Antitumor effect of radioactive cisplatin (191Pt) on nude mice

PURPOSE: To investigate the effect of (191)Pt-cisplatin in vivo in terms of the antitumor effect and general toxicity on tumor-bearing nude mice. METHODS AND MATERIALS: Tumor-bearing (human squamous cell carcinoma, AB) nude mice were divided into four groups and given, i.p., physiological saline (controls), cisplatin, (191)Pt-cisplatin (80 MBq/mg), or (191)Pt-cisplatin (160 MBq/mg), respectively. Mortality and weight were used as parameters for monitoring general toxic effect, while specific growth delay (SGD) and the area under the logarithm of the relative tumor size curve (AUC-log[RTS]) were used to evaluate the antitumor effect of the treatments. RESULTS: Both SGD and AUC-log(RTS) values showed that (191)Pt-cisplatin was significantly (P < 0.05) more effective in retarding tumor growth than nonradioactive cisplatin. No differences in mortality between the different groups could be observed and no significant differences in weight change between the mice treated with cisplatin or (191)Pt-cisplatin could be seen. CONCLUSION: (191)Pt-cisplatin is a more effective drug than nonradioactive cisplatin in retarding tumor growth on nude mice without adding systemic toxic effects. We believe that radioactive cisplatin may prove to be an alternative to conventional cisplatin; however, the possible toxic effects on organs at risk have to be thoroughly investigated