STIMULATION OF TUMOR-GROWTH IN-VITRO AND IN-VIVO BY SURAMIN ON THE VX2 MODEL

Suramin is an antitrypanosomal compound with confirmed efficacy agains t several human malignancies. It is generally assumed that its mechani sm of action includes the interaction with different growth factors, u nlike most of the anticancer drugs. Its anticancer activity has not be en tested in vivo against squamous cell carcinoma. The purpose of this study was to assess the efficacy and toxicity of suramin in vivo and in vitro on the VX2 tumor model at therapeutic monitored plasma concen trations. We determined the pharmacokinetics of suramin in rabbits, an d modelized its administration in order to obtain plasma concentration s between 150 and 300 mu g/ml throughout the treatment course of 3 wee ks. Under these conditions, antitumor effects of suramin were evaluate d in vivo by comparing liver tumor involvement in suramin-treated and control rabbits. Liver involvement was quantified by image analysis an d in vitro effects were also determined at the same concentrations. In vivo, suramin promoted liver tumor growth significantly (p < 0.05), c ompared to untreated controls. In vitro, suramin significantly stimula ted tumor cell growth at concentrations above 200 mu g/ml (p < 0.01). Suramin may have stimulatory effects on tumor growth in squamous cell carcinoma at relevant plasma drug concentrations. Caution should be ta ken in further trials in patients with squamous cell carcinomas.