Phase I-II clinical trial with alpha-difluoromethylornithine--an inhibitor of polyamine biosynthesis.

Alpha-difluoromethylornithine (DFMO) is an enzyme-activated, irreversible inhibitor of ornithine decarboxylase, the first enzyme in the synthesis of the polyamines putrescine, spermidine and spermine. DFMO has been shown to have a cytostatic and cytotoxic effect against various human tumor cell lines. The present study was designed to evaluate the toxicity and efficacy of this compound when administered orally at a dose of 1.7 g/m sq. t.i.d. added to conventional chemotherapy to 38 patients with carcinoma of the breast, stomach, prostate, female genital organs or metastatic carcinoma of unknown origin. A control group of 32 patients with similar malignancies received conventional chemotherapy only.