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UNLABELLED: There is a continued need for orally bioavailable anticancer compounds that exhibit good efficacy against breast cancer. STX140, a derivative of 2-methoxyestradiol (2-MeOE2), has been shown to have excellent oral bioavailability and significantly reduces tumor growth. A new micronized formulation of STX140 has now been developed and its pharmacokinetics (PK) in rats and effect on MDA-MB-231 breast cancer growth in nude mice was investigated. MATERIALS AND METHODS: For the PK studies, female Wistar rats were treated orally with STX140 in two separate vehicles (10% tetrahydrofuran (THF) in propylene glycol (PG) or 0.5% methyl cellulose (MC) in saline) and plasma samples taken for high performance liquid chromatography analysis over 48 h. For the tumor efficacy studies, female nude mice were inoculated with MDA-MB-231 breast cancer cells and then treated orally with a range of doses of STX140. RESULTS: The PK studies demonstrated that the THF/PG vehicle resulted in a greater oral bioavailability of STX140 compared to the 0.5% MC vehicle. However, this was not translated to the tumor efficacy studies where STX140 at 20 mg/kg in either vehicle caused a significant reduction in tumor volume. CONCLUSION: The new micronized formulation of STX140 is orally bioavailable and efficacious at inhibiting MDA-MB-231 breast tumor growth.


Journal article


Anticancer Res

Publication Date





577 - 581


Administration, Oral, Animals, Cell Line, Tumor, Dosage Forms, Estrenes, Female, Male, Mammary Neoplasms, Experimental, Mice, Mice, Nude, Rats, Rats, Sprague-Dawley, Viscosity, Xenograft Model Antitumor Assays