration. Tumor tissue is grown in advance by s.c. transplantation into nude mice. The resulting tumors are removed, cut into cubic fragments of 8 mm3, and transplanted s.c. into the right axillary region of nude mice with a trocar. When the theoretical volume of the tumor had reached about 145 mm3, oral administration of HMN-214 is started (day 1)[3].

IC50: HMN-176 showed potent cytotoxic activity against several tumor cell lines with an average IC50 of 118 nmol/L

The polo-like kinases (PLK) are a group of highly conserved serine/threonine kinases that serve as regulatory enzymes for mitotic events. HMN-214 is an oral prodrug of HMN-176, a stilbene derivative that interferes with the subcellular spatial location of polo-like kinase-1, a serine/threonine kinase that regulates critical mitotic events.

In vitro: HMN-176 showed potent cytotoxicity, with a mean IC50 of 118 nM. The cytotoxic effecacy of HNM-176 was superior to that of ADM, VP-16 and CDDP, but inferior to that of taxol and VCR. HMN-176 showed less vaiance in log(IC50) than did the reference agents. In addition, judging by its low resistance indices, HMN-176 was more cytotoxic toward the drug-resistant phenotypes of tumor cells than were the other agents tested [1].

In vivo: PK studies showed that HNM-214 was an acceptable oral prodrug of HMN-176. In the in vivo analysis of the schedule-dependency of HMN-214, the repeated administration for over 5 days elicited potent antitumor activity, as expected from the exposure-dependency of the cytotoxicity of HMN-176 and from the cytometric studies. The antitumor activity of HMN-214 against human tumor xenografts was equal or superior to that of clinically avaiable agents, including cis-platinum, adriamycin, vincristine and UFT without severe toxicity such as neurotoxicity [1].

Clinical trial: A phase I pharmacokinetic study indicated that there was no accumulation of HMN-176, the metabolite of HMN-214, with repeated dosing. Seven of 29 patients had stable disease, including 6-month stable disease in a heavily pretreated breast cancer patient. A transient carcinoembryonic antigen decline in a patient with colorectal cancer was noted [2].

Reference:
[1] Takagi M, Honmura T, Watanabe S, Yamaguchi R, Nogawa M, Nishimura I, Katoh F, Matsuda M, Hidaka H.  In vivo antitumor activity of a novel sulfonamide, HMN-214, against human tumor xenografts in mice and the spectrum of cytotoxicity of its active metabolite, HMN-176. Invest New Drugs. 2003 Nov;21(4):387-99.
[2] Garland LL, Taylor C, Pilkington DL, Cohen JL, Von Hoff DD.  A phase I pharmacokinetic study of HMN-214, a novel oral stilbene derivative with polo-like kinase-1-interacting properties, in patients with advanced solid tumors. Clin Cancer Res. 2006 Sep 1;12(17):5182-9.