The polyamine synthesis inhibitors--alpha-difluoromethylornithine (DFMO) and methylglyoxal bis (guanylhydrazone) (MGBG)--were put to antitumor tests based on the premise of treatment for human gastrointestinal cancer. The both drugs were administered intraperitoneally to BALB/c nude mice xenoplanted human gastric cancer for 10 consecutive days. Both marked antitumor effects and side effects were observed in mice treated at the dosage of DFMO 500 mg/kg/day and/or MGBG 50 mg/kg/day and/or MGBG 30 mg/kg/day brought about significant antitumor effects as well as less side effects. Microscopic observation revealed antitumor actions of these drugs as cytostatic rather than cytocidal. Tumor regrowth after the termination of this combined treatment, however, was noticed. Judging from these data, the both drugs may be effective against human gastrointestinal cancer with minor side effects.
