Growth inhibition of mouse skin tumor by serine protease inhibitor ONO-3403.

The new serine protease inhibitor, ONO-3403 is an analog of FOY-305 (Foypan). The IC50s values of ONO-3403 toward serine proteases, such as trypsin, plasmin, kallikrein and thrombin are much lower than that of FOY-305. To investigate the growth-suppressing effect of ONO-3403 on 3-methylcholanthrene-induced autochthonous solid tumors in mice, ONO-3403 was intraperitoneally administered to mice at a dose of 4 mg/kg twice a day for 5 weeks. All seven mice receiving the drug had a solitary tumor and showed potent growth suppression (p<0.001) without any apparent side effects such as hair loss and body weight loss. The results suggest that ONO-3403 may be useful for the treatment of squamous cell carcinoma.