The role of polyamines in human cancer: prospects for drug combination therapies.

Ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (AdoMetDC) are two key enzymes in polyamine (PA) biosynthesis and their inhibition leads to PA pool depletion and cell growth arrest. DFMO and SAM486A are specific inhibitors of ODC and AdoMetDC, respectively, and are the only two PA inhibitors, which have been clinically evaluated in Phase II and III cancer trials. However, drug combination therapies expected to potentiate the effects of these drugs have yet to be systematically pursued. Human cancer trials (e.g. for the treatment of neuroblastoma patients) using a DFMO/SAM486A cocktail, possibly combined with current cytotoxic drugs and concomitant with a PA-deficient diet, are warranted.